WO2017119007A1

WO2017119007A1 - Process for purification and refining of glycerol

Info

Publication number: WO2017119007A1
Application number: PCT/IN2017/050013
Authority: WO
Inventors: Sandeep Bhaskar Kale; Arvind Mallinath Lali; Bhavin Manubhai PATEL; Pamela JHA; Meghna Jatinkumar VANZA; Payal Meghshyam YELNE; Vinod GUPTA; Ashwani Kumar KOHLI; Vineet Mital
Original assignee: Institute Of Chemical Technology; Innow Llc
Priority date: 2016-01-07
Filing date: 2017-01-09
Publication date: 2017-07-13

Abstract

The present disclosure describes a process for purification and refining of glycerol, relying primarily on at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent. The process yields pure and refined glycerol with high recovery and very high purity, wherein the percentage of impurities is well within the acceptable limits.

Description

"PROCESS FOR PURIFICATION AND REFINING OF GLYCEROL"

FIELD OF INVENTION

[001] The present disclosure relates to a process for production of high purity glycerol from relatively impure glycerol.

BACKGROUND OF THE INVENTION

[002] Glycerol (or glycerine) is a polyhydroxy compound and is a viscous liquid. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. Glycerol has wide industrial applications as a raw material in the industrial production of propylene glycol, epichlorohydrin, acrylic acid, polyhydroxy butyrate etc. Glycerol is also used in medical, pharmaceutical, food, cosmetics and personal care preparations.

[003] Glycerol (also known as propane-triol) is an important product that is the backbone component of natural Fats and Oils called triglycerides). Triglycerides are esters of glycerol with short, medium and/or long-chain carboxylic/fatty acids. Fat splitting for recovery of fatty acids from oils and fats is achieved by processes such as (A) chemical saponification by acid, alkali, methoxides etc.; (B) high pressure steam fat/oil Splitting and (C) biochemical based i.e. enzymatic fat/oil splitting. These processes are typically used in the soap and cosmetic product industry where the mixture of fatty acids is further fractionated to yield high purity single component fatty acids. The aforementioned processes of fat/oil splitting typically produces a stream containing up to 30%w/w glycerol (called sweet water) with multiple impurities and content of glycerol in such crude stream is a function of the feedstock used.

[004] Similarly, another process proceeds with the replacement of glycerol moiety by alcohol, polar or non-polar group such as in trans-esterification process and is carried out in bio-diesel industry yielding biodiesel and side stream containing crude glycerol with impurities. Yet, another process of fermentation or synthesis of designer lipids also yields crude glycerol containing several impurities.

[005] The crude glycerol obtained in aforementioned processes is of variable quality, with a low selling price. This form of crude glycerol obtained is often dark in appearance with a viscosity and density higher than water. The dark appearance and part of viscosity imparted to crude glycerol is due to presence of impurities such as catalyst, various soaps, fatty alcohols, lipids, organic and inorganic salts, fatty acids, fatty acid esters, solvents like alcohols, monoglycerides, diglyceides, triglycerides, sterols, tocopherols, condensation products like diglyceorl and polyglycerols, organic and inorganic polymeric impurities, sugars, pigments, coloured impurities, water etc. Crude glycerol containing such impurities can be purified, but the conventional processes are expensive due to large requirement of processing chemicals, time and energy, and yet yielding low purity glycerol.

[006] The crude glycerol from various know processes is conventionally purified through treatment with (a) activated carbon, (b) acid addition such sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, citric acid etc.; (c) alkalis such as sodium hydroxide, potassium hydroxide, sodium methoxide or potassium methoxide, sodium or potassium salts of fatty acids to remove unreacted glycerol esters; (d) ion exchange resins; (e) ion exclusion resins; (f) flocculating materials like salts or acids, wherein each of these processes requires longer processing time, large energy and gives reduced recovery of glycerol at low purity. Further, processes involving acids or flocculating salts leads to acidic pH of glycerol resulting into loss of glycerol in the form of condensation products, and generating impurities in the process which are difficult to remove. Acidification operations are generally carried out by adding at least one strong acid, usually in the form of an aqueous solution. The strong acids used are sulfuric acid, hydrochloric acid and phosphoric acid, which generate sodium or potassium sulfates, chlorides and phosphates respectively. The presence of these salts has great hindrance in several respects during the purification of the glycerol in subsequent distillation. Indeed, it has been also observed that the sulfates, chlorides and phosphates have low solubility in glycerol and glycerol/water mixtures. This reduced solubility can be unfavourable to in distillation and results into reduced recovery of purified glycerol having low yield and purity.

[007] In another conventional process of purification of crude glycerol involves fractional distillation process where glycerol is recovered in distillate. Here, amount of energy required to recover pure fraction of glycerol in distillate is higher with requirement of longer distillation columns. The process also yields an impure glycerol fraction (called yellow glycerol) which needs recirculation in the process leading to reduced yields of relatively pure glycerol (called industry white, IW grade). The IW grade further requires treatment of carbon to make it pure glycerol for cosmetic applications. To obtain a high purity grade glycerol for pharma and food application, the two step distillation process is required with carbon treatment where energy requirement is very high and leads to reduced yields. Such iterative processes are highly critical with respect to feedstock and are cost as well as energy intensive to produce pure glycerol for desired applications.

[008] US 20150197469 describes a process of crude glycerin purification originated from transesterification with alkaline catalysis without using acidification and distillation producing 96% to 99% pure glycerin, wherein unbalancing of composition of crude glycerin is carried out by adding fatty materials and thereby separating heavy phase glycerin and residual of fatty soaps and partial glycerides. The process is carried out at 40 to 95 degree Celsius. The methanol and humidity in the product is removed by distillation and mixture of fatty, material is acidified with mineral acids or carboxylic acids. The process of this invention does not give high purity glycerin i.e. >99% and involves cumbersome operation of non-specific phase separation. Further, the presence of inorganic salts such as sodium monophosphate, sodium sulphate and sodium chloride makes the overall process of glycerol purification expensive and with undesirable corrosion problems.

[009] CN101423456 describes a process for recovering and purifying glycerol as a byproduct of biodiesel production involving use of molecular distillation to obtain a medical- quality glycerol. Such distillation of glycerol is carried out after the addition of sulfuric acid to the transesterification reaction medium and requires multiple distillation steps and higher temperature due to hindrance of salts accompanied with glycerol. The pure glycerol obtained at low yields by this process requires large energy and results in formation of impurity such as acrolein at high temperature (~ 2500C).

[0010] EP2483225 discloses the treatment of crude alkaline glycerol obtained as a byproduct of the biodiesel production from vegetable oils and animal fats using organic alkyl carboxylic acids or their aqueous solution, comprises the steps of: (a) acidification of the crude alkaline glycerol stock to pH in the range of about 4 to about 6 with organic alkyl carboxylic acids, in the presence of water in the range from about 5% to about 50%, in weight with respect to the weight of the crude alkaline glycerol stock; (b) separating the formed free fatty acids by flotation; (c) removing the alcohol present in the acidified crude glycerol stock by distillation; (d) separating the acidic glycerol.

[0011] WO 2010/136838 describes a method for processing crude glycerol waste streams comprising the step of applying a highly concentrated acid (preferably sulfuric acid with concentration in order of 30 to 100%) to a crude glycerol waste stream at pH 4.0, preferably in two stages, namely a first pH-stage having a pH of about 7 and a second pH-stage having a pH between 0 and 7. The process also involves addition of methanol to the first stage and/or to second stage. This also involves mixer-settler to remove salts formed in first stage.

[0012] US 2008/0249338 describes a method for purification of glycerol, especially from biodiesel production, using gel-type acidic ion exchange resin (catalyst beads) beads to separate free fatty acids and inorganic salts from crude glycerol. The process is able to process only crude glycerol obtained from biodiesel production and requires glycerol concentration of at least 40% and containing cations of at least 1%. The patent does not disclose macro-reticular resins. The resins used are of styrenic, acrylic r combination thereof with functionality in the form of sulfonic acid, carboxylic, phosphoric acid or combination thereof as groups. The process requires use of simulated moving bed or sequenced simulated moving bed to enable continuous separation. Further, the process of this invention is shown on artificial mixture of pure glycerol and potassium/sodium chloride and not on real feed obtained from biodiesel production which has large number of impurities of varying properties. Thus invention has no industrial applicability.

[0013] US2009/0048472 describes method for purification of glycerol from biodiesel production using alkaline catalysis, where crude glycerol is combined with acid, separating glycerol layer and then treating glycerol layer to decolourize it. The process involves use of sodium hydroxide and sodium borohydride (BOROL) followed by removal of salts by ion exchange chromatography (as per US 2008/0249338). Residual water is removed by evaporation, and borate salts and other solid removed by filtration. Overall the process is lengthy and requires corrosive chemical like borohydride. Further, the filtration of salt from viscous glycerol is cumbersome, costly and gives reduced yields due to loss of glycerol in filter cake. Such process does not give pharma and food grade glycerol.

[0014] US 2011/0004031 describes glycerin purification by adding methanol and acid (sulfuric/phosphoric acid) to crude glycerin to form a solution, filtering the solution to remove a salt of acid, separating a first layer of free fatty acids and second layer of partially pure glycerin, and distilling off methanol from second layer. The second layer is then treated for neutralization, filtering to remove excess neutralizing agent (such as calcium hydroxide), passing through plurality of ion exchange columns, deodorizing and de-watering. This the invention involves large number of general steps and further involves two basic ion exchangers, one acidic ion exchange and a mixed bed followed by carbon filter and then dewatering. The process requires crude glycerin with purity in the range of 50% to 80% and requires large number of chemicals. This method does not provide solution of sweet water obtained from fat splitting or saponification process and thus is for only specific feed material.

[0015] US2015/0126783A1 describes method for producing refined glycerin alkyl ether by removing glycerin from mixture containing glycerin and glycerin alkyl ether, by using cation exchange resin, having sulfonic acid group, carboxylic acid group or phosphoric acid group. The ion exchange resins are gel type or porous type resins and preferably are of gel type. The process is of simulated moving bed (SMB) type and cannot used for purification and refining of crude glycerol obtained from saponification and biodiesel production because the impurity profile is different and SMB is critically governed by input feed composition and impurities.

[0016] KR 1020160018245 describes method and apparatus for purifying glycerin generated in biodiesel production process comprises of neutralizing (using alkali such as caustic soda, calcium hydroxide, sodium carbonate, calcium oxide) the crude glycerin, evaporating the water and alcohol, cooling, treating it coagulant in a stirred reactor and filtering the impurities by steam injected reactor and filtering it, distilling the glycerin and cooling it followed by treating it with adsorbent agent (clay, activated carbon, zeolite, silica gel and alumina) to bleaching it and then filtering to obtain pure glycerin. Process also describes use of flocculating agents such as aluminium chloride, aluminium sulphate, iron sulphate and sodium aluminate etc. The process of this invention utilizes multiple heating and cooling steps, filtration steps and neutralization, and thereby it is energy intensive, time consuming and requires large quantities of chemicals leading to waste streams.

[0017] KR2002/0025154A describes method for preparation of high purity glycerin monoester wherein hydrophobic adsorbent resin is reacted with isopropylidiene glyceryl stearate. US2010/0274034A1 describes method and apparatus for producing fatty acid alkyl ester and/or glycerin using liquid-liquid and solid-liquid extraction of glycerol and fatty acid alkyl ester, wherein hydrophilic phase and hydrophobic phase (both are liquid) is separated to obtain separation.

[0018] CN101172935 describes boric acid resin complexation-distillation integrated technique for recycling glycerol in low concentration sweet water, involving adjusting pH of sweet water to a neutral condition, flocculating agent is added, and filtrate is obtained by filtering after settling; secondly pre-treated boric acid resin fed to chromatographic column and filtrate is fed to chromatographic column, boric acid resin column is eluted with eluent, eluent is vaporized to remove eluent agent and produce coarse glycerin, coarse glycerin is decompressed and distilled, desalted by ion exchange and glycerin of larger than 98.5% is produced after decolourization with activated carbon. The process of this invention involves large number of steps. Similarly, CN103073086A also describes adsorption of glycerin contained in waste water with boric acid treated resin and adsorbed glycerin is eluted with acid-base treatment and recycling the resin. Boronic acid (similarly boric acid) reacts with glycerin is known method in titration of cis-hydroxy compounds by adsorption separation. The present invention dies not addresses the removal of leached boric acid in glycerin product.

[0019] [0020] US869905B2 OR US2011/0263908A1 describes method of producing glycerol by transesterification with alcohol followed by treatment with activated charcoal, white clay, bentonite or synthetic zeolite to reduce odour and UV adsorbing substances. This invention also describes the use of ion exchange resins i.e. cation, anion and mixed bed for purification of glycerol followed by removal of water by distillation. The patent does not discloses the removal of specific impurities like fatty acids and fatty impurities to purify the glycerol and also the purity of glycerol.

[0021] WO2013/106249A1 describes the method of Biobased chemical production from crude glycerin involving purification of glycerin by desalting, decolourizing and concentrating bioglycerin for production of Biobased chemicals. The invention involves use of carbon, desalination by ion exchange etc, but does not discloses whether organic impurities are removed in the process.

[0022] US2009/0198088 describes method for purification of crude glycerin utilizing ion exclusion chromatography fractionation using fixed bed and moving bed (SMB) to yield glycerol consisting water and salt as first fraction, one or more dewatering steps under moderate temperature and pressure, and glycerin concentration. The patent also discloses use of ion exchange to remove salt from first fraction containing glycerol which is further treated with activated carbon and vacuum evaporation/distillation or thermal decompression to remove water to obtain 95 to 99% pure glycerol. The SMB process is difficult to operate and is cost intensive.

[0023] US 2014/0114095 describe glycerin purification method by removing impurities from waste glycerin generated in biodiesel production. The method involves heating glycerin with alkali metal, alcohol, organic fatty acid, and water under reduced pressure to removal alcohol and water; adding sulfuric acid to neutralize glycerin, centrifuging the glycerin to remove alkali metal sulphate and organic fatty acid; adding sulphate of alkaline earth metal(magnesium sulphate) to glycerin and again centrifuging it to remove sulphate of alkaline earth metal salt of organic fatty acid and passing glycerin through cation and anion exchange resin. The patent does not disclose nature of ion exchange resins.

[0024] GB2437516 describes method and apparatus for purifying glycerine using filter membranes and deionisation means, where one or more membranes of different pore sizes like micro-, ultra-, nano- or hyper-filtration are used. The deionisation is carried out by ion exchange, captive deionisation, electrodeionisation or decolourisation techniques, washing steps and conditions steps with temperature, Ph, hardness, softness, concentration etc. and thus involving multiple steps and time as well as energy consuming operation. [0025] CN102264678 (PCT/JP2009/071825) describes method of manufacturing glycerine using ion exchange reaction, a cation exchange, anion exchange and mixed resin of both, but preferably an anion exchange. The invention also involves use of clay, bentonite, zeolite for removal of odour and UV absorbing materials from glycerine. Use of clay and like material reduces the yield of pure glycerine.

[0026] JP 2007/014871 describes method for regenerating ion exchange resins for catalytic activity. JP 2001/17862A (US2002/0010359A1) describes catalyst for transesterification of oil such as zeolite, ion exchange resin etc. and does not disclose their use for separation or purification. JP 2001/302584A (US2001/0042340A1) describes process for producing fatty acid esters and fuels comprising fatty avid esters, where distillation (steam, extractive and molecular etc.) are employed. Patent does not disclose purification of glycerol formed in the reaction.

[0027] CN 103626631 describes method for decolourizing glycerol in biodiesel by-products using a resin which is a ion exchange resin and does not disclose removal of other fatty impurities as well as salt.

[0028] CN103896735 describes method for refining crude glycerol as byproduct generated in high pressure hydrolysis of grease comprising hydrolysis, treatment with hydrochloric acid, standing, removing upper layer of grease, adjusting pH to 5 to 6.5, by soda ash, then adding sodium metalaluminate, adding flocculant, stirring for 5 to 30min and filtering. Process then involves chromatographic columns filled with cation exchange, anion exchange and cation exchange resin to obtain purified glycerol. Process in this patent does not disclose the removal of fatty, coloured and organic impurities.

[0029] US2010/0249441A1 describes method for producing fatty acid alkyl ester and/or glycerin involving reaction of fat/oil with alcohol of solid catalysts, stripping alcohol by evaporation/thin film evaporation, separating the phases into fatty acid ester and glycerin with use of separation filter and removal of phosphorus, calcium and their compounds by adsorber, which is ion exchange resin. This invention dies not disclose removal of fatty material from glycerin phase.

[0030] US4683347 describes glycerine purification process where glycerol based aetals and/or ketals (dimethyl ketals) is reduced by extraction with supercritical or near critical carbon dioxide. Similarly concentration and purification glycerine by extraction with hydrocarbons is described in US 2154930, extraction with tert-amyl alchol in US 2436209 and solvent with aliphatic alcohols, aromatic alcohols, cyclic amines, ketones, ethers, aldehydes and esters for extraction of glycerin is described in US2479041. Also distillation process of separating glycerin from certain acetals/ketals is described in US 4360407.

[0031] EP13152268-2 describes biodiesel production but glycerol produced in of low purity. Method described in I. Miesiac, Prezemysi Chemiczny, vol. 82, pp 1045-47 (2003) gives poor separation of glycerol. EP1978009A and US2009/030243 A describes purification of glycerol with an ion exchange resin. JP10218810A and JP6184024 A describes use of distillation and filtration to remove oil, inorganic matter and reducing trace impurities and colour.

[0032] US4990695 and EP0358255A1 describes process of purifying crude glycerol (splitters or soap crude) using microfiltration step (after calcium hydroxide treatment) over ceramic filter material preferably comprising alumina/zirconia followed by distillation and ion exchange resin treatment. Also involves combination of microfiltration and ultrafiltration. Here the membrane fouling due to slime calcium based precipitates is severe problem and gives very low yields of impure glycerol.

[0033] EP 141358A describes process to purify glycerol by combination of alkali treatment and distillation and JP58144333 describes combination of alkali treatment followed by use of anion and cation exchange resins.

[0034] US 5527974 describes process for the purification of glycerol water (sweet water) from high pressure fat and oil hydrolysis with steam, where fat is separated on plate type phase separator and aqueous phase is passed over cross flow filtration membrane (microfiltration membrane of graphite or A1203) and at concentrate is recycle back in the plate separator. Due to presence of MONG or fatty impurities, membrane clogging/fouling is major problem in the process and hence cannot be used on larger scale.

[0035] US 7126032B 1 describes purification of glycerin from biodiesel production comprising heating a glycerin containing alcohol, water and fatty acid esters to form triglycerides by transesterification. Reaction mixture is sparged with nitrogen to remove water and low molecular weight alcohols, oily layer is separated from glycerin by reducing pH to below 7.0 and then flash distillation to separate glycerin from water, salts and glycerides. Also US6262285, 6174501 and 7138536 discusses glycerin purification after biofuel synthesis by distillation. Only distillation does not separate glycerin from organic impurities and lead to lower yield as well as gives low purity glycerol.

[0036] US 7718833B2 describes purification of glycerin obtained as a bioproducts from the transesterification of triglycerides in the synthesis of bio fuels, wherein distillation is used to strip alcohol from glycerin after adding water to the mixture of glycerin, soap, fatty acid eaters and lower alcohol; then lowering pH and recovering organic phase of fatty acid and fatty acid esters and second phase of glycerin. The separation of fatty layer/phase from glycerin phase is non-selective and gives glycerin with residual organic impurities.

[0037] US 8648219B2 describes method for purifying glycerin and products obtained there from comprises of blending crude glycerin with predetermined amount of water, acid and organic solvent, reacting acid with impurities to from ionic salts and lipids in the mixture, separating a mixture into top and bottom layer, where glycerin with salts and organic impurities is recovered as bottom layer, clarifying with micro -bubbles the bottom layer to remove organic solvent followed by ion exchange resin, electrodialysis and electro- deionization to remove ionic salts and water from glycerin, and drying the glycerin. The process is complex and cost intensive due to use to chemicals and phase separation is non- slective.

[0038] GB214576 describes improved process for electro-osmotic purification of glycerin by passing solution from anodic diaphragm of linoxyn to cathodic diaphragm of woven sail cloth.

[0039] US2011/0065942 Al describes process for preparing esters of alcohols and glycerin from triglycerides and catalysts in the presence of a controlled quantity of water. The process does not disclose purification of glycerin.

[0040] EP2431085A1 describes process for purifying glycerin derived from biodiesel production through acidifying glycerin, neutralizing glycerin, electrodialysis with cation and anion exchange membrane between anode and cathode. The process does not disclose removal of fatty and organic impurities.

[0041] US2120227 describes purification of glycerol after distillation and re-distillation followed by decolourization. This process involves use of activated carbon treatment at 75 degree Celsius with 50% volume of 0.5% sulfuric acid with pH of less than 7.0. The process involves dilution of glycerol and thus removal water in next becomes energy intensive as well as acidic treatment give formation of dimeric or polyglycerol as impurities.

[0042] US2234400 describes purification of polyhydric alcohols using one or more steam distillation and vacuum distillation, which is energy intensive process followed by carbon treatment and even then ester type impurities are present in final glycerol product.

[0043] US2381055 describes purification of glycerin obtained from fermentation through hot digestion, saponification, acidification with sulfuric acid, filtration, anion exchange resin treatment and distillation. The process of this invention is not suitable for crude glycerol obtained in biodiesel and fat splitting processes. [0044] US2487611 describes purification of anhydrous glycerin with use of acetone to the methanolic solution of glycerin, to remove precipitates/floccs of salts and other impurities, solvent is then removed by distillation and glycerin is distilled under reduced pressure. The process gave low yield of glycerol i.e. 67% to 82%.

[0045] US2960447 describes purification of synthetic glycerol through concentration by evaporation (at pH 3 to 5), adding non-volatile base like hydroxide/carbonate to form high boiling impurities at pH 9 to 12 and then flashing the glycerol, fractionation to remove low boiling impurities followed by re-distillation steps. Thus the process highly energy intensive and gives low yields. US 1466665 describes process of making synthetic glycerin from petroleum oil through reaction and saponification.

[0046] US2977291 describes purification of glycerol by distillation to remove glycols and volatile impurities, treating glycerol with sulfuric acid at 100 to 140 degree Celsius temperature for 1 to 6 hours and then neutralizing it with anion exchange resin, alkali or alkaline earth metal oxides followed by fractional distillation of glycerol. The process is highly energy intensive.

[0047] US3003924 describes method of producing glycerine from lignified cellulose through digestion, saccharification, fermentation, precipitation using calcium hydroxide and magnesium hydroxide, aeration, yeast recycle and resulting liquid medium is distilled to obtain glycerine in conventional manner. Similarly, US2741638 and US2772207 also discusses purification of glycerol from dilute solution obtained after fermentation and hydrolysis.

[0048] US5177008 describes process for manufacturing ethanol and for recovering glycerol, succinic acid, lactic acid and distiller's dry grain and solubles or a solid fertilizer, wherein stillage from fermentation/distillation is clarified using crossflow microfiltration on inorganic membranes, treating the clarified stillage using ion exclusion material for chromatographically separating glycerol from other constituents followed by purifying glycerol using ion exchange, evaporation and distillation. The process of this invention is complex and involves large number of steps leading reduced recovery of glycerol.

[0049] CN101481297A1 describes method for refining glycerol from biodiesel by-products through addition of organic solvent to the phase, adjusting pH to 1 to 7 to from a precipitate, filtration to remove solid material followed by alkaline ion exchange resin and acidic ion exchange resin treatment and elution with water. The eluate is dehydrated under reduced pressure to obtain refined glycerin. The yield of this process is very low i.e. 85%. [0050] CN203513532U describes crude glycerol refining technology system with pre- treatment tank, distillation kettle, decolourization tank, ion exchange column and high temperature evaporator. The invention does not disclose the process of refining of glycerol.

[0051] CN102229521A1 describes refined and crude glycerol by-product recovery processes using multiple ion exchange methods and CN 102775275A describes refined glycerin purification process involving lime treatment, ion exchange acidification process and thus higher chemicals consumption and large mineral content.

[0052] US2012/0245398 describes process for purification of crude glycerol obtained from saponification, hydrolysis and transesterification processes of oils/fats by reaction of the crude glycerol with cl to c6 carboxylic acids or anhydride to form glycerol esters, separating glycerol esters by distillation and then reacting those esters with alkayl or cycloalkyl alcohols followed by separation of glycerol. The glycerol obtained in the process is of yellow colour and at low yields.

[0053] US2016/0052847 describes production of partially refined waste glycerol (fermentation grade glycerol) involving de-oiling using hydrophobic solvent (alkene, alakne, acetate, fatty acid alcohol ester etc.) to extract organic impurities, dewatering by drying at elevated temperatures and desalting using polar solvent to precipitate salts. The process does not give pure glycerol.

[0054] US4655879 describes glycerol distillation after alkalization of glycerol crude in presence of air oxidation and using thin film evaporator with re-distillation of residue, rectification, and re-evaporation in packed bed column with falling film, followed by bleaching product with activated carbon. The process is highly energy intensive due to multiple distillation steps and gives two types of glycerin a colourless and yellow gray coloured, thus reducing recovery of pure glycerol and also giving difficult to purify yellow fraction.

[0055] CN105585423A describes an improved glycerol production process involving pre- treatment using activated carbon/coke, kaolin or organobentonite and regenerating spent adsorbent with hot steam, treating the pre-treated glycerol (a yellow liquid) on resin column packed with macroporous adsorbent resin like XDA-1, HYA-103 or HYA-106, regenerating the resins with 3 to 5% NaOH at a temperature and then with 0.5 to 1.5% hydrochloric acid followed by water till pH to 4 to 6. Glycerol obtained from resin column is distilled and then evaporated to obtain >80% glycerol. The process utilizes macroporous ion exchange resins which are no n- selective and utilized both acid and alkali stream which need to be treated separately enhancing the cost of overall operation. Further, the glycerol obtained if of low purity.

[0056] Carmona et al., (J Chemcial Technol Biotechnol, 2009, 84, pp-738-744 and pp-1130- 1135) has discussed purification of glycerol/water solutions from biodiesel synthesis by ion exchange for sodium removal using Amberlite 252 and Amberlite IRA- 120, and chloride removal by Amberlite IRA-420. The paper only addresses sodium and chloride removal and not any other ions and resins used showed that it has more selectivity for potassium than sodium.

[0057] Busby et al., (Meeting of American oil chemical society, 1951) showed purification of glycerol by several columns of cation, anion and mixed bed with five different ion exchangers in series followed by distillation to get glycerol product to obtain 95 to 99% pure glycerol. This involves several columns generating large effluent making the process highly expensive.

[0058] The disposal of crude glycerol is costly, and it is much advantageous to undergo purification to generate pure glycerol for its utilization in more than 1000 applications. To achieve this, there are several separations and purification processes that are developed and operated for crude glycerol obtained from biodiesel and fat splitting industries/processes. The techniques utilized till date are chemical pre-treatment, methanol removal, vacuum distillation, fractional and molecular distillation, ion exchange and ion exclusion chromatography, activated carbon, clay or bentonite treatment, and membrane separations etc.

[0059] However, current purification and refining processes for crude glycerol are high in energy requirement and are deemed not feasible for small to medium or even large scale plants (Ardi et al., progress, prospects and challenges in glycerol purification process: a review, Renewable and sustainable energy reviews, 42, 205, pp-1164-1173). It has been identified that the recovery of high quality glycerol at low energy and less effluent is playing a key role in cost reduction. Thus, there is a need to utilize crude glycerol through suitable purification and refining process technology towards sustainable growth.

[0060] During biodiesel and fat splitting processes, the impurities formed such as soap, solvent like methanol, water, salts, and material organic non-glycerol (MONG). MONG consists of fatty acids (saturated and unsaturated), fatty acids esters, sterols, tocopherol, monoglycerides, di-glycerides, triglycerides, pigments and coloured impurities, organic polymerized and coloured impurities, glycerol dimmers and oligomers, polyglycerols, sugars and condensation products etc. Inorganic impurities are mainly salts, acids and alkali, and residual catalysts. All these impurities have more tendencies to concentrate in the glycerol phase/stream during separation of biodiesel phase and glycerol phase; and fatty acids phase and sweet water phase etc. Therefore, crude glycerol has large number of organic and inorganic impurities and requires a process to remove these impurities selectively rather than developing large number of operation to purity it to meet pharmacopoeial (USP, EP, BP, JP, IP etc) and food chemical Index specifications (>99.5% assay purity) for its use in food, pharma and cosmetics as well as in other industrial applications.

[0061] None of the prior art processes provides solution for removal these impurities selectively with less number of operations and at low energy requirement making the process economically and commercially viable, green and sustainable, (a) Neutralization and acidification converts soaps into fatty acids and separates out, but increases the ash and MONG content in glycerol fraction and thus glycerol purity of >98.1% cannot be obtained even after fractional distillation making overall process costly and energy intensive, (b) Further, ion exchange and ion exclusion chromatography resins based technique could give enhanced purity by removal of free fatty acids, inorganic salts and free ion impurities. But the major issues in viable purification method using ion exchanger/ion exclusion resins is fouling by fatty acids, oils and soaps, and thus further requiring large quantities of regeneration liquids generating large quantity of waste streams/water as well as reduces resin life (Ardi et al., progress, prospects and challenges in glycerol purification process: a review, Renewable and sustainable energy reviews, 42, 205, pp- 1164- 1173). Thus, this technique requires selective removal of such fouling agents, specifically MONG fraction by some other operation so as to make ion exchange/ion exclusion technique effective on industrial scale, (c) Adsorption on activated carbon, charcoal, clay, bentonite etc is mainly used as the finish steps to refine the purified glycerol and to reduce colour as well as some fatty acids. Carbon was found to remove lauric and myristic acids effectively, although other fatty acids such as plamitic acid, oleic acid and steric acid and other unknown compounds were found in refined glycerol (Ardi et al., progress, prospects and challenges in glycerol purification process: a review, Renewable and sustainable energy reviews, 42, 205, pp- 1164- 1173), indicating that carbon though it is useful, it leaks few fatty acids and therefore requires a technique to remove such fatty acids selectively before or after carbon treatment, (d) Membrane technology is also utilized in glycerol purification but the membrane fouling by MONG, durability of membrane and high osmotic pressure due to glycerol concentration are strong limiting factors and again such technique requires selective removal of MONG for membrane to work without frequent fouling due to complex organic impurities, (e) Distillation (vacuum, fractional, molecular, membrane etc.) are established methods but requires high energy, high in maintenance and are very sensitive to feed compositions, which is bound to happen due to feedstocks used to obtain crude glycerol are natural sources. Therefore, distillation operation are operated to obtain a pure glycerol fraction in single or multiple distillations in series, and another fraction as impure glycerol with high content of MONG (called yellow glycerol), thus reducing recovery of pure glycerol. Reduced recoveries and recycle of impure fraction to distillation re-boiler are due to presence of MONG in the glycerol to be distilled and thus requires a process to remove such organic impurities selectively before or after distillation.

[0062] Thus, none of the existing or conventional techniques/processes selectively removes organic or MONG impurities and thereby give reduced yields and/or purity even after usage of number of unit operations. Further, the prior art processes left large scope for further enhancement in efficiencies of existing operation by developing a new technique/process to remove organic/MONG impurities and improve the yield and purity of glycerol with low energy and cost for industrial viability.

[0063] In order to reduce the above reported drawbacks, there is need to develop a process for purification of glycerol, free of organic, MONG and inorganic salts, using the crude glycerol or partially pure glycerol.

SUMMARY OF THE INVENTION

[0064] The subject matter described herein is directed towards a process for purification of glycerol. The present disclosure provides a process for purification of both, crude as well as partially pure glycerol.

[0065] In an aspect of the present disclosure, there is provided a process for purification and refining of glycerol, the process comprising steps of: (a) contacting glycerol with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent to obtain a first fraction of pure and refined glycerol having purity greater than 99%, wherein the order of contacting with at least adsorbent one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can vary; (b) displacing the residual glycerol from the at least one hydrophobic impurity affinity adsorbent and the at least one polar impurity affinity adsorbent by a displacing phase to obtain a second fraction of pure and refined glycerol having purity greater than 99%; and (c) subjecting the first and second fraction of pure and refined glycerol to at least one water removal treatment to obtain a final pure and refined glycerol, wherein the final pure and refined glycerol has assay purity greater than 99%, water content less than 0.5%, impurities less than 0.5%, and the recovery of the final pure and refined glycerol is greater than 98%.

[0066] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

[0067] The following drawings form a part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.

[0068] Figure 1 depicts the reproducibility of process in terms of loadability (kg of glycerol processed /lit of adsorbents) and assay purity of purified and refined glycerol over 50 consecutive cycles with regenerated and reused adsorbent and recycled regenerating liquid.

[0069] Figure 2 depicts recovery of purified and refined glycerol from the process of present disclosure over 50 consecutive cycles with regenerated and reused adsorbent and recycled regenerating liquid.

[0070] Figure 3 represents the HPLC chromatogram of standard pharmacopoeial grade glycerol.

[0071] Figure 4 represents the HPLC chromatogram of purified and refined glycerol by the process of present disclosure showing only glycerol same as that of pharmacopoeial standard.

[0072] Figure 5 represents the HPLC chromatogram of crude glycerol obtained from fat/oil splitting process (sweet water) showing glycerol and other peaks are impurities.

[0073] Figure 6 represents the HPLC chromatogram of the crude glycerol obtained from saponification process showing glycerol and other peaks are impurities.

[0074] Figure 7 represents the HPLC chromatogram of crude glycerol obtained as a byproduct of bio-diesel production (by transesterification process) showing glycerol and other peaks are impurities.

[0075] Figure 8 depicts the HPLC chromatogram of partially pure glycerol (yellow glycerol) showing glycerol and other peaks are impurities. [0076] Figure 9 represents the HPLC chromatogram of partially pure glycerol (industrial white glycerol) showing glycerol and other peaks are impurities.

DETAILED DESCRIPTION OF THE INVENTION

[0077] The present disclosure relates to a process for purification of glycerol using at least one adsorbent selected from the group consisting of hydrophobic impurity affinity adsorbent, polar impurity affinity adsorbent, and combinations thereof.

[0078] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features.

In the present disclosure, numbers of terms are used for description of the invention. The definitions of terms are as follows:

Definitions:

[0079] The articles "a", "an" and "the" are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

[0080] The terms "comprise" and "comprising" are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as "consists of only".

[0081] Throughout this specification, unless the context requires otherwise the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps.

[0082] The term "including" is used to mean "including but not limited to". "Including" and

"including but not limited to" are used interchangeably.

[0083] The terms "glycerol" and "glycerin" have been used interchangeably.

[0084] The term "crude glycerol" used herein refers to glycerol obtained from saponification, fat splitting, biodiesel production, fermentation processes recycled glycerol or from similar processes and having purity of 90% or less than 90%.

[0085] The term "partially pure glycerol" used herein refers to the fraction of glycerol having purity of more than crude glycerol but less than 98% and containing organic/MONG and ionic/inorganic impurities obtained from conventional processes such as evaporation and distillation such as yellow glycerol, and industry white (IW) glycerol.

[0086] The term "pre-treated crude glycerol" used herein refers to the glycerol obtained after treatment of crude glycerol, sweet water or partially pure glycerol with processes such as but not limited to neutralization, acidification, flocculation, coagulation, filtration, distillation, evaporation, solvent treatment, clarification, centrifugation, precipitation etc. and thereby improving purity and/or clarity of glycerol more than the starting material.

[0087] The term "flocculating agent" used herein refers to chemical agent used to increase the size of soluble/insoluble impurities as floccs in crude glycerol and partially pure glycerol and thereby improving efficiency as well as rate of removal by filtration or centrifugation.

[0088] The term "matter organic non glycerol (MONG)" used herein refers to any organic material other than glycerol such as fatty acids (saturated and unsaturated), fatty acids esters, sterols, tocopherol, monoglycerides, di-glycerides, triglycerides, pigments and organic coloured impurities, polymerized matter and coloured impurities, glycerol diamer and oligomers, polyglycerols, sugars and condensation products etc.

[0089] The term "polymeric or oligomeric matter" used herein refers to any organic or inorganic material other than glycerol and has repetitive units of same or multiple monomers.

[0090] The term "coloured impurity" used herein mean any material other than glycerol and has ability absorb visible light.

[0091] The term "organic impurity" used herein means any organic material other than glycerol.

[0092] The term "inorganic impurity" used herein means any inorganic material such as salts, acids, alkali, residual catalysts etc. in the glycerol.

[0093] The term "deashing" or "desalting" used herein refers to removal of ions/salts.

[0094] The term "pharmacopoeia grade glycerol" used herein refers to glycerol having assay purity on anhydrous basis as per United State Pharmacopoeial specification (>99.5%), European Pharmacopoeial specification (>99%), Indian Pharmacopoeial specification (98% to 101%), Japanese Pharmacopoeial specification (>99%), British Pharmacopoeial specification (98% to 101%), Food Chemical Codex (99.7%), and with specific content of impurities below the acceptable limits as per respective pharmacopoeia.

[0095] The term "recovery or yield" used herein means percent recovery of glycerol against each and overall unit operations used in the process, and the terms "recovery" or "yield" is used interchangeably in the specification. [0096] In the present invention the term "porous adsorbent" included microporous, mesoporous, macroporous, supermacroporous, and gigaporous adsorbents.

[0097] In the present invention the term "affinity" means relative specific strength of interactions of molecular species with the adsorbent, and one or more interacting groups on the adsorbent surface that result in selectivity of adsorption as well as forces of interactions depending on type of adsorbent and process conditions.

[0098] The term "retentate" as used herein, refers to the matter that is retained by the filter membrane during the filtration process and the term "retentate" has been used interchangeably with "residue".

[0099] The term "permeate" as used herein, refers to the matter that passes through the filter membrane during the filtration process and the term "permeate" has been used interchangeably with "filtrate".

[00100] As already described above, although there are processes known in the literature for purification of glycerol, most of them suffer from one drawback or the other; prominent ones being cumbersome procedures, high cost, and excess waste generation. The present disclosure provides an elegant process for production of high purity glycerol from crude glycerol obtained but not limited to from saponification, fat splitting and biodiesel production processes.

[00101] The object of the present invention is to provide a robust, cost effective process with requirement of simple equipment and mild reaction conditions for purifying glycerol obtained from saponification, fat splitting and biodiesel production processes.

[00102] The object of the present invention is to provide a recovery, purification process of crude glycerol, wherein the present invention is carried out at mild reaction conditions, i.e., low temperature, pH, less operational time, simple equipment requirements that makes the process economically feasible and can be applied to industrial production.

[00103] In an embodiment of the present disclosure, there is provided a process for purification and refining of glycerol, the process comprising steps of: (a) contacting glycerol with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent to obtain a first fraction of pure and refined glycerol having purity greater than 99%, wherein the order of contacting with at least adsorbent one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can vary; (b) displacing the residual glycerol from the at least one hydrophobic impurity affinity adsorbent and the at least one polar impurity affinity adsorbent by a displacing phase to obtain a second fraction of pure and refined glycerol having purity greater than 99%; and (c) subjecting the first and second fraction of pure and refined glycerol to at least one water removal treatment to obtain a final pure and refined glycerol, wherein the final pure and refined glycerol has assay purity greater than 99%, water content less than 0.5%, organic/MONG impurities less than 0.5%, ash content less than 0.1%, and the recovery of the final pure and refined glycerol is greater than 98%.

[00104] In another embodiment of the present disclosure, there is provided a process for purification and refining of glycerol as described herein, wherein the glycerol is obtained from a process selected from the group consisting of saponification, fat/oil splitting, biodiesel production, fermentation, and combinations thereof.

[00105] In another embodiment of the present disclosure, there is provided a process for purification and refining of glycerol as described herein, wherein the glycerol is selected from crude glycerol, partially pure glycerol, yellow glycerol, IW (industry white) grade glycerol, and combinations thereof. The process of present disclosure can be used for purification of glycerol having initial purity falling in a very wide range, making it a versatile process. A wide range of glycerol samples can be purified using the process disclosed herein, regardless of the initial purity. The process of disclosed herein can be used to purify glycerol having initial purity of up to 98%. This initial purity refers to purity of glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent.

[00106] In yet another embodiment of the present disclosure, there is provided a process for purification and refining of glycerol as described herein, wherein the glycerol is selected from crude glycerol and a combination of crude and partially pure glycerol, and the process further comprises a pre-treatment of glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent. Various pre-treatments can be adopted to remove certain impurities to make the process more efficient. It is however not necessary in all cases and in cases where partially pure glycerol is being purified, the pre-treatment step can be avoided. In cases of crude glycerol, a pre- treatment step is carried out as mentioned hereinabove, wherein the treatment method is selected from the group comprising neutralization, acidification, dilution, flocculation, filtration, flashing, distillation, evaporation, and combinations thereof. These treatment methods are routine in nature and are known to a person of ordinary skill in the art. Similar pre-treatment is also carried out if the glycerol being purified is a combination of crude glycerol and partially pure glycerol. Neutralization, for instance can be carried out to eliminate acidic or basic impurities. The neutralization generally transforms the acidic and basic impurities into insoluble salts which can be filtered out easily. Another pre-treatment method that can be resorted to is flocculation, wherein a flocculant like, but not restricted to, alum, transforms the colloidal impurities into a precipitate that can be filtered out. Charcoal treatment can also be carried out, in addition to the pre-treatment mentioned above. Charcoal treatment is generally carried out to eliminate colour of the sample being purified. The process disclosed herein allows for the flexibility to carry out the charcoal treatment at any stage of the process. In another embodiment of the present disclosure there is provided a process for purification of crude glycerol obtained from fat splitting or biodiesel production processes, wherein feed of crude glycerol may be mixed with organic solvent and then treated with flocculating agent at a temperature in the range of 5°C to 100°C for the period of 0.1 hr to 24 hrs to remove solid coloured polymeric mass.

[00107] In yet another embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein flocculating agent used in the process may be selected from the following but not limited to polyelectrolytes, alum, aluminiumchlorohydrate, aluminiumsulphate, calcium oxide, calcium hydroxide, iron (II) sulphate (ferrous sulphate), polyethylene oxide, iron (III) chloride (ferric chloride), polyacrylamide, polyDADMAC, sodium aluminate, sodium silicate.

[00108] The flocculating agent comprising polyelectrolytes, alum, aluminiumchlorohydrate, aluminiumsulphate, calcium oxide, calcium hydroxide, iron (II) sulphate (ferrous sulphate), polyethylene oxide, iron (III) chloride (ferric chloride), polyacrylamide, polyDADMAC, sodium aluminate, sodium silicate, flocculating agent being present in an amount of between about lppp to about -1000 ppm.

[00109] In yet another embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein improved purity of glycerol that can be achieved treating glycerol feed with flocculating agent and with or without charcoal or charcoal alone, and thereafter by feeding a such treated liquid fraction to a plurality of filtration stages and/or chromatographic columns in series, wherein retentate and/or eluate fraction from one stage is fed to the subsequent stage.

[00110] In yet another embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein acid/s used in the process may be selected from,but not limited to, mineral or organic acids and base/s used in the process may be selected from, but not limited to, ammonia, sodium hydroxide, potassium hydroxide, or calcium hydroxide. [00111] In yet another embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein solid-liquid separation, concentration of glycerol and removal of salts and impurities can be carried out by using membrane filtration, such as, but not limited to, microfiltration, ultrafiltration, nanofiltration, reverse osmosis, etc.

[00112] In yet another embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein solid-liquid separation and removal of salts and impurities can be carried out by using density difference in centrifugation, hydrocyclone etc.

[00113] In one embodiment of the present disclosure, liquid fraction obtained after flocculation can be subjected to a decolourizing treatment according to appropriate conventional means, such as, using activated charcoal. Similarly a deashing or desalting or purification treatment can be done by appropriate conventional means, such as hydrophobic, reverse phase, affinity, polar and/or ion-exchange resin in stirred tank and/or column chromatography mode.

[00114] The pre-treatment described herein improves the initial purity of the glycerol to varying extents. Precisely, the purity of such pre-treated glycerol is 95% or less. In one embodiment of the present disclosure, the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent is in the range of 5-95%. In another embodiment of the present disclosure, the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent is in the range of 20-90%. In one actualization of the present disclosure, the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent is in the range of 30-80%. In another actualization of the present disclosure, the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent is in the range of 5-50%. In yet another actualization of the present disclosure, the purity of crude glycerol can be 77% which on pre-treatment by a combination of acidification, filtration, neutralization, and distillation can be improved to 89.9%. In an embodiment of the present disclosure, the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent is 88.01%. In yet another actualization of the present disclosure,the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 80%. In yet another actualization of the present disclosure, the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 88%. In yet another actualization of the present disclosure, the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 94.8%. In yet another actualization of the present disclosure,the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 89.45%. In yet another actualization of the present disclosure,the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 8.3%. In yet another actualization of the present disclosure,the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 30%. In yet another actualization of the present disclosure,the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 87.4%. In yet another actualization of the present disclosure,the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 70.2%. In yet another actualization of the present disclosure,the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 92.19%. In yet another actualization of the present disclosure,the purity of pre-treated glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 5.5%. As mentioned hereinabove, in cases where glycerol being purified is partially pure glycerol, pre- treatment may not be required. In another actualization of the present disclosure, the purity of partially pure glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 96.5%. In another actualization of the present disclosure, the purity of partially pure glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can be 97.1%.

[00115] Impure glycerol contains a variety of impurities which requires the process for purification of glycerol to be of wide applicability in terms of types of impurities it can remove. Accordingly, in one of the embodiment of the present disclosure, there is provided a process for purification of crude glycerol, wherein crude glycerol may be derived from a commercial plant of saponification, fat splitting and biodiesel production processes, used as raw material for purification is available in various composition, for example 5-88% (w/w) free glycerol, 5-90% (w/w) water, fatty acid esters 0.2- 10% (w/w), 0.5-2% (w/w) partial esters and glycerides. In another embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein the feed of crude glycerol has initial content of free glycerol, fatty acids, matter organic non glycerol (MONG), salts (organic and inorganic), and colorants. The feed of crude glycerol may be mixed with organic solvent before treating with flocculating agent to remove organic impurities followed by separating organic solvent and glycerol rich fraction. The organic solvent is selected from a group but not limited to methanol, ethanol, butanol, tert-butanol, isopropanol, acetone, tetrahydrofuran, dimethyl formaamide, dimethyl sulfoxide, acetonitrile, hydroxyl methyl furfural, acetone, ethyl acetate, butyl acetate, diethyl ether, and hexane.

[00116] In a further embodiment of the present disclosure, there is provided a process for purification and refining of glycerol as described herein, wherein the hydrophobic impurity affinity adsorbent comprises; (a) base selected from the group consisting of synthetic polymer, natural polymer, and inorganic matrix; and (b) at least one hydrophobic group as an interacting group. More specifically, the hydrophobic impurity affinity adsorbent comprises one or more of (i) non-ionic adsorbent, (ii) ionic adsorbent, (iii) having a surface and/or surface group, which has selective interacting ability with organic/MONG and ionic impurities in crude or partially pure glycerol (iv) which is rigid and porous, (v) in the form of a granular beads or sheet like membrane, (vi) adsorbent has synthetic, natural polymeric base or inorganic matrix, (vii) adsorbent has a synthetic base matrix of polystyrene divinylbenzene (PSDVB), polymethacrylates, polyacrylamide, (viii) adsorbent has natural polymeric base matrix of agarose, cellulose, chitosan, dextran, (ix) is crosslinked, (x) a modified silica with aromatic and/or aliphatic moiety as substituted group having C2 to C30 carbon atoms, (xi) has interacting group which is a part of base matrix or grafted on the base matrix by known activation chemistry, (xii) the selective interacting group is unsaturated or saturated aliphatic and/or an aromatic moiety of a C1-C30 carbon molecules with or without hetero atom (e.g O, N, S) in it, (xiii) has the interacting group as halogen atom, (xiv) the interacting group is cyano, diol or amino, (xv) has the interacting group which has different binding ability or affinity or binding strength with different organic/MONG and ionic impurities in crude or partially pure glycerol, (xvi) microporous, macroporous, mesoporous, gigaporous, supermacroporous or throughporous, (xvii) a multimodal or mixed mode adsorbent based on one or more than one of a synthetic or natural polymeric matrix and having amino (primary, secondary or tertiary) or imino moiety, (xviii) adsorbent based on one or more of a polymer comprising PSDVB, polymethacrylates, polyacrylamide, a natural polymer and combinations thereof, (xix) a hydrophobic group.

[00117] In another embodiment of the present disclosure, there is provided a process for purification and refining of glycerol as described herein, wherein the polar impurity affinity adsorbent comprises: (a) base selected from the group comprising synthetic polymer, natural polymer, and inorganic matrix; and (b) at least one group selected from positively charged group, negatively charged group, and combinations thereof, as an interacting group. More precisely, the polar impurity affinity adsorbent comprises one or more of (i) ionic/polar adsorbent, (ii) having a surface and/or surface group, which has selective interacting ability with organic/MONG and ionic impurities in crude or partially pure glycerol, (iii) which is rigid and porous, (iv) in the form of a granular beads or sheet like membrane, (v) adsorbent has synthetic, natural polymeric base or inorganic matrix, (vi) adsorbent has a synthetic base matrix of polystyrene divinylbenzene (PSDVB), polymethacrylates, polyacrylamide, (vii) adsorbent has natural polymeric base matrix of agarose, cellulose, chitosan, dextran, (viii) is crosslinked, (ix) a modified silica with aromatic and/or aliphatic moiety as substituted group having charged functional group like sulfonic, carboxyl, hydroxyl, quaternary amino, polyamine, hexylamine, substituted amines, (x) has interacting group which is a part of base matrix or grafted on the base matrix by known activation chemistry, (xi) the selective interacting group is unsaturated aliphatic and/or an aromatic moiety of a C1-C30 carbon molecules with or without hetero atom (e.g O, N, S) in it, (xii) the interacting group is cyano, diol or amino, (xiii) has the interacting group which has different binding ability or affinity or binding strength with different organic/MONG and ionic/inorganic impurities in crude or partially pure glycerol, (xiv) microporous, macroporous, mesoporous, gigaporous, supermacroporous or throughporous, (xv) a multimodal or mixed mode adsorbent based on one or more than one of a synthetic or natural polymeric matrix and having amino (primary, secondary or tertiary) or imino moiety, (xviii) adsorbent based on one or more of a polymer comprising PSDVB, polymethacrylates, polyacrylamide, a natural polymer and combinations thereof and having hydroxyl or diol or polyol group, (xiv) a positively or negatively charged group, and (xv) a polymerized bis(trimethoxysilylethyl)enzene with polyhedral oligomericsilsesquioxane (POSS) bridging aromatic group.

[00118] In the present invention hydrophobic impurity affinity adsorbent and polar impurity affinity adsorbent used are rigid or gel type porous adsorbents made up of synthetic, semi- synthetic, natural or inorganic polymeric materials and they have either their surface its self and/or has ligands on the surface which are able to adsorb impurities from glycerol with high degree of selectivity/affinity compared to glycerol. The affinity ligand in such case are either part of base adsorbent or are externally grafted on the surface of such adsorbent by know activation chemistries. Therefore, said selectivity affinity is more selective than general adsorption-desorption of molecules generated in prior-art processes with ion exchange. Thus the adsorbent surface of adsorbents of present invention displays high degree of relative affinity between glycerol and organic/MONG and ionic/inorganic impurities from their mixture and makes it possible to obtain purified and refined glycerol without impurities getting in to glycerol fraction, which is obtained as unadsorbed fraction from the said adsorbents. Thus, the purification and refining in present invention is based on pure hydrophobic impurity affinity and/or polar impurity affinity and not on ion exchange or ion exclusion interactions.

[00119] In the present invention, on the said hydrophobic impurity affinity adsorbents and polar impurity affinity adsorbents, adsorption of one or more of said impurities happens and degree of adsorption or binding or affinity strength from most adsorbed to least adsorbed is polymeric mass>MONG>colouring impurities>ionic impurities>glycerol or inorganic impurities>ionic impurities>colouring impurities>MONG>polymeric mass>glycerol depending on type of adsorbent and process conditions. The affinity or selective interactions between porous adsorbent and said impurities in glycerol is based on reversible multiple or multipoint and/or mixed mode interactions involving one or more type of interactions such as hydrogen bond, electrostatic, dipole-dipole, induced dipole, van-der-waals, hydrophobic, coordinate interactions ultimately leading to selectivity/affinity.

[00120] In the embodiment of the present invention here is provided a process for purification of glycerol, wherein organic/MONG and ionic impurities adsorbs on hydrophobic impurity affinity adsorbent with higher binding selectivity and affinity indicated by their affinity constants which are in the range of 10^" 1 M to 10^" 8 M whereas glycerol does not show any affinity constant. During adsorption, affinity of organic/MONG and ionic impurities with said adsorbent trends with hydrophobic characteristics and thereby affinity of polymeric mass>MONG>colouring impurities>ionic impurities>glycerol on these adsorbents. This affinity strength keeps glycerol in unadsorbed condition and gets recovered without the organic/MONG and ionic impurities in it.

[00121] In the embodiment of the present invention here is provided a process for purification of glycerol, wherein ionic/inorganic impurities adsorbs on polar impurity affinity adsorbent with higher binding selectivity and affinity indicated by their affinity constants which are in the range of 10^" 1 M to 10^" 8 M whereas glycerol does not show any affinity constant. During adsorption, affinity of ionic/inorganic impurities with said adsorbent trends with charge characteristics and thereby affinity of inorganic impurities>ionic impurities>colouring impurities>MONG>polymeric mass>glycerol on these adsorbents. This affinity strength keeps glycerol in unadsorbed condition and gets recovered without ionic and inorganic impurities in it.

[00122] In an embodiment of the present disclosure there is provided a process for the purification of glycerol as described herein, wherein the hydrophobic impurity affinity group or polar impurity affinity group is part of base or grafted on base by known chemical transformations.

[00123] In the embodiment of the present disclosure, there is provided a process for purification of crude glycerol, wherein the hydrophobic impurity affinity adsorbent/s and/or polar impurity affinity adsorbents used are granular or spherical or irregular shaped beads or membranes can also be used as adsorbent wherein the interacting groups and/or ligand is distributed on the surface of membrane and such system is used as membrane chromatography. The membranes used can be porous or nonporous and in the form of module such as but not limited to hollow fiber, flat sheet, spiral membrane based on polyether sulfone, cellulose acetate, regenerated cellulose, nylon, polytetrafluoroethylene (PTFE) and cellulose acetate phthalate. In the preferred embodiment of present invention the cross flow type of membranes are used to avoid concentration polarization effect.

[00124] In another embodiment of the present disclosure, there is provided a process for purification of crude glycerol, wherein the ligand on the said adsorbent/s is a hydrophobic such halogen (includes chloride, bromine, fluorine, and iodine), aromatic, aliphatic etc., or hydrophilic containing amine like quaternary amine, polyamine etc, or mixed mode or hybrid groups such as polymerized bis(trimethoxysilylethyl)enzene with polyhedral oligomeric silsesquioxane (POSS) bridging aromatic group.. One skilled in the art may put same groups such as halogen or with any combination or permutation of different halogens, aromatics, aliphatic, amines etc. by methods known to those skilled in the art on modifications of adsorbents.

[00125] In an actualization of the present disclosure there is provided a process for purification of crude glycerol as described herein, wherein the glycerol is contacted with at least one hydrophobic impurity affinity adsorbent at a temperature in the range of 15 - 150 °C, for a residence time in the range of 5 minutes to 5 hours, and at a pH in the range of 1 - 12. In another actualization of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein the glycerol is contacted with at least one polar impurity affinity adsorbent at a temperature in the range of 15 - 150 °C, for a residence time in the range of 5 minutes to 5 hours, and at a pH in the range of 1 - 12. In an embodiment of the present disclosure, there is provided a process as described herein, wherein pre-treated crude glycerol or partially pure glycerol is contacted with hydrophobic impurity affinity adsorbent/s and/or polar impurity affinity adsorbent/s at temperature in the range of 15 to 150 °C, preferably in the range of 25 to 120 °C, more preferably in the range of 40 to 80°C; with residence time in the range of 5 minutes to 5 hours, preferably in the range of 10 minutes to 2 hours, more preferably 15 minutes to 60 minutes; pH in the range of 1 to 12, preferably in the range of 1.5 to 10, more preferably in the range of 3 to 9.

[00126] In another embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein purification is carried out with adsorbents mentioned above which removes impurities present in crude glycerol to a satisfactory level by their selective and affinity interactions with the adsorbents, thereby resulting in pure and colourless glycerol as a product.

[00127] In yet another embodiment of the present disclosure there is provided a process of purification of crude glycerol, wherein all organic impurities and salts in crude feed glycerol is removed by adsorption and/or absorption column chromatographic method selected from the group consisting of hydrophobic affinity interaction chromatography, reversed phase chromatography, mixed mode chromatography; most preferably hydrophobic affinity interaction chromatography, reversed phase chromatography, mixed mode chromatography.

[00128] In an embodiment of the present disclosure there is provided a process of purification of crude glycerol, wherein polar impurity affinity chromatography consists of cationic and anionic, or combinations thereof or combinations with hydrophobic group as an interacting group.

[00129] In yet another embodiment of the present disclosure there is provided a process of purification of crude glycerol, wherein organic impurities and organic salts are removed by using hydrophobic affinity adsorption and/or absorption adsorbents.

In yet another embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein adsorbents used have characteristics such as spherical and/or irregular share with particle size in the range of 5 to 1500 micron, pore size in the range of 50 to 3000 angstroms, surface area in the range of 1 m 2 /gm to 2500 m 2 /gm and surface chemistry is affinity, polar or non-polar in nature. [00130] In the embodiment of the present disclosure, there is provided a process for purification of crude glycerol or partially pure glycerol, wherein the loadability (meaning amount of glycerol to be processed per unit quality of said adsorbent) of hydrophobic impurity affinity adsorbent or polar impurity affinity adsorbents is in the range of 0.1 kg/lit to 100 kg/lit, preferably in the range of 0.5 kg/lit to 50 kg/lit, more preferably 0.5kg/lit to 25kg/lit of adsorbent on glycerol basis.

[00131] In the most preferred embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein organic impurities may be removed by passing the glycerol containing liquid fraction through a stirred tank or packed resin bed of specified configuration to obtain pure liquid fraction, wherein resins are regenerated by recycleable solvents, acids or bases or combination thereof, and without generating large waste water streams;

[00132] In yet another embodiment of the present disclosure there is provided a process for purification of crude glycerol, wherein resin used for removing organic impurities is modified sol-gel derived sorbent including but not limited to Osorb.

[00133] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein the process further comprises the step of regenerating the hydrophobic impurity affinity adsorbent, wherein the regeneration is carried out by eluting the hydrophobic impurity affinity adsorbent with a regeneration liquid to obtain eluted adsorbed impurities and regenerated adsorbent.

[00134] In another embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein the process further comprises the step of conditioning or equilibrating the regenerated hydrophobic impurity affinity adsorbent for reuse.

[00135] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein the process further comprises the step of regenerating the polar impurity affinity adsorbent, wherein the regeneration is carried out by eluting the polar impurity affinity adsorbent with a regeneration liquid to obtain eluted adsorbed impurities and regenerated adsorbent.

[00136] In another embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein the process further comprises the step of conditioning or equilibrating the regenerated ionic impurity affinity adsorbent for reuse. [00137] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein displacing phase, regeneration liquid and conditioning or equilibrating liquid for adsorbents is selected from group consisting of the one or more of following: (i) water at neutral pH of 7, (ii) acidified water at pH below 7, (iii) alkaline water at pH above 7, (iv) one or more of an alcohol including methanol, ethanol, isopropanol, tert-butanol, butanol and their mixture with water, (v) acetonitrile, (vi) chlorinated organic solvents including chloroform, dichloromethane, dichloroethane and the like, (vii) toluene, (viii) one or more of an ester including butyl acetate, ethyl acetate and the like, (ix) one or more of a ketone including acetone, methyl isobutyl ketone and the like, (x) one or more of a ion-pairing' agents or agents and one or more of an affinity and/or binding strength modifier including phosphoric acid, acetic acid, pentane sulphonic acid, trifluoro acetic acid, triphenylamine and a combination thereof, (xi) one or more of a buffer, including a citrate buffer, a phosphate buffer, an acetate buffer, a phosphate citrate buffer, a citrate-acetate buffer, borate buffer, carbonate buffer and the like, (xii) one or more of organic or inorganic salts such as sodium chloride, sodium acetate, sodium carbonate, potassium phosphate, potassium citrate, potassium carbonate, potassium acetate, ammonium sulphate, ammonium chloride (xiii) one or more of organic or inorganic acid or base such as to acetic acid, citric acid, tartaric acid, hydrochloric acid, phosphoric acid, sulphuric acid, sodium hydroxide, potassium hydroxide, triethylamine, polyethylenimine, etc., (xiv) any suitable combination of one or more of (i) to (xiii), (xv) any suitable combination of one or more of (xii) and (xiii) mentioned above, (xvi) is gas such as air, nitrogen, carbon dioxide etc, (xvii) is hot water or steam; chosen to selectively displaces the purified and refining glycerol or selectively elutes the affinity adsorbed organic/MONG and ionic/inorganic impurities from the said adsorbent as required.

[00138] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein displacing phase is selected from water at neutral pH of 7, acidified water at pH below 7, alkaline water at pH above 7, air, hot air, nitrogen, carbon dioxide, steam, or combinations thereof.

[00139] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein regeneration liquid is selected from water at neutral pH of 7, acidified water at pH below 7, alkaline water at pH above 7, steam, hot water, alcohol selected from methanol, ethanol, butanol, isopropyl alcohol or combinations or azeotropic mixtures thereof. [00140] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein regeneration liquid for hydrophobic impurity affinity adsorbent is azeotropic isopropyl alcohol containing 80% to 88% isopropyl in water.

[00141] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein regeneration liquid for hydrophobic impurity affinity adsorbent or polar impurity affinity adsorbent is azeotropic isopropyl alcohol containing 80% to 88% isopropyl in acidic water, wherein acid used is selected from group consisting of sulfuric acid, hydrochloric acid, acetic acid, citric acid, boric acid.

[00142] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein regeneration liquid for hydrophobic impurity affinity adsorbent or polar impurity affinity adsorbent is azeotropic isopropyl alcohol containing 80% to 88% isopropyl in alkaline water, wherein alkali used is selected from group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, ammonia, sodium carbonate, sodium bi-carbonate, sodium phosphate, potassium phosphate, triethylamine. The process as claimed in claim 6, wherein regeneration liquid polar impurity affinity adsorbent is acidic or alkaline water, and is with or without salts, wherein acid used is selected from group consisting of sulfuric acid, hydrochloric acid, acetic acid, citric acid, boric acid etc.; alkali used is selected from group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, ammonia, sodium carbonate, sodium bi-carbonate, sodium phosphate, potassium phosphate, triethylamine etc.; salts used is selected from group of sodium chloride, potassium chloride, sodium acetate, sodium citrate, potassium acetate, potassium citrate, ammonium chloride, ammonium acetate, sodium sulphate, potassium sulphate, ammonium sulphate, sodium carbonate, potassium carbonate.

[00143] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein regeneration liquid for hydrophobic impurity affinity adsorbent is azeotropic ethanol containing 94% to 97% ethanol in water.

[00144] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein conditioning or equilibrating liquid is water or hot water.

[00145] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein acid and/or alkali and/or salt is used at a concentration ranging from 0.001% to 15%, preferably in the range of 0.01% to 10%, more preferably in the range of 0.1% to 8% by weight.

[00146] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein regeneration liquid is recovered by the process distillation and condensation, evaporation and condensation, filtration and collecting the permeate, reverse osmosis and collecting the permeate, electro-deionisation, and combinations thereof.

[00147] In yet another embodiment of the present disclosure there is provided a process for purification of crude glycerol as described herein, wherein the displacing of residual glycerol from the hydrophobic impurity affinity adsorbent is carried out by a displacing phase selected from the group consisting of water with pH of 7, water with a pH greater than 7, water with a pH less than 7, air, hot air, nitrogen, carbon dioxide, steam, and combinations thereof.

[00148] In yet another embodiment of the present disclosure there is provided a process for purification of crude glycerol as described herein, wherein the displacing of residual glycerol from the polar impurity affinity adsorbent is carried out by a displacing phase selected from the group consisting of water with pH of 7, water with a pH greater than 7, water with a pH less than 7, air, hot air, nitrogen, carbon dioxide, steam, and combinations thereof.

[00149] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein the regenerating liquid is selected from the group consisting of neutral water having pH of 7, acidified water having pH below 7, alkaline water having pH above 7, hot water, solvents selected from methanol, ethanol, butanol, acetone, acetonitrile, tert-butanol, isopropyl alcohol or combinations or azeotropic mixtures thereof. Although the term "regenerating liquid" has been used, in context of present disclosure, regenerating liquid can include water in form of steam.

[00150] In an embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein the regenerating liquid for polar impurity affinity adsorbent is selected from the group consisting of neutral water having pH of 7, acidified water having pH below 7, alkaline water having pH above 7, hot water, solvent selected from methanol, ethanol, butanol, acetonitrile, acetone, tert-butanol, isopropyl alcohol, azeotrope, alkali selected from sodium hydroxide, potassium hydroxide, ammonium hydroxide, ammonia, sodium carbonate, sodium bi-carbonate, sodium phosphate, potassium phosphate, triethylamine, acids selected from sulfuric acid, hydrochloric acid, acetic acid, citric acid, boric acid, salts selected from sodium chloride, potassium chloride, sodium acetate, sodium citrate, potassium acetate, potassium citrate, ammonium chloride, ammonium acetate, sodium sulphate, potassium sulphate, ammonium sulphate, sodium carbonate, potassium carbonate, or combinations or azeotropic mixtures thereof. Although the term "regenerating liquid" has been used, in context of present disclosure, regenerating liquid can include water in form of steam.

[00151] In the embodiment of the present disclosure, there is provided a process for purification of crude glycerol or partially pure glycerol, wherein the equilibration/conditioning liquid, displacing phase and regeneration liquid used for said adsorbent contains the organic modifier such as but not limited to alcohols (methanol, ethanol, isopropanol, butanol), acetonitrile, chlorinated organic solvents (chloroform, die lhloro methane, dichoroethane) toluene, esters (butyl acetate, ethyl acetate), ketones (acetone, methyl isobutyl ketone), and any suitable combination of one or more than one thereof. Water may also be combined with these solvents to adjust and manipulate the desired affinity and/or interaction ability of the organic/ MONG, mono, di, tri-glycerides with the adsorbent as required. Water can be also be used in proportion from 0% to 100% depending on the type of crude or partially pure glycerol contacted with the adsorbent/s. For example, in case of conditioning and displacing 100% water was used whereas for in regeneration water concentration used was as low as 0%. The In the embodiment of the present invention there is provided a process for purification of crude glycerol or partially pure glycerol, the equilibration/conditioning liquid, displacing phase and regeneration liquid used for said adsorbent optionally contains suitable ion-pairing agent/s and/or affinity and/or binding strength modifiers such as, but not limited to, phosphoric acid, acetic acid, pentane sulphonic acid, trifluoro acetic acid, triethylamine and any suitable combination of one or more than one thereof. The concentration of ion-pairing agent in the mobile phase ranges from 0.001 %v/v to 2.5%v/v depending upon the type of ion-pairing agent selected. Buffer such as, but not limited to, citrate buffer, phosphate buffer, acetate buffer, phosphaste-citrate buffer (Macllav buffer), citrate-acetate buffer, borate buffer, carbonate buffer can be used for creating the difference between interactions or binding or affinity strength of said impurities with the said adsorbent/s. In the preferred embodiment of present invention food grade salts, solvents, buffers, acids and alkalis are used

[00152] In another embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein the water removal treatment comprises drying or de-watering steps selected from evaporation and collecting the residue, distillation and collecting the residue, passing through or contacting with molecular sieves, treating with dehydrating agents like sodium sulphate and silica, treating with dehydrating membranes.

[00153] In another embodiment of the present disclosure there is provided a process of purification and refining of crude glycerol, wherein concentration and/or dewatering of purified or partially purified liquid fraction containing glycerol to concentrated pure glycerol may be carried out by evaporation, distillation, nano filtration, diafiltration, reverse osmosis, or any other known unit operation or combinations thereof.

[00154] In another embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein organic/MONG impurities are recovered as valuable by-product.

[00155] In another embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein hydrophobic impurity affinity adsorbent/s and/or polar impurity affinity adsorbent/s is contacted with crude glycerol or partially purified glycerol in adsorption or chromatographic column/s operating in co -current or counter current or periodic counter current mode. In the process of present invention one or more of such hydrophobic impurity affinity adsorbent/s and/or polar impurity affinity adsorbents are filled in same or different columns, and one or more of such columns are operated in various combinations in parallel or in series such as in tandem chromatography mode or in periodic continuous chromatography mode.

[00156] In the embodiment of the present disclosure, there is provided a process for purification of crude glycerol or partially pure glycerol, wherein the one polar impurity affinity adsorbents column is in series with hydrophobic impurity affinity adsorbent column and which is further in series with another polar impurity affinity adsorbents column. Yet in another embodiment of the present invention there is provided a process for purification of crude glycerol, wherein the one hydrophobic impurity affinity adsorbent column is in series with two polar impurity affinity adsorbents column, and in another embodiment of the present invention there is provided a process for purification of industry white (IW) grade, wherein the one or more hydrophobic impurity affinity adsorbent column is in operated as parallel or in series such as in tandem chromatography mode or in periodic continuous chromatography mode or counter-current chromatography mode.

[00157] In the embodiment of the present disclosure, there is provided a process for purification of crude glycerol or partially pure glycerol, wherein the process is carried out in batch, semi-continuous or continuous mode. In the process, a operation in packed bed or expanded bed adsorption (EBA) or fluidized bed adsorption (FBA) or liquid solid circulating fluidized bed (LSCFB) or membrane adsorption (MBA) or improved simulated moving bed (ISMB) or moving bed or any combination thereof is used. In the process of the present invention when expanded bed or fluidized bed is used, loading, displacing, regeneration and conditioning is performed in expanded, fluidized or packed bed mode. Preferably the regeneration is carried out in packed bed mode. In case of batch system a stirred tank or agitated tank can be used and to make it continuous stirred tank (CSTR) is used

[00158] In another embodiment of the present disclosure, there is provided a process for purification of crude glycerol as described herein, wherein process for purification and refining of crude glycerol or partially pure glycerol is carried out in batch mode or semi- continuous mode or continuous mode.

[00159] In yet another embodiment of the present disclosure there is provided a process of purification and refining of crude glycerol, the adsorption and/or absorption process in carried out in but not limited to stirred tanks, packed bed, fluidized bed, expanded bed, fluidized/expanded moving bed, simulated moving bed, centrifugal, annular in batch, semi-continuous or continuous mode.

[00160] The present invention provides a process for purification and refining of crude and partially pure glycerol derived from saponification, fat splitting and biodiesel production processes or combinations thereof comprising:

1. treating the crude glycerol or partially pure glycerol to obtain pre- treated glycerol;

2. contacting pre-treated glycerol obtained from step (a) or partially pure glycerol with hydrophobic impurity affinity adsorbent/s and/or polar impurity affinity adsorbent/s in stirred tank, adsorption or chromatographic column/s to selectively or affinity adsorb the organic/MONG and ionic/inorganic impurities, and to thereby to obtain purified and refined glycerol, wherein assay purity of recovered, purified and refined glycerol is at least 99% (on anhydrous basis) with total organic/MONG impurities below 0.01%, total inorganic impurities below 0.01%, and yield of more than 98%;

3. displacing the crude glycerol or partially purified glycerol from the adsorbent/s by displacing phase to recover purified and refined glycerol, wherein total recovered purified and refined glycerol is more than 98%;

4. regenerating the hydrophobic impurity affinity adsorbent/s and/or polar impurity affinity adsorbent/s with regeneration liquid to elute adsorbed impurities, and collecting the regeneration liquid with eluted adsorbed impurities;

5. conditioning or equilibrating the regenerated adsorbent of step (d) using conditioning or equilibrating liquid for reusing the said regenerated and conditioned adsorbent/s in step (b);

6. treating the collected regeneration liquid with eluted impurities obtained from step (d) to recover the regeneration liquid by separating eluted impurities as a by-product, and recycling the recovered regeneration liquid for the regeneration of said adsorbent/s in step (d); and

7. subjecting the recovered, purified and refined glycerol obtained from step (b) and/or step (c) to one or more drying, de-watering, concentration steps or combinations thereof to obtain purified and refined glycerol with less than

0.5. water/moisture.

[00161] Similarly, in the present invention provides a process for purification and refining of partially pure glycerol such as yellow and industry white glycerol obtained from fat splitting, saponification or biodiesel production processes, wherein said process comprises:

1. contacting partially pure glycerol with hydrophobic impurity affinity adsorbent/s and/or polar impurity affinity adsorbent/s in stirred tank, adsorption or chromatographic column/s to selectively or affinity adsorb the organic/MONG and ionic/inorganic impurities, and to thereby to obtain purified and refined glycerol, wherein assay purity of recovered, purified and refined glycerol is at least 99% (on anhydrous basis) with total organic/MONG impurities below 0.01%, total inorganic impurities below 0.01%, and yield of more than 98%;

2. displacing the crude glycerol or partially purified glycerol from the adsorbent/s by displacing phase to recover purified and refined glycerol, wherein total recovered purified and refined glycerol is more than 98%;

3. regenerating the hydrophobic impurity affinity adsorbent/s and/or polar impurity affinity adsorbent/s with regeneration liquid to elute adsorbed impurities, and collecting the regeneration liquid with eluted adsorbed impurities; 4. conditioning or equilibrating the regenerated adsorbent of step (d) using conditioning or equilibrating liquid for reusing the said regenerated and conditioned adsorbent/s in step (b);

5. treating the collected regeneration liquid with eluted impurities obtained from step (d) to recover the regeneration liquid by separating eluted impurities as a by-product, and recycling the recovered regeneration liquid for the regeneration of said adsorbent/s in step (d); and

6. subjecting the recovered, purified and refined glycerol obtained from step (b) and/or step (c) to one or more drying, de-watering, concentration steps or combinations thereof to obtain purified and refined glycerol with less than 0.5% water/moisture.

[00162] In the embodiment of the present invention there is provided a process for purification of crude glycerol, wherein the affinity chromatography on porous adsorbents is carried out as

a) the solution containing glycerol with impurities such as crude glycerol or partially pure glycerol is brought in contact with a pre-equilibrated or preconditioned hydrophobic impurity affinity adsorbent/s and/or polar impurity affinity adsorbents whereby the said organic/MONG and/or ionic/inorganic impurities adsorbs through affinity interactions with selectively onto it, and purified and refined glycerol is recovered as unadsorbed fraction with at least 98% recovery and at least 99% assay purity on anhydrous basis with total organic/MONG impurities below 0.01%, and

b) draining and/or displacing the said adsorbent of step (a) using displacing liquid or air or an non-reacting gas to remove free purified and refining glycerol, in the adsorbent bed, and regenerating the said affinity adsorbent/s using regenerating liquid, and thereby eluting said affinity adsorbed impurities from the adsorbent, and collecting the regeneration liquid with eluted impurities, and treating the recovered regeneration liquid to separate out eluted impurities and regenerating liquid, wherein recovered regenerating liquid after separation of impurities is cycled in the process, and recovered impurity fraction is obtained as a by-product, and

c) conditioning or equilibrating the regenerated adsorbent/s using conditioning or equilibrating liquid for reuse of said adsorbent/s in the next cycle, and d) optionally, treating the purified and refined glycerol obtained in step (a) with one or more ion exchange resins or activated charcoal to improve colour and/or impurity profile of purified and refined glycerol, and e) optionally, drying or de-watering or water removal of purified and refined glycerol by know techniques such as distillation, evaporation or using molecular sieves and thereby obtaining purified and refined glycerol with moisture content of below 0.5%.

ADVANTAGES

[00163] The present disclosure has several advantages over prior art, which are as follows:

1) The present disclosure provides a cost effective process for purification of glycerol having wide application in medical, pharmaceutical, food, industrial applications and personal care preparations.

2) The present disclosure provides a robust but simple separation technique for removal of polymeric, organic, MONG and inorganic, coloured impurities to produce high purity of glycerol.

3) The present disclosure provides a high recovery and purity (near 100%) of glycerol from feed of crude glycerol.

4) In the process adsorbents and absorbents are regenerated and recycled in the process.

5) The present invention provides purified and refined glycerol at low cost and low energy requirements and in lesser number of steps/operations.

6) The present invention also provides organic/MONG impurities as by-product which can be used for generation of energy or further value addition to obtain fatty acids, glycerides, sterols, tocopherols etc.

EXAMPLES:

[00164] The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may vary.

Example 1: Pre-treatment of crude glycerol to obtained from various sources

[00165] Crude glycerol or partially pure glycerol obtained from biodiesel production, fat/oil splitting saponification and fermentation process was treated using different known processes such as distillation, flocculation/coagulation, filtration, neutralization, acidification etc. to obtain partially pure glycerol so as to process it using the process of present invention. In case of sweet water and crude glycerol obtained from fat/oil splitting about 0.1 to 3.0% of polymeric mass/impurities and coloured impurities were observed. It was found that the crude glycerol obtained from above sources is of varying quality and therefore, partially pure glycerol obtained after pre-treatment is also of varying quality but clear enough to be processed using adsorbents of present invention. Table 1 shows quality of crude or partially purified glycerol obtained from biodiesel production, fat/oil splitting, during distillation of biodiesel crude glycerol and crude glycerol obtained after flocculation, filtration and concentration by evaporation of sweet water from fat/oil splitting process. These glycerol containing impurities are used in the process of present invention to recover purified and refined glycerol of more than 99% assay purity and more than 98% recovery with MONG and ash below 0.01% as well as moisture below 0.5%. Industry white (IW) grade glycerol is also a partially pure glycerol and is directly used in the process to obtain purified and refined glycerol Table 2 shows the quality of glycerol obtained after applying pre-treatment steps to various crude glycerol to obtain partially pure glycerol.

Table 1: Quality of crude glycerol or partially pure glycerol obtained from biodiesel production, fat/oil splitting and fermentation process, and used in the process of present invention ( Sr. No 1 to 4 is crude glycerol from biodiesel production; Sr. No. 5 to 6 is yellow glycerol obtained after distillation of crude biodiesel glycerol; Sr. No. 7 to 8 is industry white grade glycerol obtained after distillation of biodiesel and fat/oil splitting process respectively; Sr. No 9 to 11 is sweet water from fat/oil splitting process; and Sr. No 12 and 13 is crude glycerol obtained from fat/oil splitting process after treatment with flocculation, filtration and concentration by evaporation.

(%) (%)

1 77.0 3.3 16.1 2.3 4.6 <0.01 1.25

2 61.0 2.3 2.5 29.4 6.8 0.23 1.20

3 83.4 2.7 10.7 1.5 4.2 0.18 1.25

4 74.5 2.4 14.3 4.6 6.7 0.55 1.25

5 94.8 5.4 2.0 0.0 3.2 <0.01 1.25

6 89.42 7.2 0.82 0.0 9.7 <0.01 1.26

7 96.5 7.6 1.3 0.0 1.0 <0.01 1.21

8 97.1 7.1 1.8 0.0 1.1 0.00 1.26

9 8.3 4.1 91.29 0.04 0.15 0.00 1.02

10 30.0 4.5 68.9 0.13 0.47 0.00 1.07

11 19.7 4.4 79.5 0.09 1.61 0.00 1.04

12 88 9.8 2.3 <0.5 5.4 0.00 1.23

13 84 8.9 6.4 <0.5 6.9 0.00 1.23

14 5.4 5.3 91.21 3.12 0.23 0.00 1.01

Table 2: Quality of partially pure glycerol obtained after pre-treatment to crude glycerol obtained from various sources shown in table 1 above.

filtration

Flocculation,

10 30.0 5.1 68.8 0.14 0.41 0.00 filtration

Flocculation,

filtration,

11 87.4 4.8 2.7 0.41 7.25 0.00 concentration

by evaporation

Dilution,

12 Flocculation, 70.2 9.5 25 <0.5 4.1 0.00 filtration

13 Distillation 92.19 7.1 0.6 <0.01 7.21 0.00

Flocculation,

14 5.5 5.4 91.9 2.30 0.24 0.0 filtration

Example 2: Determination of organic/MONG impurities and ionic/inorganic impurities, their affinity interaction or affinity strength with hydrophobic impurity affinity adsorbent and polar impurity affinity adsorbent

[00166] Various glycerol samples obtained after pre-treatment were analyzed for determination of organic/MONG impurities and ionic/inorganic impurities. Organic/MONG impurities were analyzed by known GC-MS and HPLC-MS methods for fatty acids, fatty acid esters, sterols, tocopherols etc., ash content was determined by gravimetric methods, water content was determined by Karl-fisher moisture analyzer, polymeric mass/impurities were determined by difference method, salt/ions and heavy metals were determined by ion chromatography and ICP-MS, glycerol content was analyzed by titration and HPLC method using amine column with 191 nm wavelength for detection etc. Further, the affinity strength or binding constant was determined by performing adsorption isotherms on hydrophobic impurity affinity adsorbent/s and polar impurity affinity adsorbent/s, wherein different concentrations (between lgm/lit to 500 gm/lit) of partially pure glycerol containing impurities was contacted with adsorbents and incubated for 12 hours and then concentration of impurities as well as glycerol was determined by known analytical methods for their quantification. Similarly, in another experiment, 100 gm/lit concentrations of partially pure glycerol containing impurities was contacted with adsorbents on rocker sharer and concentration of impurities as well as glycerol was determined at different time intervals to determine the residence time required to attain equilibrium. It is found that equilibrium attainment time for both hydrophobic impurity affinity adsorbent and polar impurity affinity adsorbent is between 5 min to 30 min. This is due to their porous nature and high diffusion constants showing faster diffusion of impurities in presence of glceyrol. The results of presence of various impurities, their range of affinity constants and range of equilibrium time is given in table 3 below. The results shows that there is distinct affinity difference between glycerol and other impurities and also between organic/MONG and ionic/inorganic impurities, which allowed us to invent a process for selectively capture/adsorb such impurities and obtain glycerol in purified and refined form with more than 99% purity.

Table 3: impurities in glycerol and their affinity or binding constants and equilibrium attainment time on hydrophobic impurity affinity adsorbent and polar impurity affinity adsorbent

Example 3: Purification and refining of glycerol in sweet water (crude glycerol) obtained from fat/oil splitting process

[00167] 1 Liter of sweet water (crude glycerol) obtained from fat/oil splitting industry and containing 6%w/w of glycerol, 0.02% inorganic impurities and 0.16% of organic/MONG impurities was taken into a beaker and a flocculating agent (Alum) equivalent to 500 ppm was added. The mixture was then stirred at 100 rpm for 3 hrs at 28±2 °C. The mixture was filtered using 0.45 μιη filter to remove flocculated mass or particulate matter in retentate. To the permeate, 0.1 % w/v activated charcoal was added and the reaction system was stirred at 100 rpm for 50 minute at 60±2 °C to remove the color and few organic impurities. The mixture was again filtered using 0.45 μιη filter, and permeate liquid i.e. partially pure glycerol was loaded into series of columns packed with polar impurity affinity adsorbent column (Diaion PK228), hydrophobic impurity affinity adsorbent (Sepabeads SP700) and another polar impurity affinity adsorbent (Osorb) column. Each column was packed with 10 ml of said adsorbent and was conditioned with water till pH of 7.0 before loading of partially pure glycerol. All three columns were connected in tandem, meaning output of first column was fed to second column and output of second column was fed to third column in series. Partially pure glycerol was loaded at linear flow velocity of 152 cm/hr. The temperature of all columns and feed glycerol was maintained at 25 °C. About 100 bed volumes (1 bed volume = volume of adsorbent packed in one column) of partially pure glycerol was passed through the columns to selectively or affinity adsorb the ionic impurities in first column, ionic and hydrophobic organic/MONG impurities in second column and ionic/inorganic impurities in third column, and thereby allowing to obtain purified and refined glycerol in unadsorbedfraction from third column. This was followed by displacing the glycerol from voids space inside the columns in a tandem mode using 100 mL of deionized water of pH 7.0. The loadability of each polar impurity affinity adsorbent and hydrophobic impurity affinity adsorbent was 6.0 kg/lit of adsorbent. The purified and refined glycerol was obtained at the outlet of third column and was collected for analysis. The columns were regenerated to selectively elute out affinity adsorbed impurities from individual column before their reuse next cycle. First polar column was regenerated with 2% sulphuric acid and 96% ethanol in water, second column was regenerated with 96% ethanol in water and third column was regenerated with 2% sodium hydroxide containing 5% sodium chloride in water. This was then followed by conditioning or equilibration of each column with water at pH 7.0 before reusing the adsorbent/s packed in each column. The fraction containing purified and refined glycerol collected from third column was analyzed for glycerol content using titration method as well as HPLC using amine column, and organic/MONG impurities using HPLC, GC, LC- MS, moisture content using Karl-fisher and ionic/inorganic impurities using ion chromatography, ICP-MS etc. It was found that about 98.6% of glycerol (i.e. 59.16 gm) is recovered. This was then dried by evaporation at 80 degree Celsius under vacuum of 2 mbar. The dried glycerol was having moisture content of 0.1%, total organic/MONG impurities were below the limit of detection on GC-MS/HPLC-MS (i.e. below 1 ppb), ash/inorganic content was 0.01%, colour index of less than 10 APHA units (or absorbance of 0.0003 at 420 nm on UV/Vis spectrophotometer), and assay purity of recovered purified and refined glycerol 99.7%. Thus, the recovered was meeting pharmacopoeial (USP, BP, EP, JP and JP) specifications. In the process, the regenerating liquid collected from first and second column was distilled to recover 99.5% of ethanol in 96% concentration for its reuse in next cycle and the 1.57 gm of organic/MONG impurities were collected as energy rich by-product. The regenerating liquid recovered from third column was evaporated at 90 degree Celsius and condensation product was collected pure water to reuse in the process.

Example 4: Purification of partially pure glycerol (Industrial White (IW) grade glycerol) obtained from fat/splitting process

[00168] 5.63 kg of partially pure glycerol i.e. IW grade glycerol containing 97.2% of glycerol and 1.575% of organic/MONG impurities specifically free-fatty acids (such as oleic, linoleic, steric, plamitic, erucicetc), sterols, di-glycerides, mono-glycerides and triglycerides etc and 1.2% water was obtained from fat/oil splitting process. This was obtained by flocculating the 30 lit of sweet water (crude glycerol) containing 29.2 %w/w of glycerol, with 250ppm of alum for 3.0 hours, followed by filtration using filter press and then evaporation of water using multiple effect evaporator (MEE). The concentrated glycerol was then 750 mm Hg of vacuum. The partially pure glycerol (IW grade) was collected as top fraction and yellow glycerol was collected at lower fraction. Both fractions are called as partially pure glycerol but 5.63 kg of IW grade was 97.2% pure with 1.575% organic/MONG impurities, where as 3.13 kg of yellow glycerol was 92.1% due to high amount i.e. 7.3% organic/MONG impurities.

[00169] The IW grade, partially pure glycerol (5.63 kg) was contacted with hydrophobic impurity affinity chromatography column packed with 100 ml of sepabeads SP207 (Mitsubishi Chemical Corporation, Japan) i.e. at loadability of 56.3 kg/lit of adsorbent to selectively adsorb organic/MONG impurities. The feed was passed through the jacketed borosilicate glass column packed bearing stainless steel adjustable flow adaptors and peristaltic pump to push the liquid through the column packed with said adsorbent. The packed adsorbents were first pre-equilibrated with water at pH of 6.8 and maintained at temperature of 50 degree Celsius using hot water circulating through a jacket. The feed IW grade glycerol was charged using a pump at the flow rate of 2.25 bed volume per hour (1 bed volume = 100 ml of said adsorbent) and residual glycerol in the void space was then displaced with deionized water in downward flow direction at same flow rate. The pressure inside the column was maintained at 1.5 bar and purified and refined glycerol was collected as unadsorbed fraction during loading and displacing step. About 1.5 bed volume of water was used to displace the glycerol from the column. The recovered glycerol was then evaporated to remove water or for de-watering and dried glycerol was then collected. 5.43 kg of purified and refined glycerol was obtained showing 99.2% recovery. Assay purity of this glycerol as per titration method of US, EP, BP, and IP pharmacopoeia was 99.9% and organic/MONG impurities were not detectable on HPLC-MS and GC-MS. The moisture content was 0.05% and ash was 0.01% meeting the standards for phama, medical, cosmetic, food and industrial applications.

[00170] After glycerol recovery, hydrophobic impurity affinity adsorbents in the column was regenerated using with 88%v/v azeotrope of isopropyl alcohol in water as regenerating liquid, about 2.0 bed volumes by passing it through the column at 2.0 bed volumes per hour flow rate. The regenerating liquid was then collected from the column and distilled to obtain 87%v/v isopropyl alcohol as pure azeotrope and was used in next cycle to regenerate the adsorbent. During distillation, 88.5 gm of organic/MONG impurities were obtained, which was selectively eluted in azeotrope isopropyl alcohol as regenerating liquid. This was then used to further fractionate, and obtain free fatty acids and fatty acid esters by fractional distillation. The adsorbents after regeneration were conditioned/equilibrated with water for next reuse for purification and refining of glycerol.

Example 5: Purification of partially pure glycerol (yellow glycerol) obtained from fat/splitting process.

[00171] 3.13 kg of yellow glycerol obtained in example 4 and containing 92.1% glycerol with high amount i.e. 7.3% organic/MONG impurities was purified using process of present invention. Partially pure glycerol (i.e. yellow glycerol) was contacted with first column packed with first polar impurity affinity adsorbent (Diaion SK1B, Mitsubishi Chemical Corporation, Japan) and output of this was passed on to the second column packed with hydrophobic impurity affinity adsorbent (Sepabeads HP20, Mitsubishi Chemical Corporation, Japan), and the glycerol from this column was then passed to third column packed with second polar impurity affinity adsorbent (Diaion WA30, Mitsubishi Chemical Corporation, Japan). Each column was having 100 ml of adsorbent and columns used were glass column with jacket where temperature was maintained at 80 degree Celsius throughout the process. In each column impurities were adsorbed selectively through affinity interactions. About 2.82 kg of purified and refined glycerol was obtained which was then used as cosmetic grade pure glycerol. This glycerol was having assay purity of 99.7% on anhydrous basis. The loadability of adsorbent was 31.3 kg/lit of adsorbent. The fraction of this pure glycerol was subjected to dehydration or water removal step using molecular sieves to obtain purified and refined glycerol with less than 0.5% moisture. The pure glycerol obtained was having organic/MONG impurities less than 0.001%. The adsorbent after recovery of glycerol, was regenerated with 2% acetic acid in 88% (azeotropic) isopropyl alcohol in water for first polar impurity affinity adsorbent column, 85% isopropyl alcohol in water at pH 5.0 for hydrophobic impurity affinity adsorbent, and 2% potassium hydroxide containing 10% potassium chloride in water as regenerating liquid to selectively elute affinity adsorbed impurities from respective column. These regenerating liquids were collecting from each column and then subjected to recovery step. Regenerating liquid from first and second column was distilled to recover azeotropic isopropyl alcohol for its recycle in the process and thereby yielding 228 gm of organic/MONG with coloured impurities as by-product. Regenerating liquid from third column was evaporated to dryness and water was recovered for its recycle in the process and salts were recovered as by-product. Thus there no any effluent in the process making it zero discharge and economically viable. The adsorbents after regeneration were conditioned/equilibrated with water acidic water of pH less than 7.0, neutral water of pH 7.0 and alkaline water of pH more than 7.0 for first, second and third column respectively their reuse for purification and refining of glycerol.

Example 6: Purification of Yellow Glycerol to high purity glycerol

[00172] 250 g of Yellow Glycerol obtained as a distillation condensate from distillation of crude glycerol obtained from biodiesel production at 250 degree Celsius under vacuum. The yellow glycerol was containing 225 g of Glycerol and 28.2 gm of organic/MONG impurities as free fatty acids, fatty acid esters, sterols, and other impurities as pigments,odour etc. was taken for purification experiment. It was fed to jacketed borosilicate glass adsorption column (Column- 1) fitted with stainless steel adaptors and filled with pre- equilibrated O. llit of first polar impurity affinity adsorbent, Diaion PK228 (Mitsubishi Chemical Corporation, Japan) adsorbent to get 0.28 meter bed height. The feed was charged using a peristaltic pump at a flow rate of 4 mL per minute followed by washing with deionised water. The unbound and wash fraction from Column- 1 was then continuously fed to jacketed borosilicate glass adsorption column (column-2) fitted with stainless steel adaptors and filled with pre-equilibrated 0.05 L of charcoal to get 0.15 meter bed height. The feeding was done at the rate of 4 ml per minute. The wash and unbound fractions from Column-2 was then fed to jacketed borosilicate glass adsorption column (Column-3) fitted with stainless steel adaptors and filled with pre-equilibrated 0.1 L of hydrophobic impurity affinity adsorbent Sepabeads SP700 (Mitsubishi Chemical Corporation, Japan) adsorbent at a flow rate of 4 mL per minute. The wash and unbound fractions from Column-3 was fed to jacketed borosilicate glass adsorption column (Column-4) fitted with stainless steel adaptors and filled with pre-equilibrated 0.1 L of second polar impurity affinity adsorbent Sepabeads HP2MG (Mitsubishi Chemical Corporation, Japan) adsorbent. Loading of yellow glycerol was at loadability of 2.5 kg/lit adsorbent. Process was carried out at temperature of 45 degree Celsius by passing hot water through the jacket of each column. Each column was then displaced with nitrogen and deionised water. The HPLC analysis of purified glycerol obtained during loading and displacing step was more than 99.5% assay purity on anhydrous basis. Adsorption efficiency of said first polar, hydrophobic and second polar impurity affinity adsorbents was selective affinity to adsorb ionic, organic/MONG and inorganic impurities respectively. The purified and refined glycerol obtained was treated in evaporation unit to removal water and glycerol meeting pharmacopeia specification was obtained, where moisture content was less than 0.4%, total MONG was less than 0.002%, ash content was <0.02% and heavy metal were less than specified limits by USP, EP, BP, IP, JP etc. about 223 gm of such glycerol was obtained showing recovery of purified and refined glycerol was 98.9%. The polar and hydrophobic impurity affinity adsorbent column were then regenerated and regenerating liquid recovered was treated to obtain 26 gm of organic/MONG impurity fraction, and pure form of regenerating liquids for their reuse in the process. The regenerating liquid used were 1.5% sulfuric acid in azeotropic ethanol, azeotropic isopropyl alcohol and 3% sodium hydroxide containing 6% sodium chloride respectively for first polar, hydrophobic and second polar impurity affinity adsorbent columns to selectively elute impurities from these adsorbent columns. Charcoal column was also regenerated with azeotropic isopropyl alcohol. After regeneration all column were conditioned with de-ionized water for reuse in the process.

Example 7: Purification of the crude glycerol obtained from biodiesel production

[00173] 10.8 Kg of crude glycerol containing 7.74 Kg of glycerol, 0.465 kg of salts in the form of sodium sulphate and sodium chloride, 1.10 kg of organic/MONG impurities (i.e. free fatty acids, fatty acid esters, sterols, tocopherols, monoglycerides, diglycerides, triglycerides etc.), 0.28 kg of polymeric mass/impurities, 0.11 Kg of methanol and 1.065 kg of water was first treated to flash remove methanol with part of water which was collected as by-product. Later in the pre-treatment process and then distilled/flashed without fractionation to obtain partially pure glycerol without salts. About 8.82 kg of partially pure glycerol is obtained containing 87.75% glycerol, 11.4% organic/MONG impurities and 0.62% of polymeric mass and coloured impurities and 0.23% of ionic impurities. The partially pure glycerol having pH of 4.2 was then processed using process of present invention. Jacketed borosilicate glass adsorptions fitted with adaptors and adsorbents pre-conditioned with water at pH 6.9 was used. Peristaltic pumps were used to pump the liquids through the columns. First column was having hydrophobic impurity affinity adsorbent, (Sepabeads SP207, Mitsubishi Chemical Corporation, Japan), second column was packed with first polar impurity affinity adsorbent (Osorb, ABS materials, USA), third column was packed with second polar impurity adsorbent (Diaion HP2MG, Mitsubishi Chemical Corporation, Japan) and finally an activated charcoal column/polar impurity affinity adsorbent (Diaion CR11, Mitsubishi Chemical Corporation, Japan) as finish step. Each column was packed with 1.5 lit of respective adsorbent and columns were operated at flow rate of 1.0 bed volume per hour in downward flow mode and at 2 bar pressure drop. In these columns impurities were adsorbed selectively through affinity interactions. After complete charging of partially pure glycerol, columns were displaced with air, nitrogen and water and purified glycerol was collected in 99.3% recovery. This glycerol was having 14.6% water and useful as cosmetic and industrial applications. Further, the purified glycerol was then evaporated to remove water and then was treated with molecular sieves to obtain purified and refined glycerol with 0.2% moisture. This pure glycerol was having assay purity of 99.78% on anhydrous basis by titration and HPLC method, ash content of 0.02%, total organic/MONG impurities of below detection limit of total 1 ppb, heavy metals were below acceptable limits as specified by various pharmacopoeia (US, JP, BP, EP, and IP). Further, the adsorbents of each column was regenerated with regenerating liquid i.e. isopropyl alcohol for hydrophobic impurity affinity adsorbent, 2% sulphuric acid in azeotropic ethanol in water for first polar impurity affinity adsorbent, and 4% sodium hydroxide containing 7% sodium chloride for second polar impurity affinity adsorbent. The organic solvent from collected azeotropic ethanol and isopropyl regenerating liquids was recovered by evaporation and condensation operation and thereby obtained these solvents for recycle in the process and organic/MONG as by-product. Sodium hydroxide containing sodium chloride liquid collected was treated by membrane filtration followed by evaporation to obtain pure water for recycle in the process and salt/inorganic products as by-product.

Example 8: Purification of the crude glycerol obtained from oil / fat splitting process

[00174] 5 Kg of Crude glycerol was obtained from fat/oil splitting where sweet water containing 11.5% glycerol was treated through flocculation, filtration and then concentration by evaporation. This 5 kg of concentrated crude glycerol contains 4.4 Kg of glycerol, 0.25 Kg of water, 0.28 Kg of fatty matter, 0.05 Kg polymeric organic mass, colour as well as 0.02 kg of salts/inorganic impurities. 2.12 Kg of deionised water was added to this feed and stirred under hot condition at temperature of 80-120 °C. 18 g of alum was added to this mixture under stirring under hot condition. The mixture was then incubated at 80 °C for 3 hrs for flocculation under slow stirring followed by filtration on 11 micron filter as a part of the pre- treatment to the crude glycerol. Total 7.08 Kg filtrate was obtained which was then processed as discussed in example 7 with change in sequence of columns to selectively adsorb the impurities with affinity interactions. The loadability used was 4.4 kg/lit of adsorbent and columns wee maintained at 55 degree Celsius temperature. Here, first column of polar impurity affinity adsorbent followed by hydrophobic impurity affinity adsorbent and then second column of polar impurity affinity adsorbent was used with 1.0 lit of each adsorbent. Final step was activated carbon as finish step to reduce the odour of the glycerol. Purified and refined glycerol obtained was with 99.84% assay purity and was containing 0.01% ash, 0.1% moisture, and other impurities below the limits of acceptance as per pharmacopoeia specifications. The recovery of the purified and refined glycerol was 98.97% and adsorbent were reused after regeneration as well as regenerating phases were recycled after distillation and recovering organic/MONG impurities as by-product.

Example 9: Purification of sweet water (3-15 % w/v Glycerol) to high purity glycerol

[00175] 20 L sweet water having glycerol content of 7 % w/v, 1 % free fatty acids, organic polymeric impurities and 0.4 % w/v salts. The sweet water was pre-filtered with 11 micron filter and then it was then treated as discussed in example 7 with 14 ml of adsorbent in respective column where total loadability is 100 kg/lit of adsorbent and temperature used was 20-25 degree Celsius. 1.38 kg of purified and refined glycerol was obtained after loading the displacing the columns with air and water leading to 98.57% recovery. Glycerol obtained after water removal by evaporation under 12mbar vacuum at 90 °C was having 99.69% assay purity. After displacing step adsorbents were regenerated with 3.5 lit of regeneration solution comprising of mixture of methanol, Water, H₂SO₄ as well as mixture of 4 % NaOH in water. During recovery of regenerating liquids 0.196 kg of MONG impurities were recovered as by-product.

Example 10: Reusability and performance of the hydrophobic impurity affinity adsorbents and hydrophobic impurity affinity adsorbents in the process of present invention

[00176] The hydrophobic impurity affinity adsorbents and hydrophobic impurity affinity adsorbentsof the process of present invention were regenerated using regenerating phase followed by conditioning (preferably using water) and were reused in the process. One typical reusability study was done for 50 consecutive trials with process as discussed in example 6 and 7 and average performance in terms of loadability and assay purity of purified and refined glycerol is shown in Figure 1, and recovery with typical input sample is shown in Figure 2. The study indicates that the process performance and performance of said adsorbents is consistent and hence commercially viable at industrial scale. Similar consistent results were obtained for crude or partially purified glycerol even after operating the process at 1000 kg/day output scale to obtain pharma grade glycerol by the process of present invention.

Example 11: Effect of variation of crude glycerol source and composition on quality of purified and refined glycerol obtained from the process of present invention

[00177] Various crude glycerols having below mentioned specifications as given into the Table 4 were processed after suitable pre-treatment as discussed in example 1. Except crude glycerol type 2, all others were processed as per process of example no 7 and crude glycerol 2 was processed using process as discussed in example no 3. It was found that process robust with respect to variation in feed quality and still gives purified and refined glycerol in above 98% recovery and above 99% assay purity with pharmacopoeial specifications.

Table 4: Various types of crude glycerol and their composition

Ash content

11 <0.01 <0.006 <0.01 <0.01 <0.01 <0.01

(%)

Other

impurities

12 <0.01 <0.01 <0.02 <0.03 <0.01 <0.03 including

MONG (%)

Colour,

13 absorbance at 0.0001 0.0002 0.0001 0.0003 0.0004 0.0003 420 nm

14 Odour odorless odorless Odorless odorless odorless odorless

Colouration No No No No No No

15 after heating at change in change in change in change in change in change in 292°C colour colour colour colour colour colour

[00178] The present disclosure thus provides an efficient method for purification of glycerol, wherein purity levels of above 99% can be achieved with recovery being above 98%. It is a common experience in the field of purification of chemical substances, that it is relatively easy to purify a substance up to a certain extent, but beyond that it is very challenging to further purify or refine the substance, especially when the impurities have already been brought down to a very small percentage, though still above acceptable limits. It was delightful to note in case of the present disclosure that, on subjecting the glycerol to purification by reverse phase adsorption (hydrophobic impurity affinity adsorbent), this percentage could be brought down to below 0.01%. Eventually after all steps were carried out, the pure and refined glycerol so obtained had a purity of 99.6% with all the impurities well within the acceptable limit. The process uses a hydrophobic impurity affinity adsorbent and a polar impurity affinity adsorbent to achieve such high levels of purity. The use of a hydrophobic impurity affinity adsorbent for purification of glycerolis hitherto unknown. The process disclosed herein scores over the traditional processes in terms of cost-effectiveness, operational simplicity, very high recovery and purity of resultant glycerol, and regeneration and recycling of adsorbents used.

[00179] Although the subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the present subject matter as defined.

Claims

I/We Claim:

1. A process for purification and refining of glycerol, the process comprising steps of:

(a) contacting glycerol with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent to obtain a first fraction of pure and refined glycerol having purity greater than 99%, wherein the order of contacting with at least adsorbent one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent can vary;

(b) displacing the residual glycerol from the at least one hydrophobic impurity affinity adsorbent and the at least one polar impurity affinity adsorbent by a displacing phase to obtain a second fraction of pure and refined glycerol having purity greater than 99%; and

(c) subjecting the first and second fraction of pure and refined glycerol to at least one water removal treatment to obtain a final pure and refined glycerol, wherein the final pure and refined glycerol has assay purity greater than 99%, water content less than 0.5%, impurities less than 0.5%, and the recovery of the final pure and refined glycerol is greater than 98%.

2. The process as claimed in claim 1, wherein the glycerol is obtained from a process selected from the group consisting of saponification, fat/oil splitting, biodiesel production, fermentation, and combinations thereof.

3. The process as claimed in claim 1, wherein the glycerol is selected from crude glycerol, partially pure glycerol, yellow glycerol, IW (industry white) grade glycerol, and combinations thereof.

4. The process as claimed in claim 3, wherein the glycerol is selected from crude glycerol and a combination of crude and partially pure glycerol, and the process further comprises a pre-treatment of glycerol before contacting with at least one hydrophobic impurity affinity adsorbent and at least one polar impurity affinity adsorbent.

5. The process as claimed in claim 4, wherein the pre-treatment is carried out by a treatment method selected from the group comprising neutralization, acidification, dilution, flocculation, filtration, flashing, distillation, evaporation, and combinations thereof.

6. The process as claimed in claim 1, wherein the hydrophobic impurity affinity adsorbent comprises; (a) base selected from the group consisting of synthetic polymer, natural polymer, inorganic matrix, and combinations thereof; and (b) at least one hydrophobic impurity affinity group as an interacting group.

7. The process as claimed in claim 1, wherein the polar impurity affinity adsorbent comprises: (a) base selected from the group comprising synthetic polymer, natural polymer, inorganic matrix and combinations thereof; and (b) at least one group selected from positively charged group, negatively charged group, and combinations thereof, as a polar impurity affinity interacting group.

8. The process as claimed in claim 1, wherein the hydrophobic impurity affinity group or polar impurity affinity group is part of base or grafted on base by known chemical reactions.

9. The process as claimed in claim 1, wherein the glycerol is contacted with at least one hydrophobic impurity affinity adsorbent at a temperature in the range of 15 - 150 °C, for a residence time in the range of 5 minutes to 5 hours, and at a pH in the range of 1 - 12.

10. The process as claimed in claim 1, wherein the glycerol is contacted with at least one polar impurity affinity adsorbent at a temperature in the range of 15 - 150 °C, for a residence time in the range of 5 minutes to 5 hours, and at a pH in the range of 1 - 12.

11. The process as claimed in claiml, wherein the displacing of residual glycerol from the hydrophobic impurity affinity adsorbent is carried out by a displacing phase selected from the group consisting of water with pH of 7, water with a pH greater than 7, water with a pH less than 7, air, hot air, nitrogen, carbon dioxide, steam, and combinations thereof.

12. The process as claimed in claim 1, wherein the displacing of residual glycerol from the polar impurity affinity adsorbent is carried out by a displacing phase selected from the group consisting of water with pH of 7, water with a pH greater than 7, water with a pH less than 7, air, hot air, nitrogen, carbon dioxide, steam, and combinations thereof.

13. The process as claimed in claim 1, further comprising the step of regenerating the hydrophobic impurity affinity adsorbent, wherein the regeneration is carried out by eluting the hydrophobic impurity affinity adsorbent with a regeneration liquid to obtain eluted adsorbed impurities and regenerated adsorbent.

14. The process as claimed in claim 13, wherein the regenerating liquid is selected from the group consisting of neutral water having pH of 7, acidified water having pH below 7, alkaline water having pH above 7, hot water, solvent selected from methanol, ethanol, butanol, acetonitrile, acetone, tert-butanol, isopropyl alcohol or combinations or azeotropic mixtures thereof.

15. The process as claimed in claims 1 or 13, furthercomprises the step of conditioning or equilibrating the regenerated adsorbent for reuse.

16. The process as claimed in claim 1, further comprising the step of regenerating the polar impurity affinity adsorbent, wherein the regeneration is carried out by eluting the polar impurity affinity adsorbent with a regeneration liquid to obtain eluted adsorbed impurities and regenerated adsorbent.

17. The process as claimed in claim 16, wherein the regenerating liquid is selected from the group consisting of neutral water having pH of 7, acidified water having pH below 7, alkaline water having pH above 7, hot water, solvent selected from methanol, ethanol, butanol, acetone, acetonitrile, tert-butanol, isopropyl alcohol, azeotrope, alkali selected from sodium hydroxide, potassium hydroxide, ammonium hydroxide, ammonia, sodium carbonate, sodium bi-carbonate, sodium phosphate, potassium phosphate, triethylamine, acids selected from sulfuric acid, hydrochloric acid, acetic acid, citric acid, boric acid, salts selected from sodium chloride, potassium chloride, sodium acetate, sodium citrate, potassium acetate, potassium citrate, ammonium chloride, ammonium acetate, sodium sulphate, potassium sulphate, ammonium sulphate, sodium carbonate, potassium carbonate, or combinations or azeotropic mixtures thereof.

18. The process as claimed in claims 1 or 16, further comprises the step of conditioning or equilibrating the regenerated adsorbent for reuse.