WO2017202240A1 - Method for reducing colour impurities in sugar liquid or syrup - Google Patents

Method for reducing colour impurities in sugar liquid or syrup Download PDF

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Publication number
WO2017202240A1
WO2017202240A1 PCT/CN2017/084926 CN2017084926W WO2017202240A1 WO 2017202240 A1 WO2017202240 A1 WO 2017202240A1 CN 2017084926 W CN2017084926 W CN 2017084926W WO 2017202240 A1 WO2017202240 A1 WO 2017202240A1
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Prior art keywords
ammonium compound
syrup
quaternary ammonium
sugar
group
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PCT/CN2017/084926
Other languages
French (fr)
Inventor
Zhaofei Chen
Shujing Cheng
Original Assignee
Rhodia Operations
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rhodia Operations filed Critical Rhodia Operations
Priority to CN201780032569.8A priority Critical patent/CN109154028B/en
Priority to BR112018074044A priority patent/BR112018074044A2/en
Publication of WO2017202240A1 publication Critical patent/WO2017202240A1/en

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    • C—CHEMISTRY; METALLURGY
    • C13—SUGAR INDUSTRY
    • C13B—PRODUCTION OF SUCROSE; APPARATUS SPECIALLY ADAPTED THEREFOR
    • C13B20/00—Purification of sugar juices
    • C13B20/14—Purification of sugar juices using ion-exchange materials
    • C13B20/144—Purification of sugar juices using ion-exchange materials using only cationic ion-exchange material
    • C—CHEMISTRY; METALLURGY
    • C13—SUGAR INDUSTRY
    • C13B—PRODUCTION OF SUCROSE; APPARATUS SPECIALLY ADAPTED THEREFOR
    • C13B20/00—Purification of sugar juices
    • C13B20/005—Purification of sugar juices using chemicals not provided for in groups C13B20/02 - C13B20/14

Definitions

  • the present invention relates to a method for purifying a sugar liquor or syrup, in particular, a method for reducing colour impurities in the sugar liquor or syrup by using a quaternary ammonium compound.
  • phosphatation process which is aimed to produce calcium phosphate floc, typically by using a phosphoric acid and milk of lime, followed by a flocculation step by adding a polymer as flocculant. By doing this, most of fine suspended impurities in the solution can be collected and subsequently removed as floatation scum.
  • the quaternary ammonium compounds can improve the precipitation of anionic high molecular weight colour impurities, which can be more readily removed as floatation scum.
  • U.S. Pat. No. 4,196,017 discloses a composition comprising a di-long chain alkyl dimethyl ammonium compound and such composition is used in the sugar decolonization process. Also, U.S. Pat. No. 3,698,951 unveils that an n-alkyl dimethyl benzyl ammonium compound can be used for clarifying sugar solutions.
  • n-alkyl dimethyl benzyl ammonium compounds are known to have relatively high toxicity which causes safety concerns. Also, when such compounds are used in the industrial scale sugar clarification process, the flocs formed which contain the colour impurities tend to be loose, as a result, the floatation rate is slow. On the other hand, the di-long chain alkyl dimethyl ammonium compounds, such as di-hydrogenated tallow alkyl dimethyl ammonium showed unsatisfactory colour removal efficiency.
  • the present invention is directed to a method for reducing colour impurities in a sugar liquor or syrup, comprising a step of adding a quaternary ammonium compound to said sugar liquor or syrup, wherein said quaternary ammonium compound has the general formula (I) :
  • R 1 and R 2 which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group having 8-24 carbon atoms, preferably 12-20 carbon atoms, the aliphatic group optionally contains a hetero atom;
  • R 3 is a saturated or unsaturated, straight or branched aliphatic group having 1-8 carbon atoms, preferably 1-3 carbon atoms, more preferably, R 3 is methyl;
  • R 4 represents– (CH 2 ) n -phenyl, wherein n is 0 or an integer of 1 to 3, the phenyl group may have at least one substituent selected from the group consisting of halide, nitrite, and sulfate on any available position, preferably, R 4 is benzyl;
  • X is an anion, for example halide such as Cl or Br, sulphate, alkyl sulphate, nitrate and acetate, preferably, X is chloride or methylsulfate.
  • the present invention is directed to a method for reducing colour impurities in a sugar liquor or syrup, comprising a step of adding a quaternary ammonium compound to said sugar liquor or syrup, wherein said quaternary ammonium compound has the general formula (II) :
  • R 5 and R 6 which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group, notably alkyl or hydroxyalkyl group, having 12-20 carbon atoms, the aliphatic group may optionally contains a hetero atom;
  • X is an anion selected from the group consisting of Cl, Br, methylsulphate and nitrate.
  • the quaternary ammonium compound may be added to the sugar liquor or syrup in the form of a diluted aqueous solution or dispersion.
  • the reaction between the quaternary ammonium compound and the colour impurities is preferably conducted under a temperature of 70-90°C, preferably 80-85°C.
  • the method may further comprise:
  • the present invention also provides the use of said quaternary ammonium compound for reducing colour impurities in a sugar liquor or syrup.
  • any particular upper concentration, weight ratio or amount can be associated with any particular lower concentration, weight ratio or amount.
  • sugar liquor or syrup means any liquor or syrup containing a sugar or a melted raw sugar.
  • the sugar is derived from a plant source, such as, a sugar cane, a sugar beet and a corn.
  • “Raw sugar” means a sugar which has been minimally processed and which contains soluble and insoluble impurities.
  • the raw sugar can be obtained from sugarjuices by the processes of clarification, evaporation to a thick sugar syrup, and crystallization. Then the crystallized product can be dissolved in water so as to obtain the sugar liquor, which is also called “melter liquor” .
  • sugar syrups which are obtained from sugar juices, can be used as the feedstock of the method of the present invention.
  • the colour impurities in the sugar liquor or syrup notably include plant pigments, melanoidins, caramels and alkaline degradation products of fructose.
  • alkyl means a saturated hydrocarbon radical, which may be straight, branched or cyclic, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl, pentyl, n-hexyl, cyclohexyl.
  • hydroxyalkyl means an alkyl radical, which is substituted with a hydroxyl groups, such as hydroxymethyl, hydroxyethyl, hydroxypropyl, and hydroxydecyl.
  • quaternary ammonium compound as used herein means a compound containing at least one quaternized nitrogen wherein the nitrogen atom is attached to four organic groups.
  • the quaternary ammonium compound may comprise one or more quaternized nitrogen atoms.
  • quaternary ammonium compound is also referred to as quat.
  • the present invention provides a method for reducing colour impurities in a sugar liquor or syrup, comprising a step of adding a quaternary ammonium compound to said sugar liquor or syrup, wherein said quaternary ammonium compound has the general formula (I) :
  • R 1 and R 2 which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group having 8-24 carbon atoms, preferably 12-20 carbon atoms, the aliphatic group optionally contains a hetero atom;
  • R 3 is a saturated or unsaturated, straight or branched aliphatic group having 1-8 carbon atoms, preferably 1-3 carbon atoms, more preferably, R 3 is methyl;
  • R 4 represents– (CH 2 ) n -phenyl, wherein n is 0 or an integer of 1 to 3; the phenyl group may have at least one substituent selected from the group consisting of halide, nitrite, and sulfite on any available position, preferably, R 4 is benzyl;
  • X is an anion, for example, halide such as Cl and Br, sulfate, alkyl sulfate, and nitrate, preferably chloride or methylsulfate.
  • R 1 and R 2 as defined in general formula (I) are alkyl groups, such as hydrogenated tallow alkyl group, stearyl group, hexadecyl group and octadecyl group.
  • R 3 as defined in general formula (I) is an alkyl group such as methyl, ethyl and propyl.
  • R 3 is methyl.
  • the quaternary ammonium compound of the present invention has the general formula (II) :
  • R 5 and R 6 which may be the same or different, represent saturated or unsaturated, straight or branched aliphatic group, notably alkyl or hydroxyalkyl group, having 12-20 carbon atoms, the aliphatic group may optionally contains a hetero atom;
  • X is an anion selected from the group consisting of Cl, Br, methylsulphate and nitrate.
  • the quaternary ammonium compounds suitable for use in the present invention include, but not limited to, di hydrogenated tallow alky methyl benzyl ammonium compound, di stearyl methyl benzyl ammonium compound, di tallow alky methyl benzyl ammonium compound, di palmityl methyl benzyl compound, di hexadecyl methyl benzyl ammonium compound, di octadecyl methyl benzyl ammonium compound and a mixture thereof.
  • the method of the present invention may employ a single quaternary ammonium compound or a mixture of more than one quaternary ammonium compounds.
  • the quaternary ammonium compound according to the present invention can provide excellent colour removal efficiency combined with fast floatation rate when being used in the sugar clarification process.
  • the quaternary ammonium compound also has minimal toxic level and satisfactory safety profiles.
  • the quaternary ammonium compound may be added to the sugar liquor or syrup in a reaction tank with metering pump and agitation apparatus, which brings the quaternary ammonium compound into contact with the colour impurities.
  • the quaternary ammonium compound is added in the form of a diluted aqueous solution.
  • the reaction may be conducted at a temperature of 70-90°C, preferably 80-85°C.
  • the quaternary ammonium compound may be present in an amount of from 100 to 700 ppm based on the weight of solid sugar in the sugar liquor or syrup.
  • the quaternary ammonium compound is present in an amount of from 100 to 500 ppm based on the weight of solid sugar in the sugar liquor or syrup. More preferably, the quaternary ammonium compound is present in an amount of 200 to 400 ppm based on the weight of solid sugar in the sugar liquor or syrup.
  • the precipitate formed in this reaction is initially very finely divided and can hardly be observed with the naked eye; but its presence can be revealed by measurement of the optical properties of the sugar liquor or syrup, for example by measuring the optical density at 420 nm, using a spectrophotometer.
  • such fine precipitate can be removed by filtration, using a filter medium having sufficiently small porosity.
  • the method ofthe present invention may further comprise:
  • the flocculant precipitate is calcium phosphate.
  • the phosphoric compound may be phosphoric acid or a phosphate compound.
  • Suitable phosphate compounds include, but not limited to tripolyphosphates, prophosphates, hexametaphophates, trisodium phosphates, sodium phosphate monobasic, calcium phosphate monobasic, ammonium phosphate monobasic, sodium phosphate dibasic, ammonium phosphate dibasic or any water-soluble phosphate salt which will not substantially decrease the pH of the sugar liquor or syrup is expected to be within the purview of this invention.
  • the phosphoric compound is phosphoric acid.
  • the phosphoric compound may be added with the quaternary ammonium compound as a homogenous blend.
  • the phosphoric compound and the quaternary ammonium compound may be provided as a solid blend which can then be added to the sugar liquor or syrup.
  • the phosphoric compound may be added separately, either prior to, simultaneously, or after the addition of the quaternary ammonium compound.
  • the phosphoric compound may be added in an amount of about 100 to about 700 ppm, preferably, about 150 to about 500 ppm, by weight of P 2 O 5 based on the weight of solid sugar in the sugar liquor or syrup.
  • the phosphoric compound may be present 0.1 to 5 times, by weight, the amount of the quaternary ammonium compound. According to one characteristic of the present invention, the phosphoric compound is present 1 to 5 times, by weight, the amount of the quaternary ammonium compound. Preferably, the phosphoric compound is present 1 to 3 times, by weight, the amount ofthe quaternary ammonium compound.
  • lime-based compound used herein refers to calcium-containing compound which can be used to neutralize the solution acidity and form precipitating insoluble calcium phosphates in the sugar liquor or syrup with the phosphoric compounds.
  • Suitable lime-based compounds include, but not limited to, calcium hydroxide, either as slurry with water (milk of lime) and lime succrate.
  • the lime-based compound may be added to the sugar liquor or syrup in a sufficient amount to raise the pH of the sugar liquor or syrup between 6 and 8, preferably about 6.8 to 7.2.
  • a flocculating agent may be added to the sugar liquor or syrup to increase the size of precipitate scum comprising calcium phosphate coagulum and other colour impurities precipitated by incorporating with the quat.
  • the flocculating agent is an anionic polyeletrolyte, such as polyacrylate, polyacrylamide, more preferably polyacrylamide.
  • the polyacrylamide may be comprised in an amount of 5-30 ppm based on the weight of solid sugar in the sugar liquor or syrup. Preferably, the polyacrylamide is present in an amount of 10-25 ppm based on the weight of solid sugar in the sugar liquor or syrup.
  • the polyacrylamide used in the present invention preferably has an average Molecular Weight of from 12,000,000 to 30,000,000 Daltons. More preferably, the polyacrylamide has an average Molecular Weight of 22,000,000 Daltons.
  • the floating foam containing colour impurities can be removed from the sugar liquor or syrup by a physical separation method including floatation such as air-floatation, filtration and the like.
  • a preferred separation method for the present invention is the air-floatation method, for which there is an additional step of micro aeration before the step of addition of the flocculating agent.
  • the micro aeration may take place to produce an aerated sugar liquor or syrup. This step can either perform in a reaction tank with a stirring device or using an air compressor.
  • the air trapped scums to float in the sugar liquor or syrup can be then removed from the liquor surface by a skimming device, such as a scrapper.
  • the colour value of the fine sugar product can be brought to be in the range of 20-150 ICUMSA units, more typically, 20-50 ICUMSA units.
  • Raw sugars obtained from sugar cane juice by simple lime treatment were dissolved in hot water (60 ⁇ 80°C) to obtain a raw sugar liquor of 60 ⁇ 65 Brix.
  • the colour value of the raw sugar liquor was in the range of 900-1300 ICUMSA units.
  • the raw sugar liquor was heated to 80-85°C, followed by addition of benzyl-bis (hydrogenated tallow alkyl) methyl ammonium chloride (obtained from the Solvay Company) at 300 ppm under stirring for 15 minutes. Then phosphoric acid was added to the raw sugar liquor at 360 ppm. The sugar liquor was neutralized to pH 6.9-7.0 by addition of lime succrate under stirring. The sugar liquor was then transferred into a separatory funnel, then 15-20 ppm of polyacrylamide (PAM) was added. The separatory funnel was shaken vertically for 10-20 seconds until large amount of small bubbles appeared, and then it was immerged in boiling water bath for 10 mins. The precipitate containing colour impurities floated up to the surface of the sugar liquor. Floatation rate was determined at different time points after the separatory funnel was immerged in the boiling water bath. 40 ml of clear sugar liquor was collected from the bottom of the separatory funnel for colour value test.
  • PAM polyacrylamide
  • the collected sugar liquor was diluted to 35-40 Brix and the pH value was adjusted to 7.0 with diluted HCl or NaOH solution.
  • the sugar liquor was then filtered with filter paper with porous size of 0.45 ⁇ m. Subsequently, the absorbance of the sugar liquor was measured at 420 nm with UV/Vis spectrometer.
  • A420 is expressed as absorbance of the sugar liquor at 420 nm wave length
  • B is the brix ofthe sugar liquor at 25°C (detection of brix ofthe sugar liquor is performed with Abbe-Refractometer, unit is o Bx) ;
  • L is the length ofthe cuvette
  • ⁇ is the density ofthe sugar liquor.
  • the results are estimated by naked eye examination and the floatation rate is expressed by dividing the amount of flocculent participates floated to the surface of the sugar liquor by total amount offlocculent participates occurring in the sugar liquor.
  • the quaternary ammonium compound (example 1) of the present invention which is a di-long chain alkyl benzyl quaternary ammonium compound, was more effective in removing colour impurities in the sugar liquor than the quaternary ammonium compound tested in comparative example 1, which contains no benzyl substituent.
  • the results show that the compound of the invention provided a faster floatation rate compared to the quaternary ammonium compound tested in comparative example 2 which has mono-long chain alkyl group and a benzyl group as substituents.
  • Raw sugars obtained from sugar cane juice by simple lime treatment were dissolved in hot water (60 ⁇ 80°C) to obtain a raw sugar liquor of 60 ⁇ 65 Brix.
  • the colour value of the raw sugar liquor was in the range of 900-1300 ICUMSA units.
  • the raw sugar liquor was heated to 80-85°C, followed by addition of benzyl-bis (hydrogenated tallow alkyl) methyl ammonium chloride (obtained from the Solvay Company) at 300 ppm under stirring for 15 minutes. Then phosphoric acid was added to the raw sugar liquor at 300 ppm. The sugar liquor was neutralized to pH 6.9-7.0 by addition of lime succrate under stirring. The sugar liquor was then transferred into a separatory funnel, then 15-20 ppm of polyacrylamide (PAM) was added. The separatory funnel was shaken vertically for 10-20 seconds until large amount of small bubbles appeared, and then it was immerged in boiling water bath for 10 mins. The precipitate containing colour impurities floated up to the surface of the sugar liquor. Floatation rate was determined at different time points after the separatory funnel was immerged in the boiling water bath. 40 ml of clear sugar liquor was collected from the bottom of the separatory funnel for colour value test.
  • PAM polyacrylamide

Abstract

Provided is a method for reducing colour impurities in a sugar liquor or syrup by using a quaternary ammonium compound, in particular, a di-long chain alkyl benzyl quaternary ammonium compound.

Description

[Title established by the ISA under Rule 37.2] METHOD FOR REDUCING COLOUR IMPURITIES IN SUGAR LIQUID OR SYRUP
This application claims priority to PCT International Patent Application No. PCT/CN2016/083425 filed on May 26, 2016, the whole content of this application being incorporated herein by reference for all purposes.
Technical Field
The present invention relates to a method for purifying a sugar liquor or syrup, in particular, a method for reducing colour impurities in the sugar liquor or syrup by using a quaternary ammonium compound.
Background Art
The following discussion of the prior art is provided to place the invention in an appropriate technical context and enable the advantages of it to be more fully understood. It should be appreciated, however, that any discussion of the prior art throughout the specification should not be considered as an express or implied admission that such prior art is widely known or forms part of common general knowledge in the field.
It has been necessary for sugar factories to produce good quality fine sugars for direct consumption. After sugar is extracted from a plant source such as a cane or a beet, the resultant mixed liquor or syrup needs to be further purified for achieving an acceptable standard of purity. One important sugar quality criteria is the whiteness of the fine sugars, thus, the removal of colour impurities by clarification is an essential part of the process for manufacturing fine sugars.
One common clarification process for reducing colour impurities in a sugar liquor or syrup is phosphatation process which is aimed to produce calcium phosphate floc, typically by using a phosphoric acid and milk of lime, followed by a flocculation step by adding a polymer as flocculant. By doing this, most of fine suspended impurities in the solution can be collected and subsequently removed as floatation scum.
One important modification to the phosphatation process is the application of a colour precipitant, such as certain quaternary ammonium compounds.
The quaternary ammonium compounds can improve the precipitation of anionic high molecular weight colour impurities, which can be more readily removed as floatation scum.
U.S. Pat. No. 4,196,017 discloses a composition comprising a di-long chain alkyl dimethyl ammonium compound and such composition is used in the sugar decolonization process. Also, U.S. Pat. No. 3,698,951 unveils that an n-alkyl dimethyl benzyl ammonium compound can be used for clarifying sugar solutions.
There are certain drawbacks associated with use of these types of quaternary ammonium compounds for the sugar clarification. For instance, n-alkyl dimethyl benzyl ammonium compounds are known to have relatively high toxicity which causes safety concerns. Also, when such compounds are used in the industrial scale sugar clarification process, the flocs formed which contain the colour impurities tend to be loose, as a result, the floatation rate is slow. On the other hand, the di-long chain alkyl dimethyl ammonium compounds, such as di-hydrogenated tallow alkyl dimethyl ammonium showed unsatisfactory colour removal efficiency.
Thus, there is a need to provide a colour sugar clarification method which can provide excellent colour removal efficiency combined with fast floatation rate. There is also a need to provide a colour precipitant which has minimal toxicity and satisfactory safety profiles.
Summary of Invention
In one aspect, the present invention is directed to a method for reducing colour impurities in a sugar liquor or syrup, comprising a step of adding a quaternary ammonium compound to said sugar liquor or syrup, wherein said quaternary ammonium compound has the general formula (I) :
Figure PCTCN2017084926-appb-000001
wherein:
R1 and R2, which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group having 8-24 carbon atoms, preferably 12-20 carbon atoms, the aliphatic group optionally contains a hetero atom；
R3 is a saturated or unsaturated, straight or branched aliphatic group having 1-8 carbon atoms, preferably 1-3 carbon atoms, more preferably, R3 is methyl；
R4 represents– (CH2) n-phenyl, wherein n is 0 or an integer of 1 to 3, the phenyl group may have at least one substituent selected from the group consisting of halide, nitrite, and sulfate on any available position, preferably, R4 is benzyl；
X is an anion, for example halide such as Cl or Br, sulphate, alkyl sulphate, nitrate and acetate, preferably, X is chloride or methylsulfate.
Notably, the present invention is directed to a method for reducing colour impurities in a sugar liquor or syrup, comprising a step of adding a quaternary ammonium compound to said sugar liquor or syrup, wherein said quaternary ammonium compound has the general formula (II) :
Figure PCTCN2017084926-appb-000002
wherein:
R5 and R6, which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group, notably alkyl or hydroxyalkyl group, having 12-20 carbon atoms, the aliphatic group may optionally contains a hetero atom；
X is an anion selected from the group consisting of Cl, Br, methylsulphate and nitrate.
The quaternary ammonium compound may be added to the sugar liquor or syrup in the form of a diluted aqueous solution or dispersion. The reaction  between the quaternary ammonium compound and the colour impurities is preferably conducted under a temperature of 70-90℃, preferably 80-85℃.
In accordance with the present invention, the method may further comprise:
(a) adding a phosphoric compound, a lime-based compound, and a flocculating agent to said sugar liquor or syrup, so as to form a flocculant precipitate；
(b) separating the flocculant precipitate from said sugar liquor or syrup.
The present invention also provides the use of said quaternary ammonium compound for reducing colour impurities in a sugar liquor or syrup.
Detailed Description
Throughout the description, including the claims, the term "comprising one" or “comprising a" should be understood as being synonymous with the term "comprising at least one" , unless otherwise specified, and "between" should be understood as being inclusive of the limits.
It should be noted that in specifying any range of concentration, weight ratio or amount, any particular upper concentration, weight ratio or amount can be associated with any particular lower concentration, weight ratio or amount.
The term “sugar liquor or syrup” , as used herein, means any liquor or syrup containing a sugar or a melted raw sugar. Typically, the sugar is derived from a plant source, such as, a sugar cane, a sugar beet and a corn. “Raw sugar” means a sugar which has been minimally processed and which contains soluble and insoluble impurities. The raw sugar can be obtained from sugarjuices by the processes of clarification, evaporation to a thick sugar syrup, and crystallization. Then the crystallized product can be dissolved in water so as to obtain the sugar liquor, which is also called “melter liquor” . Alternatively, sugar syrups, which are obtained from sugar juices, can be used as the feedstock of the method of the present invention.
The colour impurities in the sugar liquor or syrup notably include plant pigments, melanoidins, caramels and alkaline degradation products of fructose.
As used herein, the term "alkyl" means a saturated hydrocarbon radical, which may be straight, branched or cyclic, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl, pentyl, n-hexyl, cyclohexyl.
As used herein, the term "hydroxyalkyl" means an alkyl radical, which is substituted with a hydroxyl groups, such as hydroxymethyl, hydroxyethyl, hydroxypropyl, and hydroxydecyl.
The term “quaternary ammonium compound” as used herein means a compound containing at least one quaternized nitrogen wherein the nitrogen atom is attached to four organic groups. The quaternary ammonium compound may comprise one or more quaternized nitrogen atoms. In the context of the present application, quaternary ammonium compound is also referred to as quat.
The present invention provides a method for reducing colour impurities in a sugar liquor or syrup, comprising a step of adding a quaternary ammonium compound to said sugar liquor or syrup, wherein said quaternary ammonium compound has the general formula (I) :
Figure PCTCN2017084926-appb-000003
wherein:
R1 and R2, which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group having 8-24 carbon atoms, preferably 12-20 carbon atoms, the aliphatic group optionally contains a hetero atom；
R3 is a saturated or unsaturated, straight or branched aliphatic group having 1-8 carbon atoms, preferably 1-3 carbon atoms, more preferably, R3 is methyl；
R4 represents– (CH2) n-phenyl, wherein n is 0 or an integer of 1 to 3； the phenyl group may have at least one substituent selected from the group consisting of halide, nitrite, and sulfite on any available position, preferably, R4 is benzyl；
X is an anion, for example, halide such as Cl and Br, sulfate, alkyl sulfate, and nitrate, preferably chloride or methylsulfate.
Advantageously, R1 and R2 as defined in general formula (I) are alkyl groups, such as hydrogenated tallow alkyl group, stearyl group, hexadecyl group and octadecyl group.
Advantageously, R3 as defined in general formula (I) is an alkyl group such as methyl, ethyl and propyl. In particular, R3 is methyl.
In some aspects, the quaternary ammonium compound of the present invention has the general formula (II) :
Figure PCTCN2017084926-appb-000004
wherein:
R5 and R6, which may be the same or different, represent saturated or unsaturated, straight or branched aliphatic group, notably alkyl or hydroxyalkyl group, having 12-20 carbon atoms, the aliphatic group may optionally contains a hetero atom；
X is an anion selected from the group consisting of Cl, Br, methylsulphate and nitrate.
The quaternary ammonium compounds suitable for use in the present invention include, but not limited to, di hydrogenated tallow alky methyl benzyl ammonium compound, di stearyl methyl benzyl ammonium  compound, di tallow alky methyl benzyl ammonium compound, di palmityl methyl benzyl compound, di hexadecyl methyl benzyl ammonium compound, di octadecyl methyl benzyl ammonium compound and a mixture thereof.
The method of the present invention may employ a single quaternary ammonium compound or a mixture of more than one quaternary ammonium compounds.
It has been surprisingly found that the quaternary ammonium compound according to the present invention can provide excellent colour removal efficiency combined with fast floatation rate when being used in the sugar clarification process. The quaternary ammonium compound also has minimal toxic level and satisfactory safety profiles.
For implementing the method of the present invention, the quaternary ammonium compound may be added to the sugar liquor or syrup in a reaction tank with metering pump and agitation apparatus, which brings the quaternary ammonium compound into contact with the colour impurities. Preferably, the quaternary ammonium compound is added in the form of a diluted aqueous solution. The reaction may be conducted at a temperature of 70-90℃, preferably 80-85℃.
The quaternary ammonium compound may be present in an amount of from 100 to 700 ppm based on the weight of solid sugar in the sugar liquor or syrup. Preferably, the quaternary ammonium compound is present in an amount of from 100 to 500 ppm based on the weight of solid sugar in the sugar liquor or syrup. More preferably, the quaternary ammonium compound is present in an amount of 200 to 400 ppm based on the weight of solid sugar in the sugar liquor or syrup.
The precipitate formed in this reaction is initially very finely divided and can hardly be observed with the naked eye； but its presence can be revealed by measurement of the optical properties of the sugar liquor or syrup, for example by measuring the optical density at 420 nm, using a spectrophotometer. In accordance to one example embodiment of the present invention, such fine precipitate can be removed by filtration, using a filter medium having sufficiently small porosity.
The method ofthe present invention may further comprise:
(a) adding a phosphoric compound, a lime-based compound, and a flocculating agent to the sugar liquor or syrup, so as to form a flocculant precipitate；
(b) separating the flocculant precipitate from the sugar liquor or syrup.
Notably, the flocculant precipitate is calcium phosphate.
The phosphoric compound may be phosphoric acid or a phosphate compound. Suitable phosphate compounds include, but not limited to tripolyphosphates, prophosphates, hexametaphophates, trisodium phosphates, sodium phosphate monobasic, calcium phosphate monobasic, ammonium phosphate monobasic, sodium phosphate dibasic, ammonium phosphate dibasic or any water-soluble phosphate salt which will not substantially decrease the pH of the sugar liquor or syrup is expected to be within the purview of this invention. Preferably, the phosphoric compound is phosphoric acid.
The phosphoric compound may be added with the quaternary ammonium compound as a homogenous blend. For example, the phosphoric compound and the quaternary ammonium compound may be provided as a solid blend which can then be added to the sugar liquor or syrup. Alternatively, the phosphoric compound may be added separately, either prior to, simultaneously, or after the addition of the quaternary ammonium compound.
The phosphoric compound may be added in an amount of about 100 to about 700 ppm, preferably, about 150 to about 500 ppm, by weight of P2O5 based on the weight of solid sugar in the sugar liquor or syrup.
The phosphoric compound may be present 0.1 to 5 times, by weight, the amount of the quaternary ammonium compound. According to one characteristic of the present invention, the phosphoric compound is present 1 to 5 times, by weight, the amount of the quaternary ammonium compound. Preferably, the phosphoric compound is present 1 to 3 times, by weight, the amount ofthe quaternary ammonium compound.
The term “lime-based compound” used herein refers to calcium-containing compound which can be used to neutralize the solution acidity and form  precipitating insoluble calcium phosphates in the sugar liquor or syrup with the phosphoric compounds. Suitable lime-based compounds include, but not limited to, calcium hydroxide, either as slurry with water (milk of lime) and lime succrate. The lime-based compound may be added to the sugar liquor or syrup in a sufficient amount to raise the pH of the sugar liquor or syrup between 6 and 8, preferably about 6.8 to 7.2.
A flocculating agent may be added to the sugar liquor or syrup to increase the size of precipitate scum comprising calcium phosphate coagulum and other colour impurities precipitated by incorporating with the quat.
Preferably, the flocculating agent is an anionic polyeletrolyte, such as polyacrylate, polyacrylamide, more preferably polyacrylamide.
The polyacrylamide may be comprised in an amount of 5-30 ppm based on the weight of solid sugar in the sugar liquor or syrup. Preferably, the polyacrylamide is present in an amount of 10-25 ppm based on the weight of solid sugar in the sugar liquor or syrup.
The polyacrylamide used in the present invention preferably has an average Molecular Weight of from 12,000,000 to 30,000,000 Daltons. More preferably, the polyacrylamide has an average Molecular Weight of 22,000,000 Daltons.
After the flocculation, the floating foam containing colour impurities can be removed from the sugar liquor or syrup by a physical separation method including floatation such as air-floatation, filtration and the like. A preferred separation method for the present invention is the air-floatation method, for which there is an additional step of micro aeration before the step of addition of the flocculating agent. The micro aeration may take place to produce an aerated sugar liquor or syrup. This step can either perform in a reaction tank with a stirring device or using an air compressor. The air trapped scums to float in the sugar liquor or syrup can be then removed from the liquor surface by a skimming device, such as a scrapper.
Generally, by using the method of the present invention, the colour value of the fine sugar product can be brought to be in the range of 20-150 ICUMSA units, more typically, 20-50 ICUMSA units.
The present invention will now be described with reference to a number of specific examples, which should not be considered as limiting the scope of the claimed invention.
Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.
Examples
Example 1
Raw sugars obtained from sugar cane juice by simple lime treatment were dissolved in hot water (60～80℃) to obtain a raw sugar liquor of 60～65 Brix. The colour value of the raw sugar liquor was in the range of 900-1300 ICUMSA units.
The raw sugar liquor was heated to 80-85℃, followed by addition of benzyl-bis (hydrogenated tallow alkyl) methyl ammonium chloride (obtained from the Solvay Company) at 300 ppm under stirring for 15 minutes. Then phosphoric acid was added to the raw sugar liquor at 360 ppm. The sugar liquor was neutralized to pH 6.9-7.0 by addition of lime succrate under stirring. The sugar liquor was then transferred into a separatory funnel, then 15-20 ppm of polyacrylamide (PAM) was added. The separatory funnel was shaken vertically for 10-20 seconds until large amount of small bubbles appeared, and then it was immerged in boiling water bath for 10 mins. The precipitate containing colour impurities floated up to the surface of the sugar liquor. Floatation rate was determined at different time points after the separatory funnel was immerged in the boiling water bath. 40 ml of clear sugar liquor was collected from the bottom of the separatory funnel for colour value test.
For the colour value test, the collected sugar liquor was diluted to 35-40 Brix and the pH value was adjusted to 7.0 with diluted HCl or NaOH solution. The sugar liquor was then filtered with filter paper with porous size of 0.45 μm. Subsequently, the absorbance of the sugar liquor was measured at 420 nm with UV/Vis spectrometer.
Colour value is calculated by the formula:
Figure PCTCN2017084926-appb-000005
where:
A420 is expressed as absorbance of the sugar liquor at 420 nm wave length；
B is the brix ofthe sugar liquor at 25℃ (detection of brix ofthe sugar liquor is performed with Abbe-Refractometer, unit is oBx) ；
L is the length ofthe cuvette；
ρ is the density ofthe sugar liquor.
The colour removal rate was calculated according to the formula: Colour removal rate＝ (COLrawliquor–COLflotation) /COLrawliquor*100％
For the determination of the floatation rate, the results are estimated by naked eye examination and the floatation rate is expressed by dividing the amount of flocculent participates floated to the surface of the sugar liquor by total amount offlocculent participates occurring in the sugar liquor.
Comparative example 1
Experiments were conducted according to the procedure described in Example 1 except that benzyl-bis (hydrogenated tallow alkyl) methyl ammonium chloride was replaced by C14-C18 alkyl dimethyl ammonium chloride (DHT21, obtained from the Solvay Company) .
Comparative example 2
Experiments were conducted according to the procedure described in Example 1 except that benzyl-bis (hydrogenated tallow alkyl) methyl ammonium chloride was replaced by benzyl C16-C18 alkyldimethyl ammonium chloride (obtained from the Solvay Company) .
The colour removal results are shown in Table 1 below:
Table 1
Figure PCTCN2017084926-appb-000006
The floatation efficiency results are shown in Table 2 below:
Table 2
Figure PCTCN2017084926-appb-000007
The results demonstrate that the quaternary ammonium compound (example 1) of the present invention, which is a di-long chain alkyl benzyl quaternary ammonium compound, was more effective in removing colour impurities in the sugar liquor than the quaternary ammonium compound tested in comparative example 1, which contains no benzyl substituent. On the other hand, it is highly desirable that the flocculant precipitate containing the colour impurities, once occurs, can float up rapidly and separate from the clear sugar liquor. This is particularly important in the industry scale sugar clarification process as a faster floatation rate can lead to higher efficiency of the process. The results show that the compound of the invention provided a faster floatation rate compared to the quaternary ammonium compound tested in comparative example 2 which has mono-long chain alkyl group and a benzyl group as substituents.
Example 2
Raw sugars obtained from sugar cane juice by simple lime treatment were dissolved in hot water (60～80℃) to obtain a raw sugar liquor of 60～65 Brix. The colour value of the raw sugar liquor was in the range of 900-1300 ICUMSA units.
The raw sugar liquor was heated to 80-85℃, followed by addition of benzyl-bis (hydrogenated tallow alkyl) methyl ammonium chloride (obtained from the Solvay Company) at 300 ppm under stirring for 15 minutes. Then phosphoric acid was added to the raw sugar liquor at 300 ppm. The sugar liquor was neutralized to pH 6.9-7.0 by addition of lime succrate under stirring. The sugar liquor was then transferred into a separatory funnel,  then 15-20 ppm of polyacrylamide (PAM) was added. The separatory funnel was shaken vertically for 10-20 seconds until large amount of small bubbles appeared, and then it was immerged in boiling water bath for 10 mins. The precipitate containing colour impurities floated up to the surface of the sugar liquor. Floatation rate was determined at different time points after the separatory funnel was immerged in the boiling water bath. 40 ml of clear sugar liquor was collected from the bottom of the separatory funnel for colour value test.
The colour removal rate and floatation rate were measured as described above.
Comparative example 3
Experiments were conducted according to the procedures in Example 2, except that benzyl-bis (hydrogenated tallow alkyl) methyl ammonium chloride was replaced with octadecyl trimethyl ammonium chloride (CAS No. 112-03-8) .
The colour removal rate and floatation rate were measured as described above. Results are shown in Tables 3 and 4 below:
Table 3
Figure PCTCN2017084926-appb-000008
Table 4
Figure PCTCN2017084926-appb-000009
Results showed that the quat according to the invention (benzyl-bis(hydrogenated tallow alkyl) methyl ammonium chloride) provided better colour removal and faster flotation compared to octadecyl trimethyl ammonium chloride.

Claims (15)

  1. A method for reducing colour impurities in a sugar liquor or syrup, comprising a step of adding a quaternary ammonium compound to said sugar liquor or syrup, wherein said quaternary ammonium compound has the general formula (I) :
    Figure PCTCN2017084926-appb-100001
    wherein:
    R1 and R2, which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group having 8-24 carbon atoms, optionally containing a hetero atom；
    R3 is a saturated or unsaturated, straight or branched aliphatic group having 1-8 carbon atoms；
    R4 represents– (CH2) n-phenyl, wherein n is 0 or an integer of 1 to 3； the phenyl group optionally has at least one substituent selected from the group consisting of halide, nitrite, and sulfite on any available position；
    X is an anion.
  2. The method according to claim 1, wherein in the general formula (I) , R1 and R2, which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group having 12-20 carbon atoms.
  3. The method according to claim 1 or 2, wherein in the general formula (I) , R3 is a saturated or unsaturated, straight or branched aliphatic group having 1-3 carbon atoms.
  4. The method according to any one of claims 1 to 3, wherein said quaternary ammonium compound has the general formula (II) :
    Figure PCTCN2017084926-appb-100002
    wherein:
    R5 and R6, which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group, notably alkyl or hydroxyalkyl group, having 12-20 carbon atoms, the aliphatic group may optionally contains a hetero atom；
    X is an anion selected from the group consisting of Cl, Br, methylsulphate and nitrate.
  5. The method according to any one of claims 1 to 4, wherein said quaternary ammonium compound is selected from the group consisting of di-hydrogenated tallow alkyl methyl benzyl ammonium compound, di stearyl methyl benzyl ammonium compound, di hexadecyl methyl benzyl ammonium compound, di octadecyl methyl benzyl ammonium compound and a mixture thereof.
  6. The method according to any one of claims 1 to 5, wherein said quaternary ammonium compound is added in an amount ranging from 100 to 700 ppm based on the weight of solid sugar in said sugar liquor or syrup.
  7. The method according to any one of claims 1 to 6, wherein said quaternary ammonium compound is added in an amount ranging from 100-500 ppm based on the weight of solid sugar in said sugar liquor or syrup.
  8. The method according to any one of claims 1 to 7, wherein the method further comprises:
    (a) adding a phosphoric compound, a lime-based compound, and a flocculating agent to said sugar liquor or syrup, so as to form a flocculant precipitate；
    (b) separating the flocculant precipitate from said sugar liquor or syrup.
  9. The method according to claim 8, wherein the lime-based compound is milk of lime or lime succrate.
  10. The method according to claim 8 or 9, wherein the phosphoric compound is present 1-5 times, by weight, the amount of said quaternary ammonium compound.
  11. The method according to any one of claims 8 to 10, wherein the phosphoric compound is phosphoric acid.
  12. The method according to any one of claims 8 to 11, wherein the flocculating agent is present in an amount of 5-30 ppm based on the weight of solid sugar in said sugar liquor or syrup.
  13. The method according to any one of claims 8 to 12, wherein the flocculating agent is an anionic polyeletrolyte.
  14. Use of a quaternary ammonium compound for reducing colour impurities in a sugar liquor or syrup, wherein said quaternary ammonium compound has the general formula (I) :
    Figure PCTCN2017084926-appb-100003
    wherein:
    R1 and R2, which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group having 8-24 carbon atoms, optionally containing a hetero atom；
    R3 is a saturated or unsaturated, straight or branched aliphatic group having 1-8 carbon atoms；
    R4 represents– (CH2) n-phenyl, wherein n is 0 or an integer of 1 to 3； the phenyl group may have at least one substituent selected from the group consisting of halide, nitrite, and sulfite on any available position；
    X is an anion.
  15. Use according to claim 14, wherein said quaternary ammonium compound has the general formula (II) :
    Figure PCTCN2017084926-appb-100004
    wherein:
    R5 and R6, which may be the same or different, represent a saturated or unsaturated, straight or branched aliphatic group having 12-20 carbon atoms, the aliphatic group may optionally contains a hetero atom；
    X is an anion selected from the group consisting of Cl, Br, methylsulphate and nitrate.
PCT/CN2017/084926 2016-05-26 2017-05-18 Method for reducing colour impurities in sugar liquid or syrup WO2017202240A1 (en)

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US4196017A (en) * 1979-01-29 1980-04-01 Holly Sugar Corporation Method for reducing color impurities in sugar-containing syrups
WO2011060168A1 (en) * 2009-11-11 2011-05-19 Carbo-UA Limited Compositions and processes for improving phosphatation clarification of sugar liquors and syrups

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Publication number Priority date Publication date Assignee Title
WO2020062060A1 (en) * 2018-09-28 2020-04-02 Rhodia Operations Method for Purifying Xylose
CN113039291A (en) * 2018-09-28 2021-06-25 罗地亚经营管理公司 Process for the purification of xylose

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