MXPA98002661A - Process for the purification of organi sulphonates - Google Patents

Abstract

The present invention relates to a process for producing an aqueous sulphonate / low sulphate organic sulphate solution from a soluble sulfate containing organic sulfonate / sulfate comprising forming an aqueous sulfonate / organic sulfate solution, and passing the aqueous solution of the sulphonate / organic sulfate containing the soluble sulphate on a zone of nanofiltration at an elevated pressure to form a retention with a reduced sulfate content and an infiltration containing the soluble sulfate and organic material.

Description

* PROCESS FOR THE PURIFICATION OF ORGANIC SULPHONATES AND * NEWEST PRODUCT CROSS REFERENCE FOR RELATED APPLICATION (S) This application claims priority under 35 U.S.C. § 119 of the United States Provisional Patent Application Serial No. 60 / 043,061 filed on April 4, 1997.

BACKGROUND OF THE INVENTION * The invention relates to a process for removing sulfate ions from organic sulfonates and sulfates, and if required, low molecular weight organic sulfonates / sulfates, particularly sulfate and aromatic sulfonate or sulfate and sulphonate compositions. aliphatic The invention is particularly directed to the removal of sulphate ions from Alkyl naphthalenes and alkyl benzene sulphonates, naphthalene sulphonates and the oligomeric materials formed by reacting the aromatic sulfonates with aldehydes, preferably formaldehyde. Typical materials that can be treated by the process of the present invention are described in U.S. Patent 4,465,492, which is incorporated herein by reference. The organic sulfates or sulphonates or mixtures thereof, contain sulfate ions in the form of an acid or salt, which results from the use of excess sulphonation material used in their preparation. The term "organic sulfonates / sulfates" as used herein, refers to the sulphated material or sulfonated organic or mixtures thereof.

The process for sulfonation of naphthalene is described by E.A.Knaggs, "Sulfonation and Sulfation", Encvclopedia of Chemical Technology. Vol. 2, p. 145 (John Wiley &Sons, Incorporated, New York, New York, 3rd Ed., 1983), the disclosure of which is incorporated herein by reference. The materials that can be treated by the present invention include the condensation polymers of a condensable carbonyl compound and an aromatic sulfonate. Preferred examples of such condensates are condensates of naphthalene sulfonic acid formaldehyde and condensates of naphthalene sulfonic acid formaldehyde # 10 substituted with lower alkyl. Other examples are aromatic-based carbonyl condensates, including condensation products of acetone with naphthalene sulfonic acid or benzene sulfonic acid. The sulfonated aromatic compounds and particularly the Sulphonated (alkyl) naphthalenes can be used in the manufacture of the condensates. The term (alkyl) naphthalenes or (alkyl) benzene refers to naphthalenes and benzenes or their homologs containing alkyl. However, as an alternative to pre-sulfonation, naphthalene can be sulfonated during condensation with the aldehyde. Condensation and sulfonation produce a product, which is considered an acid Sulphonic acid of naphthalene aldehyde or f-naphthalene-aldehyde sulphonic acid condensate. The processes for preparing the condensates are described in U.S. Patent 2, 141, 569 (Tucker et al.), Issued December 27, 1983, U.S. Patent No. 3, 193,575 (Neville et al.), Issued on February 6, 1983. July 1965; and U.S. Patent No. 3,277,162, Johnson, issued October 4, 1966, the contents of which are incorporated herein by reference. The condensation products generally have an average number of molecular weight from about 1,500 to about 6,000 and an average weight of molecular weight from about 3,000 to about 16,000 and will contain up to about 8 to 30% by weight of non-condensed materials, such as mono- and di-sulfonated aromatic materials. The composition with weight average molecular weight or number average greater or lesser, can be treated to remove sulfate ions from the composition. * 10 The formaldehyde condensation products of (alkyl) naphthalene sulfonic acid comprise a mixture of condensation products of sulfonic acid (aikil) naphthalene and formaldehyde. The condensation products that differ for example in the degree of polymerization. The mixture can be separated by exclusion chromatography size, to selectively separate the molecular species according to size. This is a method to obtain a measure of the degree of polymerization. Aromatic aldehyde condensates are generally soluble in water or dispersible in water, and contain substantial amounts of water.

Sulfate (up to about 15 to 20% by weight of the solids), depending on the proportion of the sulfonation agent for the aromatic compound. Depending on the commercial use for the material, the level of sulfate in the composition can be reduced. If a high salt form of the composition is required, the sulfuric acid without reactions is simply neutralized and the condensate containing the sulfuric acid • Neutralized can be sold for certain uses. If a low salt material (less than about 3.0-6.0 wt.% Solids) is required, the sulfate ions should be separated in some way from the condensation product of aromatic sulfonate aldehyde. This can be achieved by neutralizing the unreacted sulfuric acid with an alkaline material, such as calcium hydroxide and separating the calcium sulfate formed from the aromatic aldehyde-sulfonate condensation product. However, dispersions or solutions in water generally have a high viscosity and filtration can be difficult. The mixture of calcium sulfate with the condensation product of aromatic aldehyde sulfonate must also be removed. This is an expensive problem because the amount of raw material that is converted to filter cake is substantial, and the filter cake must be removed in a disposal facility for hazardous waste material. In addition to the aforementioned expenses, the material is also carried with the one portion of the aromatic sulfonate-aldehyde condensation product. In view of the elimination problems and the cost of the raw material to neutralize the excess sulfate, the processes to prepare the aromatic-aldehyde sulfonate condensation products are generally optimized to provide the required sulfonation using the minimum amount of excess sulfuric acid. The diagram of a known process which requires neutralization and separation of calcium sulfate to prepare the condensation products of aryl-aldehyde sulfonate is shown in Fig. 1.

The presence of sulphate salts and the aryl mono- and di-sulfonates # Uncondensed and unpolymerized has a harmful effect on the use of condensation products as a cement additive. It would be useful to be able to easily reduce the amount of sulfate and the amount of Uncondensed and unpolymerized aryl sulphonates in the composition.

BRIEF DESCRIPTION OF THE INVENTION According to the present invention, an organic sulfonate / sulfate or particularly an aldehyde sulfonate condensation product of The aryl or aryl sulfonate having a low sulfate content can be prepared by passing an aqueous solution of an acidic or neutralized form of the organic sulfonate / sulfate or particularly a reaction product of aryl sulfonate aldehyde or aryl sulfonate, through a nanofiltration zone to separate the sulfate ions from the mixture, to provide a retention with a reduced sulfate content and an infiltration comprising mainly sulfate and a significantly lower amount of uncondensed sulfonate / organic sulfate. aryl mono- and di-sulfonates and lower molecular weight oligomers. The infiltration is then passed to a separation zone, where the The sulfate is separated from the solution of the organic mono- and di-sulfonates and low molecular weight oligomers thereof. If the sulfate is not neutralized then, the sulfuric acid solution can be concentrated and returned to the sulphonation zone to be mixed with oleum to raise the force to that required for the sulfonation reaction. The mono-25 and di-sulfonates and the low molecular weight oligomers can be mixed with the feed for the aldehyde condensation step or for the feed to the process nanofiltration step, if a low mono- and disulfonate product is not required. The invention also comprises the condensation product of Aryl sulfonate aldehyde with a reduced content of aryl sulfate and mono- and di-sulfonates and low molecular weight oligomers, which shows improved properties as a dispersant to form cement-containing materials, such as concrete. The invention also includes a method for treating a nanofiltration membrane t 10 to improve the flow velocity of the infiltration containing the sulfate and aryl mono- and di-sulfonates and low molecular weight condensation oligomers thereof through the nanofiitration membrane.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS FIG. 1 is a diagrammatic representation of a process for preparing condensation products of aryl sulfonate aldehyde with a reduced amount of sulfate in the mixture. Fig. 2 is a diagrammatic representation of the process of the present invention. Fig. 3 is a diagrammatic representation of the nanofiltration process used in the examples. Fig. 4a is a typical chromatogram of a typical naphthalene formaldehyde sulfonate condensation product.

Fig. 4b is a chromatogram of a condensation product of naphthalene sulfonate formaldehyde, which has been treated by the nanofiltration process of the invention without recycling of the mono-sulfonates, di-sulfonates and lower oligomers without condensation. Fig. 5 (a) and (b) are drawings of a spiral wound nanofiltration device. Fig. 6 (a) and (b) are graphs of the difference between concrete depression as a function of (alkyl) naphthalene mono- and di-sulfonates in the formaldehyde condensate of (alkyl) naphthalene sulfonic acid. Fig. 7 is a schematic drawing of an electrodialysis apparatus.

FIG. 8 is a flow chart of SO and mono- and di-sulfonate and sulfonic acid (alkyl) naphthalene against current flow in an electrodialysis apparatus. Fig. 9 is a schematic drawing of a bipolar electrodialysis apparatus.

DETAILED DESCRIPTION OF THE INVENTION The process of the invention is particularly useful for removing salts or acids of organic sulfonates / sulphates disposable in water or soluble in sulphated or sulphonated water. The organic sulfonates / sulfates are known products, which can be prepared by methods such as those described in US Pat. No. 2, 199,806, US Pat. No. 3,849, 162, the British patent specification 1, 101, 671, British specification No. 1, 239,016 and British specification 1, 507,772. Typical examples are sulphated alkali metal oxide adducts, partially esterified and sulfated polyhydric alcohols, alkyl sulfonates, alkyl sulfates, dialkyl sodium sulfosuccinates, alkylbenzene sulfonates, condensation products of (alkyl) naphthalene and formaldehyde sulfonic acid, condensation products of formaldehyde of ditolieter and sulfuric acid, condensation products of chloromethylated diphenylene, (alkyl) naphthalene and sulfuric acid, condensation products of mononuclear aromatics, formaldehyde, sulfonic acids of (alkyl) naphthalene and optionally sodium sulfite, or condensation products of (alkyl) naphthalene, toluene, formaldehyde and sulfuric acid. The process of the present invention is particularly useful for removing the sulfate and, if required, the mono-sulfonates and di-sulfonates from the condensation products of monosulfonic acids of (alkyl) naphthalene and / or (alkyl) benzene, which they can be substituted with an alkyl portion having 1 to 18 and preferably 1 to 10 carbon atoms ((alkyl) aryl sulfonates) and formaldehyde. These dispersants are described in US Patent 4,465,492 to Putzer, patented on August 14, 1984, which describes other materials, which may contain sulfate, which can be removed from the composition. The known processes react the aryl compound with sulfuric acid to form the sulfonate, which is reacted with an aldehyde such as formaldehyde, to form a condensation product. The processes can be carried out in a single stage. Excess sulfuric acid is used, generally from about 5% to 50% excess. If a low salt product is required, the sulfuric acid is neutralized with lime to form calcium sulfate, which is filtered out of the liquid mixture, the sulfonate is neutralized with sodium carbonate to precipitate the residual calcium as calcium carbonate and the Neutralized product is filtered again and packed for sale. The process of the prior art is shown in Fig. 1. Sulfuric acid or oleum are fed through the level of line 7 and the aromatic compound to be sulfonated is introduced into the reaction zone 3. A sulfonate is formed and a mixture comprising the aromatic sulfonate and excess and unreacted sulfuric acid, passes to the condensation zone 6 through line 4. An aldehyde such as formaldehyde and water is introduced through line 5 and mixed with the sulfonate mixture in reaction zone 6 to form the condensation product. The condensation product passes through line 7 to neutralization zone 9, where it is neutralized and diluted with water by a paste of lime introduced through line 8. Calcium sulfate is precipitated and the mixture passes to the filter V \ through line 10. ^ ~ The filter cake mixed with occluded condensation product is sent to the elimination of waste through line 12 and the liquid filtrate passes to neutralization zone 15. through line 13. In the neutralization zone 15, if a product of low calcium, low sodium is required, the condensation product is mixed with sodium carbonate introduced through line 14, filtered and the concentration is adjusted to the sale specification. The product ready to be packed and shipped is removed through line 16.

The process of the invention will be described in relation to the removal of # sulphate from (alkyl) naphthalene sulfonate and a condensation product of (alkyl) naphthalene sulfonate with formaldehyde. The sulfonation of (alkyl) naphthalenes and the condensation of sulfonated 5 (alkyl) naphthalenes with formaldehyde are well known and the sulfonation process described in relation to Fig. 1. The aromatic material such as (alkyl) naphthalene can be sulphonated by contact with oleum or sulfuric acid. If a condensate is to be formed, the sulfonated (alkyl) naphthalene is then reacted with an aldehyde, preferably formaldehyde to form the condensation product. In an alternative method, sulfonation and condensation can be carried out in a single step to produce a condensation product of (alkyl) naphthalene sulphonated formaldehyde. In the process, to ensure the substantial sulfonation of the aromatic components, an excess of oleum or sulfuric acid is used. Excess sulfuric acid does not affect the condensation reaction, but can be detrimental to the end uses for the product. By the process of the invention, the unreacted sulfate portions and if required, the (alkyl) naphthalene sulfonates without The polymerization can be separated from the reaction mixture. The reaction to form the condensation products of the (alkyl) naphthalene sulfonates is an acidic process and is carried out in the presence of excess sulfuric acid and water. To be used, the condensation product is generally neutralized with an alkaline material such as sodium hydroxide or sodium carbonate. Together with the neutralization of the condensation product, the unreacted sulfuric acid and the monomeric sulfonates are also neutralized. The neutralized product or the unneutralized product can be treated by the process of the invention to remove the monomeric sulfate and mono- and di-sulfonates of monomeric 5 (alkyl) naphthalene from the reaction mixture. The process of the invention is shown diagrammatically in Fig. 2. The (alkyl) naphthalene enters the sulfonation-condensation zone through the line 17. The formaldehyde is introduced through the line 18 and sulfuric acid through line 28. Sulfuric is added to ^ F 10 through line 28. An oleum mixture is the one that enters through line 32 and decreases the concentration of recycled sulfuric acid from the acid concentration zone 27. The (alkyl) naphthalene is sulfonated and condensed to form the condensation product. The condensation product contains the excess of unreacted sulfuric acid. A The solution of the (alkyl) naphthalene-formaldehyde condensate in water containing from about 20% to 60% by weight of condensate of (alkyl) naphthalene-formaldehyde passes into the nanofiltration zone 21 through line 20. In the zone of nanofiltration 21_, the condensation product solution of (alkyl) naphthalene-formaldehyde sulfonate is passed through a pressure nanofiltration apparatus in the range of 10,545 to 49.21 kilograms per square centimeter of calibrator and a temperature of 35 ° to 85 ° C to form a retention with a reduced sulfate content and, if required, a reduced content of mono- and di-sulfonated (alkyl) naphthalene. Infiltration, which is obtained near the end of the diafiltration cycle (which is sufficiently low in sulfate) can be used as an early water masker in the next batch of diafiltration through line 26a. Infiltration without recycling goes to the separation zone. 5 If the nanofiltration unit is sufficiently large, the sulfate concentration can be reduced to a sufficiently low level with a passage through the nanofiltration apparatus. However, the water may be added to maintain the concentration of the condensation product in the range of no more than about 40% -60% in weight of the solution. For solutions or dispersions of materials other than the condensation products of (alkyl) naphthalene-formaldehyde sulfonate, a higher concentration can be used. A preferred method for performing nanofiltration is by a diafiltration method, wherein the sulfonate reaction product of (alkyl) naphthalene formaldehyde is circulated on the nanofiltration membrane and sufficient water is added to maintain the concentration of the condensation product of (alkyl) naphthalene-formaldehyde sulfonate in the range of 30% to 45%, preferably 35% at -40% by weight of the solution. When the sulfate level has reached a required level, the nanofiltration is discontinued. The condensation product of (alkyl) naphthalene-formaldehyde sulfonate is in the retention (the material that does not pass through the membrane). Retention with the reduced sulfate content is ready to be packaged and for sale. The retention passes from the nanofiltration zone 2? _ Through from line 22 to the storage area 23.

Infiltration (the material passing through the nanofiltration membrane) flows to an infiltration treatment zone 25 through line 24. In the infiltration treatment zone 25, the sulfate is separated from the infiltration to form an aqueous stream containing sulfate and an aqueous stream containing mono- and di-sulfonates of (alkyl) naphthalene and low molecular weight reaction products. The sulfate-containing aqueous stream can be an acid stream, which passes to the acid concentration zone 27 through line 26. * 10 Concentrated sulfuric acid can be mixed with oleum and introduced into the sulfonation condensation zone as a portion of the acid feed through line 28. The oleum composition is introduced through line 29. If nanofiltration it is carried out in an unneutralized (acid) mixture, the sulfuric acid can be separated from the infiltration by an electrodialysis process, which would constitute the infiltration treatment zone 25. • Electrodialysis is a known process and uses cationic and anionic membranes and a direct current electric field for Separate ions from an aqueous stream. The condensation products of (alkyl) naphthalene mono- and di-sulfonates and oligomers are too large to pass through the membrane efficiently, and the sulfate ions are removed from the infiltration to form dilute sulfuric acid, with less than about 5% by weight and preferably less than about 1% by weight of sulfonate / organic sulfate material in a water-free base. Dilute sulfuric acid passes to the zone of • concentration of acid 27 through line 26. After concentration, the sulfuric acid is mixed with oleum composition, which enters through line 32 and is introduced into the sulfonation-condensation zone 1.9. The infiltration treated with the reduced sulfuric acid content is passed to the treated infiltration storage zone 29 via line 30. The low molecular weight oligomers and the (alkyl) naphthalene mono- and di-sulfonates can be mixed with the product of the sulfonation-condensation reaction of zone 9 to be condensed or can be introduced into the feed to the nanofiltration zone when a product with low concentration of monomers and oligomeric materials is not required. The process can be operated substantially without waste or with minimum amounts of waste, which can be disposed of in a hazardous waste disposal facility. If the sulfonation-condensation reaction product is neutralized before the nanofiltration treatment, the sulfuric acid can be recovered in a bipolar electrodialysis zone and the (alkyl) naphthalene mono- and di-sulfonated and the oligomers can be returned to the feed to the nanofiltration zone and the caustic stream of the bipolar electrodialysis unit can be returned to the neutralization step of condensed products. In an alternative procedure, when feeding to the area of nanofiltration has been neutralized, the sulphate can be separated from the mono- and di-sulfonated (alkyl) naphthalene and the products of * organic sulfonate / sulphate of low molecular weight in the infiltration, when passing the infiltration through an ion exchange zone containing an alkaline ion exchange medium and preferably a weakly alkaline ion exchange medium. The sulfate salt passes through the ion exchange zone. The mono- and di-sulfonated (alkyl) naphthalene and the oligomers in the infiltration will preferably remain with the ion exchange material and can be regenerated from the ion exchange material with an alkaline material * 10 aqueous and mixed with the feed to the nanofiltration zone. When the ion exchange is used to separate the sulfate of the mono- and di-sulfonated (alkyl) naphthalene and the oligomers in the infiltration of a neutralized reaction mixture, the sulfate is in the form of a salt and the liquid stream is discarded. Since the organic materials in the stream are present only in small quantities, the effluent containing the sulphate salts is generally suitable for discharge to municipal sewage treatment systems.

NANOFILTRACTION In the first step of the process of the present invention, the neutralized or unneutralised sulfonate / sulphate organic product or the condensation reaction mixture is treated in a nanofiltration zone. Nanofiltration is a known operation in which a solution or dispersion of a material to be treated is passed over a nanofiltration separation membrane at a pressure, which is generally in the range of about 10,545 to about 49.21.

»Kilograms per square centimeter (depending on the strength of the membrane) to cause the sulphate and the lower molecular weight materials to pass through the membrane together with the water to form an infiltration and an aqueous phase, which does not pass through the membrane, which is known as a retention. Upon passage through the nanofiltration module, the retention has a lower concentration of sulfate and, if required, lower molecular weight (alkyl) naphthalene sulfonates and oligomers thereof than the feed that * 10 enters the nanofiltration module. Nanofiltration is generally performed at a moderate pressure in the range from about 14.06 to about 35.15 kilograms per square centimeter of caliper pressure drop across the membrane. An increase in pressure normally increases the rate of infiltration formation. However, the pressure that can be used is determined by the temperature, nature of the particular nanofiltration membrane and the particular design of the nanofiltration apparatus. The reaction product is passed through the apparatus of nanofiltration at a temperature as high as possible, considering the nature of the nanofiltration membrane and the pressure used in the filtration operation. The high temperatures are useful because the condensation product of (alkyl) naphthalene-formaldehyde sulfonate provides a viscous solution at concentrations in the range of Above about 30% by weight of the condensation product of (alkyl) naphthalene-formaldehyde sulfonate. Usually, * temperatures in the range from about 40 ° C to about 80 ° C, preferably 70 ° C can be used when the process is operated with a suitable membrane. A suitable nanofiltration membrane for use in the method of the present invention comprises a hydrophilic membrane, which is generally crosslinked and has ionic groups, which is supported on a porous polymeric material, which can be further supported on a substrate, which provides strength to the composite membrane. The The membrane is preferably asymmetric because both sides of the support substrate are not the same. Only the face of the membrane, which is brought into contact with the aqueous phase to be treated, comprises the thin layer of the hydrophilic cross-linked ionic polymer material. Nanofiltration membranes are usually provided in certain degrees, which have been manufactured to reject the passage of molecules above a critical molecular size. That is, the membranes can be provided, which reject molecules with a molecular weight above about 200 to membranes which pass molecules having a molecular weight of less than several thousand.

In this context of this invention, the molecular weight is used to indicate the molecular size, but the molecular size is a more appropriate term. However, for the process of the present invention, a nanofiltration membrane having a molecular weight cut in the range from about 150 to about 1000 and preferably about 200 to about 500, can be used in the practice of the present invention. The molecular weight cutoff for the nanofiltration membrane useful in the practice of the present invention is determined by the nature of the aqueous solution from which the sulfate is to be removed, and in particular the molecular weight of the component, which is to be retention in retention and the larger molecular weight of the molecules, which pass through the membrane and collect in the infiltration. A membrane must also be selected with respect to the pH of the aqueous solution from which the sulfate is to be removed. Typical membranes for use in the nanofiltration and ultrafiltration processes are described in U.S. Patent 4,767,645 to Linder et al. , U.S. Patent 4,477,734 to Linder et al. , U.S. Patent 4,833,014 to Linder et al. , the US patent for Bartels et al. , and U.S. Patent 5,049,282 to Linder et al. (The aforementioned patents are incorporated herein by reference). The type of membrane that is selected depends on the pH of the aqueous solution to be treated with the nanofiltration unit, the required molecular weight cutoff, and the temperature and pressure at which the nanofiltration will be performed. The most critical parameters are the molecular weight cutoff, the pH and the temperature requirements for the nanofiltration step. As used herein, the term "nanofiltration" refers to a process in which an aqueous solution of an organic sulfonate / sulfate and particularly the condensation product of an aromatic (alkyl) sulfonate with an aldehyde such as formaldehyde is passed over a membrane that has a molecular weight cutoff in the range from * about 150 to 1000 and preferably about 200 to about 700 and most preferably about 200 to about 500. As is well understood in the art, nanofiltration is performed at a moderate pressure drop across the membrane in the range from about 14.06 to about 35.15, and preferably from about 17.575 to about 29.526 kilograms per square centimeter. The pressure drop through the module The nanofiltration is generally within the range of 3.515 to 14.06 kg / cm2 gauge and preferably about 3.515 to about 7.03 kg / cm2 gauge. The term "nanofiltration" as used herein overlaps with ultrafiltration in the high molecular weight cutoff range and reverse osmosis in the cutoff range of low molecular weight. Since these terms are used in the art, there is generally an overlap at each end of the molecular weight cutoff range. Membranes with higher molecular weight cutoff ranges can be used if the higher molecular weight oligomers are to be separated from the aqueous phase. A description of the different parameters used and the nomenclature for filtration is shown in the table, THE FILTRATION SPECTRUM by Osmonics, incorporated, which is incorporated herein by reference. In the operation of the nanofiltration step, the membrane is arranged so that the aqueous solution to be subjected to nanofiltration is passed on the hydrophilic surface of the membrane at a pressure in the range from about 7.03 to about 49.21 kilograms per square centimeter, where compounds with a molecular weight below the infiltration of molecular weight cutoff range pass through the membrane along with a portion of the water in the solution. The material, which infiltrates through the membrane is noted as an infiltration, while the material that does not pass through the membrane is noted as retention. In the practice of the present invention, the sulfate ions and a portion of the water pass through the membrane and are removed with the infiltration. Uncondensed (alkyl) aryl sulfonates with a molecular weight below or slightly above the molecular weight cutoff and low molecular weight oligomers also pass through the membrane at a significantly slower rate and can be collected in the infiltration. The composite membrane useful in the practice of the present invention can be used in various configurations. For example, it is possible to use the composite membrane arranged in a frame and plate configuration, in which the separation layers can be mounted on a porous support layer with a carrier layer or use the shape of hollow tubes. It is also possible to use a spiral configuration module, which includes a separating layer membrane mounted on a porous support layer and a carrier layer, the assembly typically being bent and attached or bonded along three edges with an open edge. to form a unit similar to a bag, which preferably has the separating layer on the outside. A separator that serves as an infiltration discharge channel is placed inside the unit similar to a • bag. A discharge channel is projected from the end of the unit. A separator is provided on the exterior face of the bag-like structure, which is for contacting the aqueous solution subjected to nanofiltration. An outlet of the bag-like layer is then attached to a central discharge conduit, which leaves the nanofiltration unit to provide an outlet for infiltration of the nanofiltration zone. The structure similar to a bag is then wound around the duct with the separating element, providing a The space between layers of the spiral wound element through which the aqueous phase, being subjected to nanofiltration, can flow past the surfaces of the membrane. The hydrophilic cross-linked ionic surface is exposed to the aqueous phase, from which the sulfate will be removed under high pressure. The spiral wound unit can be formed from a number of units similar to a bag, which are attached to the central conduit and then wound in a spiral manner. The spiral wound element is then mounted in a shell with a deflector-like seal between the inner surface of the pressure receptacle shell and the outer surface of the spiral wound nanofiltration module. He A baffle-like seal is useful to ensure that the liquid, which will be nanofiltered, does not deviate from the nanofiltration module. A drawing of a spiral wound nanofiltration unit is shown in Fig. 5 (a) and (b). Fig. 5 (a) is a schematic drawing of a spiral wound nanofiltration unit. Three spiral wound membrane modules 67 are arranged in the pressure receptacle 57. The feed solution enters through the conduit 58 and passes between the sheets formed by the membrane 65 and infiltration space 66., which are sealed at their edges. The sheets are separated by separators 64. The flow of the feedstock is through the separator 64. The flow around 5 of the module 67 is prevented by the seal 61. The infiltration is collected in line 59 and removed from the rest. The retention flows out of the pressure receptacle 57 through line 60. Anti- telescopic fittings 62 prevent the module intervals (separators 64, and membranes 65) from being forced by the pressure drop outside the end of the module 67. The pressure drop to flow through the spiral wound unit can be in the range of 3.515 to 7.03 kg / cm2. A coupling 68 connects several modules 67 in the pressure receptacle. The pressure drop between the retention side of the membrane and the infiltration side of the membrane is generally in the range of 14.06 a 35.15 kg / cm2 depending on the structure of the membrane. During the ultrafiltration process, a portion of the water is transferred through the nanofiltration membrane along with the sulfate ions. Since the infiltration contains a relatively low concentration of sulfate ions, it is usually necessary to add water additional to the retention to ensure that the viscosity does not increase to the point that the material does not flow easily through the surface of the membrane or that the infiltration becomes so concentrated in the sulphate portions that the membrane becomes clogged and is prevented that the nanofiltration process takes place.

It is generally necessary to introduce water into the solution to prevent the viscosity from increasing to the point that the material does not flow easily through the nanofiltration zone. The solution can be recirculated through the nanofiltration zone and water can be added to maintain the solution at a useful concentration; This type of process is known as dialfiltration. The amount of water added to the solution is sufficient to maintain the solution at a concentration, in which the viscosity does not interfere with the nanofiltration process. After the concentration of the sulfate ions in the aqueous phase approaches the required level, the addition of water can be suspended or reduced and the concentration of condensation product of (alkyl) aryl-aldehyde sulfonate in the solution can be increased. If the nanofiltration unit is relatively small, the feed stream is recirculated through the nanofiltration zone and the The volume of the feed stream is kept constant by the addition of water to the recirculation feed stream. aa In the nanofiltration of the (alkyl) aryl sulfonate condensation products, the concentration of the sulphate ions in the infiltration increases according to the concentration of the condensation product of (alkyl) aryl-aldehyde sulfonate in retention increases. However, at a concentration in the range between about 40 and 45% by weight of the condensation product of (alkyl) aryl-aldehyde sulfonate, the solution becomes viscous and the sulfate concentration in the infiltration becomes so high, that the membrane begins to clog and then nanofiltration is not possible or proceeds so slowly that the process is not % economically useful. In the operation of the nanofiltration step, it has been found useful to operate at a temperature in the range from about 35 ° C to about 80 ° C, preferably 35 ° C to about 60 ° C, with a pressure drop across the the membrane in the range from about 14.06 to about 28.12 kilograms per square centimeter to a concentration of the condensation product of (alkyl) aryl-aldehyde sulfonate in the range from about 30 * 10 to about 40% by weight. In this range, the infiltration contains a high percentage of the sulfate ion and the sulfate ion is rapidly removed from the retention. A diagrammatic representation of the nanofiltration apparatus used in the examples of the nanofiltration step is shown in Fig. 3. After the sulfate ions have been reduced in retention to the required level, if the retention has not been neutralized before or during the. nanofiltration operation, the retention can be neutralized and prepared for use. The condensation products of (alkyl) aryl-aldehyde sulfonate are generally sold as liquid solutions or dry powders. If a dry powder is required, the neutralized retention can be spray dried to form a powder material, which is readily soluble in water. The process has been described in relation to a condensation product of (alkyl) aryl-aldehyde sulfonate, but it can be applied to organic sulfonate / sulfate products.

The infiltration of the nanofiltration zone is then passed to a # Infiltration treatment zone, where the sulfate is separated from the organic material, which may have passed through the membrane as a portion of the infiltration. The method for separating the sulfate ions from the organic material in the infiltration depends on whether the sulfate ions are in the acid form or as a sulfate salt. If the sulphate is present in the form of sulfuric acid, that is, the sulphate has not been neutralized, the sulphate can be separated from the organic matter in the infiltration by means of an electrodialysis process. Electrodialysis * 10 is well known. In an electrodialysis process, the infiltration from which the sulfate will be removed is passed through a cell having an anode, cathode and alternating ammonium and cation membranes separated by thin separators. The cells are arranged in a stack of at least three cells with the infiltration introduced into alternate cells and water introduced into alternate cells. An electrolyte solution is generally introduced into the cells at the ends of a stack adjacent to the electrodes. Direct current with the positive electrode providing current to the side that has the anionic membrane and the negative pole that provides current to the side with the cationic membrane. The membranes are usually arranged with a very thin space between the cationic membrane and the anionic membrane and arranged in piles with alternating cationic and anionic membranes. The infiltration is passed in alternate cells and water is passed in alternate cells between the cells to which the infiltration is introduced. When direct current is applied to the cell stack, the anionic constituents mainly sulfates pass through the anionic membrane # in the water stream on the opposite side of the membrane and the protons of the cationic materials pass through the cationic membrane to the aqueous phase on the opposite side of the membrane. By this method, the sulfate is separated from the aqueous phase and the organic materials. The anionic membrane is selected so that materials containing anionic (alkyl) aryl sulfonate do not easily pass through the anionic membrane. The operation of an electrodialysis apparatus is described in Kirk-Othmer, CONCISE ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, pages 406 and 407 (Wiley &Sons 1985), the reference of which is incorporated herein by reference. The electrodialysis process is also described in the Chemical Engineers' Handbook. Fifth Edition, Robert H. Perry, consultant and Cecil H. Chilton, Senior Advisor, McGraw-Hill Book Company, published in 1974, pages 17-52 to 17-58, which is incorporated herein by reference. The sulfuric acid that has passed through the anionic membrane can be concentrated to 50 to about 80% by weight and returned to the sulphonation process mixed with oleum to form the (alkyl) aryl sulfonates. The infiltration from which the sulphate has been removed in the acid form can be recycled to the feed to the condensation zone or fed to the nanofiltration unit. If a nanofiltration retention material with a low content of monomeric material (alkyl) aryl sulfonate is required, the retention with the monomeric (alkyl) aryl sulfonates must be recycled to the condensation zone or, it can be separated and introduced to the feed to the nanofiltration unit when the product is not required to contain only small amounts of the (alkyl) aryl sulfonate materials. If the sulfate ions in the infiltration have been neutralized and a salt such as sodium sulfate is present in the infiltration, it is difficult to separate the sulfate from the organic material in a form that can be recycled to the step in which the sulfonation is carried out. If an electrodialysis unit is used, an aqueous stream containing sodium sulfate is formed, which must be discarded since it is difficult to recover the sodium sulfate. However, since the amount of organic material in the sodium sulphate stream is relatively low, it is sometimes possible to discard the sodium sulfate to the municipal sewage treatment facility without paying an unduly large surcharge. The infiltration containing the organic material can then be recycled in the step in which the sulfonation condensation product is neutralized. In an alternative embodiment, when the sulfate is in the salt form, the infiltration containing the sodium sulphate and the sulphonates of (alkyl) aryl and low molecular weight condensation product oligomers can be passed through a weakly basic ion exchange material. The ion exchange material will remove the organic sulfonates / sulfates and oligomers from the aqueous stream to provide a stream containing the sodium sulfate. Sodium sulfate can then be discarded, since the amount of organic material is relatively low. The organic sulfonates / sulfates and oligomers can be regenerated from the ion exchange material introduced in the neutralization step. The retention comprising condensate of (alkyl) aryl aldehyde sulfonate, which contains less than about 3.5% sulfate (dry base) can be easily obtained. Since the material also contains a lower concentration of mono- and di-sulfonated material, the dispersing capacity on materials prepared by the lime / carbonate precipitation process has improved. Approximately 8% by weight of the solid material of mono- and di-sulfonated (alkyl) aryl sulfonates and low molecular weight oligomers has been found particularly useful as a dispersant to form high strength concrete and cement compositions. Preferably, the dispersant contains less than about 0.75% by weight of sulfate and less than about 5% by weight of mono- and di-sulfonated (alkyl) aryl materials. Preferably, the (alkyl) aryl-aldehyde sulfonate condensation product contains less than about 0.5% by weight of sulfate and less than about 2.0% by weight of mono- and di-sulfonated (alkyl) aryl sulfonates. The applicants have unexpectedly discovered that the (alkyl) aryl-aldehyde sulfonate condensation products containing only these small amounts of mono- and di-sulfonated (alkyl) aryl sulfates and sulfonates unexpectedly provide a concrete or cement composition in the which the depression is so high that the amount of water in the cement or concrete can be reduced to provide a high strength concrete material.

Applicants have also discovered that the nanofiltration membrane, if treated with a weak nitric acid solution, followed by treatment with a solution of a chelating agent such as EDTA, substantially improves the rate at which the aqueous phase 5 infiltration passes. through the nanofiltration membrane and the amount of infiltration collected in a set period of time can be substantially increased. That is, the membrane is first treated by passing a solution containing from about 0.05% by weight to about 5% by weight and most preferably from 0.1% to 3% by weight of nitric acid on the nanofiltration membrane for from about one minute to about one hour at room temperature. The nitric acid solution is then washed from the membrane and an alkaline solution of a chelating agent such as NaEDTA is passed over the nanofiltration membrane. The operation It is generally performed at a sufficiently high pressure that some of the wash solution passes through the membrane and is collected as an infiltration. The applicants do not understand the effect, but neither washing with a dilute solution of nitric acid nor a dilute alkaline solution of a chelating agent such as NaEDTA alone is sufficient to improve the velocity at which the infiltration passes through the membrane. The treatment with the nitric acid followed by the treatment with the chelating agent does not substantially affect the rate at which the infiltration passes through the nanofiltration membrane from a solution such as glucose. Nor does it affect any proportion of permeability of solute - solute permeability which is the proportion of a concentration of solute in the infiltration divided by its concentration in the diet. For the applicants' knowledge, the only effect is that the infiltration rate through the nanofiltration membrane of the aqueous solution of the condensation product of (alkyl) aryl-aldehyde sulfonate is increased. The increase is substantial, which can amount to a speed of at least three times the speed of the untreated membrane.

EXAMPLE 1 The experimental work with nanofiltration was performed in an apparatus as shown in Fig. 3. The aqueous feed to the nanofiltration apparatus was stored in tank 33- The feed to the nanofiltration unit went from the feed tank 33 to through line 34 to pump 35. Feed was pumped through line 36 to filter 37, which separates the solid particles from the feed. The filtered feed passes from the filter 37 through the line 38 to the high pressure pump 39. The high pressure pump 39 raises the pressure in the liquid to 21.09 - 49.21 kg / cm2 gauge and the feed passes through the liquid. line 44 to nanofilter 48. Infiltration leaves nanofilter 48 to through line 51 and goes to storage. The retention leaves nanofilter 48 through line 49 and back pressure controller 50 and returns to feed tank 33 through line 43. Line 45 with control valve 46 is a release valve if the pressure in the nanofilter it rises above the pre-established level. The liquid which can pass through line 45 and control valve 46 returns to feed tank 33 through line 43. Line 40 and valve 41 provide or attempt to provide a positive suction head for pump 39 and a bypass for the feed in front of the high pressure pump. A pump 52 receives the power through the line 57, and pumps the supply through the line 53, the heat exchanger 54 and the line 55 to the supply tank 33 to control the temperature of the supply in the range of 40 ° C to 70 ° C. Water is introduced into the feed tank 33 through line 56 to maintain the level in the feed tank 33 and control the concentration of dissolved material in the feed. We have discovered that the membrane, which was used, could not satisfactorily process a feed with more than about 45% dissolved solids. The process was particularly sensitive when the feed contained sulfate sai from sodium, with the permeability of high sodium sulfate it is possible to precipitate salt in the membrane and cover the membrane. The nanofiitration process is also sensitive to the speed at which the solution passes over the nanofiltration membrane. Higher flow velocities promote higher infiltration rates. Because In the configuration of the spiral wound membrane used in the experiments, it is difficult to determine the flow velocity of the liquid through the nanofiltration membrane module. The volume flow velocity was determined by the flow velocity of the retentate leaving the nanofiltration unit. ^. _ If the feed solution for the nanofiltration device is Viscosity, higher temperatures in the range of 30 ° C to about 80 ° C and preferably 40 ° C to 70 ° C can be used to reduce the viscosity of the feed solution.5 High solids concentration can also produce feeding solutions with high viscosity The concentration of solids in the feed can be a limiting factor in nanofiltration.The high solids content can produce solutions with high viscosity, which can not be pumped at high flow rates over the nanofiltration membrane. However, when the solution of condensation product of (alkyl) naphthalene-aldehyde sulfonate is subjected to nanofiltration, a high concentration of solids in the feed promotes the higher sulfate concentration in the infiltration. It has been noted that as the solids approach the highest concentration allowed for consideration of viscosity (42-45% by weight of concentrated product) the sulphate permeability increases to values as high as 8. The nanofiltration process is operated as a balance between high concentrations of solids in the feed stream and reasonable speed of infiltration flow and sulfate concentration in the infiltration. High pressures promote high infiltration flow. It is preferred to use a pressure as high as is permissible considering the nature of the nanofiltration membrane, the temperature and composition of the feed stream. Pressures in the range of up to 14.06-49.21 kilograms per square centimeter of pressure and preferably 21 .09-35.15 kilograms per square centimeter are useful if it is within the structural limitations of the membrane. The pressure drop across the membrane was controlled in the range from about 14.06 to about 28.12 kg / cm2. Experiments were performed for nanofiltration of a condensation product of (alkyl) naphthalene-formaldehyde sulfonate using the apparatus shown in Fig. 3, using a 1.5793 m2 membrane arranged in a spiral configuration. The neutralized product and the unneutralized product were treated to remove sulfate from the '^ 10 product. The membrane was a Nanofiltration Membrane MPS-34 A2 Sel Ro with a molecular weight cutoff of 200, manufactured by Kiryat Weizman Ltd of Israel, distributed in the United States by LCI Corporation, P.O. Box 16348, Charlotte, NC. The membrane had a maximum temperature range of approximately 70 ° C and a pressure ratio maximum of 40 atmospheres. The membrane was received wet containing a preservative. After the membrane was arranged in the pressure shell, the membrane was washed with water and a solution of alkaline ethylenediaminetetraacetic acid (NaEDTA) to remove the preservative of the membrane. The results of the sulfate test of a reaction product of neutralized (alkyl) naphthalene-formaldehyde sulfonate with an average number of molecular weight in the range from about 3,000 to about 4,000 are shown in Table 1. The results of the test for an unconverted (alkyl) naphthalene-formaldehyde (acid) sulfonate condensation product, with an average number of molecular weight in the range from about 3,000 to about 4,000 for batches 24-27 and about 1, 500 to about 2,000 for batch 28 as shown in Table 3. The neutralized condensation product provided higher infiltration flow rates than that product by nanofiltration of the condensation product without neutralizing acid. When the feed concentration of the neutralized condensation product was in the range of 40% -45% by weight solids, the infiltration flow rate was substantially reduced and at 45% solids the infiltration flow stopped. The membrane had to be washed with water to restore normal operation. At concentration of high feed solids, above about 30-35% by weight, the concentration of sulfate in the infiltration was higher than in the feed. The average concentration of sulfate in the infiltration is 2 to 4 times the concentration of sulphate in the feed, calculated by the initial sulfate concentration plus the final sulfate concentration in the feed to the nanofiltration unit divided by two. The nanofiltration produced a condensation product of (alkyl) naphthalene-formaldehyde with a reduced sulfate content, which could be as low as 0.1% to 0.2% by weight of the dissolved solids. The content of mono- and di-sulfonate monomers and low molecular weight oligomers in the condensation product of * (alkyl) naphthalene-formaldehyde sulfonate was also reduced. Using a membrane with a cutoff of 200, the weight ratio of sulfate to organic material in the accumulated infiltration was typically in the range of about 3: 1 to about 5: 1, depending on the percentage of sulfate removed from the feed . Using larger molecular weight cutting membranes, the amount of organic material in the infiltration could be greater than about 33% by weight of the solids in the infiltration. The reduction in the amount of mono- and di- (alkyl) naphthalene sulfonates in the product (retention) improves the dispersing effect of the product in cement compositions. The improvement provides an increase in the initial depression and depression of twenty minutes for concrete. The increase in depression can be used to reduce the required amount of water to improve concrete strength. Improvements in depression by as much as 50% have been noticed. The process products are particularly useful for use in ultra high compressive strength applications, ie, concrete formulations which have compressive strength ranging from approximately 222,400 N and particularly above about 333,600 N. The composition of the invention can not be obtained by controlling the reaction conditions during the synthesis of the condensation of (alkyl) naphthalene-aldehyde sulfates. The infiltration is then treated to separate the sulfate from the organic materials in the solution. Applicants have discovered that the sulfate can be separated from the organic material in the infiltration by electrodialysis, ion exchange or treatment in a bipolar electrodialysis separation apparatus. Electrodialysis is particularly useful for separating sulfate in the form of sulfuric acid from infiltration. In electrodialysis, the infiltration is introduced into an apparatus comprising a number (stack) of compartments having alternating side walls formed of ammonium and cationic membranes (see Fig. 7 is a schematic representation of an electrodialysis cell stack. The electrodialysis cell stack 58 comprises a series of compartments 59, 60 and 61 formed by anionic membranes 69 and cationic membranes 68 arranged in a narrow vessel of liquid 73. The positive electrode 71 and the negative electrode 70 are arranged to be in contact with an electrodynamic solution in compartments 59. In electrodialysis experiments, the electrode rinsing solution was 0.5 normal sulfuric acid and was pumped into compartments 59 through line 64 and returned for storage. the rinse solution through line 65. The sulfuric acid-containing infiltrate was pumped into compartments 60 through line 62 and returned to the feed tank via line 66. An acid-conductive water solution Sulfuric was pumped into compartments 61 through line 63 and returned to sulfuric acid storage through the line 67.

# A direct current was applied to the cell stack with the electrode 71 being positive and the electrode 70 being negative. The sulfate anions in the infiltration pass through the anionic membranes 69 in the direction of the positive electrode and enter the compartment 61. The 5 sulfates in the infiltration are reduced. The organic mono- and di-sulfonates do not easily pass through the anionic membrane and remain with the infiltration. The infiltration was circulated through the chambers 60 until the sulfate is reduced to the required level. When the sulfate level in the infiltration becomes low (approximately 0.05% by weight), The (alkyl) naphthalene mono- and di-sulfonates begin to be transported through the anionic membrane and are collected in the sulfuric acid in the compartments 61. The alternating compartments contain infiltration and the compartments in the middle contain water; the cells adjacent to the electrodes usually contain an electrolyte to protect the electrodes. A direct current is applied through the stack of compartments. The positive electrode is arranged on the side with the anionic membrane and the negative electrode is arranged on the side of the cationic membrane. When the direct current is applied, the anions, mostly sulfate, they flow through the anionic membrane to the water-containing compartment and the cations, mostly protons, flow through the cationic membrane into the compartment containing water. Since the organic material has a high molecular weight, and even when it has an anionic charge, only a small amount passes through the anionic membrane due to the relatively large size of the organic molecules. The separated sulfuric acid can be concentrated by evaporation mixed with oleum and returned to the sulphidation step of the process.

* • EXAMPLE 2 A sample of SELLOGEN ™ 6067A, a (alkylene) naphthalene sulfonate was treated by nanofiltration in a tubular shaped membrane by a diafiltration process. The composition was a solution in water containing sulfate in the form of its sodium salt. Solutions of 30% and 40% by weight solids were treated. The nanofiltration membrane had an area of 0.0232 m2 and was an MPT 34A type as used in the previous experiments. The parameters and results of the experiments are shown in Table 3.

The data illustrates that the sulfate can be removed from an alkylnaphthalene sulfonate, which is not condensed with an aldehyde, plus a monofiltration process. EXAMPLE 3 Samples of a condensation product of (alkyl) naphthalene-formaldehyde sulfonate were prepared. The amount of mono- and di-sulfonate of (alkyl) naphthalene in the samples was varied. The 5 samples were compared with a commercial product (standard) which contained approximately 10% by weight solids of the (alkyl) naphthalene mono- and di-sulfonate. The rest of the samples were similar in relation to the amounts of low, medium and high molecular weight condensation species (with the exception of data parts marked with a * 10 star, which have a portion of the low molecular weight oligomers removed). Concrete was prepared using 18.7 grams of (alkyl) naphthalene-formaldehyde sulfonate dispersing agent per batch, which required 5,361.6 grams of cement. The concrete depression as prepared 15 (0 minutes) and after 20 minutes of additional mixing was measured. Figure 6 (a) is a graph of the value of the initial concrete depression (0 minutes) prepared using the samples with varying amounts of (alkyl) naphthalene mono- and di-sulfonate minus the initial depression of concrete prepared using the sample standard against% in weight of mono- and di-sulfonates of (alkyl) naphthalene. Fig. 6 (b) is a graph of the 20 minute depression value of the concrete prepared using the samples with varying amounts of (alkyl) naphthalene mono- and di-sulfonates minus the 20 minute depression of concrete prepared using the condensation product of (alkyl) naphthalene-aldehyde sulfonate standard.

The graphs clearly show that the condensation product of (alkyl) naphthalene-aldehyde sulfonate with a reduced content of (alkyl) naphthalene mono- and di-sulfonates, provides increased depression for concrete. The increase in depression is particularly apparent in the 20 minute depression values. In some cases, an increase in 20 minute depression values of greater than 50% can be achieved with materials containing less than about 2% by weight of the mono- and di-sulfonates solids (alkyl) naphthalene. * 10 A decrease in the amount of low molecular weight oligomers in the (alkyl) naphthalene-aldehyde sulfonate condensate also increases the concrete depression values containing the dispersant. Depression is an indication of the fluidity or ability to flow of concrete. Large depression values at 20 minutes is a clear indicator that the cement is more easily worked and if desired, the amount of water in the concrete formulation can be reduced to provide a concrete with equivalent viability.

EXAMPLE 4 The monofiltration infiltration samples of a non-neutralized (alkyl) naphthalene-formaldehyde sulfonate condensate composition were subjected to electrodialysis in the cell stack (cell stack TS-1-10 purchased from Tokuyama America Corp.) , which had AMX anionic membranes and CMX cationic membranes separated 0.6-0.7 mm. The The infiltration feed to the diluted unit was circulated through alternating cells. In the adjacent cells, a solution of sulfuric acid * diluted (concentrated) was circulated. A 0.5 standard sulfuric acid rinse solution was pumped through the cells adjacent to the electrodes. The example was made in a batch method. Figure 7 is a illustration of a typical electrodialysis cell stack. When an electric current was applied through the cell stack, the sulfate anions passed through the anionic membrane and into the recirculating concentrate stream. The amount of sulfate in the dilution was reduced and the sulfate content of the concentrate was «10 increased. The diluted feed was circulated through the cells at constant voltage. As the amount of sulfate in the feed decreased from 7 milliamperes / cm2 initially to about 2-3 milliamperes / cm2, the selectivity for the sulfate ion on the organic mono- and di-sulfate was excellent; the substantially non-organic mono- and di-sulfonates passed through the anionic membranes until the current reached the range of about 2-3 milliamperes / cm 2. Fig. 8 is a graph showing the flow rate for sulfate ion and the (alkyl) naphthalene sulfonates in the feed diluted to the electrodialysis cells. As can be seen from the graph, the flow of organic sulfonate is very low, which indicates that a clean separation between sulfuric acid and acid sulfonates can be obtained by electrodialysis.

EXAMPLE 5 The infiltration obtained by diafiltration of a neutralized (sodium salt) from a condensation product of (alkyl) naphthalene-formaldehyde sulfonate (LOMAR 1487H a product of Henkel Corp.) on a nanofiltration membrane MPS 34A was treated by ion exchange to separate sulfate from (alkyl) naphthalene sulfonates in the infiltration. A column 2.54 centimeters in diameter by 10.16 centimeters in length was packed with a bed of Amerlite® IRA-35 - weak base anion exchange resin. The infiltration, which contained 2.1% sulfate and 1.1% sulfonates of (alkyl) naphthalenes was passed through the bed (30 volumes of infiltration per one volume of resin). The (alkyl) naphthalene sulfonates were absorbed by the resin. The capacity of the resin was 76.89 kilograms of (alkyl) naphthalene sulfonate per cubic meter of resin. The resin was regenerated by a 4% by weight NaOH solution. Ninety-three (93) percent of the absorbed (alkyl) naphthalene sulfonates were recovered. In a water-free base and NaOH, the regenerating solution, after contact with the resin, contained 98% by weight of (alkyl) naphthalene sulfonates and 2% by weight of Na2SO based on the weight of (alkyl) naphthalene sulfonates and Na2SO4 in the regenerating solution. The ion exchange can be effectively used to separate soluble sulfate salts from a solution of sulfate salts and (alkyl) naphthalene sulfonates.

Other ion exchange resins were tested, and it was discovered that strong ion exchange resins absorb sulfate ions so that the selectivity for the sulfate removal of the organic sulfonates decreases as the basicity of the resins increases. Low basicity ion exchange resins, because of their excellent selectivity and easy regeneration, are preferred for use in the present invention.

EXAMPLE 6 A bipolar electrodialysis apparatus can be used to separate sulfate salts from the infiltration produced by nanofiltration of organic sulphonate / sulfate materials. A diagrammatic representation of a bipolar electrodialysis apparatus is shown in Fig. 8. A bipolar electrodialysis unit 74 comprises cationic membranes 77, bipolar membranes 78 and anionic membranes 79 arranged in series, to separate the unit 74 into a series of separate cells , which are thin in relation to the area of the membrane. A direct current is applied through the membrane stack via electrodes 75 and 76. Feed to the unit (diluted), which is to be treated, is circulated to the cells formed between the anionic and cationic membranes through from line 80 and removed through line 83. A caustic solution is circulated between cationic membrane 77 and bipolar membrane 78 through line 81, and removed from the cell via line 84. A solution of sulfuric acid is circulated through the cell formed between the anionic membrane 79 and the bipolar membrane 78 through line 82 and is removed through line 85. In the cell between the cationic membrane and the membrane bipolar NaOH is formed when direct current flows through the cell, and it is removed through line 84. The concentration of NaOH in the stream decreases. In the cell between the anionic membrane and the bipolar membrane, sulfuric acid is formed and the strength of the sulfuric acid stream increases. Sulfuric acid is removed through line 85. The feed stream (diluted) is reduced in the sodium sulfate content and is removed from the cell through line 83. Organic sulfonates do not easily infiltrate membranes and remain in the diluted stream. When the sodium sulphate has been reduced to the desired level, the diluted can be returned to the process to the condensation zone or as a feed to the nanofiltration zone. The stream of sulfuric acid can be concentrated and mixed with oleum as feed to the sulphation zone. Sodium hydroxide can be used to neutralize and dilute the condensation product. Using a bipolar electrodialysis cell, it is possible to substantially reduce the waste formed by the process to produce organic sulfonate / sulfate materials and particularly sulfonate (alkyl) aryl-aldehyde condensation products. Fig. 4 (a) is an HPL chromatogram of a condensation product of (alkyl) naphthalene-formaldehyde sulfonate containing nano- and (alkyl) naphthalene di-sulfonates. Fig. 4 (b) is an HPL chromatogram of a condensation product of (alkyl) naphthalene-aldehyde sulfonate. The comparison of the chromatogram shows that it is possible to remove substantially all the (alkyl) naphthalene mono- and di-sulfonates from the mixture without substantially affecting the polymeric materials by a nanofiltration process. The product with the mono- and di-sulfonates of (alkyl) naphthalene removed would also have had a low acid or salt content. The product with low acid or salt content and low (alkyl) naphthalene mono- and di-sulfonates content has improved dispersion capacity for concrete and can be used in ultra strength concrete formulations. The invention has been described in relation to removing sulfate and ionic materials of lower molecular weight from a condensation product of (alkyl) naphthalene-formaldehyde sulfate or an (alkyl) naphthalene sulfonate. However, the process can be used to Removing sulfate and low molecular weight materials from other sulphated or sulphonated organic compositions, such as sulfated alcohols, fatty acids or sulfated alkoxylated fatty alcohols and condensation products of aromatic aldehydes and sulfonates. The process of the invention produces low amounts of materials of waste, which can be eliminated and allows the recycling of organic components to the process for recovery and use. It has unexpectedly been found that normal material with low salt and condensation products of (alkyl) naphthalene-aldehyde sulfonate provide dispersants, which produce high-grade concrete. force with large depression values.

EXAMPLE 7 A bipolar electrodialysis apparatus similar to that shown in Fig. 8 is used to separate the sulfate from the infiltration obtained by nanofiltration of a crude, unneutralized (alkyl) naphthalene-formaldehyde sulfonate condensation product. The bipolar electrodialysis apparatus is modified by replacing the cathode membranes with anionic membranes. The infiltration obtained by nanofiltration of a raw, unneutralized (alkyl) naphthalene-formaldehyde sulfonate condensation product contains about 4% by weight of sulfuric acid and about 1% by weight of mono- and di-sulfonates of (alkyl) naphthalene. The infiltration feed (diluted) is recirculated through a cell between an anionic membrane and a bipolar membrane. A stream of sulfuric acid is circulated through the cells on both sides of the cell through which the diluted is circulated. When a direct current is applied through the cells, the sulfate ions infiltrate the diluted through the anionic membrane to the sulfuric acid stream and the side of the cell closest to the positive electrode. In the bipolar membrane, H2O separates into H + and OH. "The H + infiltrates the membrane next to the negative electrode and the OH" infiltrates next to the positive electrode to react with the H + ions in the diluted to form H2O.

The sulfonate is removed from the dilute and forms a stream of sulfuric acid, which can be concentrated and mixed with oleum to sulfur the starting material.

EXAMPLE 8 The samples were prepared by nanofiltration of a dispersant of condensation product of standard (alkyl) naphthalene-aldehyde sulfonate 1487-H (a commercial product). The commercial product contained approximately 10% by weight of sodium sulfate. The commercial product was desalted by nanofiltration to provide samples with reduced sodium sulfate content. The nanofiltration was done in a manner to leave the amount of mono- and di-sulfonates of (alkyl) naphthalene substantially uncharged. The concrete was prepared according to the following formula: 15 Cement 54662 grams Sand 10932 grams Stone 8231 grams Water 21 19 grams (includes water from all sources) Dispersant 19.12 grams 20 The dry ingredients were placed in a cement mixer, approximately The required water was added and the materials mixed for two minutes. The remaining water was added and the concrete was mixed for an additional two minutes. Depression of a concrete sample was measured according to 25 ASTM C143. Depression is the initial depression or 0 minutes. The concrete is returned to the mixer and mixed for an additional twenty minutes, and the depression again measured according to ASTM C143. The results are shown in Table 4. 1887Y contained 0.5% CaSO4 and approximately 2% Na2CO3 CU 171 17 was 1487H desalted by nanofiltration The data clearly illustrates that a reduction in sodium sulfate improves the performance of the dispersant. 10 A second sample was prepared by nanofiltration of an acid sample from a commercial dispersant LOMAR 18874. LOMAR 1887Y after neutralization contained 0.5% CaSO4 and approximately 2% NaCO3 based on the weight of the solids. Product 5 contained 1.12% by weight of Na2SO solids. The material LOMAR 1487H standard was also included in the test. The results of the tests are shown in Table 5.

The data illustrates the improvement in depression and compression force imparted to the concrete by the low salt product (Product 5).

Claims (20)

1. CLAIMS 1. A process for producing an aqueous sulphonate / low sulphate organic sulphate solution from a soluble sulfate containing 5 sulphonate / organic sulfate, which comprises: forming an aqueous sulphonate / organic sulfate solution; and passing the aqueous solution of the sulfonate / organic sulfate containing the soluble sulfate over a nanofiltration zone at an elevated pressure to form a retention with a reduced sulfate content and an infiltration containing the soluble sulfate and organic material.
2. 2. The process of claim 1, further including the step of passing the infiltration to an infiltration treatment zone and separating the sulfate from the infiltration, to provide a first aqueous stream containing the sulfate and a second aqueous stream containing 15 organic material.
3. 3. The process of claim 2, further comprising the step of recycling at least a portion of at least one of the first stream and the second stream to the process to form the aqueous solution of the sulfonate / organic sulfate.
4. 4. The process of claim 1, wherein the nanofiltration zone includes a membrane which retains materials that have a molecular weight greater than a molecular weight cutoff, and said cutoff is approximately 150 to 1000.
5. 5. The process of Claim 4, wherein said cut is 25 approximately 200 to 700.
6. 6. The process of claim 4, wherein said membrane includes a hydrophilic surface and said aqueous solution is passed over the hydrophilic surface at a pressure of from about 7.03 to about 49.21 kg / cm2. The process of claim 6, wherein said membrane is a spiral wound unit. The process of claim 4, wherein water is added to said aqueous solution as said solution is passed over said membrane. The process of claim 4, wherein said step of passing said aqueous solution over said membrane is conducted at a temperature from about 35 to 80 ° C, and the pressure drop through said membrane is about 14.06 to 28.12 kg. / cm2. The process of claim 2, wherein the sulfate is present in the infiltration in the form of sulfuric acid and said step of separating the sulfate from the infiltration includes subjecting the infiltration to electrodialysis and removing sulfuric acid from said infiltration. 1. The process of claim 10, wherein said process further includes the step of concentrating said sulfuric acid to about 50 to 80% by weight. The process of claim 1, wherein said process further includes the step of recycling the concentrated sulfuric acid to be used in said step to form said solution of said organic sulfonate / sulfate. 13. The process of claim 2, wherein the sulfate is present in the infiltration in the form of a salt and said step of separating the sulfate from the infiltration includes subjecting the infiltration to ion exchange. 14. The process of claim 1, further comprising the step of preparing the membrane by contacting the membrane with a nitric acid solution and subsequently contacting the membrane with a chelating agent. 15. The process of claim 1, wherein said organic sulfonate / sulfate is selected from the group consisting of sulphated alkaline oxide adducts, partially esterified and sulfated polyhydric alcohols, alkyl sulfonates, alkyl sulfates, dialkyl sodium sulfosuccinates, sulfonates of alkylbenzene, condensation products of sulphonic acid (alkyl) naphthalene and formaldehyde, condensation products of dithioether formaldehyde and sulfuric acid, condensation products of chloromethylated diphenylene, (alkyl) naphthalene and sulfuric acid, condensation products of mononuclear aromatic compounds and formaldehyde, (alkyl) naphthalene sulfonic acids and optionally sodium sulfite, or condensation products of (alkyl) naphthalene, toluene formaldehyde and sulfuric acid. The process of claim 15, wherein said organic sulfonate / sulfate is a condensation product of an alkylbenzene sulfonic acid aldehyde and / or an alkylnaphthalene sulfonic acid, where the alkyl portion contains 1 to 18 carbon atoms. carbon. 17. The process of claim 16, wherein said product of * aldehyde condensation is a condensation product of formaldehyde and alkylnaphthalene sulphonic acid. 18. An aqueous solution of a condensation product of (alkyl) naphthalene-aldehyde sulfonate containing less than about 5% by weight of the sum of (alkyl) naphthalene monosulfonates and (alkyl) naphthalene-disulfonates based on the dry solids in the solution. 19. The aqueous solution of claim 18, wherein the solution contains less than about 0.75 wt% sulfate. 20. A method for improving the permeability of a nanofiltration membrane for soluble salts in an aqueous sulphonate / organic sulfate solution, which comprises: contacting the nanofiltration membrane with a dilution of nitric acid solution and with a solution alkaline of an agent 15 chelator