Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/20—Manufacture of shaped structures of ion-exchange resins
  • C08J5/22—Films, membranes or diaphragms
  • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
  • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
  • B01D61/44—Ion-selective electrodialysis
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2309/00—Characterised by the use of homopolymers or copolymers of conjugated diene hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2339/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen; Derivatives of such polymers
  • C08J2339/04—Homopolymers or copolymers of monomers containing heterocyclic rings having nitrogen as ring member
  • C08J2339/08—Homopolymers or copolymers of vinyl-pyridine

Definitions

• the invention pertains to an electrodialysis anion selective membrane and to methods for producing such membranes.
• Bipolar electrodialysis is a membrane separation process in which high purity acid and base solutions may be generated from a salt solution by the electrodialysis water splitting process.
• apparatus designed to perform such ED function consists of a stack containing a plurality of cation-selective membranes, bipolar membranes, and anion selective membranes positioned between a pair of electrodes.
• the stack may itself comprise an assembly of unit cells in which each unit cell comprises the above membranes arranged in such fashion to provide a plurality of flow paths or channels between adjacent membranes.
• H + migration across the anion select membrane has proven problematic. This proton leak through the anion selective membrane is well known and is referred to as the Grotthuss mechanism by which protons diffuse through the hydrogen bonding network of water molecules. Anion selective membranes demonstrating substantial passage or migration of H + are detrimental to electrodialysis processes, resulting in poor anion transfer current efficiency, low concentration of acid and base and high equipment and energy costs.
• a method for preparing an acid block anion selective polymeric membrane of the type having a woven or non- woven cloth reinforcing structure is provided.
• the polymer of the membrane is prepared by the process comprising copolymerization of components of (I) an ethylenically unsaturated aliphatic or aromatic tertiary or quaternary amine monomer, (II) a cross-linking monomer, and (III) vinylbenzyl chloride in the presence of a free radical
• the molar ratio of components (I): (II): (III) is from about 20-60:30-70: 1-19. In another exemplary embodiment, the molar ratio of components I:II:III is from about 35-45:45-55: 10-15. The foregoing percentages equal 100 molar % .
• the copolymerization is conducted in the absence of nonpolymerizable solvent.
• the membrane is characterized as having a water content percent of from about 12-20 wt and a current efficiency of greater than about 93 % .
• an anionic exchange membrane is provided of the type that is used in electrodialysis apparatus.
• the membrane comprises a woven or non-woven cloth with the cloth being impregnated with a copolymer comprising the reaction products of components I, II, and III wherein I is an ethylenically unsaturated aliphatic or aromatic tertiary or quaternary amine monomer, II is a cross-linking monomer, and III is a vinylbenzyl chloride.
• the acid block anion selective membrane is prepared by copolymerizing (I) an ethylenically unsaturated aliphatic or aromatic tertiary or quaternary amine monomer and a (II) cross-linking monomer in the presence of (III) vinylbenzyl chloride (VBC).
• VBC vinylbenzyl chloride
• a free radical polymerization initiator (IV) is also present.
• no solvent is used.
• acid block means an anion selective membrane that has enhanced capacity to retard the migration of H + therethrough. Typically, this is accomplished by reducing the water content of the membrane and/or increasing the cross linking of the polymer.
• the components I, II, III, and initiator IV are mixed to form a homogenous solution.
• the resulting solution is used to impregnate a piece of cloth such as a polypropylene, polyester, acrylic, or modacrylic type cloth.
• the thus impregnated cloth is placed between glass plates, and this glass sandwich construction is then heated to initiate the polymerization. After completion of the polymerization reaction, the glass sheets are removed, leaving the polymer impregnated cloth.
• the polymer impregnated cloth is then allowed to swell by soaking in an aqueous acidic bath such as a 2N HCl solution.
• the polymer impregnated cloth or sheet may then be used as an acid block anion selective membrane in electrodialysis and other applications.
• exemplary aliphatic tertiary amines may be encompassed by the Formula A.
• R2 wherein Rl is H or CHs, X is O or NH, R2 is lower (Ci-Ce) alkylene and R3 and R4 are independently chosen from lower (Ci-Ce) alkyl.
• Exemplary component I aliphatic quaternary amine monomers may be encompassed by the Formula B.
• R5 wherein Rl , R2, R3, and R4 are as defined in Formula A; R5 is chosen from lower (Ci-Ce) alkyl; and A is an anion chosen from halo, nitrite, sulfate and other inorganic or organic anions.
• Exemplary component I aromatic tertiary amine monomers may be encompassed by the Formula C.
• Exemplary component I aromatic quaternary ammonium monomers may be encompassed by the Formula D.
• R6 is the same as in Formula C, R2, when present, is the same as in Formula A; R3, R4, and R5 are the same as in Formula B and A " is the same as defined in Formula B.
• TMAEMC trimethylaminoethylmethacrylate chloride
• the cross linking monomers II may generally be described as containing ethylenically unsaturated functionality and may be chosen from a wide class of known cross linking agents such as divinylbenzene (DVB), ethylene glycol dimethacrylate (EGDM), ethylene glycol diacrylate, 1 , 10-decane diol diacrylate or dimethacrylate, methylene bis acrylamide or bis methacrylamide, dodecamethylene bis acrylamide or bis methacrylamide, diethylene glycol diacrylate or dimethacrylate, 1 ,4 butane diol divinyl ether, triethylene glycol divinyl ether, divinyl succinate, subernate or sebacate, etc.
• VB divinylbenzene
• EGDM ethylene glycol dimethacrylate
• ethylene glycol diacrylate 1 , 10-decane diol diacrylate or dimethacrylate
• methylene bis acrylamide or bis methacrylamide dodecamethylene bis acrylamide or bis
• polymerization initiators include the azo initiators such as 2,2-azo bis (2-methylpropionitrile) 2,2'-Azobis(2-methyl- propionamidine) dihydrochloride; 1 , l'-Azobis(cyclohexane carbonitrile); 4,4'- Azobis(4-cyano valeric acid) purum etc.
• azo initiators such as 2,2-azo bis (2-methylpropionitrile) 2,2'-Azobis(2-methyl- propionamidine) dihydrochloride; 1 , l'-Azobis(cyclohexane carbonitrile); 4,4'- Azobis(4-cyano valeric acid) purum etc.
• peroxide initiators such as benzoyl peroxide, and t-butylperoxy-2-ethylhexanoate, l , l-Bis(tert-amylperoxy)cyclohexane; 1 , 1-Bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane; l , l-Bis(tert-butylperoxy) cyclohexane; 2,4-Pentanedione peroxide; 2,5-Bis(tert butylperoxy) -2,5-dimethylhexane; 2- Butanone peroxide; di-tert-amyl peroxide; Di cumyl peroxide; Lauroyl peroxide, tert- Butylperoxy-2-ethylhexyl carbonate, tert-Butyl per acetate, tert-Butyl peroxide, and tert-Butyl peroxybenzo
• ranges of addition for the components (I), (II), and (III) are as follows: Component I:II:III - (37-40%): (48-50%): 12-13 % ... molar ratio.
• the package is then moved to an oven with temperature at 90 °C for 2 hours.
• the package is taken apart to get 3 pieces of reinforced membrane sheets.
• the membrane sheets are then placed into a 2 N hydrochloric acid solution and allowed to swell until equilibrium.
• the final membrane is an acid efficiency anion membrane that can be used in bipolar electrodialysis for recovering mineral acid from salt.
• a piece of Mylar sheet is placed over the cloth.
• Another cloth and Mylar sheet are placed in the solution.
• the cloth and Mylar sheet are alternately spaced to form a package of 3 layers, and a piece of glass is placed on top of the assembly.
• the package is then moved to an oven and maintained at a temperature of 90 °C for 2 hours.
• the package is taken apart to get 3 pieces of reinforced membrane sheets.
• the membrane sheets are then placed into a 2N HC1 solution and allowed to swell until equilibrium.
• the final membrane is an acid efficiency anion membrane that can be used in bipolar electrodialysis for recovering mineral acid from salt.
• the package is then moved to an oven with temperature at 90 °C for 2 hours.
• the package is taken apart to get 3 pieces of reinforced membrane sheets.
• the membrane sheets are then placed into a 2 N hydrochloric acid solution and allowed to swell until equilibrium.
• the final membrane is an acid efficiency anion membrane that can be used in bipolar electrodialysis for recovering mineral acid from salt.
• Membrane cell testing with the above membranes and several other commercially available membranes was conducted.
• Membrane current efficiency was measured by the method set forth in Example 2 of U.S. Patent 4,822,471.
• the percent of current efficiency means that the given percent amount of current is used to transport anion through the anion membrane.
• the remaining percent of current represents the hydrogen leak through the anion membrane.
• the notation "strong" base means quaternary amine functionality with "weak” base denoting tertiary amine functionality.
• the quat amine in a membrane is measured by first converting the membrane into CI " (chloride) form by soaking the membrane in 2N NaCl solution and washing out the free CI " ion.
• DMAPMA dimethylamino propyl methacrylamide
• VBC vinyl benzyl chloride
• DVB divinyl benzene
• t-butyl peroxy-2-ethylhexanoate a clear solution without the addition of any non-polymerizable solvents.
• the solution is poured into a Mylar tray sized 10" x 11 " with a piece of glass under the Mylar tray, a piece of polypropylene cloth is laid into the solution then a piece of Mylar sheet on the cloth.
• the package is then moved to an oven with temperature at 90 °C for 2 hours.
• the package is taken apart to get 3 pieces of reinforced membrane sheets.
• the membrane sheets are then placed into a 2 N hydrochloric acid solution and allowed to swell until equilibrium.
• the final membrane is an acid efficiency anion membrane that can be used in bipolar electrodialysis for recovering mineral acid from salt.
• ⁇ Resistance is measured in 0.0 IN NaCl solution at 1000 Hz.
• the membrane A-l contains quaternary amine (strong base) tertiary amine (weak base) and higher crosslink degree due to the reaction of VBC with tertiary amine (vinyl pyridine), resulting in the membrane with lower water content, higher current efficiency but low resistant.
• the comparison membrane (C-6) contains only tertiary amine (weak base), resulting in low water content and high current efficiency, but much higher resistant of the membrane.
• Example 6 (Procedure similar to U.S. Patent 4,822,471 - Example 2)
• a three compartment electrodialysis test cell was used to determine the current efficiency (C.E.) of the membrane of present invention as a comparison with those prior art when used in an acid solution.
• the cell comprised a cathode and anode electrode of platinum coated titanium located at the terminal ends of the cell with two membranes located there between and position from each other and from electrodes with gasketed spacers to form liquid containing compartments.
• the arrangement was as follows: the anion exchange membrane to be tested, the middle compartment, a commercially available type cation exchange membrane (GE CR61CMP), the anode compartment and finally the anode electrode.
• the membranes mounted in the test cell had an active membrane of 25 cm 2 and each compartment had a liquid volume of about 40 ml each and a cross- sectional active area of 25 cm 2 .
• the solution in the cell comprised 1 N HC1 in the cathode compartment, 0.5 N HCl in the center compartment and 0.5N EhSCk in the anode compartment.
• the solutions were stirred by use of a magnetic stirrer and maintained at a temperature of 25 °C.
• Each test run operated at 20 mA/cm 2 for a 20- minute period at which time the acid concentrations in the cell were determined by titration. The results are shown in Table III as follows:
• VBC By adding the VBC to react with a portion of the tertiary amine in the monomers such as vinyl pyridine, DMAEMA, DM APM A, etc. , we can control the ratio of quaternary and tertiary amines in the resulting membrane and can also increase membrane cross linking.
• a high current efficiency can be obtained from aliphatic monomers such as DMAEMA, DM APM A, etc. , due to the resulting high crosslink degree and low water content of the membranes. Resistance is also decreased due to the introduction of quaternary amines in the membrane.
• the anion block anion selective membrane is a polymerization reaction product of I) DMAEMC, II (DVB), and III (VBC).
• the molar ratio of 1:11:111 may be on the order of 20-60:30-70: 1-19: and more preferably from 37-45:45-55: 10-15.
• the preferred initiator is t-butyl peroxy-2- ethylhexanoate. More specifically, this reaction is shown by the following reaction scheme shown in Formula E with the resulting polymer shown in Formula F.
• the acid block anion membranes of the invention are further characterized as having a water content of about 12-20% , preferably about 13-18% . Further, they exhibit a current efficiency of about 93 % and greater and have a quaternary amine functionality of about 20-70% based on total amine present with an even more specific range of about 30-40% demonstrated by the specific examples herein shown.

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• Urology & Nephrology (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Polymerisation Methods In General (AREA)
• Water Treatment By Electricity Or Magnetism (AREA)

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• 2010
  • 2010-12-23 US US12/977,923 patent/US8470896B2/en active Active
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  • 2011-12-16 EP EP11806094.6A patent/EP2655490A1/en not_active Withdrawn
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