Patent GB-862636-A (GB)
Title: Treatment of aqueous liquid solutions of chelate-forming metal ions with chelate exchange resins
IPC: B01J45/00
Filed: 1958-04-11
Abstract: A solid chelate-exchange-resin, insoluble but swellable in aqueous solution, is an addition polymer which contains at least 80% by weight of a vinylphenyl aliphatic amino-carboxylic acid and which contains recurring structural units representable by the formula <FORM:0862636/IV (a)/1> wherein the symbol R1 represents a radical selected from the group consisting of -H, -CO2M, and -CH2CO2M; the symbol R2 represents a radical selected from the group consisting of -H and -CH3; each of the symbols R3 and R4 individually represents a radical selected from the group consisting of -H, -CH3, -CH2-C6H4-CH=CH2, -CH2CO2M, -CH2CH2CO2M, -CH(CO2M) CH2CO2M, -CH2CH2-N(CH2CO2M)2, -CH2 CH2CH2-N(CH2CO2M)2, and <FORM:0862636/IV (a)/2> where n is an integer from 1 to 4, m is an integer from 0 to 2, and M is a cation, and wherein at least one of the radicals represented by the symbols R1, R3 and R4 contains a -CO2M group which together with the nitrogen atom constitutes a metal-chelating group, the resin being further characterized as having a Swelling Factor of at least 30, the Swelling Factor being defined as the arithmetic product in the equation SF=(GWC)X(V1/V) wherein the symbol (GWC) represents the Gel Water Content of the resin at its isoelectric pH in per cent by weight of water in the resin saturated with water at room temperature, and wherein the symbol (V1/V) represents the ratio of the volume of the resin saturated with water at a pH value of 10 to the volume of the resin saturated with water at the isoelectric pH of the resin, the contacting aqueous liquid solution being one that contains at least one kind of metal-containing ion that is capable of displacing the cation M from the metal-chelating groups of the resin and forming therewith a chelate structure.  The polymerization can be carried out en masse, in solution, in solubilizing liquid media or in suspension in non-solvent liquid media and can be accelerated by heating, by irradiation with ionizing radiations, or by activation with catalysts such as a ,a 1-azobisisobutyronitrile and the peroxygen compounds, e.g. persulphates and peroxides.  Copolymers can be obtained by addition interpolymerization of a mixture of vinylidene monomers containing at least 80% by weight of a vinyl phenyl aliphatic aminocarboxylic acid and one or more other vinylidene monomers such as styrene, divinylbenzene, and acrylonitrile.  Resins suitable for the present invention can also be obtained by reacting an ar-vinylbenzyl benzylamino polymer in which the amino group has at least one hydrogen atom with a haloacetic acid in an alkaline aqueous medium to convert the amino groups to N-carboxymethyl groups.  For example, polymeric ar-vinylbenzylamine is reacted in aqueous alkali with sodium chloroacetate to produce polymeric N-(ar-vinylbenzyl) iminodiacetic acid.  These resinous polymers contain a high concentration of functional groups of the kind represented by the structure <FORM:0862636/IV (a)/3> referred to herein as the chelate-forming ligand.  Specific illustrations of such groups in these chelate ion-exchange resins are the glycine radical <FORM:0862636/IV (a)/4> and the aspartic acid radical <FORM:0862636/IV (a)/5>ALSO:Monomeric vinylphenyl aliphatic aminocarboxylic acids can be prepared by reacting an ar-vinylbenzyl halide such as the chloride with an a - or b -aminocarboxylic acid having at least one hydrogen atom on the amino nitrogen atom.  For example, ar-vinylbenzyl chloride is reacted with disodium iminodiacetate in alkaline aqueous medium, and the reaction mixture is acidified to produce N-(ar-vinylbenzyl) iminodiacetic acid.  Other vinylphenyl aliphatic aminocarboxylic acids are prepared from ar-vinyl-benzylamine.  For example, ar-vinylbenzylamine is condensed with diethyl maleate to obtain diethyl N-(ar-vinylbenzyl)-aspartate which is hydrolysed to provide N-(ar-vinylbenzyl)-aspartic acid or ar-vinylbenzylamine can be reacted with sodium chloroacetate in alkaline aqueous media to produce N-(ar-vinylbenzyl) iminodiacetic acid.  In similar manner, other primary and secondary amines having a vinylphenyl group can be carboxy-methylated by reaction with haloacetic acid salts in aqueous alkaline media to produce vinylphenyl aliphatic aminoacetic acids.  Some of these aminocarboxylic acids can also be obtained from ar-vinylbenzaldehyde. For example, p-vinylbenzaldehyde is condensed with sodium cyanide and ammonium chloride in ammonium hydroxide aqueous solution, and the resulting product is hydrolyzed with alkali and then acidified to produce 2-(p-vinylphenyl) glycine.ALSO:A solid chelate-exchange-resin, insoluble but swellable in aqueous solution, is an addition polymer which contains at least 80% by weight of a vinylphenyl aliphatic amino-carboxylic acid and which contain recurring structural units representable by the formula: <FORM:0862636/I/1> wherein the symbol R1 represents a radical selected from the group consisting of -H, -CO2M, and -CH2CO2M; the symbol R2 represents a radical selected from the group consisting of -H and -CH3; each of the symbols R3 and R4 individually represents a radical selected from the group consiting of -H, -CH3, -CH2-C6H4-CH=CH2, -CH2CO2M, -CH2CH2 CO2M, -CH(CO2M)CH2CO2M, -CH2CH2-N(CH2 CO2M)2, -CH2CH2CH2-N(CH2CO2M)2, and <FORM:0862636/I/2> where n is an integer from 1 to 4, m is an integer from 0 to 2, and M is a cation, and wherein at least one of the radicals represented by the symbols R1, R3 and R4 contains a -CO2M group which together with the nitrogen atom constitutes a metal-chelating group, the resin being further characterized as having a Swelling Factor of at least 30, the Swelling Factor being defined as the arithmetic product in the equation SF = (GWC) x (V1/V) wherein the symbol (GWC) represents the Gel Water Content of the resin at its isoelectric pH in per cent by weight of water in the resin saturated with water at room temperature, and wherein the symbol (V1/V) represents the ratio of the volume of the resin saturated with water at a pH value of 10 to the volume of the resin saturated with water at the isoelectric pH of the resin, the contacting aqueous liquid solution being one that contains at least one kind of metal-containing ion that is capable of displacing the cation M from the metal-chelating groups of the resin and forming therewith a chelate structure.  The method of the invention is practised by contacting pieces of the chelate exchange resins with aqueous liquid solutions containing at least one solute ionized to provide metal-containing ions capable of interacting with the ligands of the chelate resin and forming a chelate structure therewith and details of various combinations of exchanging and eluting steps are given.  Metals which form chelates with amino acid ligands of the kind described are found in Group I-B, II-A, II-B, III-A, III-B, IV-A, VI-B, VII-B and VIII of the Periodic Classification of the Elements.  Typical such metals are copper, silver, gold, calcium, zinc, iron, cobalt, nickel, platinum and palladium.  The alkali metals, ammonia, and amines form salts with the chelate exchange resin carboxylic acid groups but presumably do not form chelate complexes.