Organic Ion Exchangers. Synthesis and Their Behaviour in the Retention of Some Metal Ions

Abstract Summary: Three pyridine strong base anion exchangers as beads were obtained by quaternization reactions of a 4‐vinylpyridine : 8% divinylbenzene copolymer of gel type. These resins possess methyl / ethyl / butyl radicals as substituents on N + atoms and have exchange capacities of 4.80 mEq/g and 2.10 mEq/mL. For pyridine strong base anion exchangers, the behaviours in the retention processes of Cr(VI) as oxyanions and Ga(III) as [GaCl 4 ] − complex anion were evaluated with the bath method. All the resins exhibited retention properties, but the retained amounts of the metal cations are different as a function of the alkyl length as substituent on N + atoms and the complex anion nature. Thus, Cr(VI) oxyanions are best retained by the resin with CH 3 as substituent on N + atoms while [GaCl 4 ] − complex anion by the resin with C 4 H 9 as substituent on N + atoms. By aminolysis reaction of an ethylacrylate : acrylonitrile : divinylbenzene copolymer as beads of macroporous type with NH 2 OH · HCl in the presence of C 2 H 5 OH a new chelating ion exchanger was performed which contains both amidoxime and hydroxamic acid functional groups. This ion exchanger has the retention property for different metal cations but its retention capacities values are strongly dependent of the nature of metal cation and the counterion as well as pH of the solution. Thus, in the static conditions Zn(II) cation with NO anion as counterion is retained with the best result at pH = 5. As an example, for the aqueous metal cation solution of 10 −2 M concentration for Zn(NO 3 ) 2 the resin possess at equilibrium a retention capacity of 6.70 mmol Zn/g dry resin and for Cu(II) from Cu(NO 3 ) 2 solution of same concentration, the retention capacity is 0.22 mmol Cu/g dry resin and Fe(III) from Fe(NO 3 ) 3 solution is not retained.