Synthesis and characterization of chelating resins containing thiol groups

Three kinds of macro-reticular bead-typed chelating resins having thiol groups were obtained from basic resins like poly(styrene-co-divinylbenzene) (PSD) and poly(styrene-co-methyl methacrylate-co-divinylbenzene) (PSNM): the chelating resin (I) was prepared by chloromethylation of phenyl rings of PSD followed by thiolation using thiourea. The chelating resin (II) was designed to provide enough space to chelate heavy metal ions; one chloromethyl group was obtained by chlorination of hydroxymethyl group provided by reduction of carboxylic ester group of PSMD and another chloromethyl group was obtained by direct chloromethylation of pendent phenyl group using chloromethyl. methyl ether. Both of chloromethyl groups were thiolated by using thiourea. The chelating resin (III) was prepared by chlorosulfonation of phenyl rings of PSD followed by thiolation using sodium hydrosulfide. The adsorbtivity toward heavy metal ions was evaluated. The hydrophobic chelating resin (I) with thiol groups showed highly selective adsorption capacity for mercury ions. However, the chelating resin (II) with thiol groups showed more effective adsorption capacity toward mercury ions than chelating resin (I) with thiol groups, and showed some adsorption capacity for other heavy metal ions like Cu2+, Pb2+, Cd2+ and Cr3+. On the other hand, the chelating resin (III) which have hydrophilic thiosulfonic acid groups was found to be effective adsorbents for some heavy metal ions such as Hg2+, Cu2+, Ni2+, Co2+, Cr3+ and especially Cd2+ and Pb2+.