Chemical modification of commercial St-DVB microspheres and their application for metal ions removal

Abstract

Multistage modification of commercially available styrene with divinylbenzene (St-DVB) microspheres is presented. The new type of modification introducing very attractive thiol (–SH) groups on the surface of polymeric matrices was made. In order to obtain thiol derivatives, the parent St-DVB microspheres were treated by H2SO4 with addition of oleum and then conversion of sulfonic groups to chloride acylsulfonic groups in the presence of PCl5 and POCl3 was carried out. Finally, the reduction of modified microspheres by using SnCl2·2H2O was conducted. The thiol groups content (elemental analysis), thermal properties (TG/DTG, DSC analysis) as well as the swelling characteristics of the functional microspheres were examined. The novel material St-DVB-SH was compared with commercial ion exchanger Ambersept GT74 to removal of heavy metal ions: Cu(II), Zn(II), Cd(II), Pb(II) and Ni(II). In order to investigate the applicability of the obtained microspheres for heavy metal ions removal, the batch method was used. On the basis of studies, the optimal pH of the solution and microspheres dose was determined. Both for St-DVB-SH and Ambersept GT74, the Langmuir and Freundlich isotherm models are used to represent adsorption equilibria. The pseudo first order, pseudo second order and intraparticle diffusion kinetic models were used to fit the adsorption kinetic data. Additionally, dynamic adsorption tests were carried out in order to establish bed exhaustion. Results of a comprehensive comparative analysis indicate that the new synthesized material St-DVB-SH is very effective for removal of heavy metal ions studied.