Authors: Kemal KESENCİ, Adil DENİZLİ, Erhan PİŞKİN
Abstract: The aim of this study is to investigate Cd(ll) adsorption from aqueous solutions onto monosize polystyrene microspheres (2 \mum in diameter) containing dithiocarbamare functional groups. Polystyrene microspheres were pepared by a dispersion polymerization and crosslinked with divinylbenzene. In order to have dithiocharbamate groups for specific adsorption of cadmium (II) ions, tirstly, chloromethyl styrene and styrene mixture were adsorbed and then copolymerized on the surface of crosslinked microspheres. Then, these microspheres were treated with benzyl amine. At the last stage of surface modification, amine groups were reacred with carbon disulphur and dithiocarbamate functional groups were formed on the surface of microspheres. Cd(II) adsorpuons onto plain, chloromethyl styrene modified and dithiocarbamate containing polystyrene microspheres were investigated at different experimental conditions. The effect of medium pH, Cd(II) initial concentration and temperature on Cd(ll) adsorption were determined. Desorption of Cd(ll) ions and reusability of polymeric microspheres were also studied. Imporunt results obtained in this study are as follows: Dithiocarbamate modification were increased Cd(ll) adsorption significantly according to plain and chloromethyl styrene modified microspheres. pH and Cd(II) initial concentrations are important parameters for Cd(ll) adsorption. Maximum Cd(II) adsorption was observed as 13.7 mg Cd(ll)/g polymer at pH 7.0. More than 85% adsorbed Cd(ll) ions were desorbed by using 0.1 M HNO_3 as desorption agent Five times adsorpuon-desorption cycles showed the feasibility of repeated use of the microspheres developed in this study.
Keywords: Polystyrene microspheres, dithiocarbamate, cadmium(II) adsorption