Removal of heavy metal ions by dithiocarbamate-anchored polymer/organosmectite composites

In this study, the dithiocarbamate-anchored polymer/organosmectite composites were prepared for the removal of heavy metal ions (lead, cadmium and chromium) from aqueous media containing different amounts of these ions (50-750 ppm) and at different pH values (2.0-8.0). Initially, the modification of the natural smectite minerals was performed by treatment with quartamin styrene and chloromethylstyrene. Then, modified smectite nanocomposites were reacted with carbondisulfide, in order to incorporate dithiocarbamate functional groups into the nanolayer of organoclay. The dithiocarbamate-anchored nano-composites have been characterized by FTIR and used in the adsorption-desorption process. The maximum adsorptions of heavy metal ions onto the dithiocarbarnate-anchored polymer/organosmectite composites from their solution was 170.7 mg g(-1) for Pb(II); 82.2 mg g(-1) for Cd(II) and 71.1 mg g(-1) for Cr(III). Competition between heavy metal ions (in the case of adsorption from mixture) yielded adsorption capacities of 70.4 mg g(-1) for Pb(II); 31.8 mg g(-1) for Cd(II) and 20.3 mg g(-1) for Cr(III). Desorption of the heavy metal ions from composite was studied in 0.5 M NaCl and very high desorption rates, greater than 93%, were achieved in all cases. Adsorption-desorption cycles showed the feasibility of repeated uses of this nanocomposite. (c) 2005 Elsevier B.V. All rights reserved.