Dithiocarbamate-incorporated monosize polystyrene microspheres for selective removal of mercury ions

Dithiocarbamate-incorporated monosize polystyrene based microspheres (2 mu m in diameter) were used for selective removal of Hg(II) from aqueous solut ions containing different amounts of Hg(II) (10-100 ppm). Adsorption rates were observed as high at the beginning of adsorption and then equilibrium w as reached in about 30 min. The maximum Hg(II) adsorption capacity of the d ithiocarbamate-incorporated PS microspheres was about 33.2 mg per gram of d ry polymer, which was observed at pH 7.0. While non-specific Hg(II) adsorpt ion onto the plain microspheres was 0.85 mg per gram of dry microsphere. Th e Hg(II) adsorption ability increased with increasing pH, in the range wher e the solubility of the Hg(II) was not affected by the pH. The preferential (i.e., competitive adsorption) binding of Hg(II) by the microspheres impli es that this sorbent system might contain higher-affinity binding sites for Hg(ll) than Cu(II), Cd(II) and Pb(II) ions. More than 96% of the adsorbed Hg(II) was desorbed in 15 min by using 0.1 M HNO3 as an elution agent. The regeneration of the dithiocarbamate-incorporated PS microspheres was also s ufficient. (C) 2000 Elsevier Science B.V. All rights reserved.