CHELATING RESINS SUPPORTING DITHIOCARBAMATE AND METHYLTHIOUREA GROUPS IN ADSORPTION OF HEAVY-METAL IONS

Two different sulfur atom containing functional groups were introduced into poly (styrene-g-ethylene glycols), PSR-ET (13) OH, consisting of a cross-linked polystyrene backbone grafted with linear poly (ethylene glycol) chains. Reaction of an amino derivative of the polymeric substrate with carbon disulfide and methylisothiocyanate produced new chelating resins of dithiocarbamate type, PSR-ET (13) CS2Na, and methylthiourea type, PSR-ET (13) TU, respectively. The adsorption behavior of these resins was studied toward Hg (II), Cd( II), Cu (II), and Pb (II) ions in different experimental conditions. The order of metal adsorption for dithiocarbamate-supported resins was Hg (II) > Pb (II) much greater than Cd (II) > Cu(II) and for methylthiourea-supported resins was Hg (II) much greater than Cu (II) > Cd (II) much greater than Pb (II). Different regeneration methods were performed with the dithiocarbamate and methylthiourea resins; the former was regenerated by complete mineralization of the metal complexes, the latter by treatment with a solution of 6 N HCl and 10% of thiourea. (C) 1994 John Wiley and Sons, Inc.