NEW SORBENTS FOR REMOVAL OF HEAVY-METAL IONS - DIAMINE-GLOW-DISCHARGETREATED POLYHYDROXYETHYLMETHACRYLATE MICROSPHERES

Polyhydroxyethylmethacrylate (PHEMA) microspheres prepared by suspensi on polymerization, were treated with diamine-plasmas [i.e. ethylenedia mine (EDA) and/or hexamethylenediamine (HMDA)] in a glow-discharge rea ctor in which the exposure time and glow-discharge power were changed between 5-30 min and 5-20 W, respectively. The microspheres were chara cterized by FTIR and elemental analysis. The maximum amounts of nitrog en deposited on the microspheres were 22.3 and 23.4 mu mol/g with the EDA- and HMDA-plasmas. Adsorption of Cu(II) and Pb(II) ions from aqueo us solutions on these sorbents was investigated under different condit ions. Adsorption equilibria were achieved in 1 h. Different adsorption capacities were obtained in the adsorption media containing different amounts of heavy metal ions and at different pH values. Adsorption ca pacity increased both with increase in exposure time and glow-discharg e power. The maximum adsorption capacities achieved were 5.3 mg Cu(II) /g; 136.2 mg Pb(II)/g and 6.8 mg Cu(II)/g; 174.2 mg Pb(II)/g for the E DA- and HMDA-plasma treated PHEMA microspheres, respectively. (C) 1997 Elsevier Science B.V.