The application of macroporous copolymers in the sorption of heavy and precious metals from aqueous solutions

Abstract

Macroporous crosslinked poly(GMA-co-EGDMA) was synthesized by the suspension copolymerisation and functionalized by the ring-opening reaction of the pendant epoxy groups with ethylene diamine. The porosity parameters (specific pore volume, specific surface area, and pore diameter, which corresponds to half of the pore volume) for the initial and amino-functionalized copolymer samples were calculated from the cumulative pore volume distribution curves obtained by mercury porosimetry. The selectivity, sorption capacity and sorption rate of amino-functionalized poly(GMA-co-EGDMA)-en were determined under static conditions. The sorption of Cu(ll) and Ag(l) ions on poly(GMA-co-EGDMA)-en was very rapid (ti/2 value about 1 min). Slower sorption was observed for Au(lll) ions with a ti/2 value of 6.5 minutes. The different rates of Au(lll), Cu(ll) and Ag(l) sorption could be applied for gold, copper and silver ion separation from mixed solutions. The sorption of Ni(ll) and Cu(ll) ions from galvanic solution under competitive conditions was also fast, with ti/2 values of 0.5 and 2 min, respectively. However, Zn(ll) sorption was considerably slower (a ti/2 of 10 min). Similar results were obtained for galvanic solution under dynamic conditions, i.e., the metal sorption capacities of poly(GMA-co-EGDMA)-en decreased in the order: Ni(ll) > Cu(ll) >> Zn(ll). The reusability of amino-functionalized poly(GMA-co-EGDMA) for Cu(ll) sorption was tested in four sorption/desorption cycles. Regeneration experiments were performed with 0.1 and 1 M H2SO4 showed a Cu(ll) capacity loss of 50 % in the first sorption/desorption cycle. The sorption capacity increased when additional neutralization with 0.1 and 1 M NaOH was performed after each sorption/desorption cycle.

Keywords

• macroporous copolymer
• ethylene diamine
• metal sorption
• galvanic solution