Surface modification of macroporous glycidyl methacrylate based copolymers for selective sorption of heavy metals

Two samples of macroporous poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), poly(GMA-co-EGDMA), were synthesized by suspension copolymerization and modified with amines. Initial poly(GMA-co-EGDMA), and the samples modified with ethylene diamine [poly(GMA-co-EGDMA)-en], diethylene triamine [poly(GMA-co-EGDMA)-deta] and triethylene tetramine [poly(GMA-co-EGDMA)-teta], were characterized by mercury porosimetry, FTIR spectroscopy and elemental analysis. The most pronounced increase of specific surface area (75%) was observed for poly(GMA-co-EGDMA)-teta sample with smaller particles (D < 150 mu m). The Cu(II) sorption was rapid, depending on porosity of amino-functionalized samples and ligand type. For poly(GMA-co-EGDMA)-deta and poly(GMA-co-EGDMA)-teta sorption half time required to reach 50% of total sorption capacity, t(1/2), were around 3 min. Sorption capacities for Cu(II), Co(II), Cd(II) and Ni(II) as well as for Cr(VI), Co(II), Cd(II) and Ni(II) ions were determined under competitive conditions as a function of pH, ligand type and porosity at room temperature. The results indicate selectivity of poly(GMA-co-EGDMA)-deta for Cu(II) over Cd(II) of 3:1 and for Cu(II) over Ni(II) and Co(II) of 6:1. The decrease in particle size of poly(GMA-co-EGDMA)-teta caused the increase of sorption capacities for all metal ions. At pH 1.8 the selectivity of poly(GMA-co-EGDMA)-teta with smaller particles for Cr(VI) over Ni(II), Co(II) and Cd(II) ions was 8.5:1.