Modification of Poly(hydroethyl acrylate)-Grafted Cross-linked Poly(vinyl chloride) Particles via Surface-Initiated Atom-Transfer Radical Polymerization (SI-ATRP). Competitive Adsorption of Some Heavy Metal Ions on Modified Polymers

Abstract

Poly(hydroethyl acrylate) (PHEA) has been grafted from the surfaces of cross-linked poly(vinyl chloride) (PVC) beads with their surface labile chlorines as initiation sites, using a copper-mediated surface-initiated atom-transfer radical polymerization (SI-ATRP) methodology. The graft reaction exhibits first-order kinetics with respect to the polymerization time in the low-monomer-conversion stage, as is typical for ATRP. A percentage of grafting (PG%) of 190.4% was achieved in 10 h. The ester groups of the poly(hydroethyl acrylate)-grafted cross-linked poly(vinyl chloride) beads (PHEA−PVC) were then hydrolyzed to yield carboxyl groups. Then, the bare PVC beads; the PHEA−PVC beads; and the hydrolyzed product, poly(acrylic acid)-grafted cross-linked poly(vinyl chloride) beads (PAA−PVC), were used for the extraction of heavy metal ions such as Cu(II), Hg(II), Zn(II), and Cd(II) in weak acidic aqueous solution. It was found that the former two had better loading capacities toward Hg(II) ion. The adsorbed ions were eluted by repeated treatment with acetic acid. The chelating resins did not lose their activity even after the 10th regeneration. The material described herein is regenerable and has the advantage of mobility of the graft chains in the removal of heavy metal ions from aqueous mixtures.