Atom transfer radical graft polymerization of acrylamide from N-chlorosulfonamidated polystyrene resin, and use of the resin in selective mercury removal

Polyacrylamide was grafted from N-chlorosulfonamide groups onto crosslinked polystyrene beads using copper-mediated atom transfer radical polymerization (ATRP) methodology. A beaded polymer with a polyacrylamide surface shell was prepared in four steps, starting from styrene-divinylbenzene (10%) copolymer beads of 210-420 μm particle size: chlorosulfonation; sulfamidation with propylamine; N-chlorination with aqueous hypochloride; and grafting using a concentrated aqueous acrylamide solution with a CuBr-tetramethylethylenediamine complex (1:2). The resulting polymer resin with 84 wt% grafted polyacrylamide has been demonstrated to be an efficient mercury-specific sorbent, able to remove Hg(II) from solutions at ppm levels. No interference arises from common metal ions such as Cd(II), Fe(III), Zn(II), and Pb(II). The sorbed mercury can be eluted by repeated treatment with hot acetic acid without hydrolysis of the amide groups.