The removal of heavy metal ions from aqueous solutions by novel pH-sensitive hydrogels

Novel non-ionic hydrogels were synthesized by radical homopolymerization of N-vinyl-2-pyrrolidone (VP) or by radical copolymerization of VP with methylacrylate (MA). A macroinimer (MIM) was used as a crosslinker and initiator, as well. The percentage of mass swelling ratios (S(M)), the molecular weight between crosslinks (M(c)) and Young's modulus of the hydrogels were investigated. The hydrogels were used as binding materials for different heavy metal ions such as Cu(2+), Cd(2+), Ni(2+) and Zn(2+) under varying conditions. The binding capability of the hydrogels toward the metal ions decreases in the following order: Cu(2+)>Ni(2+)>Zn(2+)>Cd(2+).