SYNTHESIS OF AMIDOXIME-CONTAINING MODIFIED STARCH AND APPLICATION FOR THE REMOVAL OF HEAVY-METALS

Amidoxime-containing modified starch was prepared by reaction of acrylonitrile with crosslinked starch, catalyzed by ceric ions, and subsequent derivatization with free hydroxylamine in methanol. First investigations of this new cation exchange material revealed that the maximum capacities of the modified starch for the heavy metal ions Cu2+, Hg2+, Pb2+ and Zn2+ were 1.86, 0.59, 0.52 and 0.37 mmol g-1 (dry weight), respectively. At pH 5, the order of decreasing selectivity of the cation exchanger for the various metal ions was: Hg2+ > Cu2+ > Pb2+ > Zn2+ > Ni2+ > Cr3+. The product could be reused after regeneration with diluted hydrochloric acid. The high exchange capacity for copper, which offers possibilities for applications of the material for industrial purposes, were examined in detail.