Application of insoluble cellulose xanthate for the removal of heavy metals from aqueous solution

Insoluble cellulose xanthate (ICX), O-alkyl dithiocarbonate of cellulose, was synthesized and used for the removal of heavy metal ions from aqueous solutions. ICX possessed carbon disulfide (CS2) as a functional group, which was obtained by esterification of the hydroxyl group on cellulose polymer matrix with CS2. CS2 could form complexes with divalent transition metal ions, and the resulting ICX-metal complex was water-insoluble and settled easily. The optimum composition for ICX synthesis was cellulose/NaOH/CS2=1 :2:2.3 in mole base, which showed the highest removal capacity. The selectivity and binding capacity of ICX for heavy metals were in the order of Pb2+>Cd2+Ni2+ and Cd2+>Pb2+Ni2+, respectively. More than 90% of the initial amount of heavy metals was removed within 30 min. The optimum pH was neutral or slightly alkaline, and more than 40% of initial heavy metals was removed even in the acidic range of pH 2 to 3.