Synthesis of dithiocarbamate-chitosan resin and its adsorption behavior for trace metals

Abstract

A chitosan-based resin possessing the dithiocarbamate moiety (DTC-chitosan resin) was synthesized using cross-linked chitosan as a base material. The adsorption behavior of trace metal ions on the DTC-chitosan resin was systematically examined by packing it in a mini-column (1 ml of the resin) and measuring the recovery by ICP-MS. The resin could adsorb almost 100% of 7 kinds of metals (Cu, Mo, Ag, Te, W, Hg and Bi) at pH ranges from acidic to neutral. However, elution of these metals from the resin was difficult. In this study, we improved the recovery efficiency by a pretreatment of the resin: the resin was added to 100 ml of a 0.1 M copper sulfate solution, stirred for 24 h and washed sufficiently with 1 M nitric acid and water. With this pretreatment, metals adsorbed on 1 ml of the resin were readily eluted with 1 M nitric acid (10 ml). This method was applied to the determination of metals in river-water samples; the RSDs (10-fold preconcentration) were within 5%.