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

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 I M nitric acid and water. With this pretreatment, metals adsorbed on 1 ml of the resin were readily eluted with I 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%.