Preconcentration of Trace Metals with Dithiocarbamate-Chitin

Abstract

Dithiocarbamate-chitin (DTC-chitin) is synthesized by mixing chitin powder with carbon disulfide, 2-propanol and tetramethylammonium hydroxide in benzene. The DTC-chitin contains about 0.7% of sulfur, and the IR spectra of the DTC-chitin exhibit a small band at 1480 cm⁻¹ which is assigned to N-C=S. This polymer sorbs silver and copper from acidic solutions in the range of 1 M (mol dm⁻³) nitric acid to pH 5.0, cadmium at pH 1.0–6.0, and cobalt and nickel at pH≥2.5. On the other hand, untreated chitin sorbs these metal ions only at a pH above 7.0. The maximum flow rate for quantitative retention is 15 ml min⁻¹ for 0.04 ppm of silver, cobalt and copper. The metals retained on the column are eluted with dilute nitric acid containing thiourea or hydrogen peroxide and are determined by flame atomic absorption spectrometry.