Removal of Cadmium in Water Using TCAS-Adsorbed Resin

A adsorbent for cadmium had been prepared by loading an anion-exchange resin with a novel supramolecular compound named thiacalix[4]arenetetrasulfonate (TCAS). The adsorption properties of Cd²⁺ on TCAS-adsorbed resin had been studied and the effects of varying temperature, pH value, adsorption time and initial conentration. Batchwise extraction studies had revealed a high adsorption ability of the TCAS-adsorbed resin toward this heavy metal ion with high selectivity. The maximum adsorption capacitiy of the TCAS-adsorbed resin toward Cd²⁺ was 14.45 mgldrg^-1. The removal rate of Cd²⁺ in water was up to 99% after 60 min at 20degC when a 50 mL aqueous solution of Cd²⁺ (10 mgldrL^-1) was adsorbed by 0.5 g TCAS-adsorbed resin. The desorption rate steadily retained above 98% when the pH value was in the range of 7 to 11. The data obtained from sorption isotherms of metal ions at different temperatures fit to linear form of Langmuir sorption equation. These results not only could theoretically provide the approach to use the new type of TCAS-adsorbed resin to enhance the capacity of desorption of Cd²⁺ from liquid media, but also could extensively be used in the technique for low concentration Cd²⁺ contaminated water.