Selective uptake and recovery of cadmium (II) by microcapsule containing chelating resin

A chelate resin that adsorbed 2-(p-sulphophenylazo)-1,8-dihydroxy-3,6-naphthalene disulfonate ion on an anion exchange resin was synthesized, and then polystyrene microcapsules containing the chelate resin were prepared by interfacial polymerization with W/O/W emulsions. The uptake to Cd2+, Co2+, Ni2+, Zn2+, Cu2+ and Zr4+ ions into the microcapsules was studied at 25 °C. The adsorption rate of Cd2+ ion to the microcapsules was about four times more than that of Zn2+, Co2+, Ni2+ and Cu2+ ions. None of the metallic complexes trapped to the microcapsules were affected by the outside environment like pH (1-7), and the Cd2+ ions remained unaffected in the microcapsules even in 1 M HCl solution.