Sorption characteristics of chelating resins - II. Sorption of Zn(II) and Cd(II) by Chelex 100

Chelating resins are used for preconcentrating metal ions in trace analysis . As part of a systematic study of sorption characteristics of the chelatin g resin Chelex 100, the sorption of Zn(II) and Cd(II) in different aqueous media was investigated. The distribution coefficient (DC) values for both Z n(II) and Cd(II) were extremely low (<4) in 0.5 to 6M HNO3 and H2SO4 soluti ons. In HCl solutions, the DC values for both Zn(II) and Cd(II) were higher , reaching a peak of nearly 40 in 3M HCl solutions. The DC values for both Zn(II) and Cd(II) increased with increasing pH in chloride, nitrate, and su lfate solutions (0.1M); the value was nearly 10(4) for both Zn(II) and Cd(I I) between pH 5 and 7 and pH 6 and 8, respectively.