Competition Absorption and Desorption Dynamic Character of Cadmium, Lead and Zinc by Soil in North-East of China

Abstract

The competitive absorption and desorption of cadmium (Cd), lead (Pb) and zinc (Zn) in meadow brown soil from Liaoning province in north-east China was studied in the paper in order to establish the selectivity sequences for the sorption and desorption of these heavy metals in the soil and obtain the absorption and desorption dynamic character of these heavy metals. The results showed that with the increasing of the absorption times, the absorption quantities of Cd, Pb and Zn were increased little by little. The absorption process of Cd, Pb and Zn could be divided into the fast absorption phase and the slow absorption phase. And the fast absorption phases were from the beginning to 60 min, 120 min and 120 min for Cd, Pb and Zn, respectively. The more company metals (i.e. Pb and Zn) existed in the absorption solutions, the less absorption quantities of Cd absorbed by soil. The co-existence of Cd, Pb and Zn had obviously decreased the absorption of Pb by soil. And it was the same situation that Zn absorbed by soil was decreased by the company metals such as Cd, Pb. The company metals had obvious influence on the desorption process of Cd. The existence of Pb and Zn promoted the desorption of Cd. And desorption behavior of Zn was bated by the existence of Pb and Cd. While the company metals Cd and Zn restrained the desorption of Pb. The best equation to describe the absorption and desorption dynamic character of Cd, Pb and Zn was Elovich equation, next was Two–constant equation, and the effect of First-order dynamics equation was not good.