Abstract:Based on its environmental friendly and molding properties, carboxymethyl chitosan was used as sustained release carrier, the sustained release EDTA was prepared by spray dryer with EDTA and carboxymethyl chitosan in the ratio of 1:1. Using sustained release EDTA as objects to carry out characterization analysis, sustained release kinetics research, static activation characteristics and dynamic leaching characteristics of heavy metals in soil. The results show that the encapsulation rate of sustained release EDTA can reach 87.51%, and the release process in water conforms to the Higuchi model, and has obvious sustained-release effect. Compared with EDTA, sustained-release EDTA can effectively control the surge of Pb and Cd ions while increasing the concentration of Pb and Cd ions in soil solution, so as to keep the appropriate concentration of Pb and Cd ions in soil solution continuously increasing. The dynamic elution results show that adding two different forms of EDTA could significantly increase the leaching loss of Pb and Cd, but the sustained release EDTA treatment could significantly reduce the initial leaching loss and total leaching loss of Pb and Cd, in which the total leaching loss of Pb and Cd is reduced by 19.5% and 20.9%, respectively.