Effects of EDTA,EDDS and CA on the dissolution,desorption and morphology of heavy metals in loess

doi:10.14088/j.cnki.issn0439-8114.2021.20.013

Abstract

Abstract: In order to study the effects of EDTA, EDDS and CA on the dissolution, desorption kinetics and speciation of heavy metals in loess, the dissolution, desorption behavior and variation characteristics of Cd, Cu, Pb, Zn and four heavy metals by three chelating agents under different concentrations, different pH and different time were studied by vibration centrifugation method, and the desorption process was fitted by kinetic model. The results showed that among the three chelating agents, EDTA had the most significant effect, and its removal rate of Cd was the highest; When the concentration of three chelating agents was 1 mmol/L, the dissolution rate of heavy metals reached the highest; At the same time, the lower the pH was, the higher the dissolution rate of heavy metals in loess was; When pH=4, the three chelating agents had the highest dissolution rate of heavy metals. After the use of chelating agent, the dissolution rate and desorption rate of heavy metals increased, and the desorption rate decreased with the extension of desorption time. The first 120 min was a rapid reaction stage. The double constant equation was the best one to describe the desorption kinetics of Cd, Cu, Pb,and Zn in loess, and the first-order kinetic equation had the worst fitting effect. The main removal objects of EDTA, EDDS and CA were water-soluble heavy metals. Under the desorption of EDTA, EDDS and CA, the total amount of Cd, Cu, Pb, Zn ions in loess could be effectively reduced, which also meant that the biological toxicity of contaminated soil was reduced.

Key words: chelating agent, heavy metal, dissolution, dynamic model, form

CLC Number:

YANG Ming-hang, WANG Guo-lan, JIN Zi-han, DAI En-hua, ZHANG Jun. Effects of EDTA,EDDS and CA on the dissolution,desorption and morphology of heavy metals in loess[J]. HUBEI AGRICULTURAL SCIENCES, 2021, 60(20): 72-79.

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