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Frontiers of Environmental Science & Engineering >> 2018, Volume 12, Issue 2 doi: 10.1007/s11783-018-1006-2

Phosphate-induced differences in stabilization efficiency for soils contaminated with lead, zinc, and cadmium

. College of Water Sciences, Beijing Normal University, Beijing 100875, China.. State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China

Available online: 2017-10-31

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Abstract

Phosphates can cost-effectively decrease the mobility of Pb in contaminated soils. However, Pb always coexists with other metals in soil, their competitive reactions with phosphates have not been tested. In this study, the abilities of KH PO , K HPO , and K PO to stabilize Pb, Zn, and Cd in soils contaminated with a single metal or a ternary metal for different phosphorus/metal molar ratios were investigated. Results indicated that the stabilization efficiency of KH PO , K HPO , and K PO for Pb, Zn, and Cd in single metal contaminated soil (P/M ratio 0.6) was 96.00%–98.74%, 33.76%–47.81%, and 9.50%–55.79%, respectively. Competitive stabilization occurred in the ternary system, Pb exhibited a strong competition, the stabilization efficiency of Zn and Cd reduced by 23.50%–31.64%, and 7.10%–39.26%, respectively. Pyromorphite and amorphous lead phosphate formed with excess KH PO or K HPO addition, while K PO resulted in the formation of a hydroxypyromorphite precipitate. Amorphous Zn and Cd phosphates and hydroxides were the primary products. The immobilization rate of Zn and Cd depends on pH, and increased significantly in response to the excess phosphate application. This approach provides insight into phosphate-induced differences in stabilization efficiency in soils contaminated with multiple metals, which is of theoretical and engineering significance.

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