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| Leaching characteristics of Cd in the contaminated soils with chelates and rhamnolipid |
| Received:July 02, 2016 |
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| KeyWord:cadmium;contaminated soil;chelates;rhamnolipid;leaching characteristics |
| Author Name | Affiliation | E-mail | | CHEN Dong-yue | Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, College of Resources and Environment, Southwest University, Chongqing 400715, China | | | SHI Qiu-ling | Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, College of Resources and Environment, Southwest University, Chongqing 400715, China | | | ZHANG Jin-zhong | Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, College of Resources and Environment, Southwest University, Chongqing 400715, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | jzhzhang@swu.edu.cn | | LIU Jiang | Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, College of Resources and Environment, Southwest University, Chongqing 400715, China | | | QIAN Sheng | Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, College of Resources and Environment, Southwest University, Chongqing 400715, China | |
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| Abstract: |
| The simulated pollution soils with three Cd concentration levels were prepared, the leaching characteristics of Cd from the soils were studied with chelates and rhamnolipid, and the speciation variations of Cd in soil during the joint leaching process with EDTA and rhamnolipid was also discussed. When the eluent concentration was 0.025 mol·L-1 and the initial pH was 7, the leaching process reached equilibrium at 220, 140 and 60 min with EDTA, ethylenediamine disuccinic acid(EDDS) and citric acid, respectively. The best leaching results could be obtained with EDTA, and the maximal leaching percentages were 93.16%, 93.62% and 94.09% for 0.38, 0.69 and 0.93 mg·kg-1 Cd contaminated soils, respectively. The leaching process with EDTA could be described by pseudo two-order kinetic model, and the leaching rate constant showed a decreasing order of 0.38 mg·kg-1 Cd contaminated soil, 0.69 mg·kg-1 Cd contaminated soil and 0.93 mg·kg-1 Cd contaminated soil. When the volume ratio of EDTA and rhamnolipid(0.025 mol·L-1) was 1.5:1, the leaching percentages reached 85.45%, 89.25% and 93.88% for the three contaminated soils, respectively, and the leaching equilibrium time decreased to 50 min. Joint leaching can effectively release the exchangeable, carbonate bound and organic bound Cd in the contaminated soils, and the possible mechanism is the synergistic effect of EDTA chelation and the micellar solubilization of rhamnolipid. |
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