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| Desorption characteristics of Pb2+ and Zn2+ from red soil and yellow-cinnamon soil by saponin |
| Received:July 22, 2016 |
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| KeyWord:saponin;Pb2+;Zn2+;red soil;yellow-cinnamon soil;desorption |
| Author Name | Affiliation | E-mail | | CHANG Hong | Key Laboratory of Arable Land Conservation(Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China | | | LI Li-fen | Key Laboratory of Arable Land Conservation(Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China | | | HUANG Li | Key Laboratory of Arable Land Conservation(Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China | daisyh@mail.hzau.edu.cn |
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| Abstract: |
| Incubations of Pb2+ and Zn2+ in contaminated red and yellow-cinnamon soil were conducted to investigate the effect of saponin on desorption of heavy metals. Various factors such as concentration of adsorbent(0~20 g·L-1), pH(3~7), extract times(1~3) were studied, the effect of saponins on Pb2+ and Zn2+ desorption was researched by Zeta potential analysis. Results showed that the desorption amounts of Pb2+ and Zn2+ enhanced with the increasing of saponin concentration and were negative with the acidity of saponin solution in tested soils. Under the same condition, saponin could desorb more Zn2+ than Pb2+, the highest desorption rate of Zn2+ was 47%, and 30% in the red and yellow-cinnamon soil, respectively. After single desorption, acid soluble Pb2+(38%) and Zn2+(34%) decreased most in the red soil than in the yellow-cinnamon soil. The declined content of oxidable Zn2+ was relatively less(about 14%), but still higher than that in the yellow-cinnamon soil. The reduction of reducible Pb2+ was more than other forms of Pb2+ in yellow-cinnamon soil, about 26%. The desorption amounts of all forms of Pb2+ and Zn2+ were significantly lower in the yellow-cinnamon soil than those in the red soil. The desorption effects of Pb2+ and Zn2+ by saponin were better in red soil than in yellow-cinnamon soil, these were mainly because of the differences of mineral composition and surface charge properties of the two soils.Compared with the red soil, the yellow-cinnamon soil had more constant charge minerals and less variable charge minerals. After adding saponin, the Zeta potential of the red soil decreased and that of the yellow-cinnamon soil increased, and the Zeta potentials of the two soils were generally close to zero. |
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