Remediation of Cadmium Contaminated Soil by γ-Polyglutamic Acid Modified Biochar
In order to strengthen the remediation effect of biochar on cadmium-contaminated soil,γ-polyglutamic acid was used to activate and modify corn straw biochar.The structure of γ-polyglutamic acid modified biochar was characterized by scanning electron microscopy and infrared spectroscopy.The passivation effect of γ-polyglutamic acid modified biochar on Cd2+was investigated by simulating soil cadmium pollution test.The results showed that the number of hydroxyl and carboxyl functional groups of γ-polyglutamic acid modified biochar increased significantly.Compared with the application of 1.0% original biochar,applying equal amount of γ-polyglutamic acid modified biochar in cadmium-contaminated soil significantly increased the soil cation exchange capacity,organic matter content,soil phosphatase,catalase and urease activities by 9%,17%,18%,15%and 20%,respectively.The content of residual Cd in soil increased by 15%,the content of weak acid extractable Cd decreased by 27%,and the bioavailability of Cd2+in soil decreased significantly.The content of Cd2+in roots and leaves of Chinese cabbage decreased significantly.In summary,γ-polyglutamic acid modification can improve the ability of biochar to passivate cadmium in soil,and γ-polyglutamic acid modified biochar has great potential in the remediation of cadmium contaminated soil.
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