生物可降解络合剂聚天冬氨酸治理土壤重金属污染

Removal of heavy metals from contaminated soil with biodegradable chelating agents-polyaspartic acid

土壤重金属污染会产生严重的生态环境问题,土壤淋洗技术可达到土壤修复的目的,其中络合剂的选择是达到安全、有效修复效果的关键。聚天冬氨酸(PASP)可生物降解,对环境安全。文章选择PASP作为重金属的络合剂,研究其修复土壤重金属污染的效果。结果表明,PASP对金属离子Cd、Zn和Ca均有较好的提取率,均超过50%,并且络合剂/重金属的摩尔比越高,提取效果越好,受pH的影响就越少,提取速率开始比较快,而后趋于平缓。在PASP络合物的形态分布中,在pH较低阶段,PASP-Cd络合物所占的比例较大,随着pH的升高,PASP-Zn和PASP-Ca的比例增加,同时微生物对聚天冬氨酸的降解作用对治理效果产生负面影响。PASP可作为环保型的络合剂,达到修复土壤重金属污染的目的。

The severe environmental disast has been caused with the soil heavy metal pollution. One effective remediation techniques for soil pollution is soil washing with chelating agents. The suitable alternative of chelating agents is the key to achieve the successful remediation effect. Polyaspartic Acid（PASP） can be degraded by microorganisms and safety to the environment. The aim of the research was to investigate the ability of the PASP to remove the heavy metals from soil. The results showed the extraction rates of PASP to heavy metals（Cd, Zn and Ca） was more than 50%, and the extraction rate was improved as the concentration of PASP was enhanced. The ration of PASP-Cd in speciation of PASP-heavy metals was more than others in low pH. With the value of pH improved, the rations of PASP-Zn and PASP-Ca were occupied the majority proportion in speciation. The better remediation effect was achieved with the less pH dependence in the higher concentration of PASP. The degradation of PASP by microorganisms had the hegative impaction to remediation effect. PASP, as a green chelating agent, can be used to remove the heavy metals from the contaminated soil.