超声强化EDDS/EGTA淋洗修复重金属污染土壤

Remediation of heavy metal contaminated soil by ultrasound-enhanced washing with EDDS and EGTA

采用响应面法中的Box-Behnken实验设计,研究了超声强化N,N′-乙二胺二琥珀酸(EDDS)和乙二醇双(2-氨基乙基醚)四乙酸(EGTA)复合淋洗对土壤中Cu、Zn、Pb和Cd等4种重金属的去除效果,拟合了各重金属去除率、潜在生态风险指数削减率与EDDS投加量、EGTA投加量、超声功率和初始pH等淋洗条件之间的关系,模拟值与观测值相关性高,模拟精度较高。EGTA在较广pH范围对高生理毒性的Cd具有较强的洗脱效果,酸性条件下可有效洗脱Zn;Cu去除率在酸性条件下随着EDDS投加量的增加而显著提高,Pb去除率则在碱性条件随着EDDS投加量的增加而显著提高。基于模型优化结果的验证实验显示,当EDDS/重金属摩尔质量比为0.81、EGTA/重金属摩尔质量比为3.92、超声功率为569.85 W、pH为3.95时,潜在生态风险指数削减率最大,达到86.05%,Cu、Zn、Pb和Cd去除率分别为72.48%、62.40%、59.25%和87.45%,与模型拟合结果偏差较小,表明模型具有较好的拟合和预测能力。

The Box-Behnken experimental design from response surface methodology was used to explore the efficiency of ultrasound-enhanced EDDS/EGTA washing for heavy metals（Cu, Zn, Pb, Cd） contaminated soil.The relationships between the removal rate of heavy metals, the removal rate of potential ecological risk index with the EDDS dose, the EGTA dose, the ultrasonic power and the initial solution pH were fitted. The correlation between simulated value and observed value was high and the simulation accuracy was high. EGTA showed significant removal rate of Cd with high biological toxicity in a wide range of pH and Zn under acidic condition. The removal rate of Cu increased significantly with the elevation of EDDS dose under acidic condition, while the removal rate of Pb increased significantly with the elevation of EDDS dosage in alkaline condition. The verification experiment designed according to optimization showed the potential ecological risk index reached 86.05%, and the Cu, Zn,Pb and Cd removal rates were 72.48%, 62.40%, 59.25% and 87.45%, respectively, when the EDDS/metals molar ratio was 0.81, the EGTA/metals molar was 3.92, the ultrasonic power was 569.85 W and the initial pH was 3.95.The deviation between the verification result and the simulation result was small, which showed that the model has good fitting and prediction ability.