考虑温度电动淋洗法去除污染软土中铬试验研究

针对铬污染软土，自行设计了电动淋洗试验装置，开展了铬污染软土室内土柱淋洗试验，分析了试验过程中电流、电解质溶液pH的变化以及淋洗液种类、外加电压、温度对重金属铬去除特性的影响。结果表明:电动淋洗试验可以有效去除土壤中的重金属铬；相对于单一淋洗试验，用10 V电压强化淋洗试验显著提高了重金属铬去除效果，淋洗液为十二烷基苯磺酸钠（SDS）时Cr（VI）和Cr（总）去除效率是单一淋洗法的2.79，3.12倍。当电压为10 V，温度升高至45 ℃时，淋洗液为柠檬酸（CA）和草酸（OA）的各组试验表明Cr（Ⅵ）与Cr（总）去除率均相应提高；而淋洗液为十二烷基苯磺酸钠时的试验组中Cr（VI）去除率提高了5.84%，Cr（总）去除率降低了4.25%，表明升高温度使部分Cr（VI）还原成不易迁移的Cr（III）；淋洗液为草酸的试验组中升高温度时Cr（Ⅵ）与Cr（总）去除率最高，分别达到了82.08%、77.57%，分别相应提高了27.65%、26.01%。电动淋洗试验后，铬污染软土土粒结构变得更紧密，土粒之间的孔隙减小且被填充的更加密实。

An experimental study of removal of chromium from contaminated soft soil with the electrokinetic soil flushing method considering temperature and low voltage

A series of column tests of chromium-contaminated soft soil were performed in lab using self-designed electrokinetic soil flushing apparatus considering temperature. The changes of the current and electrolyte solution pH, and the effects of the type of leaching agent (i.e. sodium dodecylbenzene sulfonate, citric acid and oxalic acid), applied voltage and temperature on the removal behavior of chromium were analyzed. The results show that chromium in soil can be removed effectively with the electrokinetic soil flushing method. Compared with the single soil flushing method using sodium dodecylbenzene sulfonate (SDS), the removal ratio of Cr(VI) and Cr(total) can increase to 2.79 and 3.12 times when the voltage of 10 V is applied. When the raising temperature increases to 45 ℃, the removal ratio of Cr(VI) and Cr(total) both are greatly improved as citric acid (CA) and oxalic acid (OA) are leaching agents, while the removal ratio of Cr(total) decreases by 4.25% when using SDS as leaching agent. The group using oxalic acid as leaching agent shows the best removal efficiency, and the removal ratio of Cr(VI) and Cr(total) reach 82.08% and 77.57%, respectively. After remediation, the soil structure has changed, and pores between soil particles become smaller and the soils are more compacted.