阴极pH控制对污染土壤电动修复效率的影响

就电动修复污染土壤过程中阴极电解产生的OH-对修复效率的影响进行了实验室研究.实验选用重铬酸钾作为污染物,配制砂土和高岭土中初始w(Cr(Ⅵ))为100和500 mg/kg,施加恒定直流电压1 V/cm,运行48 h.选用不同土壤和控制条件,实验共进行了10组.分析了实验过程中电流变化以及实验完成后土壤pH分布和铬的迁移分布,并对每组实验Cr(Ⅵ)的去除率和电能消耗进行了计算.结果表明:对阴极电解产生的pH进行控制可以明显提高Cr(Ⅵ)的去除率,同时电能耗变化不大;多种控制方式中,以盐酸的中和控制最为有效,可使去除率达到90.8%,但引起的土壤酸化问题应进一步进行研究;对电动过程中Cr(Ⅵ)的迁移转化应做深入研究.

Effect of pH Control at the Cathode for the Electrokinetic Remediation Efficiency

The experimental study on the effect of control at the cathode for the electrokinetic remediation efficiency of the chromium-polluted soils at laboratory scale was presented. Potassium dichromate was chosen as the pollutant and its initial mass concentration was 100 mg/kg soil and 500 mg/kg soil. 1 V/cm voltage was applied, and the experiments were operated for 48 h. Ten groups of experiment were performed with different soils and different control conditions. The variation of the current flow during the experiment as well as the pH distribution and movement distribution of chromium was analyzed, and the removal efficiency of hexavalent chromium and the electric energy consumption of each group of experiment calculated. The results indicate that pH control at the cathode can improve the removal efficiency of hexavalent chromium from kaolin significantly, and the electric energy consumption changes slightly. Among several methods investigated, neutralizing method of hydrochloric acid is the most effective one, which removal efficiency of hexavalent chromium reaches up to 90.8%, but it is necessary to further research how to prevent the acidification of soils. Also, the movement and transformation of hexavalent chromium in soils should be studied thoroughly.