施加不同电压对铬污染黄棕壤电动过程的影响

ELECTROKINETIC TREATMENT OF A CHROMIUM CONTAMINATED YELLOW BROWN SOIL AS AFFECTED BY VOLTAGE

研究了在控制阴极液酸度条件下,施加不同电压对铬污染黄棕壤中铬的电动过程的影响,结果表明增加应用电压显著提高了处理电流和电渗流量,所有电动处理后土柱中土壤pH均在3左右,低pH环境引起土柱中铬的氧化还原和沉淀反应并导致土柱中电压降的不均匀分布。施加20 V电压处理获得了较好的铬去除率和较低的能耗,576 h后土壤中总铬和六价铬的去除率分别达到41.1%和77.7%。控制阳极池溶液酸度将是一个能够显著提高土壤铬去除的有效方法。

Because of complex chemical reactions of chromium in soil, the mechanism of electroremediation of Cr-contaminated soil remains unclear up to now. In this paper, effects of voltage drops during electrokinetic treatments on the movement of chromium in a yellow brown soil were studied by evaluating distribution of voltage drops in soil sections, electric energy consumption, change in soil basic properties and total chromium residual in the soil. The results show that electrokinetic currents and electroosmosis flows increased with increasing voltage, and the soil pHs in all soil sections dropped to about 3 after electrokinetics. Redox and precipitation reactions occurred in the soil column during the electrokinetic treatments, which led to decrease in ions concentration in the soil solution and uneven distribution of voltage drop in the soil column. The applied electric field and low pH environment strengthened reduction reaction of hexavalent chromium to form hardly-movable trivalent chromium in the soil. Application of 20 V voltage achieved higher cr removal rate and used up less electric energy. After 576 hours, the treatment removed 41.1% and 77.7 % , of soil Cr and Cr （ Ⅵ ） respectively, and used up 147 k Wh t^-1 of electric energy. It suggests that to control anolyte pH and increase the anolyte electroconductivity is an effective method to increase Cr removal rate from the soil column and reduce electric energy consumption.