过氧化氢对铬在黄棕壤中电动过程的影响

ELECTROKINETIC PROCESSES OF CHROMIUM IN YELLOW BROWN SOIL AS AFFECTED BY HYDROGEN PEROXIDE

研究了在阳极池中添加过氧化氢对铬在黄棕壤中电动过程的影响。结果发现:经过约564h的电动处理后,土壤中六价铬的含量显著减少,最高去除率为91.6%,同时总铬去除率最高达39.6%。过氧化氢的存在对电流的影响不大,但明显降低了电渗流量。加入过氧化氢引起土壤中部分六价铬被还原成三价铬,降低了土壤中铬的移动性,从而使总铬的去除率减少,说明土壤中还原性物质的存在将不利于铬的去除。

Chromium usually existed in soil in two valences, Cr(Ⅵ) and Cr(Ⅲ), which are different in charges. Previous studies showed that Cr electrochemical processes in soil were complex due to its varied valences and strong oxidation-reduction reactions. This paper investigated Cr electrokinetic processes in Yellow brown soil as affected by hydrogen peroxide. The experiment was performed with a lab-made electrokinetic setup, made up of electric power supply, a soil column, a four channel peristaltic pump, two electrode chambers, a pH controller and two solution reservoirs. The results show that Cr(Ⅵ) concentration in the soil after 564 h electrokinetic treatment significantly decreased as compared with the initial value (C_(0)=396 (mg kg^(-1))). The presence of H_(2)O_(2), as a model reductant of soil, caused Cr(Ⅵ) reduction to stable Cr(Ⅲ). Effect of H_(2)O_(2) on electrical current was not obvious, but it significantly decreased the electroosmotic flow rate, suggesting its influence on soil (surface) structures and soil solution physical and chemical properties. All 4 treatments resulted in removal of over 85% Cr(Ⅵ) from soil. However, the total removal rate of Cr in the presence of H_(2)O_(2) decreased. The maximum removal rate of total Cr and Cr(Ⅵ) was obtained, being 39.6% and 91.6% respectively during the electrokinetic treatments.