摘要
电动修复是去除地下水中重金属污染物的有效方法。采用电动修复方法对Cr(Ⅵ)初始浓度为1000 mg/kg的污染浅层地下水进行为期4 d的处理,研究不同电压梯度(1、2、3 V/cm)对饱和带地下水中Cr(Ⅵ)去除率的影响。此外,对修复过程中的相关指标包括电流、阴阳极电解液pH、氧化还原电位(E_(h))和不同位置地下水Cr(Ⅵ)浓度进行监测,并且对电动修复前后饱和带介质的pH、E_(h)和Cr(Ⅵ)去除率进行分析。结果表明:Cr(Ⅵ)的平均去除率随电压梯度升高而升高,当电压梯度为2 V/cm时去除效率和经济性较好,去除率提升与能耗提升比值为0.52,最高去除率91.41%出现在电压梯度为3 V/cm时,但此时相应能耗较高。修复过程中Cr(Ⅵ)会在阳极附近富集,特别是当电压梯度较低(1 V/cm)时,反应结束后近阳极地下水Cr(Ⅵ)富集浓度高达2170.95 mg/L,介质中Cr(Ⅵ)浓度为1497.45 mg/kg,此时去除率为负值;阳极电解液Cr(Ⅵ)浓度呈先增长后稳定的趋势,当Cr(Ⅵ)浓度接近4000 mg/L时,已接近装置的最大迁移值,增加反应时间对Cr(Ⅵ)的回收率提升不大。修复过程中介质E_(h)降低、pH升高会促进Cr(Ⅵ)的还原和解吸,对Cr(Ⅵ)的去除具有促进作用。
Electrokinetic remediation is an effective method to remove heavy metal contaminants from groundwater.The effect of different voltage gradients(1,2,3 V/cm)on the removal rate of saturated zone groundwater Cr(Ⅵ)was studied with an initial content of 1000 mg/kg for 4 days by the electrokinetic remediation method.In addition,the relevant factors in the repair process,including current,pH and redox potential(E_(h)) of anode and cathode electrolytes,and the concentrations of Cr(Ⅵ)in different positions were monitored.PH,the removal rates of Cr(Ⅵ)and E_(h) of the saturated zone medium before and after treatments were analyzed The results showed that:1)The average removal rates of Cr(Ⅵ)increased with the increase of voltage gradient.When the voltage gradient was set at 2 V/cm,the removal efficiency and economy were better.The removal rate increase/energy consumption increase ratio was 0.52.The highest removal rate of 91.41%was observed when the voltage gradient was set at 3 V/cm,and the higher corresponding energy consumption was observed.2)During the repair process,Cr(Ⅵ)would be enriched near the anode,especially when the voltage gradient was low(1 V/cm).The Cr(Ⅵ)concentration in groundwater near the anode after the reaction was up to 2170.95 mg/L,and the concentration of Cr(Ⅵ)in the medium was 1497.45 mg/kg,with negative removal rate.The concentration of Cr(Ⅵ)in the anolyte showed a tendency to increase first and then stabilize.When the Cr(Ⅵ)concentration was close to 4000 mg/L,it was close to the maximum migration value of the device.Increasing the reaction time had little effect on the recovery rate of Cr(Ⅵ).3)The decrease of E_(h) and the increase of pH during the repair process would promote the reduction and desorption of Cr(Ⅵ),which could promote the removal of Cr(Ⅵ).
作者
程政乔
姜杰
杨浈
CHENG Zhengqiao;JIANG Jie;YANG Zhen(College of Environmental Science and Engineering,Beijing Forestry University;College of Urban and Environmental Science,Peking University)
出处
《环境工程技术学报》
CSCD
北大核心
2022年第3期816-823,共8页
Journal of Environmental Engineering Technology
基金
北京高校高精尖学科“生态修复工程学”(GJJXK210102)
国家自然科学基金项目(21677012)。
关键词
电动修复
六价铬
地下水污染
重金属
electrodynamic remediation
hexavalent chromium
groundwater pollution
heavy metal
