摘要
A soil remediation method combining in situ reduction of Cr（VI） with approaching anodes electroki- netic （AAs-EK） remediation is proposed. EK experiments were conducted to compare the effect of approaching anodes （AAs） and fixed electrodes （FEs） with and without sodium bisulfite （NaHSO3） as a reducing agent. When NaHSO3 was added to the soil before EK treatment, 90.3% of the Cr（VI） was reduced to Cr（III）. EK experiments showed that the adverse effect of contrasting migration of Cr（III） and Cr（VI） species, which limits the practical application of this technique, was eliminated in the presence of the reducing agent. Furthermore, Tessier fractionation analysis indicated that the reducing agent changed the distribution of the chemical forms of Cr. The AAs-EK method was shown to acidize the soil as the anode moved toward the cathode and this acid front pushed the ＂focusing＂ region toward the cathode. After remedia- tion, the pH of the soil was between 1.8 and 5.0 in AAs-EK experiments. The total Cr removal efficiency was 64.4% （except in the ＂focusing＂ region） when the reduction reaction was combined with AAs-EK method. We conclude that AAs-EK remediation in the presence of NaHSO3 is an appropriate method for Cr-contaminated soil.
A soil remediation method combining in situ reduction of Cr（VI） with approaching anodes electroki- netic （AAs-EK） remediation is proposed. EK experiments were conducted to compare the effect of approaching anodes （AAs） and fixed electrodes （FEs） with and without sodium bisulfite （NaHSO3） as a reducing agent. When NaHSO3 was added to the soil before EK treatment, 90.3% of the Cr（VI） was reduced to Cr（III）. EK experiments showed that the adverse effect of contrasting migration of Cr（III） and Cr（VI） species, which limits the practical application of this technique, was eliminated in the presence of the reducing agent. Furthermore, Tessier fractionation analysis indicated that the reducing agent changed the distribution of the chemical forms of Cr. The AAs-EK method was shown to acidize the soil as the anode moved toward the cathode and this acid front pushed the ＂focusing＂ region toward the cathode. After remedia- tion, the pH of the soil was between 1.8 and 5.0 in AAs-EK experiments. The total Cr removal efficiency was 64.4% （except in the ＂focusing＂ region） when the reduction reaction was combined with AAs-EK method. We conclude that AAs-EK remediation in the presence of NaHSO3 is an appropriate method for Cr-contaminated soil.
