Cathodic Hydrogen as Electron Donor in Enhanced Reductive Dechlorination

• Published in: Chinese journal of chemical engineering Vol. 21; no. 12; pp. 1386 - 1390
• Main Author: 张瑞玲 路晓霞 Danny D. Reible 焦刚珍 秦松岩
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2013
• Subjects: capping; Contaminants; dechlorination; Degradation; Electric potential; electrode; Electrodes; hydrogen; Hydrogen evolution; reductive; Remediation; Sediments; Sulfates; 原位修复; 氢气; 污染沉积物; 污染物降解; 电子供体; 石墨电极; 还原脱氯; 阴极; electrode; dechlorination; capping; hydrogen; reductive
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/S1004-9541(13)60639-4

In situ capping is an attractive and cost-effective method for remediation of contaminated sediments, but few studies on enhancing contaminant degradation in sediment caps have been reported, especially for chlorinated benzenes. Electrically enhanced bioactive barrier is a new process for in situ remediation for reducible compounds in soil or sediments. The primary objective of this study is to determine if electrodes in sediment could create a redox gradient and provide electron acceptor/donor to stimulate degradation of chlorinated contaminant. The results demonstrate that graphite electrodes lead to sustainable evolution of hydrogen, displaying zero-order kinetics in the initial stages with different voltages. The constant rates of hydrogen evolution at 3, 4, and 5 V are 1.05, 2.54, and 4.3 nmol·L 1·d 1, respectively. Even higher voltage can produce more hydrogen, but it could not keep long time because the over potentials on electrode surfaces prevent its function. The study shows that 4 V is more appropriate for hydrogen evolution. The measured and evaluated concentration of 1,2,3,5-tetrachlorobenzene in pore water of sediment and concentration of sulfate show that dechlorination is inhibited at higher concentration of sulfate.