title: A mechanistic study of arsenate removal from artificially contaminated clay soils by electrokinetic remediation.
abstract: Batch desorption experiments and bench-scale electrokinetic experiments were performed to elucidate the electrokinetic remediation mechanisms of arsenate from artificially contaminated kaolinite. The electrokinetic experiments in which a constant voltage was applied demonstrated that high soil pH favored arsenate remediation with respect to both the remediation time and electricity consumption. It was also demonstrated that applying a pulse voltage (1 h ON, 1 h OFF) significantly improved the electricity consumption efficiency when the soil pH was maintained at the initial value during the experiments; this trend was not observed when the soil pH was gradually increased from the cathode side. These electrokinetic experimental results, with the support of arsenate desorption data obtained from batch experiments, indicate that the remediation rate-limiting step varied with soil pH. When the soil pH was maintained at the initial value of 7.2 during the experiments, arsenate desorption was the remediation rate-limiting step rather than the migration of dissolved arsenate toward the anode. Conversely, when the cathode pH was not controlled and the soil pH was correspondingly increased gradually from the cathode side, the migration of hydroxyl and desorbed arsenate ions toward the anode played a more important role in the control of the overall remediation efficiency.
authors: Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi, 755-8611, Japan. Electronic address: tsuzuki@yamaguchi-u.ac.jp.
authors: Tasuma
authors: T
authors: Suzuki
authors: Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi, 755-8611, Japan. Electronic address: r063vn@yamaguchi-u.ac.jp.
authors: Mai
authors: M
authors: Moribe
authors: Department of Sustainable Environmental Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi, 755-8611, Japan. Electronic address: n007fj@yamaguchi-u.ac.jp.
authors: Yohhei
authors: Y
authors: Okabe
authors: Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi, 755-8611, Japan. Electronic address: niinae@yamaguchi-u.ac.jp.
authors: Masakazu
authors: M
authors: Niinae
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D001149:Arsenates / Q000737:chemistry*; D000077215:Clay; D004563:Electrochemistry; D004566:Electrodes; D052918:Environmental Restoration and Remediation; D006863:Hydrogen-Ion Concentration; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D001149:Arsenates; D012989:Soil Pollutants; C025657:arsenic acid; D000077215:Clay