title: Conceptual design and experiments of electrochemistry-flushing technology for the remediation of historically Cr(Ⅵ)-contaminated soil.
abstract: A conceptual design and experiments, electrochemistry-flushing (E-flushing), using electrochemistry to enhance flushing efficiency for the remediation of Cr(Ⅵ)-contaminated soil is presented. The rector contained three compartments vertically superposed. The upper was airtight cathode compartment containing an iron-cathode. The middle was soil layer. The bottom was anode compartment containing an iron-anode and connected to a container by circulation pumps. H2 and OH(-) ions were produced at cathode. H2 increased the gas pressure in cathode compartment and drove flushing solution into soil layer forming flushing process. OH(-) ions entered into soil layer by eletromigration and hydraulic flow to enhance the desorption of Cr(Ⅵ). High potential gradient was applied to accelerate the electromigration of desorbed Cr(Ⅵ) ions and produced joule heat to increase soil temperature to enhance Cr(Ⅵ) desorption. In anode compartment, Fe(2+) ions produced at iron-anode reduced the desorbed Cr(Ⅵ) into Cr(3+) ions, which reacted with OH(-) ions forming Cr(OH)3. Experimental results show that Cr(Ⅵ) removal efficiency of E-flushing experiments was more than double of flushing experiments and reached the maximum of removal efficiency determined by desorption kinetics. All electrochemistry processes were positively used in E-flushing technology.
authors.affiliation: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, PR China; Key Laboratory of Southwest Resources Exploitation and Environmental Hazards Controlling Engineering of Education Ministry, Chongqing University, Chongqing 400030, PR China; School of Resources and Environmental Science, Chongqing University, Chongqing 400044, PR China. Electronic address: lidongbayan@cqu.edu.cn.
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.affiliation: School of Resources and Environmental Science, Chongqing University, Chongqing 400044, PR China.
authors.forename: Delin
authors.initials: D
authors.lastname: Sun
authors.affiliation: School of Resources and Environmental Science, Chongqing University, Chongqing 400044, PR China.
authors.forename: Siyang
authors.initials: S
authors.lastname: Hu
authors.affiliation: School of Resources and Environmental Science, Chongqing University, Chongqing 400044, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, PR China; Key Laboratory of Southwest Resources Exploitation and Environmental Hazards Controlling Engineering of Education Ministry, Chongqing University, Chongqing 400030, PR China; School of Resources and Environmental Science, Chongqing University, Chongqing 400044, PR China.
authors.forename: Xingzhong
authors.initials: X
authors.lastname: Yuan
mesh_terms: D000327:Adsorption; D002857:Chromium / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D052918:Environmental Restoration and Remediation / Q000379:methods*; D006859:Hydrogen / Q000737:chemistry; D006878:Hydroxides / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D007700:Kinetics; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D012989:Soil Pollutants; D002857:Chromium; C074702:chromium hexavalent ion; D006859:Hydrogen; C031356:hydroxide ion; D007501:Iron
keywords: Chromium; Contaminated soil; Electrochemistry flushing; Electrokinetic remediation; Flushing