Conceptual design and experiments of electrochemistry-flushing technology for the remediation of historically Cr(Ⅵ)-contaminated soil. (February 2016)

• Record Type: Journal Article
• Authors: Li, Dong; Sun, Delin; Hu, Siyang; Hu, Jing; Yuan, Xingzhong
• Is Part Of: Chemosphere. Volume 144(2016)
• Page Start: 1823
• Page End: 1830
• Publication Date: 2016-02
• Subjects: Contaminated soil -- Flushing -- Electrokinetic remediation -- Electrochemistry flushing -- Chromium; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2015.09.077
• Languages: English
• ISSNs: 0045-6535

Abstract

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. Graphical abstract: Schematic of setup for E-flushing experiments. Highlights: Cathode product H2 and vapor provide driving force for flushing. Cathode product OH − ions enhance the desorption of Cr(VI). Joule heat enhances the desorption of Cr(VI). High potential gradient enhances eletromigration and desorption. Cr(VI) was reduced by the anode product Fe 2+ .