Enhanced anodic oxidation and energy saving for dye removal by integrating O2-reducing biocathode into electrocatalytic reactor. (August 2020)

• Record Type: Journal Article
• Authors: Mo, Yinghui; Du, Manman; Yuan, Tingting; Liu, Mengxin; Wang, Hong; He, Benqiao; Li, Jianxin; Zhao, Xin
• Is Part Of: Chemosphere. Volume 252(2020)
• Publication Date: 2020-08
• Subjects: Methylene blue (MB) -- Electrochemical oxidation -- Bioelectrochemical system -- Improved decolorization and mineralization -- Energy efficient; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.126460
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Simultaneous enhancement of dye removal and reduction of energy consumption is critical for electrochemical oxidation in treating dyeing wastewater. To address this issue, this work presented a novel process termed biocathode-electrocatalytic reactor (BECR). The dual-chamber BECR employed O2 -reducing biocathode instead of normal stainless steel (SS) cathode and MnOx /Ti anode to reduce O2 in the cathode chamber and treat methylene blue (MB) in the anode chamber, respectively. BECR successfully started up at 0.7 and 1 V and substantially improved MB and total organic carbon (TOC) removal compared with the electrocatalytic reactor with SS cathode (ECR-SS), e.g., removal of MB (150 mg L −1 ) increased from 27.0 ± 0.2% to 78.1 ± 0.4% at 1 V. To achieve the same TOC removal, BECR reduced the energy consumption by approximately 45.7% compared with ECR-SS (19.5 and 35.9 kWh (kg TOC) −1 for BECR and ECR, respectively). To explain the above merits of BECR, M(·OH) (·OH adsorbed on the anode surface) generation, potential of MnOx /Ti anode ( E a ), and their correlation were investigated. When coupled with O2 -reducing biocathode, MnOx /Ti anode considerably accelerated M(·OH) generation because E a increased. The increased E a in BECR was due to the fact that its cathodic reaction was converted to the four-electron O2 reduction, which exhibited a higher cathodic potential than hydrogen evolution reaction on SS cathode in ECR-SS. Thereby, BECR simultaneously promoted dye removal and reduced energy consumption, showing promise in treating dyeing wastewater. Graphical abstract: Image 1 Highlights: Biocathode-electrocatalytic reactor (BECR) started up under 0.7 and 1 V. BECR removed dye better than the reactor with stainless steel cathode (ECR-SS). Energy consumption of BECR was less than ECR-SS to achieve the same TOC removal. Coupling of biocathode facilitated the generation of M(·OH) from MnOx /Ti anode. High anodic potential of MnOx /Ti anode in BECR promoted the generation of ·OH.