title: Enhanced hydroxyl radical generation in the combined ozonation and electrolysis process using carbon nanotubes containing gas diffusion cathode.
abstract: Combination of ozone together with electrolysis (ozone-electrolysis) is a promising wastewater treatment technology. This work investigated the potential use of carbon nanotube (CNT)-based gas diffusion cathode (GDC) for ozone-electrolysis process employing hydroxyl radicals (·OH) production as an indicator. Compared with conventional active carbon (AC)-polytetrafluoroethylene (PTFE) and carbon black (CB)-PTFE cathodes, the production of ·OH in the coupled process was improved using CNTs-PTFE GDC. Appropriate addition of acetylene black (AB) and pore-forming agent Na2SO4 could enhance the efficiency of CNTs-PTFE GDC. The optimum GDC composition was obtained by response surface methodology (RSM) analysis and was determined as CNTs 31.2 wt%, PTFE 60.6 wt%, AB 3.5 wt%, and Na2SO4 4.7 wt%. Moreover, the optimized CNT-based GDC exhibited much more effective than traditional Ti and graphite cathodes in Acid Orange 7 (AO7) mineralization and possessed the desirable stability without performance decay after ten times reaction. The comparison tests revealed that peroxone reaction was the main pathway of ·OH production in the present system, and cathodic reduction of ozone could significantly promote ·OH generation. These results suggested that application of CNT-based GDC offers considerable advantages in ozone-electrolysis of organic wastewater.
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Donghai
authors.initials: D
authors.lastname: Wu
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China. ghlu@hhu.edu.cn.
authors.forename: Guanghua
authors.initials: G
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, P.O. Box 2606, 202 Haihe Road, Harbin, 150090, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Qiuhong
authors.initials: Q
authors.lastname: Lin
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Yan
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Jianchao
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
mesh_terms: D004058:Diffusion; D004566:Electrodes; D004572:Electrolysis / Q000295:instrumentation / Q000379:methods*; D017665:Hydroxyl Radical / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D017665:Hydroxyl Radical; D037742:Nanotubes, Carbon; D010126:Ozone; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Carbon nanotubes; Gas diffusion cathode; Hydroxyl radicals; Ozone-electrolysis; Response surface methodology