Degradation Of Chlorophenol On Photocatalysis,microbial Fuel Cell And Coupling System

With the increasing demands of human society for energy conservation and environmental protection,water treatment technology is developed more and more towards to the direction of low energy consumption,low cost and no secondary pollution.At present,as the new wastewater treatment technology,PC technology has high efficiency but not suitable for treating wastewater with complex components,MFC technology can simultaneously degradate and mineralizate the different pollutants through the domestication of functional microorganism accompanied by the producing electricity,but it costs a long processing time.Recently,the combined of various technologies have gradually become a research hotspot of the pollutant treatment.PC-MFC coupling technologies in-situ or indirectly utilizate catalyst to oxidate the organic matter under the irradiation and the microorganisms biodegradation,mineralize the complex components in wastewater,or promote photogenerated electrons-holes separation of catalytic material by generating electricity through the MFC system,which achieve the efficient degradation and resource utilization of target pollutants,and provide a new idea for the development of environment-friendly wastewater treatment technology.In this paper,PC,MFC and PC-MFC coupling systems were constructed by the design and preparation of high-performance materials and the inoculation and domestication of high-activity microorganism.O-chlorophenol（2-CP）,2,4-dichlorophenol（2,4-DCP）and 2,4,6-trichlorophenol（2,4,6-TCP）were taken as the target pollutants respectively,the performance and mechanism of the systems were systematically and deeply studied,the details were as follows:（1）Pt-TiO₂/H₃PW₁₂O₄₀ composite film was synthesized by sol-gel,hydrothermal and spin coating technology;The prepared catalysts were characterized by a variety of analysis and testing methods.It was found that the noble metal Pt was embedded in the TiO₂/H₃PW₁₂O₄₀ pores,surface plasmon resonance effect（SPR effect）was fully embodied to enhance the light absorption of the composite film.Schottky junction was formed between TiO₂ and Pt,which promoted the separation of photogenerated electrons and holes;After 240 min,single chlorophenol could be degradated completely,the removal rates of 2-CP+2,4-DCP complex chlorophenol system were100%（2-CP）and 83.1%（2,4-DCP）,respectively,and the degradation rates of2-CP+2,4-DCP+2,4,6-TCP complex chlorophenol system were 91.2%（2-CP）,75.3%（2,4-DCP）and 60.1%（2,4,6-TCP）,respectively.Quinone structure compounds were not detected in the degradation process,and the toxicity decreased significantly with the increasing degradation time.It can be found that Pt-TiO₂/H₃PW₁₂O₄₀ composite film had excellently non-selective photocatalytic degradation and toxic removal properties for single and composite chlorophenol systems.（2）The biofilm on the anode was inoculated with activated sludge collected from the South Suburban Sewage Treatment Plant（Changchun City,China）and domesticated in the nutrient solution containing chlorophenols,which was used to construct MFC system;The amount,morphology,and functional bacteria attached on the bio-electrodes were found by scanning electron microscopy（SEM）and 16s rRNA sequencing.Azospirillum and Acinetobacter were confirmed as the main functional bacteria in MFC-2-CP,and Acinetobacter and Geobacter were confirmed as the main functional bacteria in MFC-2,4-DCP and MFC-2,4,6-TCP.It was found that 2-CP,2,4-DCP and 2,4,6-TCP could be efficiently degraded and mineralized in current MFC,which were ordinally dechlorinated,hydroxylated and hydrogenated to generate cyclohexanol with less toxicity,and then open the ring to generate long chain hydrocarbon,and finally mineralize to generate CO₂ and H₂O.（3）In situ,MFC powered and indirect PC-MFC coupling systems were constructed by various methods.The indirect PC-MFC coupling system showed the outstanding performance on the degradation and mineralization of chlorophenols through the comparative study,the degradation rates of 2-CP,2,4-DCP and 2,4,6-TCP were 70%,74.9%and 74.5%,and the mineralization rates were 75.6%,83.2%and83.7%,respectively.Among the indirect PC-MFC coupling systems,PC+MFC coupling mode was more suitable to degrade chlorophenols with more chlorine substituents,and MFC+PC coupling mode was more suitable to degrade chlorophenols with less chlorine substituents.It can be seen that indirect PC-MFC coupling system had a preferable synergistic effect,which was more favorable to the efficient and rapid removal in the actual chlorophenols wastewater.