Research On Novel Optical Fibers For Enhancing Photobiocatalytic Degradation Of Toxic Organic Wastewater And Resource Conversion

Currently,environmental pollution and energy shortages are two major issues restricting the development of today's society.The degradation of toxic organic pollutants and the production of renewable energy have become one of the hot topics of common concern in the fields of environment and energy research.Actively developing toxic pollution purification technology that is environmentally friendly and in line with economic development,and at the same time realizes the transformation of resources in the treatment of toxic pollutants,has become an important strategic requirement related to China's sustainable development and the realization of a"Beautiful China".Intimate Coupling of Photocatalysis and Biodegradation?ICPB?is the direct coupling of photocatalytic technology and biofilm degradation technology in the same reactor.The photocatalytic reaction rapidly degrades the high-concentration wastewater to a low concentration,and the biofilm uses the secondary products of photocatalytic degradation for growth and metabolism.In addition,biofilm growth and metabolism consume low toxic organic carbon source and release metabolite O₂,photocatalytic reaction degrades high toxic organic matter and consume O₂,the two are coupled in the same reactor,can promote each other,achieve the rapid and complete mineralization of toxic organic pollutants.Therefore,ICPB technology overcomes the shortcomings of incomplete photocatalytic degradation alone and long degradation time of biofilm alone,and greatly improves the degradation efficiency of toxic organic wastewater.It is widely recognized as the most cutting-edge and potential toxic pollution treatment technology in the world.However,this technology also has the disadvantages of low photocatalyst activity,serious attenuation of light by the carrier,resulting in low degradation efficiency of toxic organic wastewater;limited biofilms,difficult biomass collection,and difficulty in achieving resource conversion in wastewater treatment.In order to improve ICPB technology and further improve the degradation efficiency and resource conversion ability of the reactor to toxic organic wastewater,the following three research works were mainly carried out in this paper:?1?In order to improve the photocatalytic activity and light energy utilization and conversion efficiency,a new visible light-responsive photocatalytic hollow fiber was developed.First,an up-conversion luminescent agent(Er³⁺:YAlO₃)was prepared by the sol-gel method,and then TiO₂,Er³⁺:YAlO₃,SiO₂ was configured as a photocatalytic sol by using ethanol as a dispersion liquid,and the sol was coated on hollow quartz by a pulling method.On the surface of the optical fiber,a visible light-responsive photocatalytic fiber based on Er³⁺:YAlO₃/SiO₂/TiO₂?EYST?material was developed;secondly,an experimental system for photocatalytic optical fiber degradation of phenol wastewater was established to optimize parameters such as temperature,concentration,and pH of the waste liquid,and investigate the performance of photocatalytic fiber degradation of phenolic wastewater.Experimental research shows that:4-CP wastewater has a concentration of 100mg/L,a flow rate of 10ml/min,a temperature of 55?,and a pH of 6,and the degradation rate of EYST photocatalytic fiber reaches 69.82%within 10hours.The carbon degradation rate is 42.57%and the dechlorination rate is 65.21%?2?Based on the research of EYST coated photocatalytic fiber,in order to further improve the performance of photocatalytic reactor in degrading phenol-containing wastewater,N/Ag/SiO₂/TiO₂?NAST?ultraviolet-visible light catalytic material was developed and coated on the surface of hollow fiber,NAST coated photocatalytic hollow fiber was obtained.A new photocatalytic-biodegradable direct coupling?ICPB?reactor was designed,and a NAST-coated photocatalytic optical fiber degradation system for phenol wastewater was established.The degradation performance of NAST-coated photocatalytic fibers in toxic organic wastewater containing phenol in the ICPB reactor was investigated.Experimental research shows that the thickness of the catalytic material on the surface of the NAST-coated photocatalytic optical fiber is 20?m,the volume of the waste liquid in the ICPB reactor is 100ml,the temperature is 35?,and the pH is 7;the degradation rate of phenol wastewater?200mg/L?by NAST coated photocatalytic fiber was 99.15%within 14 hours,the TOC degradation rate reaches 81.11%;the degradation rate of 4-CP wastewater?50mg/L?reaches 96.04%within 10 hours,the TOC degradation rate reaches 68.02%,and the dechlorination rate It is 68.22%.?3?In order to achieve efficient degradation of phenol-containing wastewater and resource conversion?microalgal biomass production?,an ICPB reactor based on NAST-coated photocatalytic fiber and Scenedesmus obliquus was constructed.The degradation performance of toxic organic wastewater by biofilm?B?,photocatalysis?P?and photocatalytic-biofilm direct coupling?ICPB?systems were compared and studied.Experimental research shows that:ICPB system is significantly better than the B system and the P system in the degradation of wastewater.When the ICPB system and the P system have the same experimental conditions,the time required for the IPCB system to completely degrade 200 mg/L of phenol wastewater is 8 hours less than the P system.The degradation rate of total organic carbon in the liquid phase is 1.31 times that of the P system.The time required to completely degrade 50 mg/L 4-CP wastewater is 6 hours less than that of the P system.The degradation rate of total organic carbon in the liquid phase is P system.1.39 times,the dechlorination rate is 1.30 times that of P system.After the ICPB reaction system was operated for 20 days,the performance of degradation of4-CP remained unchanged;the dry weight of the microalgae biofilm and the biofilm oil content in the ICPB reactor reached 197mg and 24.81%.respectively,the dry weight and oil content were improved compared with the biofilm cultured in normal nutrient solution.