Preparation Of G-C₃N₄ Based Photoanode And Photocatalytic Synergistic Fenton Degradation Of Antibiotic Wastewater

In recent years,due to the overuse of antibiotics,water pollution is becoming increasingly serious.The existence of antibiotics has been detected in the water environment all over the world,causing serious harm to human health.Based on this,it is urgent to develop an efficient,green,economic,non-toxic and easy to operate method for the treatment of antibiotic wastewater.There are many kinds of advanced oxidation treatment technology,but the single photocatalysis technology has some problems such as incomplete degradation of antibiotic wastewater.Therefore,in order to efficiently remove antibiotic pollutants from wastewater,the combination of photocatalysis and Fenton catalytic oxidation has attracted the attention of most scholars.Graphite phase carbon nitride has been widely used in the field of photocatalysis due to its advantages of low cost,simple preparation,chemical stability and non-toxicity.However,unmodified carbon nitride still faces some problems such as easy recombination of photogenic carriers and unsatisfactory absorption of visible light.Therefore,in this thesis,two different heterojunction composite photocatalytic materials Fe₂O₃/g-C₃N₄ and Ni Fe₂O₄/g-C₃N₄ were prepared from the perspective of improving the easy recombination of carbon nitride photocarriers.And deposited on the surface of graphite felt with porous structure,g-C₃N₄ cornerstone ink felt photoanode material with functional integration of adsorption enrichment,photocatalysis and Fenton-catalyzed oxidation as one,and two typical antibiotics tetracycline and norfloxacin were selected as target pollutants for efficient degradation.The main research contents and conclusions are as follows:（1）Fe₂O₃/g-C₃N₄composite photocatalyst was prepared by calcination and hydrothermal method,and then FCN composite was fixed on the surface of graphite felt by electrophoretic deposition to make FCN/GF composite photoanode material,which was characterized by a series of characterization methods.Taking tetracycline（TC）as the target pollutant,the effects of different factors on the degradation of TC in the adsorption photovoltaic self fenton synergistic system were investigated.The results showed that in the adsorption photovoltaic self fenton synergistic system,the6wt%FCN/GF composite photoelectric electrode material showed the best catalytic activity for the degradation of TC at p H=3 and applied bias voltage of 1.4V,reaching91%at 180min,and showed good stability.Its reaction kinetics constant was 2.5 times that of pure g-C₃N₄ photoelectrode,It is 7.16 times,2.37 times and 1.82 times of that of photocatalysis,photoelectrocatalysis and electro fenton,indicating that there is a good synergistic effect between the adsorption photoelectric self fenton system.This excellent catalytic activity is mainly attributed to:on the one hand,the good adsorption performance of graphite felt plays a key role in the degradation of TC by photoelectric self fenton;On the other hand,the introduction of Fe₂O₃ enhances the visible light response range of g-C₃N₄,inhibits the recombination of photogenerated electrons and holes,and further promotes the transfer of photogenerated electrons under the effect of an external electric field.At the same time,photogenerated electrons can promote the redox cycle between Fe³⁺/Fe²⁺in Fenton reaction.At the same time,the dissolved oxygen in the solution is converted into H₂O₂,forming the self cycle of H₂O₂ in the synergistic system,thus inducing·OH,to achieve the purpose of efficient degradation of TC.（2）Ni Fe₂O₄/g-C₃N₄ composite photocatalyst material was prepared by simple hydrothermal and impregnation method,and the NFO/CN was electrodeposited on the surface of graphite felt to prepare the NFO/CN/GF composite photoanode material.Through the characterization analysis of the composite materials and the exploration of the catalytic effect of different influencing factors on the degradation of norfloxacin（NOR）in the adsorption synergistic photoelectric self fenton system,the influence law between the structure and morphology of the catalytic materials and the synergistic degradation was analyzed.The results showed that the introduction of Ni Fe₂O₄improved the visible light absorption capacity of g-C₃N₄,accelerated the separation and migration rate of photogenerated carriers,reduced the resistance of photogenerated electron transport,and enhanced the catalytic activity of the adsorption photovoltaic self Fenton synergistic system.When the degradation efficiency of norfloxacin by 15%loading of NFO/CN/GF reaches 85%within 180 min,its degradation efficiency is superior to that of photocatalysis and photocatalysis.The test of free radical capture shows that adsorption photoelectric self fenton synergism produces·OH,O₂^-,h⁺and other active species,among which·OH plays a major role in the degradation of NOR,realizing the efficient utilization of H₂O₂ and improving the catalytic degradation activity of norfloxacin.