Study On Photoelectrocatalytic Degradation Of Organic Pollutants In Water By Magnetic Nanomaterial

In recent decades,with the rapid development of industry and agriculture,water pollution and governance have become a global issue.Some wastewater containing emerging pollutants such as antibiotics,dyes,chlorinated organic pollutants,endocrine disruptors,and phenols has caused serious environmental problems due to their irregular discharge into environmental media.According to statistics,over 25%of the global population suffers from water related health problems.How to effectively remove high residual and refractory organic pollutants,especially dyes and antibiotics,from wastewater is an urgent issue in the field of water environmental remediation.These emerging pollutants have the characteristics of low persistence and biodegradability,and are difficult to effectively remove through traditional physical or biological methods,posing a serious threat to human health and ecosystems.In this thesis,an efficient visible light photocatalysis system was constructed,using magnetic nanomaterials as photocatalysts to study the performance and mechanism of their degradation of typical refractory organic pollutants in water.The main research contents are as follows:（1）Sol gel method and hydrothermal method were used to prepare Fe₃O₄@Si O₂@Mesoporous Ti O₂（FST）composite photocatalyst.TEM EDX,FTIR,XRD,and XPS analysis confirmed the successful synthesis of nano photocatalysts.In order to maximize the potential of new composite photocatalysts,this study used methylene blue（MB）as a model pollutant to construct a FST photocatalyst/H₂O₂ synergistic degradation system.By fine-tuning the relevant factors involved in the degradation process,the optimal degradation performance of the new composite photocatalyst was achieved.Finally,the degradation of other refractory organic pollutants under visible light sources was studied using the newly developed FST photocatalysis/H₂O₂ synergistic degradation system.The removal rate of Rhodamine B solution under visible light for 2 min has reached 86.3%,and the removal rate after 6 minutes can reach 96.6%.This method is still efficient when removing methyl orange,and the removal rate of methyl orange is 97.7%within 7 min.The degradation rate of amoxicillin by FST photocatalysis/H₂O₂ synergistic system was 83.9%,and the COD removal rate was 60.1%.（2）Successfully prepared Fe₃O₄@viod@Mesoporous Ti O₂（FT）photocatalyst,SEM,TEM EDX,FTIR,XRD,and XPS analysis confirmed the successful synthesis of the nano catalyst,with a unique interlayer hollow structure.In order to maximize the potential of new composite photocatalysts,a Fenton like composite photocatalyst system was constructed and its application to the degradation of amoxicillin（AMX）was studied using a response surface model.Single factor analysis showed that operating parameters such as p H value,applied voltage,and initial concentration of H₂O₂ had significant effects on the degradation rate of AMX.The optimal operating conditions are p H=6.43,potential=0.41V,and H₂O₂content=1.96%.Under these conditions,the degradation rate of AMX can reach 98.70%(10mg·L^-1).The degradation rate of AMX in wastewater from a farm in Jinan,Shandong Province was 81.67%.·OH was determined as the main oxidant,and a reliable mechanism and reasonable degradation pathway were proposed.Fenton composite photocatalysis system has good feasibility in breaking the structure of antibiotics and reducing the pollution of antibiotic wastewater.Therefore,it can be used as an effective pretreatment of AMX wastewater.（3）The composite was synthesized on conductive glass by co precipitation method and hydrothermal method Fe₃O₄@Cd In₂S₄ as a photoelectric anode,Cu O@Cu₂O The electrode is used as a photocathode to construct Fe₃O₄@Cd In₂S₄/Cu O@Cu₂O/PMS photocatalytic/Fenton like synergistic degradation system.Using different characterization methods Fe₃O₄@Cd In₂S₄The morphology,structure,optical properties,and electrical properties of the photoelectric anode were investigated Fe₃O₄@Cd In₂S₄ The optimal ratio of photoelectric anode Fe₃O₄ to Cd In₂S₄.The synergistic system has high catalytic activity and stability,and has excellent degradation effects on amoxicillin trihydrate（AMX,98.78%）,tetracycline hydrochloride（TC,91.43%）,ofloxacin（OFX,82.69%）,and bisphenol A（BPA,94.81%）within 30 minutes.The removal efficiency of TOC was 79.91%（AMX）,70.84%（TC）,69.56%（OFX）,and 76.56%（BPA）,respectively.In addition,the main active species capture experiments show that·OH and SO₄^·-play a key role in the reaction system.The possible degradation pathways of AMX and the degradation mechanism of the synergistic system were proposed.This work provides new insights into the synergistic effects of Fenton like processes and photocatalysis that have broad prospects in environmental remediation.