Performance Of LDH-Based Photocatalytic Reactor For Water Pollutants Removal And Its CFD-Assisted Simulated Optimization

For overcoming the limitation of conventional wastewater treatment that is difficult to achieve the complete removal of emerging pollutants in water,this study used layered double hydroxides（LDH）as base materials,and synthesized several novel LDH-based composite photocatalysts by coupling with doping-modified ZnO for treating a typical endocrine disruptor bisphenol A（BPA）.The approach integrating computational fluid dynamics（CFD）with statistical analysis was applied for the simulation and optimization of reactor,which aims to construct high-performance photocatalytic reaction system.The obtained results would provide certain references for promoting the development of advanced wastewater treatment.The main contents and conclusions of this study are presented as follows:（ⅰ）To study the synthesis,characterization and photocatalytic performance of a ternary Ag/ZnO/Zn Al-LDH composite photocatalyst,the structure-activity effect resulting from different synthesis parameters on the?OH formation of composite was investigated,and the BPA degradation performance of Ag/ZnO/Zn Al-LDH was compared with unary and binary materials.Based on the comprehensive characterization and the?OH formation trend of Ag/ZnO/Zn Al-LDH,the enhanced mechanism of photocatalytic performance was proposed.The obtained results indicate that the Ag/ZnO/Zn Al-LDH synthesized with the optimum parameters showed a better performance,which can degrade 80%of BPA after 6 h under visible light.The reaction rate constant of Ag/ZnO/Zn Al-LDH,0.24 h^-1,was about 4.8-,2.2-and 12.0-fold higher than that of ZnO,Ag/ZnO and Zn Al-LDH,respectively.The enhanced photocatalytic performance was mainly attributed to the significant improvement of optoelectronic properties,thus promoting?OH formation and increasing BPA degradation.（ⅱ）To study the synthesis,characterization and photocatalytic performance of a magnetically separable Cu/ZnO/Co Fe-CLDH composite photocatalyst as well as the process mechanism of BPA degradation,the properties characterization and degradation performance of Cu/ZnO/Co Fe-CLDH were comprehensively investigated and compared.Moreover,the formation trend of reactive oxygen species was analyzed,and the intermediate products during BPA degradation were identified.The obtained results indicate that Cu/ZnO/Co Fe-CLDH exhibited excellent physicochemical,optoelectronic and magnetic properties,and could achieve a synergistic process of visible-light photocatalysis and persulfate activation for complete BPA removal with a reaction rate constant of 0.74 h^-1.Quite apart from?OH,the formed SO₄·^-,·O₂^-,and ¹O₂ also contributed to BPA degradation.The possible pathways of BPA degradation were proposed according to the identification of intermediates,the ecotoxicity effect of reflected a decreasing trend.（ⅲ）To simulate the flow pattern change and BPA treatment in the photocatalytic reactor for enabling the structure design to be optimized,the influences of different influent flowrate and BPA mass fraction on the treatment efficiency were studied.Moreover,response surface methodology was further used for analyzing the optimum height,width and inlet diameter of reactor.The obtained results demonstrate that excessive influent flowrate led to the phenomena of generating local vortex near the wall region and increasing bottom pressure,resulting in a reduced treatment efficiency.The reactor with optimized structure showed a better flow field feature,which is capable of ensuring a higher treatment efficiency.