Preparation Of BiPO₄-based Photocatalysts And Their Photocatalytic Degradation Performance

In China,the water pollution is very serious.And the majority of water pollution is caused by organic pollutants.In many cases,organic contaminants have low concentrations in water and are often difficult to remove.Photocatalytic degradation,which can completely mineralize pollutants with no secondary pollution and no selectivity to pollutants,has great potential in the application of environmental remediation.However,the current photocatalyst still has a series of problems such as poor activity,high photogenerated carriers recombination efficiency and poor stability.Nowadays,photocatalysis research focuses on developing high active photocatalysts and improving the efficiency of photocatalytic conversion processes.In this work,BiPO₄ was modified by semiconductor coupling and three-dimensional network hydrogel structure construction to enhance the photocatalytic activity.The degradation of phenol and methylene blue（MB）under UV light（254 nm）was investigated.BiPO₄/CoAl-LDH composite was prepared by chemical adsorption method.The optimal catalyst was explored from the aspects of coupling ratio,preparation method and preparation temperature.The obtained 1%BiPO₄/CoAl-LDH composite has the highest phenol degradation rate constant under UV light irradation,which is 2.77 times that of pure BiPO₄.The excellent hole-transporting ability of CoAl-LDH can effectively improve the photogenerated electron-hole separation efficiency of the composite catalyst,thereby the photocatalytic activity is improved.BiPO₄-SiO₂ hybrid hydrogels were constructed by coupling with SiO₂ three-dimensional hydrogel.The BiPO₄-SiO₂ hybrid hydrogels can efficiently adsorb the pollutants and show higher photogenerated carriers migration rate due to the three-dimensional network structure.The 90% BiPO₄-SiO₂ hybrid hydrogels can rapidly degrade methylene blue by the synergies of adsorption enrichment and photocatalytic degradation and its degradation rate constant is 3.46 times that of BiPO₄.They also have the advantage of easy separation from water system and good stability,which have broad application prospects in the water treatment.