Preparation Of Bismuth-based Composite Photocatalysts And Their Degradation Of Bisphenol Endocrine Disrupting Chemicals

Endocrine Disrupting Chemicals（EDCs）are widely used in the production of detergents,plasticizers,flame retardants,etc.EDCs are very harmful to organisms and can cause toxic effects such as neurological,immunological and reproductive effects.Therefore,it is significative to develop green and efficient treatment methods to reduce their concentration in the environment.Photocatalysis is a green photochemical technology without secondary pollution.Bismuth-based photocatalysts have received attention from researchers for their adjustable band gap energy and excellent visible light absorption performance,however,they have problems such as easy recombination of electron-hole pairs and weak photogenerated electron reduction ability,and these shortcomings limit the widespread use of bismuth-based photocatalysts.In this paper,two catalysts,Bi₂WO₆/BiOI-x and x wt.%Pt/BiOBr,were prepared by using the deposition of constructed heterojunction and metal nanoparticles to inhibit the recombination of electron holes of the catalysts.Both of these catalysts could improve the visible light absorption ability of the corresponding monomer bismuth system catalysts and significantly improve the photocatalytic activity.The structure,morphology and optical properties of the composite materials were studied through characterization.Then the photocatalytic degradation experiment was carried out with bisphenol EDCs as the target degradation substance,and the photocatalytic experiment under visible light was carried out to explore the degradation mechanism of pollutants.Details were as follows:（1）Bi₂WO₆/BiOI-x series photocatalysts were prepared by co-precipitation method.The results showed that Bi₂WO₆/BiOI-2 was the composite with the best composite ratio,which had more active sites and improved absorption of visible light compared with that before the composite.Its complexation of electrons and holes was suppressed,with better photocatalytic performance.In addition,the photocatalytic experiments were carried out for Bi₂WO₆/BiOI-x photocatalysts with different composite ratios,different initial concentrations,different catalyst dosing amounts and different p H conditions of solution.Selecting the Bi₂WO₆/BiOI-2 photocatalyst to conduct experiments,it was found that the degradation rate of BPA was 93.06%after the 3 hours when the initial concentration of bisphenol A（BPA）was 10 mg·L^-1,p H was 7 and the dosage was 0.1 g/100 m L.The stability of Bi₂WO₆/BiOI-2 was investigated by degradation experiments for 10 mg·L^-1BPA solution（five cycles）.The degradation rate decreased from 93.06%to 80.33%,and the results showed the stability of the composite was good.By the free radical capture experiments,it was found that the degradation of BPA by Bi₂WO₆/BiOI-2 photocatalyst was mainly dominated by·OH and·O₂^—.N-type catalyst Bi₂WO₆and P-type catalyst BiOI formed n-p heterojunction structure,which improved the absorption ability of visible light,inhibited the recombination efficiency of photogenerated carriers,and enhanced the photocatalytic activity.（2）BiOBr was prepared by the solvothermal method,then x wt.%Pt/BiOBr series photocatalysts were prepared by the photoreduction method based on BiOBr.The results showed that 0.3 wt.%Pt/BiOBr was the composite with the best Pt loading.Compared with pure BiOBr,Pt/BiOBr had lower forbidden band width and improved photogenerated electron transfer photocatalytic performance.After that,the photocatalytic experiments were carried out for x wt.%Pt/BiOBr photocatalysts with different Pt loadings,different initial concentrations,different p H conditions of solution and different catalyst dosing amounts.Selecting the 0.3 wt.%Pt/BiOBr photocatalyst to conduct experiments,it was found that when the initial concentration of BPA and bisphenol S（BPS）was 10 mg·L^-1,p H was7,the dosage was 0.1 g/100 m L,the degradation rates of BPA and BPS were 96.45%and98.23%after the 3 hours,respectively.After 5 cycles,the degradation rates of both BPA and BPS were still maintained above 86%,so its stability was good.By the radical capture experiments,it was found that the degradation of BPA and BPS was mainly dominated by hole（h⁺）and·O₂^—.Figure[43]table[6]reference[129]...