Study On The Removal Of BPA From Water By Bioluminescence Of Biodegradation Of BPA And Bi ₃ 3 / BiFeO 3 Photocatalyst

As a representative environmental endocrine disruptors, bisphenol A (BPA) has been widely applied in industry as plastic additives. It is easy to get into water directly or indirectly, which may damage to the ecological environment and poses a threat to human health. How to remove BPA simply and effectively has become a hot and difficult issue in environmental governance.In this paper, fast photolysis of BPA was conducted under alkaline conditions by using alkali as additives. Photodegradation of10mg/L BPA in alkaline aqueous solutions(0.1mol/L NaOH) were investigated under an UV disinfection lamp (k=254nm,20W). After120min illumination, the removal ratio of BPA was up to100%. Various alkaline such as NaOH, KOH, Ca (OH)2, can be used as the source of the alkali. With increasing the alkali content, BPA photolysis removal ratio increased. While the increasing the initial concentration of BPA, photolysis removal ratio reduced. Moderate concentration of SO42-(5mmol/L) may promote the photolysis of BPA in alkaline conditions.However the existence of Cl-has a little influence on BPA photolysis in alkaline condition.Photodegradation of10mg/L BPA in alkaline aqueous solutions(0.1mol/L NaOH) were investigated under simulated sunlight (λ≥420nm,500W Xe lamp). Aafter180min of illumination, the removal ratios of BPA reached83.4%.BiFeO3as a typical bismuth-containting photocatalysts, has been studied widely in the photocatalytic field due to its narrow band gap and good photoresponse to the visible light. But the catalytic ability of pure BiFeO3was not ideal. Many researchers tried to improve the its photocatalytic performance by doping or coupling BiFeO3with other semiconductors.In this thesis, Bi2O3/BiFeO3composite photocatalyst was prepared using Bi(NO3)3·5H2O and Fe(NO3)3·9H2O via sol-gel method. The composite photocatalysts characterized by XRD, SEM, TEM and UV-vis spectrophotometer. The prepared photocatalysts were applied for the photodegration of BPA under visible light (λ≥420nm,500W Xe lamp). Meanwhile, condition parameters of the photocatalysis experiment were optimized. The photocatalytic activity of Bi2O3/BiFeO3, Bi2O3, BiFeO3, and P25 were compared and the degradation kinetics equation of BPA was studied.Controlling the condition in the material preparation process as followes:molar ratio of Fe/Bi was1:3, the calcination temperature was500℃, the volume of acetic acid was5ml, the calcination time was2h, the photocatalytic activity of Bi2O3/BiFeO3composite photocatalyst was the highest. In the Bi2O3/BiFeO3composite photocatalyst, the mass fraction of Bi2O3was64.7%. mass fraction of BiFeO3was35.3%.Under the optimal degradation conditions:0.5g/L catalysts,10mg/LBPA, the pH value was6.3, under visible light illumination (λ≥420nm,500W Xe lamp), the removal ratio of BPA reached100%after300min of illumination.Comparing with P25, Bi2O3and BiFeO3, Bi2O3/BiFeO3composite photocatalyst prepared under the optimal conditions had the highest photocatalytic activity on BPA.The obtained degradation rate of BPA over Bi2O3/BiFeO3was about8.71times than that on P25,3.65times than that on Bi2O3,3.65times than that on BiFeO3. Photocatalytic degradation of BPA follwed pseudo first order reaction kinetics equation.