Study On The Photocatalytic Degradation Of Acetaminophen By TiO₂ Composite

Acetaminophen?Ace?not only belongs to the typical representative pharmaceutical and personal care products?PPCPs?,but also one of the most used analgesic drugs.With the continuous increase in the production and consumption of PPCPs in recent years,a large number of wastewater containing Ace has entered into the natural water environment.However,the traditional water treatment technology can not completely remove it from the wastewater,so it poses a great threat to life or health safety of organism.As an energy-saving,efficient and high processing speed technology,photocatalytic degradation has been paid more and more attention.Titanium dioxide?TiO₂?is widely used in sewage treatment,building coatings and air purification,because of its environmentally friendly,non-toxic,effective catalytic efficiency and stable chemical properties.This paper took TiO₂ as the research object and discussed the combination of different semiconductors to investigate their structure,crystal morphology,surface morphology change and its photocatalytic degradation efficient on Ace after modification.In this study,the impact factors of photocatalytic activity of TiO₂ composite were discussed,and the best loading ratio and photocatalytic operation conditions were further determined.The possible mechanism and path of photocatalytic degradation were speculated.The main works of this thesis can be listed as follows:?1?WO₃/TiO₂/SiO₂ was prepared by sol-gel method and the impregnation method.FTIR,XRD,UV-VIS and SEM were used to characterize the composites and evaluate their performance.The results showed that the composites mainly exist in anatase phase,since the existence of Si atoms effectively inhibits the transformation of Ti from anatase to rutile phase.At the same time,the combination of SiO₂ and WO₃ into the composite system expands the spectral response range of the photocatalysts to the visible light region.Thus,the absorption spectrum was reduced to the lower energy band region and the photocatalytic performance of the photocatalyst was improved correspondingly.?2?This study also prepared the composites with different WO₃ load ratios?1,3,5,7 wt%?.It was founded that the 3 wt%WO₃/TiO₂/SiO₂ has a good crystallinity,large specific surface area and no obvious agglomeration was observed.Moreover,it also has the highest photocatalytic removal rate of Ace under the same catalytic conditions.We also found that when the initial concentration of Ace was 5 mg/L,pH=9 and 1.5 g/L of catalyst,the obtained composite could achieve 95%photocatalytic degradation rate of Ace after 4 h reaction.?3?The photocatalytic degradation process of WO₃/TiO₂/SiO₂ photocatalyst was in accordance with the first-order reaction kinetics equation.And 3 wt%WO₃/TiO₂/SiO₂ had the highest rate constant among all the photocatalysts.Quinone imide was the first detected intermediate product during the photocatalytic degradation process,but it was easily hydrolyzed into quinone.Those intermediate products were eventually oxidized into CO₂,H2O or other compounds.?4?In order to avoid the limits of complicated operation,tedious preparation process of traditional sol-gel method,solid phase sintering method were employed to prepare BaTiO₃/TiO₂ photocatalyst in this study.The characterization results of XRD,FTIR,UV-VIS and SEM showed that the combination of these two compounds expands the spectral response range of catalysts.And the absorption band edge moved to the long wave direction,which has successfully expanded its absorption to visible light range.Compared with the original TiO₂,the ability of photocatalytic degradation of Ace by composite catalyst has been obviously enhanced.