Study On Preparation Of P25 Composites And Their Photocatalytic Degradation Of DMSO

With the acceleration of urban modernization,the control and treatment of water pollution has always been one of the major problems that human society needs to solve.Advanced oxidation processes?AOPs?have been an attractive governance method,and engineering nanomaterials?ENM?have been increasingly studied as heterogeneous catalysts in AOPs.The semiconductor photocatalytic material represented by commercial TiO₂?P25?has been regarded as an ideal water pollution treatment material in recent years due to its own unique properties.However,its application range is limited due to it's extremely easy to recombine electron-hole pairs and its narrow light absorption range.In this dissertation,P25 is used as a substrate to prepare composite materials.While reducing the electron-hole pair recombination rate,the spectral response range of P25 was improved.The main research work of this paper is as follows:First,using urea and P25 as raw materials,P25/g-C₃N₄ composites were prepared by impregnation method and mixed calcination method.Photocatalytic activity of catalyst with100 mg/L dimethyl sulfoxide?DMSO?as target pollutant.The materials were characterized by TEM,XRD,FI-IR,UV-Vis DRS and PL.The results show that P25 is well supported on g-C₃N₄,the photo-response range of P25 is widened,and the photocatalytic performance is improved.The factors that affect the photocatalytic performance of the materials were also investigated.The photocatalyst PCN prepared by the impregnation method had the best photocatalytic performance when the amount of g-C₃N₄ was 50 mg,and the degradation rate of DMSO reached 65%after 2 hours of light exposure.The photocatalyst PGN prepared by the hybrid calcination method has the best photocatalytic performance when the raw material ratio is 8,the calcination temperature is 550°C,and the calcination time is 3 hours.The degradation rate of DMSO reaches 67%after 2 hours of light exposure.Second,using graphite,concentrated sulfuric acid,concentrated phosphoric acid and potassium permanganate?KMnO₄?as raw materials,graphene oxide?GO?was prepared by the mixed acid method.After thermal reduction step,reduced graphene oxide?RGO?was prepared.P25-RGO composite was prepared by a one-step hydrothermal method.The photocatalytic activity of the catalyst was measured with 100 mg/L dimethyl sulfoxide?DMSO?as the target pollutant,and the materials were characterized by TEM,XRD,FI-IR,UV-Vis DRS and PL.The results show that the composite material was successfuly prepared and widened the optical response range of P25.The factors influencing the photocatalytic performance of the material were investigated:when the amount of RGO was 25mg,the hydrothermal reaction temperature was 120°C,and the hydrothermal reaction time was 3h,the photocatalytic performance of the material was the largest.After 2 hours,the degradation rate of DMSO reached 73%.Finally,the photocatalytic mechanism of composite materials was explored.Third,on the basis of the prepared composite material P25-RGO,the metal ion Fe³⁺was loaded with a ferric nitrate solution.Composite materials were prepared using a hydrothermal reaction.The photocatalytic activity of the catalyst was measured using 100 mg/L dimethyl sulfoxide?DMSO?as the target pollutant,and the prepared materials were characterized by TEM,XRD and FI IR.The TEM image showed that a large amount of P25 was supported on the layered reduced graphene oxide.And at the same time,some dispersed Fe³⁺particles were deposited on each P25,which proved that the composite was successfully prepared.The factors influencing the photocatalytic performance of the material were also investigated:when the concentration of iron nitrate was 4mM,the hydrothermal reaction temperature was 120°C,and the hydrothermal reaction time was 3h,the photocatalytic performance of the material was the largest.After 2h,the degradation rate of DMSO reached 77%.After that,the photocatalytic mechanism of composite materials was explored,and various pathways that can generate hydroxyl radicals·OH were demonstrated.