Preparation Of Modified Shell Powder/La-TiO₂ And Photocatalytic Degradation Of Organophosphorus Pesticide Wastewater

Organophosphorus pesticide wastewater has the characteristics of high concentration of pollutants,high toxicity and poor biodegradability,which is a difficult problem in the field of water treatment.In recent years,photocatalytic oxidation technology using TiO2 as a photocatalyst has become a research hotspot for the treatment of difficult biodegradable organic wastewater.However,TiO2 has the disadvantages of high photo-generated carrier recombination rate and weak adsorption capacity,which limits its application.In this experiment,TiO2 was doped and modified,and the photocatalytic degradation of organophosphorus pesticide wastewater by modified TiO2 was studied.Omethoate pesticide wastewater as the research object,the effect of modified shell powder loaded with rare earth lanthanum-doped TiO2 on the treatment of omethoate pesticide wastewater was studied.The research content includes:Optimized preparation and characterization of modified shell powder;Preparation,optimization of process conditions and characterization of modified shell powder/La-TiO2 composite photocatalyst;Experimental study on photocatalytic degradation of omethoate pesticide wastewater by modified shell powder/La-TiO2,and the optimal reaction conditions were obtained.The results of preparation of modified shell powder showed that when the calcination time was 2h,the calcination temperature was 1000?,and the sieved particle size was 200 mesh,the modified shell powder had the largest adsorption amount of omethoate.The results of SEM and BET showed that the modified shell powder was loose and had excellent adsorption capacity and pore structure,which laid a good foundation for the subsequent loading of TiO2.The optimum preparation conditions of modified shell powder/La-TiO2 were obtained by single factor test and orthogonal test:The amount of La doping was 0.5%of the amount of the TiO2 substance,the calcination temperature was 550?,the calcination time was 3h,the sol system pH was 3,and the amount of the modified shell powder was 1.25%of the mass of the TiO2.It can be seen from the SEM image that the modified shell powder is covered with a layer of spherical Ti02 fine particles,indicating that the loading of TiO2 on the modified shell powder is good.From the results of XRD characterization,it can be seen that the La-doped TiO2 exists in the anatase phase.The undoped TiO2 is mainly composed of rutile phase and anatase phase,indicating the presence of rare earth La doping can inhibit the phase transition of TiO2.The modified shell powder/La-TiO2 photocatalytic degradation of omethoate has a good treatment effect.For the concentration of 80mg/L omethoate wastewater,when the catalyst dosage is 1000mg/L,the reaction temperature is 25?,the LJV lamp power is 560W,the COD removal rate and the organic phosphorus degradation rate are 81.15%and 74.43%,respectively.The modified shell powder loaded with rare earth lanthanum doped TiO2 lattice produced distortion,inhibited the transformation of TiO2 from anatase phase to rutile phase,improved the adsorption capacity of TiO2,and modified shell powder/La-TiO2 photocatalytic degradation of organic phosphorus pesticide wastewater has better degradation effect than TiO2,indicating that modified shell powder/La-TiO2 is feasible for degrading organophosphorus pesticide wastewater.