Study On Preparation And Degradation Of Ce/N Co-doped TiO₂/Refined Diatomite Photocatalytic Materials

With the improvement of people's living standards and the rapid development of the pharmaceutical industry,the pollution of antibiotics in the water environment has become more serious,threatening human health and the balance of the ecosystem.Conventional water treatment processes have limited treatment capacity for antibiotics,so it is difficult to remove them completely.Nano-TiO₂ material has a strong photocatalytic activity and is widely used in CO₂ conversion,sewage treatment,antibacterial and sterilization,air purification and other aspects.However,in the application of nano-TiO₂ material degrading organic wastewater,due to its poor dispersibility,small particle size,low recycling and recovery utilization,its photocatalytic efficiency is reduced,and its operation cost is expensive,so its practical application is poor.Diatomite is one of the advantageous mineral resources in China.It is loose,light,porous and has excellent adsorption characteristics.As a preparation material of sewage treatment agents with excellent performance,it is used in the field of environmental protection to treat medical wastewater,industrial wastewater and urban domestic wastewater.In this study,diatomite was used to immobilize TiO₂,and environmental water pollutants were adsorbed on the surface of TiO₂,so as to exert the targeted enrichment effect of diatomite and improve the photocatalytic degradation efficiency of TiO₂.At the same time,TiO₂/diatomite composite photocatalyst was made into granules or introduced into magnetism to optimize the recycling performance.Crude diatomite was impregnated with dilute sulfuric acid at 15 wt%concentration to remove impurities and retain the original pore structure,thereby preparing acid-leaching pretreated diatomite.Ce/N co-doped TiO₂/acid-leaching diatomite composite granules with different doping amounts were prepared by sol-gel method and based on the preparation process of N-doped composite powders.Through the characterization tests of Ce/N co-doped composite granules,such as X-ray diffraction,transmission electron microscope and X-ray photoelectron spectroscopy,and the degradation of rhodamine B under visible light,the properties of the co-doped composite photocatalytic granules were explored.After 3 hours visible light degradation of RhB,the photodegradation rate of the co-doped composite granule with the best photocatalytic effect was 87.18%.After 5 cycles of experiments,the photodegradation rate of the co-doped composite granule with the best photocatalytic effect was 83.19%.The results show that the co-doped composite granules have good stability and recycling performance.The acid-leaching diatomite was prepared by sol-gel method and supported with good magnetic nickel ferrite crystals on the surface of acid-leaching diatomite,and further supported with Ce/N co-doped TiO₂ nanocrystalline on the surface.The magnetic Ce/N co-doped TiO₂/acid-leaching diatomite composite powders were prepared.Through a series of characterization tests and degradation of rhodamine B under visible light,the properties of magnetic co-doped composite photocatalytic powders were explored.NiFe₂O₄ is an inert photocatalytic material,and its combination with TiO₂ can reduce the electron-hole composite rate and improve the photocatalytic efficiency.The combination of NiFe₂O₄ and diatomite is conducive to the separation of diatomite,and at the same time,it improves the pore structure of diatomite and improves its adsorption performance.After 3 hours visible light degradation of RhB,the photodegradation rate of the magnetic co-doped composite powder with the best photocatalytic effect was 96.53%.After 5 cycles of experiments,the photodegradation rate of the magnetic co-doped composite powder with the best photocatalytic effect decreased slightly to 95.37%.The results show that the magnetic co-doped composite powders have better stability and recycling performance.With the antibiotic tetracycline as the target degradation material,the above-mentioned co-doped composite granules and magnetic co-doped composite powders were used to perform visible light degradation experiments,and the effects of common impurities in water on the photodegradation process were also studied.Then,under visible light,the photobactericidal effects of these two photocatalysts on Escherichia coli,Staphylococcus aureus,and Klebsiella pneumonia were studied,and the recycling performance was also studied.After 4 hours visible light degradation of TC,the photodegradation rate of the co-doped composite granule with the best photocatalytic effect was 97.20%;after 3 hours visible light degradation of TC,the photodegradation rate of the magnetic co-doped composite powder with the best photocatalytic effect was 98.22%.After 2 hours of visible light bactericidal experiments on Escherichia coli,Staphylococcus aureus and Klebsiella pneumoniae,the bactericidal rates of the co-doped composite granules with the best photocatalytic effect were respectively 86.42%,87.68%and 84.79%,and the bactericidal rates of the magnetic co-doped powders with the best photocatalytic effect were respectively93.68%,94.68%and 92.94%.The results show that the two composite photocatalysts have good stability in visible light degradation of TC and sterilization,and the results of 5 cycles show that they have excellent recycling performance.