Preparation Of WO₃-based Composites And Their Performance Study In Degradation Of Antibiotics

In recent years,with the large-scale use of antibiotics and the random discharge of wastewater,the safety of water environmental has become more and more serious.Semiconductor photocatalytic technology can use sunlight to degrade organic pollutants,which has attracted much attention because of the green environmental protection,low energy consumption and high efficiency.Tungsten trioxide(WO3)is widely used in photocatalytic research because of the moderate bandgap,response to visible light,and stability under acidic and oxidizing conditions.However,the photogenerated electron-hole pairs of single WO3 has a high probability of recombination,which greatly limits the practical application of WO3.Therefore,it is significant to construct heterojunction around WO3 materials by compounding with other semiconductor materials to improve their photocatalytic efficiency.In this paper,Ag2WO4/WO3 and Ag Cl/WO3/g-C3N4 composites were designed and prepared,and the crystal structure,morphology,elemental composition and optical properties of samples were analyzed by XRD,SEM,TEM,XPS,UV-vis DRS,PL and other characterization methods,and tetracycline(TC)and oxytetracycline(OTC)were used as target degradants to explore the reaction mechanism of photocatalytic research,the specific research content is as follows:(1)WO3 nanosheets were prepared by hydrothermal method,and Ag2WO4/WO3 composites with different mass ratios were synthesized by co-precipitation method.The results indicated that catalyst showed the highest photocatalytic activity compared with pure WO3 and Ag2WO4 materials when the mass ratio of Ag2WO4 and WO3 was 1:2,and the degradation efficiency of TC and OTC after 75 min of illumination were 77.4% and 67.4%,respectively.This was because the construction of heterojunction effectively inhibited the recombination of photogenerated electron-hole pairs,increased the specific surface area of the photocatalyst and broadened the response range to visible light.The main active species of Ag2WO4/WO3 composites photodegradation process were revealed superoxide radicals(·O2-)and holes(h+)by radicals capture experiments,which conformed to the Z-type heterojunction reaction mechanism.(2)Ag Cl/WO3 binary catalysts and g-C3N4 powder were synthesized by one-step hydrothermal method and high-temperature thermal polymerization method,respectively,and then Ag Cl/WO3/g-C3N4 ternary photocatalysts were obtained by high-energy ball milling process.The effects of different Ag/W molar ratios and g-C3N4 composite amounts on photocatalytic activity were investigated.The results showed that ball milling could increase the specific surface area of Ag Cl/WO3/g-C3N4 composites,providing a large number of reactive sites for the photocatalytic process.At the same time,the formation of heterojunction effectively promoted the transfer of photogenerated carriers,which was more conducive to improve the photocatalytic performance.After 60 min of illumination,the degradation efficiency of Ag Cl/WO3/g-C3N4 on TC and OTC reached 76.1% and 59.3%,respectively.Combinding with radicals capture experiments,the double Z-type reaction mechanism of Ag Cl/WO3/g-C3N4 ternary composites during degradation was inferred.