Study On Bismuth Tungstate Based Photocatalyst For Degradation Of Tetracycline Hydrochloride

Tetracycline antibiotics are a kind of efficient broad-spectrum antibiotics,which have antibacterial activity against chlamydia,Escherichia coli,mycoplasma,gram-negative bacteria and Gram-positive bacteria,so they are widely used in medical treatment,aquaculture,agriculture and animal husbandry.Tetracycline antibiotics have the characteristics of good water solubility and not volatility,and can be stored in the natural environment for a long time.Therefore,they can enter the human body through the food chain and other ways,bringing potential harm to the human body.At present,a large number of studies have shown that there are residues of tetracycline drugs in natural water bodies,soil and animals and plants.Therefore,it is necessary to develop an efficient and feasible technology to degrade tetracycline wastewater.Semiconductor photocatalysis is an advanced oxidation technology,which can effectively remove dyes,heavy metal ions and organic pollutants from water.The technology uses semiconductors as catalysts to convert solar energy into chemical energy that degrades organic pollutants in the water,thus achieving water purification.Compared with traditional activated carbon adsorption or biodegradation methods,photocatalysis technology has significant advantages in removing non-biodegradable organic pollutants such as pesticides,antibiotics and dyes.It can convert pollutants into CO₂ and H₂O.Therefore,photocatalysis technology has broad application prospects in the degradation of tetracycline wastewater.The purpose of this study is to treat the high concentration tetracycline hydrochloride simulated wastewater by photocatalysis.Based on the visible light catalytic material Bi2WO6,it is modified to improve the photocatalytic efficiency and recyclability,explore the photocatalytic efficiency,identify the active free radicals generated in the process of photocatalysis,and analyze the degradation mechanism of tetracycline hydrochloride.The main findings are as follows:（1）Bi₂WO₆ photocatalyst with three-dimensional nanoflower spherical structure assembled from a large number of two-dimensional nanosheets was prepared by hydrothermal method.By studying the effects of CTAB addition and reaction p H on the structure and properties of Bi₂WO₆,the optimal preparation conditions of Bi₂WO₆ were determined and the photocatalytic reaction was carried out to explore the effects of catalyst dosage and initial concentration of pollutants on photocatalytic efficiency.The study shows that when the addition of CTAB is 0.05 g and p H=3,the degradation rate of Bi₂WO₆ to 10 mg/L tetracycline hydrochloride is about 77%in 2 h.（2）Based on Bi₂WO₆,Ag₃PO₄@Bi₂WO₆ composite photocatalytic materials were prepared by chemical precipitation,and the morphological structure and photoelectrochemical properties of Ag₃PO₄@Bi₂WO₆ were studied by characterization methods such as XRD,SEM,XPS,UV-vis,PL photoluminescence spectroscopy,and the degradation effect of Ag₃PO₄@Bi₂WO₆ on tetracycline hydrochloride under different Ag₃PO₄ contents was explored.The results showed that the degradation rate of Ag₃PO₄@Bi₂WO₆ composite to tetracycline hydrochloride reached 90.9%in 2 h,and the degradation rate was 2.3 times that of pure Bi₂WO₆.（3）The Fe₃O₄@Bi₂WO₆ magnetic composite photocatalytic material was synthesized by two-step hydrothermal method.BET analysis yielded that the specific surface area of Fe₃O₄@Bi₂WO₆ material was 42.26 m²/g,which was 29%higher than that of Bi₂WO₆ material.Due to its higher specific surface area,the adsorption performance of Fe₃O₄@Bi₂WO₆ material for tetracycline hydrochloride is significantly better than that of pure Bi₂WO₆.Hysteresis loop analysis shows that Fe₃O₄@Bi₂WO₆material is superparamagnetic and has the ability to be quickly recovered under an applied magnetic field.