Synthesis,Modification Of Bi₂WO₆ And Photocatalytic Degradation Of Sulfadiazine

Increasingly serious antibiotic pollution threatens ecosystems and human health.Sulfonamide antibiotics are the longest-used synthetic antibiotics in history and one of the most widely used antibiotics in agriculture and animal husbandry in recent years.Sulfonamide antibiotics are detected in lakes,rivers,oceans and other surface water and groundwater.Semiconductor photocatalytic oxidation technology is an environmentally friendly green water treatment technology,especially suitable for the effective treatment of trace pollutants in water environment.Bi₂WO₆ has received extensive attention due to its excellent photocatalytic performance.There are also problems such as limited band gap,low utilization of visible light,high recombination rate of photogenerated carriers,and less exposure of active sites.In this paper,Bi₂WO₆ with ultra-thin structure was synthesized by hydrothermal method by adding CTAB.The prepared materials were characterized by XRD,XPS,TEM and electrochemical performance tests.The characterization results show that the performance improvement is to improve the separation efficiency of photogenerated carriers by reducing the migration path of photogenerated carriers.The effect of Bi/W ratio on the photocatalytic performance of Bi₂WO₆ was investigated.In addition,a series of condition optimization experiments were carried out.It was found that 50 mg·m BWO-2 could achieve 80.75%degradation efficiency of sulfadiazine after 90 min illumination at a concentration of 20 mg·L^-1 p H=9,and the corresponding rate constant（k）was 0.0179 min^-1.At the same time,the photocatalytic degradation of sulfadiazine by m BWO-2 was carried out for four cycles.The results showed that the stability of the prepared catalyst was general.In addition,the study found that different concentrations of Cl^-,SO4₂^-,NO₃^-can inhibit the degradation of sulfadiazine.With the increase of ion concentration,the trend of inhibiting sulfadiazine degradation will be enhanced.The main active substances in the photodegradation process of sulfadiazine were investigated by free radical capture experiments,and it was verified that the hole（h⁺）was the main active substance in the system.g-C₃N₄/m BWO-2 ultrathin nanosheet heterojunctions were constructed by a simple hydrothermal method,and sulfadiazine was degraded under simulated sunlight to explore its photocatalytic degradation performance.The prepared materials were characterized by XRD,XPS,TEM and electrochemical performance tests to verify the microstructure,elemental composition and crystal structure of the prepared materials.The photocatalytic activity of g-C₃N₄/m BWO-2 composites with different mass ratios was investigated.The effects of initial solution p H,catalyst dosage and initial sulfadiazine concentration on degradation efficiency and inorganic anions were studied.Under simulated sunlight irradiation for 90min,the degradation rate of sulfadiazine could reach 86.98%,and the corresponding rate constant（k）was 0.0242 min^-1.Through electrochemical experiments and free radical shielding experiments,the excellent photodegradation performance is attributed to the fact that the synthesized70%CNNs/m BWO-2 heterostructure can promote the transfer of carriers.This work provides a feasible method for the degradation of sulfadiazine in the environment.