Photocatalytic Degradation Of Carbamazepine In Water By ZnIn₂S₄/Quartz Sand

Due to excessive usage of the pharmaceutically active compounds?PhACs?by human beings and incomplete metabolism for drugs by the bodies,PhACs and their metabolites that entering into water environment have brought a potential threat to aquatic ecosystem and human health.Nowadays,PhACs are detected in surface water,groundwater and drinking water at different concentrations from ng/L to ?g/L.Photocatalytic oxidation is a kind of high efficiency,low cost,easy to operation,no secondary pollution and continuously applied technology,and has a good prospect in the removal of persistent organic pollutants,such as PHACs.In this paper,ZnIn₂S₄ and ZnIn₂S₄/quartz sand visible light catalysts were prepared by hydrothermal synthesis,and the anti-epileptic drug carbamazepine?CBZ?was selected as the target pollutant.The catalytic activities of ZnIn₂S₄ and ZnIn₂S₄/quartz sand were examined by photocatalytic degradation of CBZ in water under different irradiations by iodine gallium lamp,halogen tungsten lamp and sunlight respectively.Photocatalytic reaction kinetics,identification of active species and exploration of reaction mechanism were carried out in this study,and the surface morphology,crystal structure,specific surface area and optical properties of the catalysts were characterized separately by SEM,XRD,BET and UV-vis DRS.Based on experimental research,main achievements were listed as below.?1?Under irradiation of iodine gallium lamp?main wavelength of 350-450 nm,light intensity of 148000 Lx?,dosage of ZnIn₂S₄ 40mg/L and CBZ initial concentration of 100?g/L,the degradation rate of CBZ reached 100% at 20 min.Active species trapping experiments confirmed that hydroxyl radical?·OH?was a main active species in the reaction process,and the removal of CBZ were mainly depended on oxidative degradation of ·OH and direct oxidation by the hole.?2?The optimum calcination temperature was 200? and the optimum loading rate was 0.7‰ during the preparation of ZnIn₂S₄/quartz sand.Under conditions of CBZ initial concentration 100?g/L and dosage of ZnIn₂S₄/quartz sand 56g/L,CBZ was degraded completely at 15 min under irradiation by iodine gallium lamp.?3?While not adding the catalyst,the removal rate of CBZ reached 53.8% at 15 min under direct photodegradation by iodine gallium lamp.It indicated that the photocatalytic degradation of CBZ by ZnIn₂S₄/quartz sand was in accordance with pseudo-first order reaction kinetics,and the photodegradation rate of CBZ remained above 80% after repeated usage of the catalyst for six times.?4?Under irradiation of halogen tungsten lamp?main wavelength of 350-2500 nm,light intensity of 43000 Lx?,dosage of ZnIn₂S₄/quartz sand 56g/L and CBZ initial concentration of 100?g/L,the degradation rate of CBZ reached 62.5% at 120 min.when the catalyst was not added,the photolysis of CBZ didn't happen under irradiation of halogen tungsten lamp.?5?Under irradiation of sunlight?295-2500 nm,126000 Lx?in the outdoor,when the light intensity was,the degradation rate of CBZ reached 98% at 30 min under the same conditions as that of halogen tungsten lamp.Similarly,the photolysis of sunlight can not remove CBZ without the presence of the catalyst.The research results provide a theoretical basis for the development of visible light photocatalyst,and also give a technical support for practical application of photocatalytic oxidation technology in the removal of PhACs in aquatic environment.