The Synthesis Of WS₂ Nanomaterial And Its Application In Wastewater Treatment

Tungsten disulfide（WS₂）,as a typical transition metal sulfide（TMDC）with a layered structure similar to graphite,has a huge application prospect in photocatalysis.The morphology and structure of the material have a great influence on its catalytic performance.Therefore it is meaningful to explore a simple synthetic method to pre-pare WS₂ with excellent morphology and structure.In addition,the narrow energy gap（1.4 e V）makes the photogenerated carriers easy to recombine.Consequently,some modifications to widen the energy gap of WS₂ are needed,thereby enhancing the photocatalytic activity.In this paper,the economical and environmental-friendly hydrothermal and sol-vothermal methods were used to synthesize WS₂ materials with different morpholo-gies and structures.The prepared materials are characterized by XRD,SEM,TEM,UV-Vis spectroscopy,XPS,BET,and Zeta potential tests.During hydrothermal syn-thesis process,the effects of synthesis process parameters including precursors,sur-factants,reaction temperature,and reducing agent on the yield and structures of WS₂nanomaterials were studied.A nanoflower-like WS₂ was successfully synthesized by solvothermal method.The nanostructure has a high specific surface area,but the ad-sorption performance is not good due to its surface hydrophobicity.The photocataly-sis experiments proved that WS₂ nanoflower has a good degradation rate on rhoda-mine B（Rh B）dye under ultraviolet radiation.Next,WS₂/WO₃ herterostructures were prepared by partial oxidation strategy.The introduction of oxygen atoms makes the material more hydrophilic and the sur-face potential is more negative.Compared with pure WS₂,the adsorption performance of WS₂/WO₃ heterostructures got a dramatic improvement.The adsorption kinetics,adsorption thermodynamics and other parameters（p H,dosage,temperature,etc.）on adsorption process were studied.It was revealed that the adsorption of dye was an endothermic physical adsorption process.Finally,the WS₂/WO₃ heterostructures were applied in synergistic treatment of organic dye acid orange II and Cr（VI）.The experimental results showed that the WS₂/WO₃ material has good photocatalytic performance,and the removal rate de-creases with the increasing p H of the solution.The removal rate of WS₂/WO₃ for composite system pollutants was higher than that of single pollutant system,and it was attribute to the presence of acid orange II or Cr（VI）assisting the separation of photo-generated carriers.In addition,the degradation pathway of acid orange II was explored.The recycling performance of WS₂/WO₃ material has also been tested,which showed a good stability.In this paper,we studied the hydrothermal and solvothermal preparation method of WS₂ material detailedly,and carried out systematic research and discussion on the modified WS₂ material in terms of adsorption and photocatalysis.It provides a feasi-ble experimental and theoretical instruction to the application of WS₂-based materials for industrial wastewater treatment.