Preparation And Photocatalytic Activity Of Zinc Tungstate Based Composites

With rapid development of modern industrialization and population growth,the environmental pollution is increasingly serious.Recently,researchers have developed a number of techniques to cope up this issue.Among various reported approaches,photodegradation of defined sewage via suitable photocatalysts are of great importance.Zinc tungstate?ZnWO₄?has attracted massive attention and considered to be one of the most potential photocatalysts attribute to its unique physical and chemical properties.Moreover,ZnWO₄ is a monoclinic crystal and high stability,which is not only easy to deliquesce,but also have the ability to resist strong light and radiation?small photo corrosion?.On photochemistry point of view,ZnWO₄ has a big band gap,high excitation energy,relatively good UV-light photocatalytic activities.It is of great importance to synthesize ZnWO₄ based nanomaterials and investigate its photocatalytic activities for environmental remediation particularly for organic pollutant degradation.In brief,this work will open a new gateway for the synthesis of zinc tungstate-based nanomaterials and their employment for environmental protection.Firstly,ZnWO₄ photocatalysts were successfully synthesized through a hydrothermal method.Accordingly,CuWO₄,FeWO₄,and NiWO₄ were selected as model for coupling with ZnWO₄.Three kinds of CuWO₄/ZnWO₄,FeWO₄/ZnWO₄and NiWO₄/ZnWO₄ composites were obtained through chemical-stirring technique.Based on the measurements including XRD,SEM,and UV-Vis,it has been proved that the as-synthesized composites have enhanced photocatalytic performances as compared to pristine ZnWO₄.Secondly,the as-synthesized composites?CuWO₄/ZnWO₄,FeWO₄/ZnWO₄ and NiWO₄/ZnWO₄?was employed for the photocatalytic degradation of tetracycline hydrochloride.Subsequently,the photocatalytic activities was investigated under different experimental parameters via utilizing absorbance of tetracycline hydrochloride as an index.Noticeably,by altering pH?3,5,9,10,11 and 12?of the degradation-reaction-solution mixture,adding different capture agents?methanol,triethanolamine,ascorbic acid,sodium sulfate and isopropanol?and anions(SO₄^2-,Cl^-,NO₃,CO₃²and PO₄³)to reaction solution remarkably effect the photocatalytic activities of subject samples.It has been confirmed the photocatalytic activities of ZnWO₄ is greatly improved after introducing NiWO_4,CuWO₄ and FeWO₄.When the pH value of the solution is 11,or there is CO₃^2-,the photocatalytic activity is the highest,and the degradation rate can reach 80%?The results show that ascorbic acid has the strongest inhibitory effect on solution degradation,It shows that the superoxide radicals(·O^2-)captured by ascorbic acid are the main active substances.In summary,this research work would help us to successfully synthesis ZnWO₄based photocatalysts,deeply understand its importance and effectively utilized it for pollutants degradation and water purification.