Preparation And Photocatalytic Activity Of Bismuth Oxyhalide-based Composite Materials

Our country produces about 150,000 tons of antibiotics each year,which are widely used in animal husbandry and breeding.Residues of antibiotics can be easily accumulated in the surface water,causing serious problems to humans and ecology.In particular,tetracycline antibiotics have the high chemical stability in water.The traditional methods of treating antibiotics in wastewater mainly include adsorption,biological,and electrolysis.These methods are difficult to eradicate these pollutants completly.Factors such as high operating costs and mass transfer limitations caused by high energy consumption still limit its applicability in large-scale production.In this thesis,Ni（OH）₂nanomaterials were successfully synthesized by chemical precipitation method.BiOCl and BiOI were selected to be combined with them by chemical stirring method,and Ni（OH）₂/BiOCl was successfully prepared.The ratio of BiOI in BiOI/NiO composite photocatalysts is 1%,3%,5%,7%,and through the measurements of XRD,SEM,UV-Vis,etc.,the results show that the phase,stricture,optical,property are evaluated for Ni（OH）₂/BiOCl,BiOI/NiO two kinds of composites.Secondly,Ag nanoparticles were loaded on the surface of Ni（OH）₂/BiOCl and BiOI/NiO.Using the absorbance of tetracycline hydrochloride as the inspection index,the photocatalytic activity of catalysts was tested under several different conditions.The pH value of the reaction solution was evaluated how affect the photocatality activity.The pH value of solution was adjusted to 3,5,9,10,11,and 12 respectively.Different capture agents were added to the solution,namely methanol,triethanolamine,ascorbic acid,sodium sulfate and isopropanol.This work also studied the impurity ions how affective photocatality activity,namely SO₄^2-,Cl^-,NO₃^-,CO₃^2-,PO₄^3-.Test the effect of these factors on the photocatalytic activity of the prepared catalysts.After loading with Ag nanoparticles on the Ni（OH）₂/BiOCl and BiOI/NiO surface.The Ni（OH）₂/BiOCl/Ag and BiOI/NiO/Ag photocatalysts showed a higher photoactivity.Degradation of tetracycline hydrochloride under different pH values of the solution shows that the photocatalytic activity is highest at neutral pH value.By adding different impurty ions to the solution,it was found that the photocatalytic activity decreased sharply in the presence of SO₄^2-,Cl^-,CO₃^2-,NO₃^-and PO₄^3-.In summary,the composites of Ni（OH）₂/BiOCl and BiOI/NiO show high photocatalytic activities and play an effective role in the degradation of antibiotic wastewater.The above result is of grewt significant for continuing to explore the bismuth oxyhalide-based composite materials.