Preparation Of Ag₃PO₄ Photocatalyst And Its Degradation Of 2-naphthol

The presence of polycyclic aromatic hydrocarbons in industrial wastewater poses a serious hazard to the environment and human health,and it is difficult to completely remove it by conventional water treatment methods.As a kind of"green technology",photocatalysis has the advantages of fast reaction rate,high mineralization efficiency and no secondary pollution.It is considered to be the most promising method in environmental protection.The photocatalyst Ag₃PO₄ has a high quantum yield and can absorb visible light with a wavelength of less than 520 nm,but there is a serious photo-corrosion phenomenon,which limits its practical application.Therefore,improving the activity and stability of Ag₃PO₄ in photocatalytic degradation of organic matter based on the above defects will be the focus of future research.In this study,three kinds of Ag₃PO₄ photocatalysts were prepared by chemical precipitation method using AgNO3,CH3COOH and silver ammonia solution as silver precursors.Among them,Among them,Ag₃PO₄（N）has good activity and stability,and is thermally annealed to obtain Ag3PO4-400.Ag3PO4-400 was characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,UV-Vis DRS and X-ray photoelectron spectroscopy（XRS）.The effects of thermal annealing on the morphology,size and light absorption properties of Ag3PO4 were analyzed.The changes of Ag3PO4 activity and stability before and after annealing were investigated.The effects of catalyst dosage,initial concentration of naphthol,solution pH,coexisting anion and cation and humic acid on photocatalytic degradation of naphthol were investigated.The regenerative and degradation mechanism of Ag₃PO₄--400 were studied.The results show that Ag3PO4（N）and Ag3PO4-400 have strong light absorption in the visible region,and the structure,morphology and crystal form of Ag₃PO₄ are changed by annealing treatment,but no other impurities are produced.Ag3PO4-400 showed enhanced photocatalytic activity and stability for the degradation of naphthol.After the experiment,Ag3PO4-400 was regenerated.The regenerated Ag3PO4-400 still had good photooxidation ability.When the initial concentration of the naphthol solution is 20 mg/L and the dosage of the catalyst is 0.20 g,the degradation rate of the naphthol can reach 99.8%after 8 min.The change of pH has little effect on the degradation of the naphthol.The photocatalytic activity of Ag3PO4-400 is inhibited by the presence of ions and high concentrations of humic acid.The active substance capture experiments showed that h⁺and·O₂^-are the main active species of photocatalytic degradation of naphthol by Ag₃PO₄-400,and·OH only acts at the beginning of the reaction.In the photocatalytic process,naphthol is converted into more complex intermediates,which are gradually attacked by reactive groups,open-loop,chain-broken,and form small molecular acids,which eventually mineralize into CO₂ and H₂O.