Metal Oxides Composite For Adsorption And Photocatalytic Degradation Of Naphthalene

With the continuous increase of the world population and the continuous development of industry and agriculture,there is a serious energy crisis and environmental pollution.The organic pollutants in water sources are on the rise all over the world,seriously endangering human health.The main cause of water pollution is the burning of fossil fuels such as coal,oil and natural gas.The PAHs produced after burning can enter water bodies,soil and atmosphere,and can cause cancer,teratogenesis,mutation and degradation,etc.,which has attracted widespread attention.In this paper,nano-metal oxide Fe₂O₃-Al₂O₃-Ni O-Cu O（FACN）heterojunctions were prepared by separate precipitation and doping method.The surface physical and chemical properties of the composites were characterized by XRD,SEM,TEM,XPS and N₂ adsorption-desorption.The results show that the composite is mainly composed of Fe₂O₃,Al₂O₃,Ni O and Cu O mixed oxide crystal particles with mesoporous structure characteristics of about 50 nm,and also contains a small amount of Na Al O₂,Na Fe O₂and Fe OOH crystals,which gradually increase with the increase of calcining temperature.PL and UV-Vis diffuse reflectance spectra show that the composite has an extended absorption edge and a narrow bandwidth（1.75 e V）.In addition,the adsorption of naphthalene and the photocatalytic performance of the composite in visible light were also investigated.The optimum reaction conditions were determined as follows:the concentration of naphthalene solution was 0.1 mmol/L,the illumination duration was 6h,and the dosage of catalyst was 0.3 g.Under these conditions,the photocatalytic adsorption and degradation rate of naphthalene was 83.5%.For further comparison,the removal efficiency of naphthalene and the photocatalytic activities of the mono-metal oxide and tri-metal oxide heterojunctions composed of FACN composites were evaluated under the condition of dark reaction.Results show that FACN composites under the dark reactions of naphthalene removal rate was 42.3%,the single metal oxide materials of naphthalene degradation rate was 43.6%～52.9%,the three metal heterojunction composites of naphthalene degradation rate was 64.5%～74.4%,the degradation of metal heterojunction composites are less than four rate,more illustrates the heterojunction plays an important part in photocatalytic reaction,show that the composite material is a kind of efficient adsorbent and catalyst.Finally,we used GC-MS to qualitatively analyze the organic phase after photocatalytic degradation of naphthalene,and obtained a variety of small molecules.Through the analysis of degradation products,we deduced the possible mechanism of photocatalytic degradation of naphthalene.