Preparation Of RGO/TiO₂ Double-shell Hollow Sphere Nanocomposites And Their Properties For Degradation Of Methyl Orange And Aniline In Water

With the deepening of industrialization,environmental problems have intensified and water pollution problems have become very serious.Dye wastewater has complex structure and stable properties,so how to treat it effectively has been a difficult point in the field of wastewater treatment.Aniline is an important organic chemical product and pharmaceutical raw material,which is widely used in the chemical industry and the pharmaceutical industry.However,it has an obvious mutagenesis,carcinogenesis,teratogenesis effect,entering the water body will pose a serious threat to the environment and human beings,so it is urgent to effectively deal with it.TiO₂ photocatalytic technology is an effective method for the treatment of pollutants in water.It has received extensive attention for it can degrade pollutants completely,with advantages of low selectivity,no secondary pollution,low cost and so on.But it has two major defects,photogenerated electron-hole pairs are easy to recombine,as well as the larger band gap of TiO₂ which can only use UV light.In this paper,the reduced graphene oxide/titanium dioxide double-shell hollow sphere nanocomposite?rGO/TiO₂HS?was prepared by modifying the microstructure of TiO₂ and composited with rGO.XRD,SEM,FT-IR,UV-vis diffuse reflection spectrum and N₂ adsorption-desorption analysis were performed to characterize the prepared materials.The TBOT hydrolysis method was screened to effectively control the size of Ti0₂,and the calcination temperature and rGO load were adjusted,so the preparation process of rGO/TiO₂HS composite was optimized.The catalytic properties of the composite catalysts were studied with typical benzene anilines and azo dyes MO as the target degradants.The effects of different factors on the photocatalytic degradation of aniline were also analyzed.The degradation mechanism of photocatalytic degradation of MO and aniline in water by rGO/TiO₂HS composite photocatalyst was further analyzed by active substance capture experiment and UV-Vis absorption spectroscopy.The main findings are as follows:?1?Using TBOT as precursor and SiO₂ as template,rGO/TiO₂HS composites were prepared by sol-gel method.The characterization results show that the rGO/TiO₂HS composite is a nano-hollow sphere with an average inner diameter of 200 nm and a wall thickness of 55 nm.It exhibits a pure anatase phase crystal form with high crystallinity.rGO and TiO₂ is tightly bound with C-O-Ti chemical bond.Its absorption in the visible region is enhanced,so it has good light absorption ability.Its own high specific surface area and typical mesoporous structure.?2?When sulfuric acid as TBOT hydrolysis inhibitor,the ratio of ethanol/water is 10/1,and the mass ratio of TBOT to template is 1/1,the hydrolysis rate of TBOT can be effectively controlled,and rGO/TiO₂HS composite with stable structure and excellent photocatalytic performance is prepared.When the calcination temperature is 650?,the rGO/TiO₂HS composite is a pure anatase phase with good crystallinity.When the rGO loading content is 2.5 wt%,the effect of rGO can be fully exerted,and its photocatalytic activity the strongest.?3?After 30 min of UV irradiation,the photocatalytic degradation rate of MO by rGO/TiO₂HS composites can reach 100%,and the reaction rate is 1.9 times that of pure TiO₂HS.The photocatalytic performance of rGO/TiO₂HS nanocomposites can be attributed to the following aspects:rGO has excellent conductivity and large specific surface area.The doping of rGO can transfer electrons to promote the effective separation of electron-hole pairs,and can increase the specific surface area of the material which can facilitates the circulation of the material,thereby effectively enhancing the photocatalytic degradation of MO.rGO/TiO₂HS composites have high stability.Through capture experiments,h⁺and·OH play a major role in the photocatalytic degradation of methyl orange.?4?Degradation of aniline wastewater by UV-driven rGO/TiO₂HS catalyst is better than TiO₂HS.The degradation rate of aniline by UV light for 20 min is over98.08%,and it has increased degree of mineralization that the degradation rate of TOC is 78.56%after 60 min.Faintly acidic conditions are beneficial to the degradation of aniline;the effect of Cl^-can be neglected,HCO₃^-and PO₄^3-respectively inhibit the degradation of aniline,and effect of PO₄^3-is stronger;humic acid can consume·OH significantly reduces the degradation rate of aniline.·OH and·O₂^-play a major role in the photocatalytic degradation of aniline.In the process of aniline degradation,aniline firstly be degraded to intermediate products such as aminophenol,nitroso benzene,azobenzene,p-benzoquinone and phenolic substances,which are further degraded into simple organic acids and inorganic acids such as maleic acid and oxalic acid,and finally be mineralize to inorganic substances such as CO₂,H₂0,NH₃,NH₄⁺,and N0₃^-.