Study On The Preparation Of Bi-based Photocatalysts And Its Visible-light-responsive Photocatalytic Performance For Organic Wastewater

Photocatalytic oxidation technology is a simple and effective technology to remove organic matter in waste water,which has great potential in organic wastewater degradation.However,There are some problems which seriously restrict the application of photocatalytic technology in practical wastewater treatment,such as low quantum efficiency,poor utilization of visible light in sunlight.Therefore,the development of photocatalyst which can effectively utilize visible light is an important question in the field of water treatment.In this study,Sn-Bi OCl,Sn/Bi OCl/RGO and Bi₂Sn₂O₇/RGO photocatalysts with he capability of visible-light response were prepared by liquid-phase precipitation method,and hydrothermal method,and the p H and graphene loading were adjusted through the whole experiment the crystal form,microstructure,physical adsorption properties,chemical structure,optical properties,band structure and photochemical properties of the photocatalysts were measured by characterization of X-ray diffraction analysis?XRD?,UV-Vis diffuse reflectance spectroscopy?DRS?,fluorescence spectroscopy?PL?,transmission electron microscopy?HRTEM?,specific surface area?BET?,scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy FT-IR and X-ray photoelectron spectroscopy?XPS?.The photocatalytic activity of the prepared photocatalyst were evaluated by the degradation of Malachite green?MG?,rhodamine B?RhB?,methyl orange?MO?,orange-IV?OG4?,methylene blue?MB?and gentian violet?GV?under sunlight irradiation.This study provides a theoretical basis for the subsequent development and treatment of Bi-based photocatalyst for the degradation of organic wastewater.The main contents and conclusions are as follows:?1?Study on the preparation,characterization and properties of Sn-doped Bi OCl photocatalyst: The photocatalyst was synthesized by p H-dictated route,and the effect of p H on the microstructure and properties of the photocatalyst was discussed.The results show that p H has a great effect on the microstructure and properties of the photocatalyst.The Sn-doped Bi OCl catalyst prepared at p H = 6?BS-6?is composed of nano-sheets,and its specific surface area is 83.4402 m2/g;The photocatalytic activity was evaluated by degradation of dye wastewater under natural sunlight irradiation,BS-6 exhibited the best photocatalytic activity,and the optimum dosage and concentration were 0.5 g/L and 35 mg/L,respectively.In addition,BS-6 exhibited good stability and circulation through the cycle experiments.?2?Study on the preparation,characterization and properties of Sn/Bi OCl/RGO photocatalyst: The activity of Sn-doped Bi OCl photocatalyst was improved by loading reduced graphene oxide?RGO?.The results show that the RGO loading has an important effect on the microstructure and properties of the composite photocatalyst,when the amount of RGO loading is 0.25 wt%?BG-0.25?,resulting a highest activity.When the initial concentration of pollutants is 80 mg/L and the dosage of catalyst is 0.5 g/L,the degradation rate of RhB can reached 99% under sunlight irradiation for 8 h.It can be observed that Sn-doped Bi OCl is broken by ultrasound,and evenly distributed in the graphene sheet through SEM.?3?Study on the preparation and visible-light-responsive performance of Bi₂Sn₂O₇/RGO photocatalyst: A novel Bi₂Sn₂O₇/RGO composite photocatalyst was successfully prepared by hydrothermal method.The effect of the graphene concentration on the prepared Bi₂Sn₂O₇/RGO photocatalyst was studied.The results showed that when the graphene concentration is 20 wt%?BG-20?,the photocatalyst had the best activity compared with pure BSO.The degradation effect of BG-20 on methylene blue and gentian violet dye wastewater was studied.The results showed that BG-20 could effectively remove methylene blue and gentian violet in water,Methylene blue and gentian violet can be degraded 99% and 91% in 120 minutes.Moreover,the prepared BSO and BG-20 were characterized,XRD shows that the graphene loading can't change the crystal of BSO photocatalyst,but the crystallinity of the photocatalyst become weaker.It can be seen by scanning electron microscopy,BSO was broken by ultrasound and then evenly distributed in the graphene sheet.UV-vis demonstrates that the band-gap of BG-20?2.3 e V?was narrow compared with BSO.In addition,XPS and Raman spectra demonstrate the presence of graphene and the graphene was successfully reduced to reduced graphene.