Supported TiO₂ Composite Photocatalyst For The Degradation Of Dye Wastewater

With the rapid development of the dye industry,dye wastewater pollution of the environment is increasing day by day,the dye wastewater has the causal effect of carcinogenic mutagenicity.If the dye wastewater is not treated directly,the environment will cause serious harm to the ecological environment.The photocatalytic oxidation technology,which is represented by TiO₂ photocatalyst,has the advantages of thorough degradation,low cost,chemical stability and good light stability in the degradation of dye wastewater.The improvement of TiO₂ to make it widely used in industrial production,environmental protection is of great significance.In this study,TiO₂ was supported on three organic synthetic carriers,and three supported photocatalysts were prepared:Cu₂S-Cu-TiO₂/MC photocatalyst,Cu₂S-Cu-TiO₂/EDA photocatalyst,TiO₂/PVA-GA catalyst of light.The degradation rate of the material on the representative molecular dye solution?methyl orange solution,rhodamine B solution?was used as an index to optimize the preparation process of the material and explore the optimum degradation conditions.Through the relevant characterization of the material,the degradation mechanism was discussed.Cu₂S-Cu-TiO₂/MC photocatalyst was prepared by a simple precipitation carbonization method using Schiff base polymer formed by p-phenylenediamine and glyoxal as carrier.The X-ray diffraction?XRD?and X-ray photoelectron spectroscopy?XPS?show that Cu₂S,Cu and TiO₂ exist in Cu₂S-Cu-TiO₂/MC photocatalyst.Scanning electron microscopy?SEM?and transmission electron microscopy?TEM?images show that the material forms a spherical structure of TiO₂ coated with Cu₂S and Cu.The specific surface area test?BET?results show that the material has a high specific surface area?76.14 m²/g?and a mesoporous structure?average pore diameter of 16.26 nm?.The UV-Vis diffuse spectrum?UV-Vis DRS?and the fluorescence spectrum?PL?show that the recombination of photogenerated electrons and hole pairs is suppressed.The composite materials showed good photodegradation performance in high concentration?300 mg/L?of methyl orange and Congo red solution under visible light.Cu₂S-Cu-TiO₂/EDA photocatalyst was prepared by precipitation carbonization method using piperazine derivatives formed by polymerization of ethylenediamine?EDA?and glyoxal?GO?as carrier.The optimum preparation ratio of the material is n n?EDA?:n?GO?:n?Cu?:n?Ti?=4:1.2:2:1,the optimum preparation temperature is 750?.The optimum degradation conditions were 30 mg,methyl orange concentration 100mg/L,pH=8.0,H₂O₂ concentration 1 mmol/L.Scanning electron microscopy?SEM?and transmission electron microscopy?TEM?images show that the material has many irregular pore structures.Cu₂S,Cu and TiO₂ particles are embedded in the surface of these pore walls.The specific surface area test results show that the specific surface area of the material is 11.38 m²/g and the average pore size is 46 nm.The fluorescence spectra show that the recombination of photogenerated electrons and holes is inhibited,indicating that the photon quantum efficiency of the photocatalyst is improved by this method.TiO₂/PVA-GA photocatalyst was synthesized by hydrothermal method using high molecular polymer crosslinked with polyvinyl alcohol?PVA?and glutaraldehyde?GA?as carrier.Rhodamine B was used as the representative dye molecule to optimize the preparation of the material and to test the optimal degradation conditions.The results show that the degradation performance of the composites is the best when the mass fraction of TiO₂ is 12%.The optimum degradation pH of the material was 2.0,and the optimum concentration of H₂O₂ was 1 mmol/L.X-ray diffraction?XRD?and X-ray photoelectron spectroscopy?XPS?show that the prepared TiO₂ is anatase phase and TiO₂ is modified by C atom.Scanning electron microscopy?SEM?and transmission electron microscopy?TEM?images show that nano-TiO₂ is more evenly distributed in the pores of the carrier.In the fluorescence spectrum?PL?,it can be concluded that the recombination of photogenerated electrons and hole pairs of the material is suppressed.Indicating that TiO₂/PVA-GA photocatalyst has both load and doping effect.