Study On Degradation Of Yellow Orange ? Dye Wastewater By Pulsed Discharge Plasma Inducing Supported Modified TiO₂

Due to the printing and dyeing wastewater has characteristics such as huge quantity,large variations in water quality,large chroma,high organic content and complex components.The traditional methods can not meet the increasingly stringent emission requirements.Advanced oxidation technology has attracted extensive attention in the field of wastewater treatment due to its extremely strong oxidation,complete degradation of pollutants and no secondary pollution.In advanced oxidation technology,pulsed discharge plasma?PDP?is a new type of water treatment technology that combines the physical and chemical effects of light,electricity,heat,etc.,but the light effect is often overlooked.TiO₂ photocatalytic technology has high catalytic efficiency and low cost,and has broad application prospects in the field of wastewater treatment.However,TiO₂ has a large band gap energy and a low photo quantum efficiency,and the powder TiO₂ is not easily recovered.Based on this,in this study combines PDP with modified TiO₂,and the printing and dyeing simulation wastewater was treated by UV produced by PDP inducing supported modified TiO₂.The MWCNTs-TiO₂/?-Al₂O₃ and V/N-MWCNTs-TiO₂/?-Al₂O₃ were prepared by sol-gel method.The two catalysts were characterized by XRD,SEM,FT-IR,UV-vis and XPS.The effects of different parameters on the degradation of simulated printing and dyeing wastewater AO7 in PDP inducing supported modified TiO₂ system were investigated,and the best experimental conditions were determined.The reuse of two types of catalysts in the water treatment system was analyzed.The relevant mechanism in the printing and dyeing wastewater treatment by PDP inducing supported modified TiO₂ was discussed.Conclusion as follows:?1?MWCNTs-TiO₂ catalyst and V/N-MWCNTs-TiO₂/?-Al₂O₃ catalyst were characterized by XRD,SEM,FT-IR,UV-vis and XPS.The results show that TiO₂ still has the structure of anatase TiO₂ after modified by MWCNTs,V and N.TiO₂ is uniformly distributed on the surface of MWCNTs,and combine with MWCNTs,V,and N through chemical bonds.The visible response of MWCNTs-TiO₂/?-Al₂O₃ catalyst and V/N-MWCNTs-TiO₂/?-Al₂O₃catalyst are obviously higher than that of TiO₂.?2?The effects of different systems such as PDP,PDP inducing TiO₂/?-Al₂O₃,PDP inducing MWCNTs-TiO₂/?-Al₂O₃,TiO₂/?-Al₂O₃ adsorption and MWCNTs-TiO₂/?-Al₂O₃adsorption on AO7 were compared.It was found that the degradation of AO7 by PDP inducing MWCNTs-TiO₂/?-Al₂O₃ system is higher than other systems.The influence of different parameters on AO7 degradation was invetigated.It was found that the degradation rate of AO7 increased with the increase of voltage and frequency;The degradation rate of AO7 increased first and then decreased with the increase of air volume,and degradation rate of AO7 decreased with the increase of AO7 initial concentration.Acidic conditions and lower conductivity are conducive to the degradation of AO7;the degradation rate of AO7 increases with the increase of the amount of catalyst.After MWCNTs-TiO₂/?-Al₂O₃ catalyst and V/N-MWCNTs-TiO₂/?-Al₂O₃ catalyst were reused six times,the degradation rate of AO7remained above 85%.When n?V?:n?N?=1.0:0.5,the photocatalytic activity of V/N-MWCNTs-TiO₂/?-Al₂O₃ catalyst is the strongest.?3?The analysis of degradation mechanism of AO7 by PDP inducing supported modified TiO₂ shows that:MWCNTs can effectively transfer photoelectron of TiO₂,and photoelectron can react with O₂ on catalyst surface to form O₂^-and oxidize degradation AO7.The V and N doping can replace the Ti⁴⁺and O^2-in the partially anatase TiO₂ lattice respectively,which reduces the recombination rate of photogenerated carriers and increases the photon efficiency.Active substances such as·OH?O₃?and H₂O₂ will be generated in PDP system.On the one hand,AO7 can be directly degraded.On the other hand,the modified TiO₂ can be induced to produce electrons and holes,improve the photocatalytic activity of TiO₂,and finally degrade AO7 into small molecule organics,CO₂ and H₂O.