Preparation Of Porous Semiconductor Ceramics And Research On Visible Photocatalytic Degradation Dyeing Wastewater

Industrial wastewater pollution is one of the most serious environmental problems in the world.In industrial wastewater discharge,dyeing wastewater accounts for the largest proportion.The addition of different dyes and additives leads to complex composition of dyeing wastewater,high content of organic pollutants and difficult to degrade,inorganic salts,organic dyes,fiber impurities,surfactants and other substances make dyeing wastewater treatment was particularly difficult.Presently,the treatment methods of dyeing wastewater mainly include biochemical and chemical methods,among which the most promising treatment technology was photocatalytic oxidation,aerobic and anaerobic method.Photocatalytic oxidation has been widely welcomed by researchers for its environmental protection,cleanliness,no secondary pollution and sustainability.TiO₂,Zn O,Bi₂O₃ and other semiconductors were commonly used photocatalysts for wastewater treatment.Due to its advantages of non-toxicity,high photocatalytic efficiency,low cost and strong comprehensiveness,TiO₂ was widely used in environmental fields such as hydrogen production and wastewater catalytic degradation.However,the photocatalytic activity of pure TiO₂ was limited by wide band gap,easy recombination of photogenerated electron-hole pairs and difficult recovery.At present,the bandgap width of TiO₂ was mainly reduced by modification technology,and its photogenerated electron-hole pair recombination was inhibited,and TiO₂ was loaded on the carrier by sol gel,hydrothermal synthesis,impregnation coating,vapor deposition and other methods to improve its recovery efficiency.Aiming at the difficulties of TiO₂ catalyst recovery and low visible light catalytic activity,this study studied and prepared ceramic photocatalyst fired with TiO₂ as the main catalyst to catalyze the treatment of simulated dyeing wastewater under visible light.The effect of composite Al₂O₃,SiO₂ and ZrO₂ insulators on the structure and properties of ceramic catalyst was studied in detail,and the photocatalytic degradation performance of the catalyst on simulated dyeing wastewater was studied.The effect of TiO₂ and sintering temperature on the structure and properties of ceramic catalyst was studied,and the photocatalytic degradation performance of the catalyst on simulated dyeing wastewater was studied.The effects of CeO₂,Zn O,Cu O and Cr₂O₃ on the structure and properties of the catalysts were studied,and the photocatalytic degradation performance of the catalysts on simulated dyeing wastewater was studied.The effects of catalyst morphology and reduction treatment on catalyst structure and properties were studied,and the effects of experimental parameters on the degradation rate of simulated dyeing wastewater were studied.The research showed that the TiO₂ as the main catalyst of ceramic photocatalyst could maintain high photocatalytic activity in the process of ceramic preparation;The addition of Al₂O₃ as the main raw material of ceramic matrix could inhibited the agglomeration of TiO₂;When rutile TiO₂ was used as the main catalyst and Al₂O₃ was used as the main raw material,adding appropriate amount of SiO₂ could promote the partial conversion of rutile TiO₂ to anatase TiO₂（R-A phase transformation）,refine the TiO₂ grain and greatly improve the mechanical properties of the catalyst.Anatase TiO₂ as the main catalyst,Al₂O₃ as the main raw material,adding 5 wt%SiO₂,suitable sintering temperature could improve the crystallinity and photocatalytic performance of the ceramic.The addition of CeO₂,Zn O,Cu O,Cr₂O₃ and other semiconductors could construct n-n and p-n heterojunction to promote the separation of photogenerated holes and electron pairs,and increase the number of carriers on the catalyst surface.In the nitrogen atmosphere,Na BH₄ was added to calcination,and oxygen vacancy was introduced into the ceramics to improve their hydrophilic and photocatalytic properties.At 1000 ^oC sintering temperature,anatase TiO₂ as catalyst,Al₂O₃as the main raw material,adding 5 wt%SiO₂,6 wt%Zn O and 5 wt%corn starch to prepare porous ceramsites,calcining porous ceramics at 350 ^oC to reduce it,black porous ceramsites catalyst can be prepared.At this time,the water absorption of ceramsite catalyst is 45.24%,the open porosity is 61.97%,the bending strength is 1.32MPa,the surface contact angle is11.50^o,and the band gap is 2.81 e V.Under the simulation of a solar intensity,0.36 g black ceramide and 1.6 mmol/L oxidant PMS were added.After 120 min,the degradation rates of10 mg/L,100 m L,p H 4 methyl orange,methylene blue and Rhodamine B simulated wastewater were 99.43%,91.38%and 99.28%.