Preparation Of TiO₂/lithium Silicate Powder And Photocatalytic Degradation Of DMP Wastewater

Dimethyl phthalate?DMP?is a plasticizer with strong solubility in a variety of resins.It is widely used in coatings,plastics and other fields.Because DMP is connected to the medium by hydrogen bonding or van der Waals force,it will be continuously released into the surrounding environment during the use of these products,causing water pollution.Because TiO₂ photocatalytic technology has excellent performance in the treatment of refractory organic pollutants,it is considered to be one of the most promising water treatment technologies.In this thesis,the self-made TiO₂/lithium silicon powder and La-TiO₂/lithium silicon powder catalyst are used to photocatalyticly degrade DMP simulated wastewater,which is of practical significance for the treatment of water containing PAEs.In this paper,TiO₂/lithium silicon powder was prepared by uniform mixed precipitation method,and La-TiO₂/lithium silicon powder was prepared by impregnation method.The prepared catalyst was used to photocatalyticly degrade DMP simulated wastewater.The factors affecting the degradation of DMP simulated wastewater by TiO₂/lithium silicon powder,La-TiO₂/lithium silicon powder and H2O2 system were studied.The mechanism of degradation of DMP simulated wastewater by TiO₂/lithium silicon powder and H2O2 system was studied.The following experimental conclusions were obtained:?1?The optimum preparation conditions for TiO₂/lithium silicon powder?1#?are:w_TiO2=5.17%,hydrolysispH=1.5,hydrolysis temperature t=75°C.,aging time t=60 min,calcination temperature T=600°C.,calcination time:T=120 min.?2?The optimum preparation conditions for TiO₂/lithium silicon powder?2#?are:the 1#catalyst was immersed in a 0.01 mol/L cerium nitrate solution for 20 h;the calcination conditions were:T=600°C,T=120 min.?3?BET,SEM and XRD analysis of 1#and 2#catalysts showed that:The 1#and 2#catalysts have undergone major changes in the morphology of lithium silicon powder,and the pore size and specific surface area have also changed.?4?The best experimental conditions for photocatalytic degradation of DMP wastewater by using 1#as catalyst are:catalyst dosage is 2.0g/L,initial pH of solution is 6.5,reaction is10h.Under these conditions,the degradation rate was 72.96%at that time.?5?The best experimental conditions for photocatalytic degradation of DMP wastewater by using 2#as catalyst are:the dosage of the catalyst is 0.8g/L,the initial pH of the solution is6.5,and the reaction is 10h.Under these conditions,the degradation rate was 76.19%at that time.?6?The degradation of DMP wastewater by H2O2 combined with photocatalysis showed that the addition of H2O2 significantly improved the degradation rate and degradation efficiency of DMP,and its degradation process conforms to the first-order kinetic equation.?7?The photocatalytic product of DMP under the combination of H2O2 and TiO₂/lithium silicon powder was determined by LC/MS.According to the detected intermediate product,the hydroxyl radical simultaneously attacks the side chain and benzene ring of DMP.