Preparation,Characterization And Photocatalytic Properties Of TiO₂-based Nanomaterials

At present,Advanced Oxidation Processes?AOPs?,which has better degradation effect in chemical process,has been widely used in industrial wastewater treatment,among which Fenton oxidation technology and photocatalytic oxidation method have attracted many scholars'attention because they can degrade most of the organic matters.A photocatalytic composite with titania as the substrate and Fenton-like ferrite?MnFe₂O₄and BiFeO₃?as dopant was prepared by co-precipitation and sol-gel method.Photocatalytic properties and Photo-Fenton properties of the composites were determined by degrading dyestuff.In this experiment,the target pollutants of methylene blue and methyl orange were used to determine the influencing factors of catalytic performance.The samples were characterized by XRD,SEM and UV-Vis.By analyzing the influence factors of MnFe₂O₄/TiO₂?TMF?and BiFeO₃/TiO₂?TBF?on the catalytic performance of the target pollutants,the optimum conditions were determined from the aspects of the doping amount,the dosage of the catalyst,the p H value of the system,the concentration of hydrogen peroxide in the photo-fenton reaction and the intensity of the light source:?1?To methylene blue light in TMF fenton experiment,through the doping amount of catalysts,supply,the system of p H value,concentration of hydrogen peroxide and the influence of light intensity and other conditions on the catalytic properties were studied and found:TMF for MB dye degradation rate in the light of 300 W halogen lamp,MnFe₂O₄doping amount of TiO₂was2%,the catalyst dosage is 0.6 g/L,p H value of 11,the concentration of hydrogen peroxide is 8 mmol/L,reaction for 180 min,the TMF of MB degradation rate is as high as 96.8%.?2?Under the optimal catalytic conditions,the actual printing and dyeing wastewater of a certain plant was degraded by optical Fenton,and the removal rate of COD reached 61.2% under the condition that the original COD value was low and the traditional method was difficult to continue processing.?3?Found by experiments in additional magnetic field can be effectively separated under the action of photocatalyst,benefit for the recycling of the catalyst,when MnFe₂O₄/TiO₂ catalyst recycling experiment after repeated four times,the degradation of MB capacity can reach more than 90% still shows that catalyst after four experiments can still maintaining high catalytic activity.?4?Of Methyl Orange in TBF light fenton experiment,through the doping amount,quantity of catalysts,system of p H,concentration of hydrogen peroxide and the influence of light intensity and other conditions on the catalytic properties were studied and found:when the light source for 300W halogen lamp,BiFeO₃ doping amount of TiO₂ was 1%,the catalyst dosage is 0.8 g/L,p H value of 8,hydrogen peroxide concentration is 6 tendency for L,reaction 180 min,TBF for the degradation of MO rate as high as 90.02%.At the same time,when the light source is ultraviolet,it also has catalytic ability to dye.?5?Through the free radical capture experiment of TBF photo-fenton degradation MO system,the photocatalytic mechanism was analyzed.The results showed that hydroxyl free radical and superoxide free radical played a major role in the degradation of MO in this experiment,and the mechanism process was predicted reasonably based on the results.