Preparation Diatomite Loaded TiO₂ Photocatalyst And Its Photocatalytic Activity

Semiconductor photocatalytic technology is a kind of new treatment technology which can effectively exhibit solar energy or ultraviolet light conversion and great potentials in environmental pollution.Among various catalysts,TiO₂ photocatalyst is the most active studied due to its high chemical stability,strong oxidation and high photocatalytic activity,but TiO₂ is easy to agglomerate and seriously the loss.Therefore,this experiment adopts the porous structure carriers to load TiO₂,the coupling of the two produces synergistic effect to improve the capacity of TiO₂,which solves the difficulty in the separation of TiO₂ and is difficult to recycle.In this paper using traditional sol-gel method,having a high photocatalytic activity TiO₂/diatomite composite photocatalyst.The removal rate of fulvic acid UV254 and TOC was used as the evaluation index of the catalytic performance.The effects of different preparation conditions and reaction on the photocatalytic effect were investigated in order to provide reference and basis for the photocatalytic degradation of natural organic matter.Research results show that:?1?It is V[Ti?OC4H9?4]:V[H2O]:V[C2H5OH]:V[HAC]=10:4:40:4,calcined at 500 °C for 2 h.The optimum conditions for the preparation of TiO₂ catalyst are similar to spherical,uniform size,particle size around 20 nm,the UV254 and TOC removal efficiency of 78.5%-82.1% and 33.4%-34.7%.?2?The diatomite carriers calcined at 500 °C has the most obvious removal efficiency.Determining the preferred preparation condition of TiO₂/diatomite: V[Ti?OC4H9?4]:V[H2O]:V[C2H5OH]:V[HAC]=10:4:40:4,and calcined at 500 °C for 2 h,controled the load of 35%.The removal rate of UV254 and TOC were 97.4% 98.3% and 54.3% 55.2%,respectively.The prepared TiO₂/diatomite composite catalyst was anatase crystal,and the TiO₂ covered on the top of the diatomite uniformly.?3?With fulvic acid solution as test wastewater,under the action of ultraviolet irradiation,the removal efficiency of TiO₂/diatomite composite catalyst was the most obvious,and the removal rate of UV254 and TOC reached 95.8% and 44.5%,respectively.The adsorption effect is obviously improved dued to the existence of diatomite carriers.The optimum dosage of the composite catalyst is 1.43g/L.?4?The removal efficiency of UV254 and TOC could reach 92.7% and 40.9% with 75 mg/L of persulfate at 90 min,respectively,which was equivalent to the removal efficiency of UV254 and TOC without persulfate after 180 min.The addition of persulfate produced H+,which contributed to only 38.7% and 24% of the UV254 and TOC removal,respectively.By increasing persulfate dosing,the removal efficiency of fulvic acid firstly increased and then stayed at an equilibrium state.Under the conditions of this experiment,the most optimal dosage of persulfate was 75mg/L.Under the existing of persulfate,the highest photocatalytic efficiency was shown with pH from 5⁷.After TiO₂/diatomite composite catalyst repeated use of five times,UV254 and TOC removal rate can still reach 90.1% and 42.4%.Composite catalyst loss rate of only 5.6% was TiO₂ loss rate of 1/4,And the composite catalyst has large particle size which can be 2?m microfiltration membrane interception.?4?Under the condition of 15 W UV irradiation,the dosage of TiO₂/diatomite composite catalyst was 1.43 g/L,the dosage of persulfate was 75 mg/L,and the pH value was 7,which could effectively degrade fulvic acid,humic acid and oxytetracycline.The fluorescence intensity of fulvic acid is gradually attenuated under the photocatalytic degradation,and the humic acid is degraded into intermediate products such as protein and amino acid.