Photocatalytic Degradation Of Gaseous Benzene With TiO₂ Coated On Fiberglass Cloth

The large emission of VOCs in industry has high concentration and many kinds of complex pollutants,which has severely disrupted the air quality of relevant area,and have great harm on human health.In different types of industrial VOCs sources,the occurrence times of benzene homologues are higher than those of other types of VOCs.In 2016,the detection of VOCs was incorporated into the "13th Five-Year plan" and the "Plan for Reducing VOCs in Key Industries" was published.Under the promotion of policies,the potential demand for effective VOCs governance will break out.In this paper,nanometer titanium dioxide photocatalytic method is applied to carry out the research on removing benzene efficiently.Based on the previous researches and the economic and operational analysis,titanium dioxide was prepared by sol-gel method,and coated on fiberglass by silica sol.Then self-made photocatalytic reactor was used to promote the research on photocatalytic removal of benzene exhaust.The results are as follows:The effects of different proportions of sol-gel method and calcination conditions on the removal efficiency of benzene has been investigated by single factor experiments.As the molar ratio of ethanol and butyl titanate has increased from 5 to25,the removal rate of benzene has increased from 42% to 81%.With the molar ratio of acetacetone and butyl titanate has increased from 0.15 to 0.39,the removal rate of benzene has reduced from 88% to 77%.As the molar ratio of water and butyl titanate has increased from 0.98 to 4.9,the removal rate of benzene has increased from 76% to88%,and then has slightly decreased to 85%.With the PH value from 1 to 5,the benzene removal has increased from 65% to 87%,and then down to 73%.As the calcination temperature has increased from 350 to 550,the removal of benzene has decreased from 88% to 83%,then increased to 85%,and then decreased to 22%.With the increase of calcination time from 1h to 4h,benzene removal has increased from85% to 88%,and then decreased to 82%.The optimum molar ratio of anhydrous ethanol and butyl titanate is 25,the optimum molar ratio of acetacetone to butyl titanate is 0.15,the optimum molar ratio of water to butyl titanate is 3,the optimum PH is 3,the optimum calcination temperature is 350,and the optimum calcination is1.5h.At this time,the removal efficiency of TiO2 is best,which reaches around 88%.The effects of relevant humidity,initial concentration of benzene,residence time and gas temperature on the removal rate of benzene has been investigated by thesingle factor test which adoptes the best self-made titanium dioxide.The relative humidity in 50%-60% has the highest photocatalytic efficiency for benzene removal,about 76%.When the initial concentration of benzene has increased from 30-50mg/m3 to 550-650mg/m3,the removal rate of benzene has decreased from 91% to 27%.When residence time has extended from 45 s to 120 s,benzene removal rate has increased from 65% to 92%.The prolongation of residence time not only improves the benzene removal rate,but also improves the carbonization rate of benzene completely.When the gas temperature has increased from 40 to 65,the removal rate of benzene has increased from 82% to 91%.High temperature is favorable for the desorption of water on the catalyst surface and the complete carbonization rate of benzene.In addition,this paper proves that the UV light has no degradation force to benzene.The removal rate of the self-made nano TiO2 to benzene is higher than the removal rate of common nano TiO2 to benzene,about 50%,which shows that the self-made catalyst has good catalytic performance.At the same time,this paper verifies the single use time of the self-made catalyst.By comparing the catalytic removal rate of different initial concentration of benzene,this paper finds that the catalyst is more suitable for the treatment of the concentration range below 250mg/m3.When 650mg/m3 inactivated TiO2 was incorporated into H2O2,catalyst regeneration could quickly restore the photocatalytic performance of TiO2 catalyst and achieve the efficiency before deactivation.Finally,the effect of H2O2 with TiO2 on photocatalytic degradation of benzene has been investigated.The treatment efficiency of TiO2 with H2O2 is slightly higher than the sum of their individual benzene removal rate.Although has a certain synergy,the effect is not significant.The addition of H2O2 at high concentration do not inhibit the deactivation of the catalyst.The intermediate detection only detects phenol.Other related intermediate gaseous products are not found.In the range of experimental volume flow,the relationship between photocatalytic oxidation rate and gas residence time is in good agreement with L-H dynamic simulation.ln(1-?)/? and V/Q? have a linear relationship.