Photocatalytic Degradation Of Organics For Hydrogen Production

In this thesis,using organic pollutants from waste water as electron donors,the photocatalytic hydrogen evolution and decomposition of the pollutants over Pt/TiO₂ have been investigated.The preparation of visible-light resposive photocatalyst Cd_0.5Zn_0.5S and it's photocatalytic reaction for hydrogen production as well as decomposition of organic was searched.The reseach work is composed of two parts:In the first part,using furfural,furfuryl alcohol and furoic acid as electron donors,the photocatalytic hydrogen evolution has been investigated.The adsorption of pollutants furfural,furfuryl alcohol and furoic acid on TiO₂ is consistent with a Langmuir-Hinshelwood kinetic model,with adsorption constants 9.43×10²,3.88×10² and 1.48×10³L/mol,respectively.In 4.00×10^-3mol/L furfural,furfuryl alcohol and furoic acid solution,the efficiency of hydrogen evolution was enhanced respectively by 33.8%,260%and 444%after 10h irradiation,compared to that in pure water.The pollutants decreased by 10.0%,16.3%and 48.5%and the COD(chemical oxygen demand) by 10.0,18.0 and 28.4mg/L.h in the reaction system of furfural,furfuryl alcohol and furoic aeid after 5h irradiation respectively.The initial-pH effect on hydrogen evolution rate was investigated.Under weakly alkaline condition,the rate of the hydrogen generation reached maximum in the reaction systems of furfural and furoic acid,whereas under weakly acidic condition,the rate reached maximum in that of furfuryl alcohol.A possible reaction mechanism was discussed according to the intermediate products of degradation.In the second part,the activity of visible-light photocatalyst Cd_xZn_1-xS was compared and using glucose as the electron donor,the hydrogen production over visible-light photocatalyst Cd_0.5Zn_0.5S was inverstegated.The glucose can obviously enhance the efficiency of hydrogen evolution,the output of H₂ increased almost proportionally to the irradiation time within 5h irradiation,and the COD had decreased by 26.6%.The effect of initial concentration of glucose on the rate of hydrogen evolution is consistant with a Langmuir-Hinshelwood kinetic model.The effects of concentration of NaOH,ways of Pt loading on photocatalytic reaction had researched.The photocatalytic reaction process was monitored by cyclic voltammetry. The result showed that the degradeation rate of glcose was quite rapidness.