Effect of electron acceptors H_2O_2 and O_2 on the generated reactive oxygen species ~1O_2 and OH~· in TiO_2-catalyzed photocatalytic oxidation of glycerol

The effect of the electron acceptors H2O2 and O2 on the type of generated reactive oxygen species（ROS）,and glycerol conversion and product distribution in the TiO2-catalyzed photocatalytic oxidation of glycerol was studied at ambient conditions.In the absence of an electron acceptor,only HO^·radicals were generated by irradiated UV light and TiO2.However,in the presence of the two electron acceptors,both HO^· radical and ^1O2 were produced by irradiated UV light and TiO2 in different concentrations that depended on the concentration of the electron acceptor.The use of H2O2 as an electron acceptor enhanced glycerol conversion more than O2.The type of generated value-added compounds depended on the concentration of the generated ROS.

Photocatalytic activity of metal nanoparticle-decorated titanium dioxide for simultaneous H_(2) production and biodiesel wastewater remediation

A set of metal nanoparticle-decorated titanium dioxide(Mx/TiO_(2);where x is the percent by mass,%)photocatalysts was prepared via the sol-immobilization in order to enhance the simultaneous hydrogen(H_(2))production and pollutant reduction from real biodiesel wastewater.Effect of the metal nanoparticle(NP)type(M=Ni,Au,Pt or Pd)and,for Pd,the amount(1%–4%)decorated on the surface of thermal treated commercial TiO_(2)(T_(400))was evaluated.The obtained results demonstrated that both the type and amount of decorated metal NPs did not significantly affect the pollutant reduction,measured in terms of the reduction of chemical oxygen demand(COD),biological oxygen demand(BOD)and oil&grease levels,but they affected the H_(2) production rate from both deionized water and biodiesel wastewater,which can be ranked in the order of Pt_(1)/T_(400)>Pd_(1)/T_(400)>Au_(1)/T_(400)>Ni_(1)/T_(400).This was attributed to the high difference in work function between Pt and the parent T400.However,the difference between Pt1/T400 and Pd1/T400 was not great and so from an economic consideration,Pd/TiO_(2) was selected as appropriate for further evaluation.Among the four different Pdx/TiO_(2) photocatalysts,the Pd3/TiO_(2) demonstrated the highest activity and gave a high rate of H_(2) production(up to 135 mmol·h−1)with a COD,BOD and oil&grease reduction of 30.3%,73.7%and 58.0%,respectively.