The promoting role of bismuth for the enhanced photocatalytic oxidation of lignin on Pt-TiO2 under solar light illumination

In this work, bismuth (Bi) and platinum (Pt) were utilized to promote the oxidation of lignosulfonate over TiO2 under solar light illumination at facile condition. The characterization results revealed the presence of Bi and Pt covering on TiO2 surface with zero valent state. And, the Bi1%/Pt1%-TiO2 photocatalyst performed excellent reactivity in oxidation of lignosulfonate to produce valuable compounds and CO2 due to the generation of photo-generated hole (h(+)) and superoxide radicals (O-2(center dot)), which were confirmed by quenching experiments. After 1 h of photocatalytic reaction, almost 85% of lignosulfonate was conversed into guaiacol, vanillic acid (VA), vanillin, 4-phenyl-1-buten-4-ol and other intermediates that were idenrified and quantified using HPLC. We found that the amount ratio of added Bi and Pt was the essential effect to the oxidative efficiency of lignin due to the produced additional active sites on TiO2 surface. This study provides a new strategy for generating h(+) and Of radicals under solar light and suggests its application for the selective oxidation of lignin. (C) 2016 Elsevier B.V. All rights reserved.