Photocatalytic reduction of potassium chromate by Zn-doped TiO ₂ /Ti film catalyst

The aim of this work was to investigate the photocatalytic (PC) reduction of potassium chromate by Zn-doped TiO ₂ /Ti film catalysts. The film catalyst was prepared by plasma electrolytic oxidation method in H ₂ SO ₄ solution with different dosages of ZnSO ₄ . The composition and structure of the film catalysts was studied by XRD, SEM and EPMA. The removal rate of potassium chromate was investigated under the conditions of the different dosages of ZnSO ₄ and the initial concentration of chromate potassium, and the reductive product during the PC reduction process was analyzed. The results showed that the film catalyst was composed of anatase TiO ₂ and rutile TiO ₂ with the porous structure. When the dosage of ZnSO ₄ was 0.2 g/L, the film catalyst presented the highest catalytic activity, which related to the amount and the crystal grain size of anatase TiO ₂ in the film. The PC reduction of potassium chromate by the film catalyst obeyed the pseudo-first-order kinetic equation. The UV-vis spectrum and XPS analyses proved that chromate Cr(VI) was reduced to Cr(III), which existed in the form of insoluble Cr(OH) ₃ .