Effects of Electron Donors on the TiO2 Photocatalytic Reduction of Heavy Metal Ions under Visible Light

The effects on TiO2 (Degussa P25) photocatalytic reduction of Cr(VI) under visible light, using methanol, methanal and formic acid as electron donors were investigated. The results showed that the photocatalytic reduction of Cr(VI) could be encouraged by methanol, methanal and formic acid. The fastest rate of Cr(VI) photoreduction was observed in the presence of formic acid followed by methanal and methanol. Cr(VI) could hardly be reduced by TiO2 without electron donors. The conversion percent of Cr(VI) was 100% using formic acid as electron donors after 80 min. For the methanal and methanol systems, the conversion percent of Cr(VI) were 93.62% and 22.69% after 6 h, respectively.