VISIBLE AND UV-A LIGHT-INDUCED PHOTOCATALYSIS OF FORMIC AND OXALIC ACIDS WITH S-DOPED, Fe-LOADED TITANIA

In the present study, visible light‐induced photocatalysis of aqueous solutions of formic and oxalic acid with S‐doped, Fe‐loaded TiO2 (SFT) was investigated. The effect of formic and oxalic acid concentrations (50 and 100 mg/L), initial pH (3 and 7) and catalyst concentrations (5 and 10 g/L) under visible or UV-A light on degradation rate was evaluated. The removal efficiencies of formic acid and oxalic solutions (50 mg/L) under UV light irradiation with SFT were 10% and 67%, respectively. The experimental run conducted with formic acid solutions (50 mg/L), 53 and 40% dissolved organic carbon (DOC) removal efficiencies were achieved at 120 min reaction time under visible light irradiation at pH 3.0 for 5 and 10 g/L catalyst concentrations, respectively. At the same experimental conditions the obtained DOC removal efficiencies for oxalic acid were 41% for 5 g/L and 51 % for 10 g/L catalyst concentration. Photocatalytic oxidation the process under visible light was generally slower at pH 7. Increasing the photocatalyst concentration from 5 to 10 g/L increased oxalic acid degradation, but decreased formic acid degradation for visible light irradiation. Our experimental results have clearly indicated that SFT has a potential as a photocatalyst that can be activated via visible light irradiation for the photocatalytic mineralization of the studied model pollutants formic and oxalic acid under UV/Vis light irradiation.