Influence of Salts on the Photocatalytic Degradation of Formic Acid in Wastewater

Conventional wastewater treatment technologies have difficulties in feasibly removing persistent organics. The photocatalytic oxidation of these contaminants offers an economical and environmentally friendly solution. In this study, TiO(2) membranes and Ag/TiO(2) membranes were prepared and used for the decomposition of dissolved formic acid in wastewater. The photochemical deposition of silver on a TiO(2) membrane improved the decomposition rate. The rate doubled by depositing ca. 2.5 mg of Ag per 1 g of TiO(2). The influence of salinity on formic acid decomposition was studied. The presence of inorganic salts reduced the treatment performance of the TiO(2) membranes to half. Ag/TiO(2) membranes had a larger reduction of ca. 40%. The performance was recovered by washing the membranes with water. The anion adsorption on the membrane surface likely caused the performance reduction.