LED-Based UV Oxidation of Pharmaceuticals: Effects of Wavelength and Intensity, pH, and TiO2 Loading.

The presence of pharmaceuticals in water resources has alarmed water and health authorities. In this study, ultraviolet(UV)-based oxidation was evaluated to decompose sulfamethoxazole, ibuprofen, and triclosan in comparison. In particular, as an alternative UV source to problematic conventional mercury lamps, light emitting diode (LED), so-called UV-LED, was evaluated for the decomposition of the pharmaceuticals in water under various conditions varying UV wavelength, irradiation intensity, reaction pH, and TiO2 loading. Photolytic decomposition of the pharmaceuticals was also compared with their photocatalytic decomposition. Photolytic decomposition of the pharmaceuticals was solely determined by relation between their UV absorption characteristics and the UV emission spectra of LEDs. Both photolytic decomposition and photocatalytic decomposition were greatly affected by reaction pH. The presence of TiO2 in cases that significant photolysis was present, rather inhibited the overall decomposition process. However, in all cases, photocatalysis showed better mineralization than photolysis.