Paper Title
Dye Sensitized Tio2-Catalyzed Photodegradation Of Sulfamethoxazole Under Visible Light: Light Tunable Sensitizer

Abstract
Visible-light-induced photocatalysis is potentially advantageous and could be an efficient approach to degrade pollutants because it can be used to selectively target specific wavelength for the photodegradation of organic pollutants in wastewater. This study demonstrates the photodegradation of sulfamethoxazole (SMX) using [Pt(3,3'-dicarboxy-2,2'-bpy)(1,2-benzenedithiolate)] (Complex 1) and [Pt(4,4'-dicarboxy-2,2'-bpy)(1,2-benzenedithiolate)] (Complex 2) sensitized titanium dioxide (TiO2) under blue or yellow light (420 nm or 580 nm, respectively) irradiation in water. The Complex 1-sensitized TiO2 photocatalytic oxidation of SMX reached almost 100% removal under 420 nm irradiation for 3 hours in water. In addition, the formation of hydroxyl radicals can be facilitated by bubbling O2 during the photodegradation in which an effective decomposition of SMX was observed. Based on HPLC and UV-Vis studies of the decomposed products, it was found that SMX underwent cleavage of aromatic rings during the photodegradation process. In this research, we have demonstrated that Complex 1 assisted TiO2-catalyzed SMX photodegradation with O2 bubbling under blue light (or yellow light) irradiation is an effective process in eliminating this emerging organic contaminant. The degradation rate was quantitatively monitored by both HPLC and UV-Vis methods. Effects of hydroxyl radicals on decomposition of SMX are significant. The mechanisms of Complex 1 assisted TiO2-catalyzed SMX photodegradations with O2 bubbling are different between 420 nm (by π to π* transition) and 580 nm (by MLCT) light irradiations. Additionally, one of important findings is that SMX and its ring-containing intermediates were found to be totally destroyed by system (Complex 1/TiO2/O2 bubbling)-catalyzed SMX photodegradation under blue light irradiation within 3 hours. In contrast, the degradation was slower under yellow light irradiation. Index Terms - Emerging Contaminant, Photodegradation, Sulfamethoxazole (Smx); Visible Light Irradiation.