Exploration of novel advanced oxidation systems with high efficiency toward radical generation is of significant importance due to the extensive and versatile application of reactive species in the wastewater treatment. Herein we report a simple UV-catalytic homogeneous advanced oxidation system (UV/Fe3+/hydrogen sulfite (BS)), which is capable of generating abundant radicals (e.g., SO3-, SO4-, SO5- and HO) in the aqueous environment. Sulfamethoxazole (SMX) degradation using this system was tested. Results indicated that SMX could be degraded effectively by UV/Fe3+/BS and sulfate radical (SO4-) and hydroxyl radical (HO•) were verified to be presented in this system and be contributive to SMX removal. The acidic pH (4.0) and a low BS/Fe3+ ratio (10:1) were suitable for SMX degradation. The presence of fulvic acid (FA) and HCO3- strongly inhibited the degradation of SMX, but obvious acceleration was observed in the presence of NO3- due to its contribution on additional radical generation by photosensitization. Based on the detected transformation products through LC-MS analysis, the degradation pathway of SMX by UV/Fe3+/BS was proposed including hydroxylation and bond cleavage.
Keywords: Ferric ion; Hydrogen sulfite; Hydroxyl radical; Sulfamethoxazole; Sulfate radical; UV.
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