Photocatalytic degradation of saccharin under UV-LED and blacklight irradiation

BACKGROUNDThe photocatalytic treatment of the artificial sweetener saccharin (SAC), an emerging environmental contaminant, was investigated. UVA irradiation was provided by an environmentally friendly light-emitting diode (UV-LED), whose efficiency was compared with a conventional blacklight fluorescent lamp (UV-BL). RESULTSThe effect of the initial SAC concentration (2.5-10mg L-1), TiO2 concentration (0-500mg L-1), water matrix (absence/presence of humic acids), and treatment time on process efficiency was evaluated. Under the best conditions assayed ([SAC](0)=2.5mg L-1, [TiO2]=250mg L-1), SAC was degraded within 20 and 90min under UV-LED and UV-BL irradiation, respectively. Liquid chromatography-high resolution mass spectrometry (LC-HR/MS) revealed that SAC degradation proceeds via hydroxylation of the phenyl ring, cleavage of C-N bond and further oxidation reactions. Finally, UV-LED was found to be up to 16 times more energy efficient than UV-BL. CONCLUSIONSIn all cases, UV-LED achieved higher photocatalytic efficiency, in terms of organic degradation, and was found to be significantly more energy and cost efficient than conventional UV-BL irradiation source, thus rendering LED-photocatalysis a sustainable technology for the treatment of persistent contaminants. (c) 2017 Society of Chemical Industry