Photocatalytic degradation of an artificial sweetener (Acesulfame-K) from synthetic wastewater under UV-LED controlled illumination

The photocatalytic degradation of an artificial sweetener, acesulfame-K (ACE) was investigated using an ultraviolet light emitting diode (UV-LED) based irradiation in presence of titanium dioxide (TiO₂), zinc oxide (ZnO), hydrogen peroxide (H₂O₂), peroxomonosulfate (PMS, HSO₅⁻) and peroxodisulfate (PDS, S₂O₈²⁻). The pH of ACE solution showed significant effect on the degradation of ACE. It was observed that low pH value enhanced the ACE degradation rate. After 120 min by UV-LED/TiO₂ treatment, the degradation of ACE reached up to 90%, while in UV-LED/ZnO, UV-LED/H₂O₂, UV-LED/PMS, and UV-LED/PDS degradation rate were found to be 63%, 87%, 76% and 86% respectively. PMS and PDS both oxidant showed good results without the generation of any secondary sludge like other heterogeneous catalysts. The present study showed that in presence of catalysts and oxidants, UV-LED illumination significantly enhanced the degradation rate of ACE in comparison to direct photolysis by UV-LED. Possible degradation pathway of ACE was determined by gas chromatography-mass spectrometry (GC–MS) which confirmed the ACE degradation by generation of three byproducts.