Integrating Photocatalysis into Sustainable Chemistry Education: A Laboratory Experiment on Antibiotic Degradation Using Commercial TiO2

This study presents a laboratory module designed to introduce undergraduate students to fundamental concepts of photolysis through the degradation of sulfamethoxazole (SMX), a widely used antibiotic and an emerging environmental contaminant. The module comprises three interconnected 4 h practical sessions. Participants investigate SMX decomposition under four illumination conditions (UVC, UVB, UVA, and visible light), comparing direct photolysis with commercial TiO2 (P25)-mediated photocatalysis. Core activities include constructing kinetic profiles, performing pseudo-first-order regression analyses, interpreting UV-Vis absorbance spectra, and elucidating degradation mechanisms through radical quenching tests and electron paramagnetic resonance spectroscopy. Representative results demonstrate significant direct photolysis of SMX under UVC as well as UVB, and negligible photocatalytic degradation under visible light. The above results, corresponding to the light absorption spectrum of SMX and the UV-Vis diffuse reflectance spectrum of TiO2, facilitate the understanding of the photolysis process. Hydroxyl radicals (•OH) were identified as the primary reactive species during the SMX degradation under UVA/TiO2. The experimental framework relies exclusively on conventional instrumentation (photoreactor, HPLC, UV-Vis spectrophotometer) and commercially available reagents, ensuring broad accessibility. This laboratory module contributes to sustainability-oriented education by offering a cost-effective, reproducible, and adaptable platform for introducing advanced oxidation processes in water remediation.