Solar and UV for photocatalytic degradation of spiramycin using nitrogen-doped TiO2

The extensive use of antibiotics in both veterinary and clinical settings has unintentionally led to their presence in surface waters, raising significant concerns. Macrolides, a class of antibiotics classified as ‘emerging contaminants’, have the potential to infiltrate the environment and negatively impact human health. To address this issue, band gap engineering through surface modification of titanium dioxide (TiO₂) has shown promising efficacy in mitigating such harmful contaminants. In our study, spiramycin (SPR) was subjected to both UV and solar radiation in the presence of a suitable catalyst in a slurry batch reactor. The synthesized catalysts were characterized using various techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDX), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), and Brunauer–Emmett–Teller (BET) analysis. Optimization of key parameters indicated a maximum degradation of 91.08% degradation for 10 mgL⁻¹ SPR with 2NTiO₂ within 180 minutes under solar radiation. The reaction kinetics revealed that SPR degradation followed the Langmuir–Hinshelwood (L–H) model. Additionally, the intermediates formed during the degradation process were identified using liquid chromatography–mass spectroscopy (LCMS) and a degradation pathway was proposed. A significant reduction in the toxicity of SPR was observed following the photocatalytic treatment.