Degradation of levofloxacin by a photodeposited Pt/TiO2 porous ceramic composite under UV irradiation and analysis of transformation pathways.

A recoverable Pt/TiO2 porous ceramic composite was prepared by photodeposition for ultraviolet (UV)-driven degradation of levofloxacin (LEV). The catalyst was characterized by structural, microscopic, surface, optical and elemental analyses, and its activity, stability, reactive species, transformation products and predicted toxicity were evaluated. Pt deposition preserved the anatase/rutile structure of P25 TiO2, introduced dispersed metallic Pt, enhanced long-wavelength absorption and improved LEV removal. Under optimized conditions (1.0 wt% Pt, 2.0 g/L catalyst, pH 9.0), 94.98 ± 0.56% of LEV was degraded within 40 min, outperforming TiO2. The composite retained high activity over six cycles with low Pt leaching. Scavenger tests indicated that •OH was the dominant reactive species, with h+ and •O2- also contributing. LC-MS detected 18 transformation products and supported five tentative degradation pathways. Quantitative structure-activity relationship (QSAR) predictions predictions suggested reduced bioaccumulation and lower mutagenicity/developmental-toxicity concerns for several terminal products, although experimental toxicity validation remains necessary.