Photoelectrocatalysis of Cefotaxime Using Nanostructured TiO₂ Photoanode: Identification of the Degradation Products and Determination of the Toxicity Level

Nanostructured TiO₂ thin films were fabricated via a facile, economical, and energy-efficient microwave-assisted dip-coating (MWDC) technique. Further, the resulting TiO₂ films were characterized by means of X-ray diffraction, high-resolution transmission electron microscopy, selected-area electron diffraction, Fourier transform Raman spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy techniques for their phase structure, morphology, and optical and surface properties. TiO₂-mediated photoelectrocatalytic degradation of the antibiotic cefotaxime (CFX) in an aqueous solution was studied by varying the pH under UV illumination. The degradation intermediates and possible reaction degradation path of CFX were analyzed by electrospray ionization time-of-flight mass spectrometry (MS). The MS spectra revealed that degradation of CFX occurs through β-lactum corresponding to the cleavage of the cephem nucleus. Moreover, the antibacterial activity of CFX prior to and after photoelectrocatalytic degradation was carried out to analyze the toxicity against <i>Staphylococcus aureus</i> and salmonella typhi bacteria. Interestingly, it was observed that the antibiotic activity was drastically inhibited after photoelectrocatalytic degradation of the CFX solution. The photoelectrocatalytic stability of a nanostructured TiO₂ electrode was evaluated by recycling the degradation experiments. It was observed that there was no significant decrease in the catalytic activity, indicating potential applications of the TiO₂ electrode prepared by the MWDC method