Interaction of levofloxacin with reverse micelle sol-gel synthesized TiO2 nanoparticles: Revealing ligand-to-metal charge transfer (LMCT) mechanism enhances photodegradation of antibiotics under visible light

Abstract

Synthesis of TiO2 through reverse micelle sol–gel (RMS) route showed 18 nm mean diameter with homogeneous particle size distribution (PDI = 0.11). TiO2 nanomaterial with a bandgap of 3.15 eV exhibited degradation efficiency of 83% towards levofloxacin (LFX) aqueous pollutant of 50 mg/L under 6H of the visible LED light. Visible light photoactivity ascribed to ligand to metal charge transfer (LMCT) process between the targeted antibiotic pollutant and titania photocatalyst. At neutral pH, photocatalytic degradation performance of TiO2 was observed higher due to adsorption of LFX through N of piperazinyl ring causing LMCT. The basic pH encouraged adsorption of LFX through the carboxylate group, which showed comparatively lesser activity. In acidic pH conditions, the lowest photoactivity resulted from the synergetic effect of lower adsorption and participation of the ketone-carboxyl adsorption site of LFX with TiO2.