Synthesis, spectroscopic characterizations and antimicrobial activity of copper and zinc complexes of levofloxacin, ciprofloxacin and 3-carboxy-4-quinolone

Photocatalytic performance and interaction mechanism of reverse micelle synthesized Cu-TiO2 nanomaterials towards levofloxacin under visible LED light

The degradation performance of Cu-TiO₂ nanomaterials towards levofloxacin (LFX) antibiotic was investigated under an environmentally benign visible LED light source. Cu-TiO₂ nanomaterials were prepared using the reverse micelle sol-gel method with different copper content ranging from 0.25 to 1.0 wt% concerning titania. Characterization of Cu-TiO₂ samples was performed by XRD, TEM, UV-Vis, BET, ICP-MS, FTIR and XPS techniques. 0.5 wt% Cu-TiO₂ showed crystallite size below 6 nm, surface area (69.85 m²/g) and significant visible light absorption capacity. Both Cu¹⁺ and Cu²⁺ are formed in lower Cu-doped TiO₂ samples, whereas only Cu²⁺ is present in higher Cu-doped TiO₂ samples as evident in XPS analysis. 0.5 wt% Cu-TiO₂ has shown the optimum photocatalytic degradation of 75.5% under 6 h. of a visible light source. FTIR analysis of LFX adsorbed Cu-TiO₂ materials indicated the pollutant-catalyst interaction, where the declining trend was observed in photocatalytic degradation efficiency for higher Cu-doped TiO₂ samples due to copper-LFX complex formation. Copper-LFX complexes are formed due to the presence of Cu²⁺ in higher Cu-doped TiO₂ nanomaterials, which might have hindered the photocatalytic activity under visible light. Effects of initial pollutant concentration, catalyst loading and visible light intensity on the degradation of LFX are studied. Photocatalytic degradation pathways of LFX using best performing Cu-TiO₂ material were also proposed based on the LC-MS analysis.