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

Abstract

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.