New evidence for disinfection, self-cleaning and pollutant degradation mediated by GF-TiO2-Cu mats under solar/visible light in mild oxidative conditions

This study presents the performance of GF-mats loaded with TiO2 and Cu under solar/visible light leading to bacterial inactivation and pollutant degradation at both solid-air and solid-liquid interfaces. The GF-mats show effective water disinfection, self-cleaning and degradation of an organic pollutant in solution. Cleaning of the GF-mats was found to be a necessary step before grafting TiO2 and Cu/CuO in amounts of TiO2 (10%-25% by weight) and Cu (0.03%-0.45% by weight) respectively. A GF-mat consisting of 15.4% TiO2 and 0.45% Cu led to bacterial disinfection within similar to 30 min under solar irradiation (290-800 nm light) and within similar to 60 min under visible light irradiation (400-800 nm). The oxidative radicals generated on the TiO2-Cu surface leading to disinfection, self-cleaning and abatement of the pollutant were identified and the diffusion length from the GF-mat was estimated for the most active HO2 center dot radical. The pH/surface potential changes in solution during the degradation of methylene blue (MB), which was taken as a model pollutant, were followed by means of a microelectrode. A GF-mat loaded with TiO2 13.1% and Cu 0.03% by weight led to the degradation of a dilute pollutant solution within similar to 100 min. The pollutant degradation was assessed by high performance liquid chromatography (HPLC) by following the decrease of the intensity of its characteristic absorbance peaks. The TiO2 and Cu eluted from the mat during the degradation of MB were detected by inductively coupled plasma mass-spectrometry (ICP-MS). The surface properties of the mats were investigated by scanning electron microscopy (SEM). Evidence is presented for the redox events on the GF-TiO2-Cu mats during the self-cleaning reactions by XPS. (C) 2017 Elsevier B.V. All rights reserved.