Solid waste derived nanocomposite of Ag (0) loaded Fe2O3-SiO2 for solar power degradation of antibiotics

Abstract

The utilization of solid waste (red mud) from aluminum industries is a major challenge to the scientific community. The main content in red mud is iron. Removal of iron from the red mud as hematite (Fe2O3) by hydrometallurgical route and the surface modification through a co-catalyst for degradation of antibiotics was focused in the present work. The extracted Fe2O3 was embedded with SiO2 to increase the surface area and then different weight percentage of Ag was impregnated onto the surface of Fe2O3-SiO2 as a co-catalyst. Different characterized techniques like XRD, BET, SEM, XPS, PL, EIS, M−S were used to evaluate the surface morphological and electrochemical properties of the composite. From the XRD, the observed peaks were indexed in agreement with the rhombohedral (hexagonal) structure of α-Fe2O3 with lattice constants of a = 0.5034 nm, and b = 1.75 nm. From BET, it is seen that the surface area of extracted α-Fe2O3 from red mud is found out to be 13.204 m2/g and it was increased (230.318 m2/g) after modification with SiO2 again after impregnation of Ag onto the surface of Fe2O3-SiO2 surface area slightly decreased (203.972 m2/g) because of pore blocking. From the band gap energy, it confirmed that all the materials reveal the visible light active photocatalyst. Due to the surface plasmon resonance (SPR) effect of Ag (0), more polarized light was absorbed by the catalyst and created a Schottky barrier at the junction and favored the charge separation and increased the photocatalytic efficiency. 3 % Ag (0) loaded over Fe2O3-SiO2 illustrated the highest ciprofloxacin (CIP) degradation (94 %) under solar light irradiation. The synergism between Fe2O3-SiO2 and Ag, Surface Plasmon Resonance (SPR) effect of Ag (0), charge separation and reduction in electron-hole recombination were major cause of improvement of CIP degradation under visible light.