Synthesis of metallic silver nanoparticles decorated mesoporous SnO 2 for removal of methylene blue dye by coupling adsorption and photocatalytic processes

Abstract

© 2017 Elsevier B.V. Herein, we report a successful route for synthesis SnO2 and SnO2 decorated with 5 wt% metallic silver nanoparticles by sol-gel route using PVP as structure and pore directing agent. X-ray diffraction [XRD], N2-adsorption-desorption isotherm, diffuse reflectance spectra [DRS], Photoluminescence [PL] and high resolution transmission electron microscope [HRTEM] were selected to give a clear clue on the physicochemical features of the prepared nanoparticles. Homogeneous dispersion of metallic silver nanoparticles on the surface and the pore wall of SnO2 are accompanied by creation of various types of pores ranging from supermicropores to wide mesoporous system that results in remarkable increase in surface area, pore volume and C-BET constant by about 50%. This situation can explain the exceptional increase in the amount of dye adsorbed under dark conditions. Both adsorption and photocatalytic reactivity of silver decorated SnO2 are responsible by nearly the same extent for removal of methylene blue dye. COD experimental result confirms the degradation of the majority of methylene blue dye. The scavenger study indicates that all charge carrier and reactive radicals contribute by the same extent in case of pure SnO2. However, the positive holes and hydroxyl radicals are the predominant reactive species on Ag/SnO2. This result confirms the electron transfer from SnO2 conduction band to Ag Fermi level, so, the positive holes and the hydroxyl radical are more available to oxidize the organic pollutants. A new photocatalyst can be developed as an economically feasible and environmentally friendly method to mineralize wastewater from organic pollutants.