Highly efficient visible-light-driven photocatalytic degradation of organic pollutants by using magnetically separable supported heterogeneous nanocomposites (SiO2/Fe3O4/Ag2WO4)

Abstract

In this work, the heterogeneous photocatalyst (SiO2/Fe3O4/Ag2WO4) that is composed of active nanomaterials precipitated onto mesoporous nanosilica was synthesized using multistep methods. The nanosilica was synthesized using the Stöber method. 10% Wt. of Fe3O4 and Ag2WO4 NPs were precipitated on the surface of nanosilica to produce supported SiO2/Fe3O4/Ag2WO4 magnetic nanoparticles (MNPs). Different techniques were used to characterize the synthesized supported MNPs, including UV-DRS, XRD, VSM, BET, BJH, and FE-SEM. The photocatalytic degradation activity of synthesized supported MNPs was conducted through a batch reactor towards methylene blue dye (M.B) under visible light irradiation (40 W LED and 55 W Xenon lamps). The experimental results showed a high degradation efficiency (approximately 100%) related to SiO2/Fe3O4/Ag2WO4 after 45 min of irradiation time. The SiO2/Fe3O4/Ag2WO4 revealed high adsorption activity, where 60% of its removal efficiency was during the first 60 min of adsorption in the dark. The kinetics studies revealed that the photocatalytic activity of SiO2/Fe3O4/Ag2WO4 was nearly 4.2 and 3.9 times higher than pure Ag2WO4 and SiO2/Fe3O4, respectively. The significantly improved photocatalytic activity of the SiO2/Fe3O4/Ag2WO4 MNPs was attributed to their higher stability and specific surface area, in addition to a synergistic outcome between Ag2WO4 and SiO2/Fe3O4 that leads to efficient electron–hole pairs separation. The effects of several parameters were also examined for supported MNPs, including catalyst dose, initial concentration of M.B, pH, and H2O2 addition. The reusability and recyclability study revealed that the synthesized SiO2/Fe3O4/Ag2WO4 are highly stable and can be used with high feasibility for removal of different organic dyes from wastewater.