Hydrothermal synthesized magnetically separable mesostructured H2Ti3O7/γ-Fe2O3 nanocomposite for organic dye removal via adsorption and its regeneration/reuse through synergistic non-radiation driven H2O2 activation.

Abstract

Hydrogen titanate (H2Ti3O7) nanotubes/nanosheets (HTN) are emerging class of adsorbent material which possess unique property of activating hydrogen peroxide (H2O2) to generate the reactive oxygen species (ROS), such as superoxide radical ions (O2.-) and hydroxyl radicals (·OH), effective in the decomposition of surface-adsorbed dye. However, HTN are non-magnetic which create hurdle in their effective separation from the treated aqueous solution. To overcome this issue, magnetic nanocomposites (HTNF) composed of HTN and maghemite (γ-Fe2O3) nanoparticles have been processed by subjecting the core-shell magnetic photocatalyst consisting of γ-Fe2O3/silica (SiO2)/titania (TiO2), having varying amounts of TiO2 in the shell to the hydrothermal conditions. HTNF-5 magnetic nanocomposite consisting of 31wt% H2Ti3O7, typically having nanotube morphology with the highest specific surface area (133m2g-1) and pore-volume (0.22cm3g-1), exhibits the highest capacity (74mgg-1) for the adsorption of cationic methylene blue (MB) dye from an aqueous solution involving the electrostatic attraction mechanism and pseudo-second-order kinetics. Very fast magnetic separation followed by regeneration of HTNF-5 magnetic nanocomposite has been demonstrated via non-radiation driven H2O2 activation. It has been ascertained for the first time that the underlying mechanism of dye decomposition involves the synergy effect between the constituents of HTNF magnetic nanocomposite.