Delaminated montmorillonite with iron(III)-TiO2 species as a photocatalyst for removal of a textile azo-dye from aqueous solution

摘要

A set of mesoporous delaminated montmorillonites containing iron(III)-titanium oxide species was synthesized using two minerals: a bentonite as support and an ilmenite as source of Fe-TiO2 species. Several values of both sulphuric acid concentration and temperature were employed to extract Fe-TiO2 species from an ilmenite. Analyses by X-ray fluorescence, X-ray diffraction, scanning electron microscopy and nitrogen adsorption-desorption confirmed the successful formation of delaminated (or exfoliated) mesoporous structures. Optical properties of solids were determined by UV-Vis diffuse reflectance spectroscopy, and their band gap energy values were also calculated. A small UV-shift of band gap values regarding that of commercial photo-active TiO2 was detected as consequence of the quantum size effect, suggesting that photocatalytic experiments should be performed under UV-radiation assistance. The synthesized solids showed good activity in the photocatalytic oxidation of a textile dye (reactive yellow 145: RY 145), achieving conversions higher than 70% and chemical oxygen demand removal between 60% and 80%.