Synthesis of a novel visible light responsive γ-Fe2O3/SiO2 /C-TiO2 magnetic nanocomposite for water treatment

Abstract

Recovery of TiO2 from a solution after photocatalysis is a matter of concern since it allows for reusability and better purification. Maghemite nanoparticles coated with silica and carbon doped titanium dioxide were synthesized through a stepwise approach via co-precipitation and sol-gel methods. The prepared nanoparticles were characterized using fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET) analyses and thermogravimetric analysis (TGA). The particles were then evaluated for photocatalytic activity under sunlight irradiation and strict ultraviolet (UV) light. Characterisation by FTIR, XRD and EDS substantiated the existence of the intended structure of the nanocomposite and the particles were found to be well within the nanometre range with a quasi-spherical shape and a particle size distribution of 15-22 nm. BET suggested an average surface area of 55.2035 m2/g and an average pore diameter of 8.36201 nm which was an indication of a good adsorption surface. A 5 ppm methylene blue solution was degraded with an efficiency of 96.8% after 3 h of solar irradiation. Though TEM and SEM indicated particle agglomeration, photocatalysis using these nanoparticles was seen to be effective. A visible light active nanocomposite that exhibited good stability and magnetism was synthesized and it has great potential in water treatment and green chemistry as a whole.