Visible light improved, photocatalytic activity of magnetically separable titania nanocomposite

A visible light improved, magnetically separable TiO2 nanocomposite was successfully synthesized with silicon dioxide (SiO2) as coating and supported on a permanent magnet Viz., nickel ferrite (NiFe2O4). Thus synthesized photocatalysts was further characterized for its crystalline phase, particle size, surface morphology, inorganic composition, adsorption-desorption hysteresis, BET surface area, pore size distribution, magnetic hysteresis, saturation magnetization, coercivity, elemental composition, chemical state, electronic state and visible light absorption spectra analysis with respective techniques. The crystallographic peak and inorganic elemental composition revealed the structure and composition of pure and nanocomposite TiO2. The prepared titania nanocomposite resulted in lower band gap energy (2.26 eV) and higher visible light absorption between 400 and 800 nm than that of pure TiO2 (2.76 eV). The photocatalytic activity was investigated with a recalcitrant phenolic compound namely 2,4-dichlorophenol (2,4-DCP) as a model pollutant under direct bright and diffused sunlight irradiation. An almost complete degradation of 2,4-DCP was achieved with an initial concentration of 50 mg/L for TiO2 nanocomposite in 90 min and 5 h under bright and diffused sunlight conditions. Similarly pure TiO2 resulted in a nearly complete degradation in 180 min under bright and approximate to 90% in 5 h under diffused conditions. Further the TiO2 nanocomposite was recovered under a magnetic field with a mass recovery approximate to 95%. The nanocomposite also exhibited improved remanence, saturation magnetization and coercivity property along with good stability against magnetic property losses for reuse. (C) 2012 Elsevier B.V. All rights reserved.