Photocatalytic degradation of polycyclic aromatic hydrocarbons under visible light irradiation in water using TiO2/MgO nanocomposites

An extensive class of pollutants found in soil, water, and bottom sediments are categorized as polycyclic aromatic hydrocarbons. A possible method of breaking down polycyclic aromatic hydrocarbons is thought to be the photochemical approach. The potential application of mesoporous nanocomposites on TiO2/MgO as catalysts for the photooxidation of polycyclic aromatic hydrocarbons under the infuence of visible light was assessed in this work. TiO2/MgO nanocomposites were successfully obtained by the self-propagating high-temperature synthesis using methotitanic acid and magnesium nitrate as metal precursors. An important step in the synthesis was the conversion of the titanium precursor into a water-soluble form with the subsequent addition of glycine and citric acid at a carbon/nitrogen (C/N) molar ratio of 0.25. This synthesis via solutions allowed the target materials with major phases of magnesium metatitanate MgTiO3, magnesium dititanate MgTi2O5, and magnesium titanate Mg2TiO4 to be obtained after heat treatment at 750 °C. Heterostructured mesoporous TiO2/MgO powders with a specifc surface area of 22.0–28.4 m2 /g had an average diameter of the predominant pores of 10–30 nm. The greatest degree of photocatalytic oxidation of fuorene, pyrene, and benzpyrene (80, 68, and 53%, respectively) was obtained when it was combined with the TiO2/MgTi2O5/MgTiO3 nanocomposite under visible light irradiation. This study showed that mesoporous TiO2/MgO nanocomposites could be used as photooxidation catalysts for polycyclic aromatic hydrocarbons. The maximum level of photocatalytic oxidation of polycyclic aromatic hydrocarbons in TiO2/MgO nanocomposites occurred at pH 7 and a photocatalyst dose of 1 mg/L under the infuence of normal solar radiation.