Photocatalytic degradation of dimethyl phthalate in an aqueous solution with Pt-doped TiO2-coated magnetic PMMA microspheres

This study investigates the photocatalytic degradation of dimethyl phthalate (DMP) with both the titanium dioxide-coated magnetic poly(methyl methacrylate) (TiO2/mPMMA) and platinum-doped TiO2/mPMMA (Pt-TiO2/mPMMA) microspheres. The TiO2/mPMMA and Pt-TiO2/mPMMA microspheres are employed as novel photocatalysts that offer high photocatalytic activity, magnetic separability and good durability. The photocatalytic experiments of DMP under various conditions are conducted to examine the effects of the initial DMP concentration, photocatalyst dosage, UV radiation intensity and Pt doping content on the degradation of DMP. In addition, the correlations of the photocatalytic kinetics and quantum yield for DMP removal are proposed associated with the system parameters. According to the experimental results, there exists a distinct relationship between the reduction percentages of total organic carbons and DMP. Furthermore, the photodegradation mechanism of DMP in the photocatalytic process is established based on the identification of the intermediates. Moreover, the good repeatability of the photocatalytic performance with the use of the Pt-TiO2/mPMMA microspheres has also been demonstrated in the multi-run experiments. Therefore the Pt-TiO2/mPMMA microspheres are considered as a practical and promising photocatalyst in a suspension reaction system and they can be effectively recovered after use. This study provides useful information about the applications of the TiO2/mPMMA and Pt-TiO2/mPMMA microspheres for the photodegradation of DMP.