ZnSO4-TiO2 doped catalyst with higher activity in photocatalytic processes

Abstract This study presents the synthesis and activity of ZnSO 4 –TiO 2 coated Raschig rings (RR). The activity of the Zn-doped catalyst (from now on Zn–TiO 2 /RR) was found to be higher than of the pure Degussa P25 TiO 2 during the photodegradation of organic compounds. The most suitable doping level of TiO 2 for Zn was 4 mol% noted as Zn (4% mol)–TiO 2 /RR during the degradation of azo-dye Orange II and of the transparent 2-propanol solutions. The degradation kinetics of the probe molecules was systematically investigated as a function of the catalyst make-up and some of the solution parameters. XPS measurements show Zn 2p 3/2 peak positions for Zn–TiO 2 sample in the range 1021.58–1022.00 eV. This energy range was observed to be lower than 1022.54 eV recorded for the reference ZnSO 4 sample. This shift indicates that the Zn-atoms act as electron acceptors in the Zn-doped TiO 2 and may be responsible for the higher catalytic activity observed for the Zn (4% mol)–TiO 2 /RR compared to the TiO 2 /RR photocatalyst during Orange II degradation. Insight is given onto the complex oxidation/reduction processes takes place at the interface of Zn–TiO 2 . The changes occurring in the Zn, TiO 2 and S catalyst components are discussed as a function of the time of reaction. The Zn–TiO 2 catalyst was characterized by elemental analysis (EA), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), confocal microscopy, X-ray photoelectron microscopy (XPS) and X-ray diffraction (XRD).