ZnSO4-TiO2 doped catalyst with higher activity in photocatalytic processes

This study presents the synthesis and activity Of ZnSO4-TiO2 coated Raschig rings (RR). The activity of the Zn-doped catalyst (from now on Zn-TiO2/RR) was found to be higher than of the pure Degussa P25 TiO2 during the photodegradation of organic compounds. The most suitable doping level of TiO2 for Zn was 4 mol% noted as Zn (4% mol)-TiO2/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-TiO2 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 ZnSO4 sample. This shift indicates that the Zn-atoms act as electron acceptors in the Zn-doped TiO2 and may be responsible for the higher catalytic activity observed for the Zn (4% mol)-TiO2/RR compared to the TiO2/RR photocatalyst during Orange II degradation. Insight is given onto the complex oxidation/reduction processes takes place at the interface of Zn-TiO2. The changes occurring in the Zn, TiO2 and S catalyst components are discussed as a function of the time of reaction. The Zn-TiO2 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). (C) 2007 Elsevier B.V. All rights reserved.764167118519