Synthesis of FeWO4 heterogeneous composite by the sol-gel process: enhanced photocatalytic activity on malachite green

Abstract

Synthesis and characterization of mixed oxide FeWO4 as a photocatalyst in the photodegradation of malachite green (MG) by UV irradiation at 254 nm in a closed reactor was performed. The synthesis was carried out by the sol-gel method (or the citric acid sol-gel method) at room temperature using sodium tungstate(VI) and iron(II) sulfate as precursors. Characterization of the photocatalyst was performed using X-ray diffraction (XRD), FT-IR spectrometry, Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDXS), BET and X-ray fluorescence (XRF) methods. In order to assess its effectiveness in the degradation of MG, various photo-catalytic tests were carried out. The results obtained showed that the oxide prepared by the sol-gel method has more interesting photocatalytic properties and that the acidity of the medium accelerates the photo-degradation, the optimal conditions were determined such as strongly acidic (pH = 3), and [FeWO4] = 0.5 g L-1 with the rate constant k equal to 0.068 min(-1).