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

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.