Photocatalytic degradation of navy blue textile dye by nanoscale cobalt aluminate prepared by polymeric precursor method

Abstract The photocatalytic degradation of Novacrom of navy blue textile dye was investigated using nanocrystalline cobalt aluminate spinel (CoAl2O4) as a photocatalyst. This compound was prepared by thermal decomposition of a polymeric precursor obtained by the sol-gel method. The crystallization process of the precursor was evaluated by thermogravimetry-differential thermal analysis (TG/DTA). The structural characterization was carried out by X-ray diffraction (XRD) and Fourier Transform Infrared Transmission Spectrometry (FTIR). The morphological properties were investigated by transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET). The optical properties of CoAl2O4 nanoparticles were evaluated by UV-Visible diffuse reflectance measurements. The crystallization of CoAl2O4 spinel phase was entirely completed at 900 °C. This obtained powder was formed of relatively spherical grains with size about 25 nm and exhibits a specific surface area close to 34 m2/g. The optical band gap energy was estimated to be about 2.4 eV. The photodegradation process of the dye was followed by UV-Visible absorption spectroscopy analyzes. The photocatalytic activity tests under UV light irradiation show a 42% of discoloration efficiency after 150 min. The addition of H2O2 increases this rate to 67%.