TiO2 nanoparticles containing sulphonated cobalt phthalocyanine: Preparation, characterization and photocatalytic performance

In order to utilize visible light more efficiently in the photocatalytic reaction, TiO2 nanoparticles containing different amounts of sulphonated cobalt phthalocyanine (CoPcS) were synthesized. The prepared photocatalysts were characterized by X-ray diffraction, N2 physisorption, UV–vis diffuse reflectance spectroscopy, transmission electron microscopy, thermogravimetric analysis, and FTIR. The characterization results show that CoPcS is anchored on the surface of TiO2 through SO2-O-TiO2 bonds. The photocatalysts were used for the degradation of 2,4-dichlorophenol (2,4-DCP) monitored by UV–vis spectrophotometry. The catalysts revealed enhanced activity for the degradation of 2,4-DCP compared to that of pure TiO2, which is attributed to the cooperative function of the two components of the photocatalyst. The photocatalyst containing 2.24 wt% CoPcS exhibited the highest photocatalytic activity for 2,4-DCP degradation, which was completed within 150 min using a 0.2 g/L dose of this photocatalyst in a 40 mg/L solution of the pollutant. The reactions follow zero-order kinetics, and the observed rate constants values change with initial concentrations of 2,4-DCP. The recyclability of the catalyst was tested, it can be used at least five times before the photocatalytic efficiency reaches that of pure TiO2 and oxalic acid and maleic acid were the major intermediate species at the final stage of the degradation process as identified by gas chromatography-mass spectrometry.