Photocatalytic degradation of 4-chlorophenol under visible light by using TiO2 catalysts impregnated with Co(II) and Zn(II) phthalocyanine derivatives.

In order to realize the photocatalytic reactions by visible light more efficiently, the photocatalytic activity of polycrystalline TiO 2 samples impregnated with carboxy functionalized Co(II) or Zn(II)-phthalocyanine as heteregoneous photocatalyst has been investigated. For this purpose, metallophthalocyanines(MPc) substituted with mercapto benzoic acid groups on each benzo moiety were incorporated into TiO 2 semiconductors to prepare TiO 2 –MPc composites as heterogeneous catalysts. TiO 2 and TiO 2 –MPc composites were characterized by making use of X-ray diffraction (XRD), infrared spectroscopy (FTIR) and UV–vis diffuse reflectance spectroscopy. The characterization results show that MPcs are anchored on the surface of TiO 2 through CO–O–TiO 2 bonds. The optimum loading of the dyes on TiO 2 were 0.49 μmol/g TiO 2 for ZnPc and 0.56 μmol/g TiO 2 for CoPc, nearly independent of TiO 2 used. These novel heterogeneous photocatalysts were used for the degradation of 4-chlorophenol (4-CP) in aqueous media in the presence of visible irradiation monitored by GC–MS spectroscopy. The catalysts revealed enhanced activity in visible region for the degradation of 4-CP when compared with that of pure TiO 2 , which is attributed to the cooperative function of the two components of the photocatalyst. The amount of remaining 4-chlorophenol residue was determined by using an internal standard (phenol) with gas chromatography–mass spectrometry and during the first 30 minutes 99% degradation of 4-chlorophenol was observed. [ABSTRACT FROM AUTHOR]