Covalent immobilization of phthalocyanine on graphene oxide for the degradation of phenol

In this study, 4-(4-aldehyde-phenoxy) phthalo nitrile (AlPPN) was firstly synthesized from the reaction between nitro groups of 4-nitrophthalonitrile and hydroxyl groups of p‑hydroxy benzaldehyde, and then 4-β-(4-aldehyde-phenoxy)cobalt phthalocyanine (CoAlPc) was prepared by means of the reaction between AlPPN and cobalt chloride catalyzed by DBU. Finally, CoAlPc was covalently immobilized onto amino-modified GO surface via the Schiff-base reaction to prepare CoAlPc/GO hybrids. Their structure and morphology were characterized by FT-IR, TEM, XRD and UV–Vis absorption spectra. These samples are tested for photocatalytic degradation of phenol under visible light irradiation. The loading of CoAlPc on support materials is to the benefit of its photocatalytic activity, and the photocatalytic activity of CoAlPc supporting on GO is higher than that on polyglycidyl methacrylate-modified silica (PGMA/SiO2). The dosage of CoAlPc/GO has significant effects on the photocatalytic degradation of phenol under visible light irradiation. A low dosage (0.2 g/L) of CoAlPc/GO exhibits the best photoactivity, whose degradation rate for phenol achieves 100% for 5 min and the intermediate (o-benzoquinone) mineralizes completely for 1 h in the presence of H2O2 under visible light irradiation. CoAlPc/GO still has stable photocatalytic activity after repeated use for 7 times.