Facile, green encapsulation of cobalt tetrasulfophthalocyanine monomers in mesoporous silicas for the degradative hydrogen peroxide oxidation of azo dyes

By immobilizing anionic cobalt tetrasulfophthalocyanine monomers into structure's cavities of MCM-41 with a matching pore size, a green, efficient and robust catalyst was first prepared under certain pH conditions. This approach proceeds with advantages from the viewpoint of green chemistry, in which the only solvent is water. Studies of the dye removal and the catalyst reuse showed that the catalyst could be reused effectively for the degradation of mostly common dyes. [Display omitted] ► A facile and green approach to improving catalytic activity of cobalt tetrasulfophthalocyanine for removal of dyes was proposed. ► By immobilizing anionic cobalt tetrasulfophthalocyanine monomers into structure's cavities of MCM-41 with a matching pore size, a robust catalyst was prepared under certain pH conditions. ► Phthalocyanine was largely incorporated into the mesoporoes and its aggregation was prevented. ► High activity for the oxidative degradation of dyes in water with H 2O 2 was demonstrated. ► CoTSPc@MCM-41 could be reused effectively for the degradation of mostly common dyes. A facile and green approach that improves the catalytic lifetime of cobalt tetrasulfophthalocyanine (CoTSPc) for the degradation of dyes is presented. Structurally ordered mesoporous silicas (MCM-41, MCM-48 and SBA-15), microporous aluminosilicates (ZSM-5) and macroporous alumina (γ-Al 2O 3) with different pore sizes were selected for the immobilization of CoTSPc, and a wide range of pH conditions (pH values from 4 to 12) were tested with the CoTSPc immobilization procedure. In the catalytic oxidation study, CoTSPc that was immobilized to MCM-41 silica (CoTSPc@MCM-41) prepared at a pH of 12 showed the longest catalytic lifetime. The TOC removal and discoloration of C. I. Acid Red 73 was approximately 60% and 82%, respectively, in the presence of CoTSPc@MCM-41 with H 2O 2 after 3 h. These results indicate that MCM-41, which has a matching size between its mesopores (30 Å) and CoTSPc molecules (25 Å), can prevent CoTSPc molecules from aggregating and improve its catalytic lifetime. In addition, the ability of CoTSPc@MCM-41 to degrade other dyes, and the reuse studies, demonstrated that CoTSPc@MCM-41 could be reused for the degradation of most common dyes.