Synthesis and characterization of porphyrin-modified chitosan biopolymer and its application in the degradation of methylene blue under visible light

In this research, first, the cobalt (III) complex of 20,15,10,5-tetrakis (tetra(4-carboxyphenol)) porphyrin (Co-THPBP) was synthesized and its terminal acidic groups were chlorinated using thionyl chloride. Then, in order to stabilize the desired complex on the chitosan polymer substrate, the chlorinated cobalt-porphyrin complex was modified using protected 4-aminophenol, and as well as by deprotection of the terminal hydroxyl group of 4-aminophenol, the modified complex was attached to the chitosan polymer substrate. The prepared compounds were characterized using Fourier transform infrared spectroscopy (FT-IR), 1H NMR, Ultraviolet–visible spectroscopy (UV-Vis), scanning electron microscope (SEM), Diffuse Reflectance Spectroscopy (DRS). The prepared compound was applied for the photocatalytic removal of methylene blue in the presence of visible light. The results confirmed that the presence of chitosan polymer substrate has a significant effect on increasing the photodegradation of methylene blue dye.