Efficient oxidative degradation of Azo dyes by cobalt(II) porphyrin complex supported on modified bentonite and chitosan: structural characterization and mechanistic insight

Abstract Cobalt(II) complex of 5, 10, 15, 20 tetrakis [4-(hydroxy)phenyl] porphyrin [Co(II) TP-OHPP] 1 , [Co(II) TP-OHPP]/CPTES−Bentonite Clay 2 composite, [Co(II)TP-OHPP] / CPTES−Bentonite Clay/ Chitosan 3 composite, has been used to study the catalytic degradation of a group of azo dyes (e.g., Methyl Orange, Methyl Red, and Orange II) by hydrogen peroxide in an aqueous solution. 1 HNMR, FT-IR, SEM, XRD, TGA, DLS and UV-Vis were used to characterize the structures and characteristics of the soluble and supported catalyst. The UV-Vis spectra of the reaction mixture were recorded at λmax = 464, 505, and 485 nm for M.O, M.R, and O II dyes, respectively, in order to track the oxidation reaction. [Co(II)TP-OHPP]/CPTES−Bent/Cs 3 composite, shows the highest supported catalyst in the degradation process of the three anionic dyes with superior catalytic efficiency, underscoring its enhanced degrading capabilities. A comprehensive study was conducted using advanced techniques to evaluate its performance. Total organic carbon analysis (TOC) showed oxidation of M.O, M.R, and O II dyes revealing the elimination of 69%, 85%, and 66% mineralization under mild reaction conditions. The composite stability and reusability were evaluated. GC-MS analyses were used to identify any remaining organic components in the reaction mixture. There has been discussion about the oxidation reaction’s mechanism.