Oxidative degradation of RB19 dye by a novel γ-MnO2/MWCNT nanocomposite catalyst with H2O2

The catalytic oxidation of an anionic reactive blue 19 (RB19) dye solution using a novel synthesized γ-MnO2/MWCNT nanocomposite catalyst with H2O2 was investigated. Three different molar concentrations of MnO2 loaded over modified MWCNT with nitric acid were prepared. The impact of initial molar concentrations of H2O2 (0.076–0.333 M), catalyst loading (0–0.05 g), initial pH of solution (2–10), and initial dye concentration (50–500 mg/l) on the decolorization process was studied. Morphology, crystallinity and textural characteristics of the modified MWCNT before and after deposition of MnO2 were examined by SEM, XRD, EDX, FTIR and N2 adsorption at 77 K, respectively. It was found that the core–shell nanostructure was formed by the uniform incorporation of birnessite-type (γ-MnO2) nanoflakes growth around the surface of the activated MWCNT. The present study highlighted that the prepared 0.5MnO2/MWCNT nanocomposite catalyst and 0.333 M H2O2 exhibited a higher catalytic oxidation of a RB19 dye than other catalysts at a slightly acidic pH. Recycling studies with 0.5MnO2/MWCNT nanocomposite catalyst with 0.333 M H2O2 showed that it can be reused within three runs in oxidation experiments. Finally, the prepared nanocomposite catalyst with 0.5MnO2 has the amenability to operate efficiently in the decolorization of dyes from wastewater.