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Dye is a common pollutant present in many chemical industrial waste water. Advanced oxidation processes are widely used for dye degradation. In this study, the degradation of trypan blue dye was examined by Fenton process. Neutralized red mud catalyst was used as a source of ferrous ion for Fenton’s process. The dye degradation performance has been analyzed by using circulating fluidized-bed reactor. The influence of some key parameters such as pH, initial dye concentration, catalyst dosage and hydrogen peroxide concentration on the degradation of dye has been investigated. All the experiments were performed for 90 min. The initial dye concentration was taken as 1.56 × 10−5 and 2.60 × 10−5 mol L−1 and the amount of catalyst was varied from 0.5 to 0.7 gm/L. The hydrogen peroxide was taken in the ratio of 1:20 with the catalyst. The effect of pH was studied in the varying range from 3–5. It was found that the more the acidic pH, more will be the rate of degradation. The increase in pH results in the lower degradation rate. As the amount of catalyst was increased, the degradation rate got increased. The optimized results were obtained at pH 3, catalyst dosage of 0.7 gm/L and dye concentration of 1.56 × 10−5 mol L−1. Subsequently, the reaction kinetics of Fluidized-bed reactor was also studied.

This study reports a green approach for the modification of titanium dioxide (TiO2) nanoparticles with immobilization of silver nanoparticles. One of the natural sources i.e., Mangifera indica leaf extract was utilized as reducing and capping agent for the fabrication of Ag-TiO2 nanocatalyst. Further, the surface morphology and band-gap energy of prepared Ag-TiO2 were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and UV–Vis spectroscopy. Also, it was characterized by X-ray Powder Diffraction (XRD) which provides the information regarding the crystallinity of the Ag-TiO2. Subsequently, photo activity of Ag-TiO2 was investigated for the degradation of methylene blue (MB) dye wastewater through visible light driven photoreactor. The Ag-TiO2 provided highest (68%) of photo-degradation efficiency within 110 min for 7.81 × 10−5 mol/L initial MB concentration at pH 8 by using 0.19 g/L photocatalyst. Further, addition of 10 mM H2O2 boost up the MB photodegradation to 74%. The kinetic study confirmed the MB degradation followed first order rate of reaction.