Application of Ni-Fe catalyst from fluidized-bed crystallisation reactor for treatment of RB5 azo dye using a Fenton-like system

This study addresses the persistent challenge of Reactive Black 5 (RB5) dye removal from wastewater by utilizing Ni-Fe bimetallic catalysts recovered from semiconductor industry wastewater. This novel approach enhances the heterogeneous Fenton-like process for RB5 dye degradation. The catalyst, synthesized using a fluidized bed crystallization (FBC) reactor, was characterized by SEM, XRD, FTIR, and XPS, confirming its suitability for the application. Key operational parameters such as hydrogen peroxide concentration, catalyst dosage, and initial reaction pH (pHi) significantly influenced RB5 removal efficiency. Using 1 g/L of catalyst, 1 mM of H2O2, and 100 mg/L of RB5, 86.4 % decolorization and 82.6 % TOC removal were achieved in 90 minutes. UVC radiation enhanced decolorization by 12.4 % but negatively impacted TOC removal. Langmuir adsorption isotherm with a KLvalue of 0.91 mg/L provided the best fit, indicating the dominance of adsorption over oxidation at pH pHi. Kinetic analysis showed that second-order kinetics consistently offered the most robust model fit, except when UVC was applied alongside the catalyst and H2O2, where first-order kinetics were more favorable. This research advances sustainable wastewater treatment technologies, demonstrating a promising solution for effluents from textile and semiconductor industries and promoting resource conservation and environmental responsibility.