Application of Box-Behnken Design Model for Statistical Optimization of As(III) Removal Using Iron Manganese Bimetal Oxide Composite

This study utilized the magnetic Fe₃O₄-MnO₂ composite for As(III) removal by Box–Behnken design (BBD) model based on response surface methodology. The main objective of this study was to reduce the operational runs with the help of modeling with maximum accurate output and oxidized toxic from As(III) to As(V) with the help of MnO₂, after that As(V) adsorbed on the composite surface. The composite had a good surface area (247.09 m²/g), magnetic property (16.50 emu/g), and mesoporous nature. Under batch-optimized conditions, as obtained from the model (0.190 g composite dose, initial As(III) concentration 10.34 mg/L and pH 3.2) about 96% As(III) was removed from the aqueous solution. Langmuir model was able to describe the equilibrium data analysis with an uptake capacity of 81.16 mg/g. The adsorption process of As(III) on the Fe₃O₄-MnO₂ composite surface was best fitted to the pseudo-second-order kinetics model. Thermodynamics analysis suggested the spontaneous and endothermic nature of As(III) adsorption. The regenerated composite was able to remove 88% of As(III) and its stability was also checked up to the fourth cycle. Adsorption mechanism studies showed that As(III) oxidized to As(V) and then adsorbed on the Fe₃O₄-MnO₂ composite surface.