Novel Solid-State Ion Exchange Process for Preparation of the Optimal Mn/Bentonite Nanocomposite from Various Manganese Sources for Methyl Orange Dye Degradation Using Heterogeneous Photo-Fenton-Like Processes. Taguchi Method, Kinetics, Reusability

The development of effective, sustainable Advanced Oxidation Processes (AOPs) is necessary for treating industrial wastewater containing resistant azo dyes. Long reaction times and excessive solvent consumption are common obstacles to the conventional liquid-phase production of heterogeneous catalysts. Addressing these limitations, this study introduces a novel, solvent-free Solid-State Ion Exchange (SSIE) strategy for fabricating high-performance manganese-intercalated bentonite nanocomposites. It presents a comparative analysis of Mn/Bentonite nanocomposites prepared from different sources of Mn: Mn nanoparticles (Mn NPs), MnSO₄, and Mn(NO₃)₂ for degrading Methyl Orange (MO) dye in a heterogeneous photo-Fenton-like manner. Comprehensive characterization via FT-IR, XRD, SEM-EDX, XPS, and N۲ physisorption confirmed the successful intercalation and uniform dispersion of active manganese species within the clay host, resulting in enhanced textural properties. To identify the best composite with the highest MO dye degradation ratio, the Taguchi method for composite optimization with the following factors (Mn source, Mn loading weight percentage, mixing speed, calcination temperature, and calcination time) is employed. MO dye degradation kinetics, loading-dependent adsorption contributions, and photo-Fenton-like reactions are revealed by photocatalytic studies under UV irradiation in the presence of H₂O₂. Adsorption and degradation are separated by pseudo-first-order kinetic modeling, which also reveals rate-limiting stages. The optimized composite achieved superior degradation efficiencies compared to conventionally prepared counterparts. According to kinetic modeling, the catalytic surface's synergistic production of reactive hydroxyl radicals drove the degradation process, which followed pseudo-first-order kinetics. Additionally, longevity experiments over successive reaction cycles showed minimal metal leaching and outstanding structural stability. In the end, this study confirms solid-state ion exchange as a scalable, environmentally friendly synthesis route for creating durable heterogeneous photocatalysts appropriate for real-world environmental uses.

کلیدواژه ها:

Bentonite ، Degradation ، Nanocomposite ، Mn Sources ، Methyl Orange (MO) dye ، Photo-Fenton-Like ، Solid-state ، Ion exchange