Palm Leaf-Derived Activated Carbon as a Dual Adsorbent–Catalyst for Methyl Orange Removal: Catalytic Oxidation and Kinetic Insights

A mesostructured activated carbon (PL–AAC) was engineered from palm leaf biomass via a specific chemical activation protocol and systematically evaluated as a bifunctional adsorbent–catalyst for the advanced oxidative removal of methyl orange (MO) from aqueous media. Physicochemical characterization confirmed the successful transformation of the lignocellulosic precursor into a hierarchically porous carbon framework, exhibiting enhanced surface area (2 → 56 m2/g), increased pore volume (0.0106 → 0.0227 cm3/g), and a dominant mesopore distribution (~3–5 nm). FTIR analysis revealed the presence of oxygen-containing functional groups (hydroxyl, carbonyl, and carboxyl), while SEM images demonstrated the formation of interconnected pore channels. Nitrogen adsorption–desorption isotherms showed Type IV behavior with H4 hysteresis, confirming the presence of narrow slit-shaped mesopores and micropores. This study introduces the novel application of palm leaf-derived activated carbon as a dual-function material that integrates adsorption and catalytic oxidation within a single system. Under acidic conditions (pH 2–3), PL–AAC in the presence of H2O2 achieved near-complete MO removal (≈98–100%), driven by the synergistic interaction between adsorption and in situ generation of reactive hydroxyl radicals. Kinetic analysis revealed that the degradation follows a pseudo-second-order model (R2 = 0.916), indicating that surface-mediated interactions govern the process. Furthermore, PL–AAC maintained high catalytic efficiency over four regeneration cycles with negligible performance loss, demonstrating excellent stability and reusability. These findings highlight the effective valorization of palm leaf waste into a sustainable, low-cost, and high-performance material for advanced wastewater treatment applications.