Synthesis, characterization and adsorption performance of banana peel-derived activated carbon for methylene blue removal: Kinetic and isotherm studies

Accelerated industrialization and urbanization have intensified the discharge of chemically stable synthetic dyes into aquatic systems, necessitating robust remediation strategies. This study evaluates the synthesis and application of activated carbon derived from Musa acuminata (banana) peel (BPAC), prepared via phosphoric acid activation, for the sequestration of Methylene Blue (MB). The synthesized activated carbon was characterized using FTIR, XRD, and SEM confirmed the development of a porous architecture with surface functional groups conducive to dye interaction. Batch adsorption experiments were conducted to optimize MB sequestration by using Response surface methodology of experimental design. The highest removal efficiency of 91.50% was achieved at pH 8.50, an adsorbent dosage of 0.20 g, an initial MB concentration of 11.30 mg/L, and a contact time of 183 min. Kinetic studies revealed that the adsorption process followed the pseudo-second-order model (R² ≈ 0.99), indicating chemisorption as the rate-controlling step. Equilibrium data were best described by the Langmuir isotherm (RMSE = 0.0031, χ² = 0.00018), with a maximum adsorption capacity of 18.28 mg/g, while Freundlich and Temkin models showed weaker fits. These results establish banana peel as a viable biomass precursor for the production of activated carbon tailored for cationic dye remediation, providing a technical basis for the valorization of agricultural waste in wastewater treatment.