Adsorbents were derived from banana peel through chemical treatment using phosphoric acid, potassium hydroxide, and sodium hydroxide to adsorb methylene blue from water. The adsorption of methylene blue was performed at varying concentrations and contact times. The equilibrium data fitted well with Langmuir equation, with a maximum monolayer adsorption capacity of 99.28 mg/g (28%). Phosphoric acid-treated adsorbent exhibits a greater capacity despite a lower affinity than the other adsorbents. A two-stage batch adsorber model was developed to optimize the adsorbent dosage for performance evaluation. Banana peel is a promising resource of adsorbent for wastewater treatment.