Isotherm, kinetics and two-stage adsorber design modelling of durian seed activated carbon for methylene blue removal

Abstract This study aimed to assess the adsorption characteristics and two-stage adsorber design performance of durian seed activated carbon for the removal of methylene blue. The adsorption performance was analyzed using isotherm and kinetic models. The results revealed that phosphoric acid activation produces activated carbon with a higher methylene blue capacity of 256 mg/g. The adsorption data could be well described by the Langmuir isotherm, while the kinetics obeyed the pseudo-second-order model. Using the Langmuir parameters, a two-stage adsorber system was designed to determine the optimum carbon dosage. The required mass of activated carbon could be reduced by 46.6% for the treated effluent volumes between 20 mL to 500 mL. In this configuration, the first stage employs a larger amount of activated carbon, while the second stage is to enhance the removal efficiency and minimize total adsorbent usage. Overall, the findings highlight the economic potential of a two-stage adsorption system for efficient dye removal in wastewater treatment.