Isotherm, kinetic, thermodynamic, and reusability studies of oil palm EFB-derived activated carbon for leachate treatment

Municipal solid waste (MSW) leachate poses significant environmental challenges due to its high concentrations of organic and inorganic pollutants. This study investigates the adsorption efficiency of activated carbon derived from oil palm empty fruit bunches (EFBAC) for landfill leachate treatment. EFBAC was synthesized via physical activation, involving carbonization at 450 °C and activation at 800 °C under limited air conditions. Batch adsorption experiments evaluated the effects of contact time, adsorbent dosage, pH, and temperature on the removal of chemical oxygen demand (COD), ammoniacal nitrogen (AN), and color. Optimal conditions achieved maximum removal efficiencies of 72.1% for COD, 57.5% for AN, and 69.0% for color. Isotherm analysis identified the Sips, Dubinin-Radushkevich, and Koble-Corrigan models as the best fits for COD, AN, and color, respectively. Kinetic studies indicated a pseudo-second-order mechanism, highlighting chemisorption as the rate-limiting step, while thermodynamic evaluation confirmed the process as spontaneous and endothermic. Although adsorption performance declined after the first reuse cycle, EFBAC demonstrated significant potential as a cost-effective and sustainable adsorbent for leachate treatment. These findings contribute to the circular economy by valorizing agricultural waste and align with the United Nations' Sustainable Development Goals (SDGs) for responsible production and climate action.