Potassium Hydroxide-Activated Palm Kernel Shell Carbon for Methylene Blue Adsorption: Reagent Recovery and Regeneration Strategies

Abstract

This study investigates the preparation and characterization of activated carbon derived from palm kernel shell, utilizing recovered potassium hydroxide (KOH) as the activating agent. The research seeks to address dye water pollution and the release of toxic chemicals from washing activated carbon upon its activation that are detrimental to aquatic ecosystems. Fresh activation was performed in a furnace at a temperature of 550 °C for one hour. The resultant activated carbon was washed and the recovered KOH solution was used for subsequent activation. The activated carbons were characterized to determine their surface area, morphology, functional groups and batch adsorption capacity. The fresh activated carbon exhibited a yield of 14.2% and a surface area of 7.24 m²/g. Notably, the surface area of 55.1 m²/g of the activated carbon produced using recycled KOH solution was greater with an enhanced level of methylene blue removal. The adsorption data could be described by the Redlich-Peterson isotherm and pseudo-second-order kinetic models, suggesting a hybrid of physicochemical interactions. The adsorption process is endothermic and spontaneous when the temperature of the solution is high. This work also showcases the regeneration of activated carbon by using 0.1 M HCl and distilled water as solvents, underscoring the sustainability and cost-effectiveness of manufacturing activated carbon.