Mangosteen Peel-Derived Hydrochar Prepared via Hydrothermal Carbonization for Methylene Blue Removal

Abstract

Abstract Hydrothermal carbonization (HTC) arises as an improved carbonization step developed to enhance the carbon porosity and reduce the production cost by thermally treating feedstock under milder operating conditions. This work aimed to generate hydrochar from mangosteen peel (MPHTC) via hydrothermal carbonization for the removal of methylene blue from aqueous solution. In the study, hydrochar was synthesized at an optimized carbonization temperature (200 °C) with a production yield of 82.75% and a methylene blue removal of 75.93%. The adsorption capacity of adsorbent enhanced with the increasing initial dye concentration due to high driving force for efficient mass transfer. The hydrochar was capable of attaining its maximum adsorption capacity at 131.58 mg/g. The derived hydrochar performed a higher uptake of dye molecules under basic conditions rather than acidic conditions owing to the presence of OH group for the attachment of cationic dye. It was determined that Freundlich isotherm and pseudo second order kinetic models best fitted the experimental data. External film diffusion was found to be the rate-controlling step for the batch adsorption process. The results revealed that MPHTC is a promising adsorbent for treatment of cationic dye for effluent wastewater.