Mesoporous activated carbon from mangosteen (Garcinia mangostana) peels by H3PO4 assisted microwave: Optimization, characterization, and adsorption mechanism for methylene blue dye removal

This study reported a facile method to synthesize mangosteen peels activated carbon (MSPAC) from an abundant Malaysian biomass waste (mangosteen peels) via microwave-assisted H3PO4 activation. The process resulted in high carbon content and mesoporous structure with a high surface area (681.41 m2/g). MSPAC was applied as an adsorbent for methylene blue (MB) dye removal from aqueous solutions. The response surface methodology approach was established via Box-Behnken Design (BBD) to optimize a series of adsorption conditions: MSPAC dose (0.02–0.06 g), solution pH (3–9), and time (5–20) for MB adsorption. The BBD method indicated that the best adsorption parameters for maximum MB removal are an MSPAC dose of 0.06 g, an MB solution pH of 6, and a time of 20 min. The result showed that the PSO kinetic model best represented the adsorption kinetics, whereas the Langmuir model best characterized the equilibrium results, with the maximal monolayer adsorption capability of 163.6 mg/g for the MB dye adsorption onto MSPAC. Thermodynamic findings demonstrated that MB uptake onto MSPAC was a spontaneous and endothermic process. The results of this work show that quite rapidly manufactured MSPAC is an excellent environmentally friendly adsorbent for removal of cationic synthetic dyes from polluted water.