Fabricating a biochar from Artocarpus heterophyllus peels for methylene blue sequestration from synthetic wastewater: Isotherm, kinetic, and thermodynamic analysis

Abstract

In the current work, biochar prepared from the peels of Artocarpus heterophyllus was modified using phosphoric acid and employed to remove Methylene Blue (MB) from synthetic wastewater. The morphological properties of acid activated A. heterophyllus peels biochar (AAPB) were analyzed using Scanning Electron Microscopy and found to be more porous with increased surface area. Using Mercury Intrusion Porosimetry AAPB represented a total surface area of 612 m2/g and pore volume of 1.225 cc/g which is higher than that of raw Artocarpus peels. In batch studies, process factors like pH, AAPB dosage, and initial concentration of MB were optimized for better MB removal. The maximal MB removal percentage using AAPB was reported to be 99.0% under optimal circumstances with a residual MB concentration below the permissible levels. The Freundlich isotherm fit the isotherm analysis of the MB removal process well, with a regression coefficient of 0.99 (R 2). The monolayer adsorption capacity was elucidated as 127.44 ± 9.7 mg/g through isotherm analysis. The kinetic investigation showed that the adsorption process followed pseudo-second order kinetics. The biosorption process was exothermic and had favorable thermodynamics, according to the thermodynamic study. These results showed that biochar made from acid-modified A. heterophyllus is a practical choice for removing synthetic dyes from wastewater.