Mechanistic insights into the adsorption of methylene blue by particulate durian peel waste in water

Abstract

This study aims to investigate the adsorption of methylene blue (MB) over particulate durian peel waste, which is chemically activated with hydrogen peroxide. The equilibrium data are well described by the Freundlich isotherm model, which indicates that the MB adsorption takes place predominantly on multilayers and heterogeneous surfaces of the biosorbent. The Freundlich adsorption constants, KF and n, are 11.06 L/g and 2.94, respectively. Thermodynamic data suggest that the MB adsorption occurs spontaneously and endothermically. The enthalpy and entropy for the MB adsorption are obtained as 10.26 kJ/mol and 0.058 kJ/mol K, respectively, in the temperature range of 303–323 K. Based on the stepwise desorption method, the adsorption of MB is dominated by physical interactions, particularly hydrogen bonding. HIGHLIGHTS Durian peel waste is utilized as a biomass-derived sorbent for the removal of methylene blue in water.; Chemical activation with hydrogen peroxide increases the removal efficiency.; Surface carboxyl group plays a key role in the adsorption process.; The adsorption process is primarily governed by physical interactions including hydrogen bonding and electrostatic interaction.;

Keywords

• adsorption isotherms
• adsorption mechanism
• durian peel
• hydrogen bonding
• methylene blue