Powdered Myrtle Leaves: A Sustainable Biosorbent for Effective Methylene Blue Adsorption

For the adsorptive removal of poisonous Methylene Blue (MB) dye from aqueous media, dried myrtle leaves (PML), a local forestry waste, have been used as an affordable biosorbent. By analyzing the prepared biosorbent, it was possible to gain a clear understanding of its structure, functional groups, morphology, content, textural characteristics, and surface charge. Subsequently, the effects of time, initial MB concentration, pH, PML dosage, temperature, agitation speed, and PML particle size were investigated using batch sorption experiments. The maximum MB uptake was measured at 150.427 mg.g^-1 in the evaluated equilibrium data, which was in closer agreement with the Langmuir model. In contrast, the kinetic data adequately resembled the PSO model. The thermodynamic evaluation manifested spontaneous activity (ΔG°<0), which was mainly physical and exothermic (ΔH°=−19.622 kJ.mol^-1). A further study of PML recyclability uncovered excellent regeneration capacity through four adsorption/desorption cycles. Along with other findings, the procedure could involve hydrogen bonds, π–π and n–π interactions, pore filling, electrostatic attraction, and Van der Waals forces.