Equilibrium, kinetic, and thermodynamic applications for methylene blue removal using Buxus sempervirens leaf powder as a powerful low-cost adsorbent

In this work, methylene blue adsorption using the unconventional, natural, and low-cost adsorbent, Buxus sempervirens (Boxwood) leaf powder (BLP), was studied. Several experiments were conducted for the investigation of different process variables. Also different techniques such as XRF, XRD, SEM, FT-IR and N2 adsorption-desorption analysis were applied for the characterization of BLP. Adsorption kinetic models showed that the pseudo-second-order by R^2 = 0.999 was well adapted. Two isotherms models, Langmuir and Freundlich, were selected to check of the amount of color removal. Methylene blue (MB) maximum adsorption capacities can attain 384.61 mg.g^-1 from the Langmuir isotherm. The values of ΔG0 for adsorption of MB onto BLP ranges from -19.44 to -24.07 kJ.mol^-1, demonstrating that the adsorption process was spontaneous and irreversible. The removal of dye was considerably increased by increasing the temperature, which suggested that the adsorption process was endothermic. All results indicate that BLP can be feasibly employed for the elimination of MB from an aqueous solution.