Kinetic and Thermodynamic Study of Methylene Blue Adsorption onto Activated Carbon Obtained from the Peel of musa paradisiaca

In this work, we fabricated activated carbon using the peel of musa paradisiaca (banana) as the carbonaceous material source. The activated carbon was obtained after applied a carbonization process under nitrogen atmosphere at 723.15 K. The activated carbon was chemically modified using three chemical agents (citric acid, tartaric acid, and EDTA). The surface properties of the materials were characterized by nitrogen sorptometry at 77 K. Furthermore, we determined the zero-load point of all materials. The kinetic and isothermal behavior of the materials to remove methylene blue from aqueous solution was studied. The thermodynamic parameters of the process for all materials were determined by applying the van’t Hoff equation. Results showed that after chemical activation, there was an increase in the content of oxygenated groups onto activated carbon. Furthermore, the BET surface area of activated carbon was reduced from 808 to 724 m2 g−1. The volume of micropores was smaller after chemical activation and the volume of mesopores was greater. The zero-load point of materials was in a range between 4.96 and 5.60. Kinetic and isothermal results showed that after chemical modification, the removal capacity increased from 30.2 for activated carbon to 52.6 mg g−1 for activated carbon modified with EDTA. Finally, the thermodynamic parameters showed that methylene blue adsorption using all materials was an endothermic and spontaneous process; the ΔG° value of activated carbon was −4.35 kJ/mol, and the ΔG° value of activated carbon modified with EDTA was −6.28 kJ/mol.