Removal of dye from Water Using raw Pomegranate Peels: Isotherm and Thermodynamic study

This study investigates untreated Tunisian pomegranate peels (PGP) as a low-cost and eco-friendly biosorbent for the removal of Methylene Blue (MB) from wastewater. The material was characterized by N2 adsorption-desorption (BET), FTIR spectroscopy, Boehm titration, and point of zero charge (pHpzc), revealing abundant functional groups suitable for dye binding. Adsorption isotherms were determined at three temperatures (30, 40, and 50 °C) and analyzed using the usual Langmuir and Freundlich models. The Langmuir model provided the best fit, with a maximum adsorption capacity of 101 mg/g at 30 °C. Thermodynamic analysis revealed negative ΔG°, ΔΗ°, and ΔS° values, indicating a spontaneous, exothermic process driven mainly by physical adsorption. These results demonstrate that raw PGP is an effective and sustainable biosorbent for dye removal, contributing to the valorization of agricultural waste.