Thermodynamics and Kinetics Studies of Methylene Blue Adsorption Onto Yemeni Palm-Date Stones

Abstract

A raw and baked date stones were used for the removal of methylene blue (MB) from aqueous solutions. The maximum adsorption capacity was 111 mg/g for raw and 41 mg/g for baked date stones with 10 mmol/l initial concentration of MB, 5 pH and 0.5 g/l adsorbent dose. The adsorption isotherm was found to follow the Langmuir model. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equation were selected to follow the adsorption processes. Kinetic studies showed that the adsorption followed pseudo-second order model. Various thermodynamic parameters such as Δ????, Δ???? and Δ???? were evaluated. The results in this study indicated that the raw Yemeni palm-date stones could be employed as an effective adsorbent for the removal of MB from aqueous solutions.