Defatted Jojoba for the removal of methylene blue from aqueous solution: Thermodynamic and kinetic studies

The removal of the methylene blue from aqueous water by adsorption with defatted Jojoba has been studied in a batch operation mode. The percentages removal of dye increases with increasing contact time, Jojoba dosage and temperature achieving the equilibrium at 40 min. The maximum removal (80% approx.) has been achieved at 50 degrees C, 0.8 g/50 mL of Jojoba dosage, 200 mg/L initial concentration of MB and the pH range between 6.2 and 6.8. The dynamic isotherm has been successfully modeled by the Langmuir with R-2=0.98. The negative thermodynamic parameters Delta G (-14.4, -15.4, -16.8) at 25, 35, 40 and 50 degrees C, respectively indicate spontaneous adsorption. The pseudo-second order kinetic model is much more reasonable for MB adsorption process. (C) 2011 Elsevier B.V. All rights reserved.