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 °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 R2 = 0.98. The negative thermodynamic parameters ΔG (− 14.4, − 15.4, − 16.8) at 25, 35, 40 and 50 °C, respectively indicate spontaneous adsorption. The pseudo-second order kinetic model is much more reasonable for MB adsorption process.

Research Highlights
► The Jojoba is good adsorbents to remove MB dye from aqueous solutions.
► MB adsorption on Jojoba increases with the increase of pH up to 6.8 and then it gradually decreases.
► The adsorption process obeys the Langmuir isotherm and a pseudo-second order kinetic model.
► The MB adsorption onto Jojoba is a spontaneous, exothermic and physical process.