The use of low-cost adsorbent (Canola residues) for the adsorption of methylene blue from aqueous solution: Isotherm, kinetic and thermodynamic studies

• MWCNTs were used as efficient adsorbent for the removal of Congo red.
• The optimized contact time and pH were found to be 60 min and 11 respectively.
• Removal capacity increases with increase in pH.
• Adsorption capacity decreases with increase in temperature.
• Adsorption capacity increases with increase in time but reaches equilibrium after 60 min.

The batch adsorption was carried out to study and investigate pH, initial concentration of MB, adsorbent dosage and contact time. The best efficiency of MB removal by Canola residues were obtained at pH alkaline, dose adsorbent of 3.5 g/L, initial concentration of MB of 25 mg/L and contact time of 75 min. The maximum dye removal was obtained to be 97.5%. As the Canola concentration was increased from 0.5 to 5 g/L, the equilibrium adsorption capacity of Canola (qe) decreased from 16.7 to 4.87 mg/g, whereas, the MB removal efficiency increased from 33.4% to 97.5%. The adsorption kinetics and equilibrium data were in good agreement with the pseudo-second-order kinetic model and Sips adsorption isotherm respectively. Thermodynamic parameters suggest that the adsorption is a typical physical process, which is spontaneous and endothermic. The study demonstrated that biomass is effective to remove MB under a wide range of experimental conditions.

The SEM image of dried Canola: (a) before use and (b) after use.Figure optionsDownload as PowerPoint slide