The present work is aimed at evaluating the kinetics and dynamic adsorption of methylene blue by CO2- activated carbon gels. The carbon gels were characterized by textural properties, thermal degradation and surface chemistry. The result shows that the carbon gels are highly microporous with surface area of 514 m2/g and 745 m2/g for resorcinol-to-catalyst ratios of 1000 (AC1) and 2000 (AC2), respectively. The kinetics data could be described by pseudo-first-order model, with a longer duration to attain equilibrium due to restricted pore diffusion as concentration increases. Also, AC1 exhibits insignificant kinetics with fluctuating adsorption with time at concentrations of 20 and 25 mg/L. However, AC1 reveals a better performance than AC2 in dynamic adsorption due to concentration gradient for molecules diffusion to active sites. The applicability of Yoon–Nelson and Thomas models indicates that the dynamic adsorption is controlled by external and internal diffusion.

Kinetics and dynamic adsorption of methylene blue by CO2-activated resorcinol formaldehyde carbon gels
    Abstract
    1 Introduction
    2 Materials and methods
        2.1 Materials
        2.2 Preparation and characterization of carbon gels
        2.3 Adsorption studies
            2.3.1 Adsorption kinetics
            2.3.2 Column adsorption
    3 Results and discussion
        3.1 Characteristics of carbon gels
        3.2 Adsorption kinetics
        3.3 Column adsorption
    4 Conclusion
    Acknowledgements 
    References

• Azrul Nurfaiz Mohd Faizal(Centre of Lipids Engineering and Applied Research, Ibnu‑Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia/School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia)
• Muhamad Hazim Abdul Halim(School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia)
• Muhammad Abbas Ahmad Zaini(Centre of Lipids Engineering and Applied Research, Ibnu‑Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia/School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia)