The purpose of this study was to remove lead and arsenic ions from aqueous solutions using the activated carbon prepared from Citrus limon tree leaves. Characteristics of the prepared adsorbent were studied thoroughly using BET, SEM, EDS and mapping, XRD, and RAMAN analyses. The results of experiments showed that the highest adsorption efficiencies were 97.67% and 95.89% for Pb (II) and As (III), respectively. Additionally, the adsorbent was successfully regenerated four times and therefore it was able to perform the adsorption and desorption processes well. Moreover, the results of adsorption kinetics showed that the pseudo second-order kinetic model was more effective for the description of adsorption mechanism of both metals. Furthermore, the equilibrium studies indicated that Langmuir and Freundlich isotherm models were desirable for lead and arsenic ions, respectively.

    Abstract
    1 Introduction
    2 Materials and methods
        2.1 Chemicals
        2.2 Preparation of stock solution
        2.3 Preparation of adsorbent
        2.4 Experimental procedure
    3 Results and discussion
        3.1 Adsorbent characterizations
        3.2 Effect of solution pH
        3.3 Effect of adsorbent dosage
        3.4 Effect of ions initial concentration
        3.5 Effects of contact time and temperature
        3.6 Desorption and regeneration experiments
        3.7 Adsorption isotherms
        3.8 Kinetic study
        3.9 Thermodynamic study
    4 Conclusion
    References

• Fahime Nemati(Department of Chemical Engineering, School of Chemical Engineering, Kherad Institute of Higher Education, Bushehr, Iran)
• Dariush Jafari(Department of Chemical Engineering, Bushehr Branch, Islamic Azad University, Bushehr, Iran)
• Hossein Esmaeili(Department of Chemical Engineering, Bushehr Branch, Islamic Azad University, Bushehr, Iran)