Production and characterization of activated carbon from Leucaena plant wastes for removal of some toxic metal ions from waste solutions

Abstract

The use of chemically activated biomass from Leucaena as an economic agricultural waste was investigated for the removal of Cu(II) and Pb(II) ions. The structural morphology and composition of the studied activated carbon were evaluated by scanning electron microscope (SEM), XRD, FTIR, X-ray fluorescence, and CHNS elemental analyses. SEM and FTIR analyses indicated that a lot of cavities and functional groups, such as carboxyl and amino groups, were present on the external surface of activated carbon. Effects of various parameters such as contact time, pH, temperature, and adsorbent dose on the adsorption percentage of Cu(II) and Pb(II) have been investigated. The data indicated the proportional dependence of the adsorption of these metals on both pH of the solution and the amount of adsorbent up to 0.05 g. On the basis of distribution studies, the linear relations between log K_d and pH were observed for Cu²⁺ and Pb²⁺ ions with slopes 0.53 and 1.20, respectively, with the selectivity order Pb²⁺ > Cu²⁺. Thermodynamic parameters, ΔH°, ΔS°, and ΔG° were calculated and indicated an endothermic and spontaneous process. The values of breakthrough capacity were calculated and found to be equal to 4.92 and 15.09 mg/g for Cu²⁺ and Pb²⁺, respectively.

Keywords:

• Leucaena plant wastes
• Activated carbon
• Heavy toxic metals
• Distribution studies
• Thermodynamic parameters
• Separation

Acknowledgement

The authors would like to thank Prof. Dr Nabil Belacy, Prof. of Physical Chemistry, Atomic Energy Authority, Cairo, Egypt, for his carefully reviewing this article to be in an acceptable form.