Enhanced Removal of Pb(II), Cd(II), and Zn(II) Ions from Aqueous Solutions Using EDTA-Synthesized Activated Carbon Derived from Sawdust

Abstract

EDTA synthesized activated carbon derived from sawdust, was utilized as adsorbent for the removal of Pb(II), Cd(II) and Zn(II) ions from aqueous solutions.The adsorptive characteristics and elemental composition of this activated carbon were studied using SEM and EDX techniques respectively, the analysis revealed that SAC-EDTA contained 71.95% by weight of carbon contents which are requisites for the high adsorption capacity.The effect of initial metals ions concentration, adsorbent dose, contact time, and solution pH were examined at equilibrium for optimum values, experimental data were also fitted into two different isotherms: Langmuir and Freundlich, to establish the best fit for the adsorption process.From the results, the studied metals ions were best described by Langmuir with maximum monolayer coverage (q max ) of 89.29 mg•g -1 for Pb(II), 60.24 mg•g -1 for Zn(II) and 47.85 mg•g -1 for Cd(II), and R 2 value of 0. 981, 0.9732 and 0.9605 respectively.The Freundlich isotherm also gave a favourable performance with K f values of 16.43, 11.98 and 10.21 mg•g -1 L 1/n •mg -1/n , and R 2 values of 0.9919, 0.9867 and 0.9797 respectively.Therefore, this study demonstrates that SAC-EDTA adsorbent could be used to adsorb heavy metals in our environment.Hence, the order of adsorption affinity is Pb 2+ > Zn 2+ > Cd 2+ .