Lead removal in aqueous solution by activated carbons prepared from Cola edulis shell (Alocacée), Pentaclethra macrophylla husk (Mimosaceae) and Aucoumea klaineana sawdust (Burseraceae)

Abstract

Three activated carbons prepared from vegetable matters of Gabonese biomass are being investigated as adsorbents for the removal of Pb (II) ions from aqueous solutions by means of batch technique. The equilibrium adsorption level was determined to be a function of pH, contact time, temperature and adsorbent dosage. The experimental adsorption data are well applicable to both Freundlich and Langmuir models with the correlation coefficients higher than 0.9. The adsorption process followed the pseudo second order kinetics (R²>0. 9). The enthalpy change [ΔH = 41.237 kJ for activated carbon prepared from Cola edulis shell (CAo°), -3.963 kJ/mol for activated carbon prepared from Pentaclethra macrophylla husk (GAo) and -1.6 kJ/mol for activated carbon prepared from Aucoumea klaineana sawdust (QAo)] implied that the adsorption was endothermic and exothermic for CAo and GAo or QAo, respectively.

Key words: Vegetable carbons, surface functional group, adsorption capacity, Pb(II) ions, isotherms.