Abstract

This study examined the adsorption of copper onto raw Globimetula oreophila leaves. The adsorbent surface nature was examined using scanning electron microscopy and Fourier transform infrared spectroscopy. Adsorption parameters such as the –log₁₀[H⁺], point of zero charge, initial metal concentration, mass of biomass and contact time were determined. Copper adsorption decreased gradually with pH. The point of zero charge (PZC) obtained was 4.5. The percentage adsorption capacity increased from 97.6 to 99.3% as the initial amount of copper rose from 20 to 100 mg/L. Temkin isotherm gave the best fit (R²=0.99) in describing the adsorption equilibrium process. Contact time effect resulted in an equilibrium attained in 15 min due to the initial rapid increase in adsorption. Kinetic data were excellently fitted to the pseudo-second order model. Thermodynamic studies affirmed a spontaneous and endothermic adsorption process. The activation energy and the energy of adsorption obtained affirmed that the adsorption process was chemisorption. G. oreophila is a recommendable adsorbent for the remediation of copper contaminated soil.

Key words: Globimetula oreophila, kinetics, adsorption, isotherm, copper.