Characterization of Manganese Oxide and the Adsorption of Copper(II) and Lead(II) Ions from Aqueous Solutions

Abstract

The characterization and sorption properties of manganese oxide towards Cu(II) and Pb(II) ions from aqueous solution were investigated. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared (IR) analyses were used to characterize the manganese oxide. Parameters affecting the adsorption of Cu(II) and Pb(II) ions, such as the adsorbent dosage, the ionic strength of the solution, the contact time, the solution pH, the initial metal ion concentration and the temperature, were investigated. The binding of Cu(II) and Pb(II) ions to manganese oxide was highly dependent on the pH of the solution, with the extent of adsorption increasing as the pH of the system increased. The uptake of both Cu(II) and Pb(II) ions was found to increase with temperature. Furthermore, the removal efficiency of Cu(II) and Pb(II) ions from aqueous solution increased with increasing adsorbent dosage and decreased with ionic strength. The adsorption equilibrium and adsorption kinetics of Cu(II) and Pb(II) ions onto manganese oxide were studied. The adsorption process was spontaneous and exothermic, with the order of affinity being Pb(II) > Cu(II). The same behaviour was observed during competitive adsorption, viz. adsorption from a binary solution of the ions concerned.