Chemical speciation of lead adsorbed onto volcanic ashes by ICP-OES and XANES

Abstract

This study focuses on the assessment of the VA materials from the Cameroon volcanic line (CVL) for their use as natural adsorbents to remove Pb(II) pollutant from aqueous solutions. The chemical speciation of lead adsorbed onto volcanic ashes based by means of inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray absorption near edge spectroscopy (XANES) study is reported. The ashes from CVL are used to remove lead in aqueous solutions. The maximum value of the adsorption capacity of lead in volcanic ashes was 7.60 mg g-1 at pH 5. Regarding the adsorption process, the contribution of the mixture lead components after adsorption and a strong interaction of adsorbed lead with the surface of volcanic ashes were proven. The chemical elements present in the volcanic ash and their concentrations are determined by ICP-OES. Chemical speciation was carried out measuring Pb saturated volcanic ash sample at the L3 edge (13035 eV) at the XAFS beam line in Elettra Sincrotrone Trieste. The XANES measurements showed that the lead removal occurred mainly by microprecipitation of lead acetate and carbonate associated with a possible ion-exchange forming lead monoxide.