Americium adsorption on alumina in the presence of humic materials

Abstract

The adsorption of americium at trace concentrations (10⁻⁸ M) on α-Al₂O₃ has been measured as a function of pH (4–10) at two different ionic strengths (0.10 and 0.01 M NaClO₄) and in the presence of humic materials (0–10 mg/l: fulvic acid from a groundwater and humic acid from a surface water). A somewhat enhanced adsorption is obtained at pH < 7 in the presence of 1 mg/l of humics, while a drastic reduction is obsrved at higher pH. A general large decrease of the adsorption is observed at 10 mg/l of humics, except at pH 5. The distribution and speciation of americium (in solution or in solid phase) are expected to be entirely dominated by the association with organic matter in most environmental water systems.