Complexation Studies of Eu(III) with Alumina-Bound Polymaleic Acid:  Effect of Organic Polymer Loading and Metal Ion Concentration

Abstract

To contribute to the comprehension of the metal ion sorption properties in mixed mineral-organic matter systems, interaction studies between Eu(III) and polymaleic acid (PMA)-coated alumina colloids were carried out at pH 5 in 0.1 M NaClO4. The studied parameters were the metal ion concentration (1 x 10(-10) to 1 x 10(-4) M) and PMA loading on alumina (gamma = 10-70 mg/g). The data were described by a surface complexation model. The constant capacitance model was used to account for electrostatic interactions. The results showed thattwo sites were necessary to explain the sorption data. At high Eu loading, Eu is surrounded by one carboxylate group and one aluminol group. The existence of this ternary surface site was in agreement with time-resolved laser-induced fluorescence spectroscopy measurements. At low metal ion concentrations, a surface site corresponding to a 1:1 Eu/COO-stoichiometry was deduced from modeling. Spectroscopic data did not corroborate the existence of this latter site. This discrepancy was explained by postadsorption kinetic phenomenon: a migration of the metal ion within the adsorbed organic layer.

Removal of Cu2+ and Cd2+ from Aqueous Solution by Bentonite Clay Modified with Binary Mixture of Goethite and Humic Acid

“…Adsorption of humic substance onto clay is important in relation to speciation and mobility of pollutants in the environment (Chorover et al 1999;Guzman et al 2003). Because of its high functionality (carboxyl, hydroxyl, and amino groups), humic substance can strongly complex metal ions and thereby modify the retention, adsorption, migration, and bioavailability of metal ions in the natural environment Wang et al 2005Wang et al , 2006Montavon et al 2002;Xu et al 2008;Stevenson 1994). The results indicate that humic substance enhances cation adsorption at low pH values but reduces the adsorption at high pH values.…”

“…The results indicate that humic substance enhances cation adsorption at low pH values but reduces the adsorption at high pH values. The increase of adsorption is explained by the adsorption of humic substance on mineral surface followed by the interaction of metal ions with surface adsorbed humic substance, whereas the reduction of adsorption at high pH is interpreted by the formation of soluble metalhumic substance complexes in solution, which reduces the metal ion adsorption (Montavon et al 2002).…”

Sorption of Eu(III) on GMZ bentonite in the absence/presence of humic acid studied by batch and XAFS techniques

“…The solid-water interface interactions of long-lived radionuclides, especially the lanthanides and actinides, have attracted much attention in the performance assessment of nuclear waste repository [1][2][3][4]. In nuclear waste repository, the sorption and migration processes of radionuclides in backfill materials are considered to be very important because the distribution, mobility, cycling and bioavailability of radionuclides are controlled by the sorption properties.…”

Comparison of complexed species of Eu in alumina-bound and free polyacrylic acid: A spectroscopic study

“…Polycarboxylic acids [15][16][17][18] were selected as model systems allowing to study the role of the polyelectrolyte character and of carboxylic groups in the interaction. In a recent study using polyacrylic acid (PAA) [17], the interaction of M(III) (M=Cm,Eu) with mineraladsorbed PAA appeared different from the interaction with dissolved PAA. The M(III)/PAA interaction can be described by considering PAA as a classical organic ligand [19].…”