J. Phys. IV France
107
(2003)
609
DOI: 10.1051/jp4:20030377
Sorption of silver(I) onto the surface of pure and natural quartz
sands
M.A. Hernandez Cortazar1 and P. Behra1, 2
1
Institut de Mécanique des Fluides et des Solides, UMR 7507 du CNRS,
Université Louis Pasteur, 2 rue Boussingault, 67000 Strasbourg, France
2
École Nationale Supérieure des Ingénieurs
en Arts Chimiques et Technologiques,
Laboratoire de Chimie Agro-Industrielle, UMR 1010, INRA/INP-ENSIACET,
118 route de Narbonne, 31077 Toulouse cedex 4, France
Abstract
Silver is a heavy metal which is present at different oxidation states in the environment and
which can be released into aquatic systems from agricultural activities or industries (mines,
metallurgy, pharmaceutical and electronic activities, electrochemistry, photography, nuclear industry
and power plants...). The aim of this work was to understand the Ag(I) sorption at low concentrations
in aquatic systems, specially natural porous media such as soils, sediments and ground waters. Kinetic
and thermodynamic experiments were performed in batch reactors at room temperature in the dark. A
pure silica sand and a natural aquifer quartz sand were used. Silver concentration and pH (2, 4, 6 and 8) play an important
role, while the ionic strength (NaNO
3) does not affect neither sorption kinetics
nor sorption thermodynamics. For each point, more than four days were necessary to observe
equilibrium state. Ag sorption rate law does not appear to be simple, with a change in the reaction
order depending on experimental conditions. Sorption isotherms were modelled with Langmuir type
relationship for a Ag-range concentration from nanomolar to millimolar. In both kinetic and
thermodynamic experiments, one to three sites were necessary to take into account the surface
heterogeneity of the natural quartz sand depending on experimental conditions.
© EDP Sciences 2003
