CONICET | Buscador de Institutos y Recursos Humanos

Clay materials used as low?permeability barriers at landfill sites can also chemically attenuate inorganic contaminants (heavy metals) in leachate. In this study, the Cu(II) removal capacity from aqueous media of a calcareous mudstone, which has the potential to be used as a liner material, was evaluated through both batch and column tests. Batch experiments were conducted varying contact time, pH and Cu(II) concentration. In order to simulate waste leachates composition, the effect of the presence of some organic compounds on Cu(II) uptake was also evaluated. Column tests of compacted calcareous mudstone ?sand mixtures were performed to evaluate sorption in dynamic systems. Our data show that the studied raw calcareous mudstone exhibited higher removal capacity in a wider pH range than a commercial Na-bentonite, which is a widely used heavy metal sorbent and clay liner. Calcite is an important component of the calcareous mudstone and it is in the form of very small and highly porous calcareous nannofossils which contributed to its sorcitive sorption/reactive properties. The presence of an anionic surfactant or phenol slightly affected the removal of Cu(II). In the size fraction < 2 µm, where only clay minerals are present, Cu(II) sorption was favored by the presence of humic acids, which add new adsorption sites for this metal. The extremely high retardation factor obtained for the calcareous mudstone as raw material is in good agreement with the high adsorption capacity experimentally proved in batch tests and demonstrated a great ability of this material to retain heavy metal mass during the transport in solution within the soilporous media. Calcareous mudstones are very common in almost all the sedimentary basins in the world; therefore, the obtained results are fundamental when considering them as a low-cost geomaterial for geoenvironmental applications.

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