Autor: Joan Gutiérrez (IDAEA-CISC)
Adsorption of REE on Al- and Fe- oxyhydroxysulphates under theconditions of the AMD-impacted estuary of Huelva.
Abstract:
In the Tinto and Odiel basins (South of Spain), the waters of numerousstreams and rivers affected by acid-mine-drainage (AMD) are enriched inrare-earth elements (REEs). Under AMD conditions, schwertmannite andbasaluminite (Fe-Al- oxyhydroxysulfates, respectively) retain REE via chemisorption. At the Estuary of Huelva the acidic Odiel and Tintorivers mix with seawater, strongly affecting the marsh ecosystem. Highionic strength and pH may affect the stability of REE retention on Fe-Al- oxyhydroxysulfates. This presentation focuses on the effects ofionic strength on REE sorption/desorption on basaluminite and schwertmannite. Series of batch experiments were conducted at different pH (4.5-7) and ionic strength (0.25-0.5 M) under atmospheric pressure to obtain equilibrium constants for the REE oxyhydroxysulfate sorption/desorption reactions. Additionally, Extended X-ray Adsorption Fine-Structure (EXAFS), High Energy X-Ray Scattering (HEXS) and density functional theory (DFT) simulations were performed to elucidate binding characteristics at the surfaces of the REE- enriched oxyhydroxysulfates.
