ADSORPTION OF REE ON AL-AND FE-OXYHYDROXYSULPHATES UNDER THE AMD-IMPACTED ESTUARY OF HUELVA -WEBINAR

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Groundwater Hydrogeology and geochemistry webinar.
ADSORPTION OF REE ON AL-AND FE-OXYHYDROXYSULPHATES UNDER THE AMD-IMPACTED ESTUARY OF HUELVA.
In the Tinto and Odiel basins (South of Spain), the waters of numerous
streams and rivers affected by acid-mine-drainage (AMD) are enriched in
rare-earth elements (REEs). Under AMD conditions, schwertmannite and
basaluminite (Fe-Al- oxyhydroxysulfates, respectively) retain REE via
chemisorption. At the Estuary of Huelva the acidic Odiel and Tinto
rivers mix with seawater, strongly affecting the marsh ecosystem. High
ionic strength and pH may affect the stability of REE retention on
Fe-Al- oxyhydroxysulfates. This presentation focuses on the effects of
ionic 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.