Simultaneous sequestration of uranyl and arsenate at the goethite/water interface

This study highlights the simultaneous sequestration of U(VI) and arsenate at the goethite/water interface. The uptake trends and speciation of these two components were related with molar arsenate/U(VI) ratio, solution pH, contact order and aging time. A metastable [UO₂(H₂AsO₄)₂·H₂O] was observed after 3 days and then this solid completely transformed into Na₂(UO₂AsO₄)₂·3H₂O after 7 days. The disodium ethylenediamine tetraacetate ligand gave rise to the complete dissolution of Na₂(UO₂AsO₄)₂·3H₂O phase and the release of U(VI) and arsenate back into the solution. The experimental findings facilitated us better comprehend the migration and fate of coexisting U(VI) and arsenate in the aquatic environment. (author)