Removal of Aqueous Uranyl and Arsenate Mixtures after Reaction with Limestone, PO43–, and Ca2+
Year: 2023
Type: article
Abstract: The co-occurrence of uranyl and arsenate in contaminated water caused by natural processes and mining is a concern for impacted communities, including in Native American lands in the U.S. Southwest. We investigated the simultaneous removal of aqueous uranyl and arsenate after the reaction with limestone and precipitated hydroxyapatite (HAp, Ca 10 (PO 4 ) 6 (OH) 2 ). In benchtop experiments with an initial pH of 3.0 and initial concentrations of 1 mM U and As, uranyl and arsenate coprecipitated in the presence of 1 g L –1 limestone. However, related experiments initiated under circumneutral pH conditions showed that uranyl and arsenate remained soluble. Upon addition of 1 mM PO 4 3– and 3 mM Ca 2+ in solution (initial concentration of 0.05 mM U and As) resulted in the rapid removal of over 97% of U via Ca–U–P precipitation. In experiments with 2 mM PO 4 3– and 10 mM Ca 2+ at pH rising from 7.0 to 11.0, aqueous concentrations of As decreased (between 30 and 98%) circa pH 9. HAp precipitation in solids was confirmed by powder X-ray diffraction and scanning electron microscopy/energy dispersive X-ray. Electron microprobe analysis indicated U was coprecipitated with Ca and P, while As was mainly immobilized through HAp adsorption. The results indicate that natural materials, such as HAp and limestone, can effectively remove uranyl and arsenate mixtures.
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, National Institutes of Health, Office of Science, National Institute of Environmental Health Sciences, Division of Chemical, Bioengineering, Environmental, and Transport Systems, Basic Energy Sciences, Division of Equity for Excellence in STEM, Core Research for Evolutional Science and Technology
Awards: G2042306365, G222768804, TOPOLOGICAL STRUCTURAL RELATIONSHIPS, PROPERTIES, AND NANO-STRUCTURES..., CREST Center for Water and the Environment, Phase II, TOPOLOGICAL STRUCTURAL RELATIONSHIPS, PROPERTIES, AND NANO-STRUCTURES..., G5436786387, G5606647632, G5613623313, G5648016710, TOPOLOGICAL STRUCTURAL RELATIONSHIPS, PROPERTIES, AND NANO-STRUCTURES OF U(VI) NO(V) AND PU(V) MATERIALS, G6671297155, CAREER: Understanding Reactivity in American Native Impacted Uranium Mines (URANIUM): Research, Education and Outreach, UNM Metals Exposure and Toxicity Assessment on tribal Lands in the Southwest (METALS) Superfund Research Program
OpenAlex ID: W4389132508