Velasco Carmen A, Brearley Adrian J, Gonzalez-Estrella Jorge, Ali Abdul-Mehdi S, Meza María Isabel, Cabaniss Stephen E, Thomson Bruce M, Forbes Tori Z, Lezama Pacheco Juan S, Cerrato José M
Department of Civil, Construction and Environmental Engineering, MSC01 1070, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Department of Earth and Planetary Sciences, MSC03 2040, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Environ Sci Technol. 2021 Dec 7;55(23):16246-16256. doi: 10.1021/acs.est.1c05429. Epub 2021 Nov 19.
We investigated interfacial reactions of U(VI) in the presence of Suwannee River natural organic matter (NOM) at acidic and neutral pH. Laboratory batch experiments show that the adsorption and precipitation of U(VI) in the presence of NOM occur at pH 2 and pH 4, while the aqueous complexation of U by dissolved organic matter is favored at pH 7, preventing its precipitation. Spectroscopic analyses indicate that U(VI) is mainly adsorbed to the particulate organic matter at pH 4. However, U(VI)-bearing ultrafine to nanocrystalline solids were identified at pH 4 by electron microscopy. This study shows the promotion of U(VI) precipitation by NOM at low pH which may be relevant to the formation of mineralized deposits, radioactive waste repositories, wetlands, and other U- and organic-rich environmental systems.
我们研究了在酸性和中性pH条件下,萨凡纳河天然有机物(NOM)存在时U(VI)的界面反应。实验室批次实验表明,在NOM存在的情况下,U(VI)在pH 2和pH 4时发生吸附和沉淀,而在pH 7时,溶解有机物对U的水相络合作用更有利,从而防止其沉淀。光谱分析表明,在pH 4时,U(VI)主要吸附在颗粒有机物上。然而,通过电子显微镜在pH 4时鉴定出了含U(VI)的超细至纳米晶体固体。这项研究表明,在低pH条件下,NOM会促进U(VI)沉淀,这可能与矿化沉积物、放射性废物处置库、湿地以及其他富含U和有机物的环境系统的形成有关。