From Adsorption to Precipitation of U(VI): What is the Role of pH and Natural Organic Matter?,Environmental Science & Technology

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From Adsorption to Precipitation of U(VI): What is the Role of pH and Natural Organic Matter?
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2021-11-19 , DOI: 10.1021/acs.est.1c05429
Carmen A Velasco ₁ , Adrian J Brearley ₂ , Jorge Gonzalez-Estrella ₃ , Abdul-Mehdi S Ali ₂ , María Isabel Meza ₁ , Stephen E Cabaniss ₄ , Bruce M Thomson ₁ , Tori Z Forbes ₅ , Juan S Lezama Pacheco ₆ , José M Cerrato ₁

Affiliation

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.

中文翻译：

从 U(VI) 的吸附到沉淀：pH 值和天然有机物的作用是什么？

我们研究了在酸性和中性 pH 值下，在 Suwannee 河天然有机物 (NOM) 存在下 U(VI) 的界面反应。实验室批量实验表明，在 NOM 存在下，U(VI) 的吸附和沉淀发生在 pH 2 和 pH 4，而 U 与溶解有机物的水络合在 pH 7 时有利于防止其沉淀。光谱分析表明，在 pH 值为 4 时，U(VI) 主要吸附在颗粒有机物上。然而，在 pH 值为 4 时，通过电子显微镜识别出含有 U(VI) 的超细至纳米晶固体。这项研究表明 NOM 在低 pH 值下促进 U(VI) 沉淀，这可能与矿化沉积物、放射性废物储存库、湿地和其他富含 U 和有机物的环境系统的形成有关。

更新日期：2021-12-07

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