Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2026 Jan:159:460-470.
doi: 10.1016/j.jes.2025.04.081. Epub 2025 May 8.

Unveiling the interaction of uranyl and arsenate: Insights into the formation mechanisms of uranyl arsenate minerals

Penggang Li  1 , Ping Zhang  1 , Zhihui Yang  2 , Lin Yu  1 , Junhao Zheng  1 , Mengying Si  2 , Qi Liao  2 , Feiping Zhao  3 , Weichun Yang  4
Affiliations

Unveiling the interaction of uranyl and arsenate: Insights into the formation mechanisms of uranyl arsenate minerals

Penggang Li et al. J Environ Sci (China). 2026 Jan.

Abstract

Uranyl arsenate minerals, which exhibit low solubility, serve as major sinks for U and As, playing a crucial role in controlling the mobility of U and As in the environment. However, the specific mechanisms underlying the formation of uranyl arsenate minerals have remained largely elusive. Herein, the formation pathway of the non-charged UO2(H2AsO4)2·nH2O0 complex was investigated to elucidate the early formation of the UO2(H2AsO4)2·nH2O mineral (where n represents the stoichiometric number of H2O), a representative uranyl arsenate mineral. Based on the combination experiments of U(VI) and As(V), our findings underscore the significant dependence of UO2(H2AsO4)2·nH2O0 formation on solution pH (4.0-10.0). Density functional theory (DFT) calculations reveal a two-step reaction involving two distinct pathways (Pathway 1 and Pathway 2) for the formation of UO2(H2AsO4)2·nH2O, and the intermediate was confirmed by in situ Raman and fluorescence spectroscopy. Specifically, the hydroxyl‑connected uranyl (UO2OH+) reacts with the protonated arsenate (H2AsO4-) species to form the intermediate UO2HAsO4·H2O (Pathway 1) or UO2OHH2AsO4 (Pathway 2) with a U/As ratio of 1:1. Meanwhile, all the transition states also were obtained and the energy barrier suggested that the UO2(H2AsO4)2·2H2O0 formed by Pathway 1 is thermodynamically favored over Pathway 2, and may serve as the primary fundamental structural unit or precursor for the early formation of the UO2(H2AsO4)2·nH2O mineral phase. Altogether, this study contributes to advancing the understanding of the formation of uranyl arsenate minerals at the molecular scale and provides a theoretical basis for predicting and regulating uranium and arsenic mobilization in their coexisting environment.

Keywords: Arsenate; Mineral; Pathway; Thermodynamics; Uranyl.

PubMed Disclaimer

Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.