Uranyl Arsenate Complexes in Aqueous Solution: Insights from First-Principles Molecular Dynamics Simulations

Mengjia He, Xiandong Liu, Jun Cheng, Xiancai Lu, Chi Zhang, Rucheng Wang

Research output: Contribution to journalArticle

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Abstract

In this study, the structures and acidity constants (p Ka's) of uranyl arsenate complexes in solutions have been revealed by using the first principle molecular dynamics technique. The results show that uranyl and arsenate form stable complexes with the U/As ratios of 1:1 and 1:2, and the bidentate complexation between U and As is highly favored. Speciation-pH distributions are derived based on free energy and p Ka calculations, which indicate that for the 1:1 species, UO2(H2AsO4)(H2O)3+ is the major species at pH < 7, while UO2(HAsO4)(H2O)30 and UO2(AsO4)(H2O)3- dominate in acid-to-alkaline and extreme alkaline pH ranges. For the 1:2 species, UO2(H2AsO4)2(H2O)0 is dominant under acid-to-neutral pH conditions, while UO2(HAsO4)(H2AsO4)(H2O)-, UO2(HAsO4)(HAsO4)(H2O)2-, and UO2(AsO4)(HAsO4)(H2O)3- become the major forms in the pH range of 7.2-10.7, 10.7-12.1, and >12.1, respectively.

Original languageEnglish
Pages (from-to)5801-5809
Number of pages9
JournalInorganic Chemistry
Volume57
Issue number10
Early online date9 May 2018
DOIs
Publication statusPublished - 31 Oct 2018

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arsenates
Molecular dynamics
molecular dynamics
aqueous solutions
Computer simulation
Complexation
Acidity
acidity
Free energy
simulation
free energy
arsenic acid

Keywords

  • Journal Article

Cite this

Uranyl Arsenate Complexes in Aqueous Solution : Insights from First-Principles Molecular Dynamics Simulations. / He, Mengjia; Liu, Xiandong; Cheng, Jun; Lu, Xiancai; Zhang, Chi; Wang, Rucheng.

In: Inorganic Chemistry, Vol. 57, No. 10, 31.10.2018, p. 5801-5809.

Research output: Contribution to journalArticle

He, Mengjia ; Liu, Xiandong ; Cheng, Jun ; Lu, Xiancai ; Zhang, Chi ; Wang, Rucheng. / Uranyl Arsenate Complexes in Aqueous Solution : Insights from First-Principles Molecular Dynamics Simulations. In: Inorganic Chemistry. 2018 ; Vol. 57, No. 10. pp. 5801-5809.
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AU - Lu, Xiancai

AU - Zhang, Chi

AU - Wang, Rucheng

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AB - In this study, the structures and acidity constants (p Ka's) of uranyl arsenate complexes in solutions have been revealed by using the first principle molecular dynamics technique. The results show that uranyl and arsenate form stable complexes with the U/As ratios of 1:1 and 1:2, and the bidentate complexation between U and As is highly favored. Speciation-pH distributions are derived based on free energy and p Ka calculations, which indicate that for the 1:1 species, UO2(H2AsO4)(H2O)3+ is the major species at pH < 7, while UO2(HAsO4)(H2O)30 and UO2(AsO4)(H2O)3- dominate in acid-to-alkaline and extreme alkaline pH ranges. For the 1:2 species, UO2(H2AsO4)2(H2O)0 is dominant under acid-to-neutral pH conditions, while UO2(HAsO4)(H2AsO4)(H2O)-, UO2(HAsO4)(HAsO4)(H2O)2-, and UO2(AsO4)(HAsO4)(H2O)3- become the major forms in the pH range of 7.2-10.7, 10.7-12.1, and >12.1, respectively.

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