Structure and spectroscopic study of aqueous Fe(III)-As(V) complexes using UV-Vis, XAS and DFT-TDDFT

Liyuan Chai; Jinqin Yang; Ning Zhang; Pin-Jiun Wu; Qingzhu Li; Qingwei Wang; Hui Liu; Haibo Yi

doi:10.1016/j.chemosphere.2017.05.018

Structure and spectroscopic study of aqueous Fe(III)-As(V) complexes using UV-Vis, XAS and DFT-TDDFT

Chemosphere. 2017 Sep:182:595-604. doi: 10.1016/j.chemosphere.2017.05.018. Epub 2017 May 3.

Authors

Liyuan Chai¹, Jinqin Yang², Ning Zhang³, Pin-Jiun Wu⁴, Qingzhu Li⁵, Qingwei Wang¹, Hui Liu¹, Haibo Yi⁶

Affiliations

¹ School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China.
² School of Metallurgy and Environment, Central South University, Changsha 410083, China.
³ College of Science, Central South University of Forestry and Technology, Changsha 410004, China.
⁴ Industrial Application Group, Synchrotron Radiation Research Center, Hsinchu 30076, China.
⁵ School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China. Electronic address: [email protected].
⁶ State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China.

PMID: 28525873
DOI: 10.1016/j.chemosphere.2017.05.018

Abstract

Aqueous complexes between ferric (Fe(III)) and arsenate (As(V)) are indispensable for understanding the mobility of arsenic (As) in Fe(III)-As(V)-rich systems. In this study, aqueous Fe(III)-As(V) complexes, FeH₂AsO₄²⁺ and FeHAsO₄⁺, were postulated based on the qualitative analysis of UV-Vis spectra in both Fe(III)-As(V)-HClO₄ and Fe(III)-As(V)-H₂SO₄ systems. Subsequently, monodentate structures were evidenced by Fe K-edge EXAFS and modeled as [FeH₂AsO₄(H₂O)₅]²⁺ and [FeHAsO₄(H₂O)₅]⁺ by DFT. The feature band at ∼280 nm was verified as electron excitation chiefly from Fe-As-bridged O atoms to d-orbital of Fe in [FeH₂AsO₄(H₂O)₅]²⁺ and [FeHAsO₄(H₂O)₅]⁺. The structural and spectral information of Fe(III)-As(V) complexes will enable future speciation analysis in Fe(III)-As(V)-rich system.

Keywords: DFT-TDDFT; Fe(III)-As(V) complexes; UV–Vis spectra; XAS.

MeSH terms

Arsenates
Arsenic / chemistry*
Ferric Compounds / chemistry*
Models, Molecular*
Molecular Structure
Spectrum Analysis / methods*
Water / chemistry*

Substances

Arsenates
Ferric Compounds
Water
Arsenic
arsenic acid