期刊
CHEMICAL GEOLOGY
卷 464, 期 -, 页码 14-22出版社
ELSEVIER
DOI: 10.1016/j.chemgeo.2016.08.010
关键词
Goethite; Oxalate; Density functional theory; Infrared; Dissolution; Redox
资金
- National Science Foundation (NSF) [CHE-0714121]
Oxalic acid is an important, biologically-produced species in the natural environment. The deprotonated form, oxalate, is dominant in aqueous solutions under circumneutral pH conditions and is a strong ligand for Fe(III). The high affinity of oxalate for Fe(III) means that Fe(III)-oxalate surface and aqueous complexes are common and can lead to ligand-enhanced dissolution. Fe(II) adsorption onto goethite (alpha-FeOOH) has been shown to enhance dissolution-recrystallization reactions. The goethite (010) face is one of the more common and reactive surfaces on this environmentally critical Fe-hydroxide phase. Hence, this study models both separate and coordinated adsorption of oxalate and Fe(II) onto the (010) face of goethite in order to test for synergistic effects of ligand-promoted and reductive dissolution. Periodic and cluster density functional theory (DFT) energy minimizations were performed to determine the structure, vibrational frequencies and energies of various configurations. The adsorption mechanism of oxalate is verified via comparison to observed IR spectra. The potential roles of oxalate and Fe(II) in ligand-enhanced reductive dissolution of goethite are discussed. (C) 2016 Elsevier B.V. All rights reserved.
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