Electrolyte Ion Binding at Iron Oxyhydroxide Mineral Surfaces

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• 作者：Philipp A. Kozin ; Andrey Shchukarev ; Jean-Fran莽ois Boily
• 刊名：Langmuir
• 出版年：2013
• 出版时间：October 1, 2013
• 年：2013
• 卷：29
• 期：39
• 页码：12129-12137
• 全文大小：469K
• 年卷期：v.29,no.39(October 1, 2013)
• ISSN：1520-5827

文摘

Electrolyte ion loadings at the surfaces of synthetic goethite (伪-FeOOH) and lepidocrocite (纬-FeOOH) particles that were pre-equilibrated in aqueous solutions of 10 mM NaCl and NaClO₄ at 25 掳C were investigated by cryogenic X-ray photoelectron spectroscopy (XPS). Atomic concentrations of Cl^{鈥?/sup>, ClO₄鈥?/sup>, and Na+ were correlated to potential determining ion (pdi; H+, OH鈥?/sup>) loadings obtained by potentiometric titrations. While Cl鈥?/sup> promoted more pdi adsorption than ClO₄鈥?/sup>, due to its greater charge-to-size ratio, both ions followed the same loading dependence on pdi adsorption, in contrast to previous studies supporting the concept for negligible perchlorate adorption. Lepidocrocite particles exhibited a stronger response of electrolyte adsorption to pdi loadings due electrolyte ion adsorption on the proton inactive (010) plane. These particles also acquired greater sodium loadings than goethite. These loadings were moreover considerably enhanced by perchlorate adsorption, possibly due to a thickening of the interfacial region in NaClO₄ on the (010) plane. Finally, goethite particles with rougher surfaces acquired greater pdi and ion loadings than on those with smoother surfaces. No strong differences could be discerned between Cl鈥?/sup> and ClO₄鈥?/sup> loadings on these materials. This work thus identified key aspects underpinning the relationship between pdi and electrolyte loadings at FeOOH mineral surfaces of environmental and technological importance.}