Characterization of Phosphate and Arsenate Adsorption onto Keggin-Type Al30 Cations by Experimental and Theoretical Methods
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- 作者：Katie W. Corum ; Melissa Fairley ; Daniel K. Unruh ; Maurice K. Payne ; Tori Z. Forbes ; Sara E. Mason
- 刊名：Inorganic Chemistry
- 出版年：2015
- 出版时间：September 8, 2015
- 年：2015
- 卷：54
- 期：17
- 页码：8367-8374
- 全文大小：467K
- ISSN：1520-510X
文摘
Keggin-type aluminum oxyhydroxide species such as the Al30 (Al30O8(OH)56(H2O)2618+) polycation can readily sequester inorganic and organic forms of P(V) and As(V), but there is a limited chemical understanding of the adsorption process. Herein, we present experimental and theoretical structural and chemical characterization of [(TBP)2Al2(渭4-O8)(Al28(渭2-OH)56(H2O)22)]14+ (TBP = t-butylphosphonate), denoted as (TBP)2Al30-S. We go on to consider the structure as a model for studying the reactivity of oxyanions to aluminum hydroxide surfaces. Density functional theory (DFT) calculations comparing the experimental structure to model configurations with P(V) adsorption at varying sites support preferential binding of phosphate in the Al30 beltway region. Furthermore, DFT calculations of R-substituted phosphates and their arsenate analogues consistently predict the beltway region of Al30 to be most reactive. The experimental structure and calculations suggest a shape鈥搑eactivity relationship in Al30, which counters predictions based on oxygen functional group identity.