Title: “Thought experiments” as dry-runs for “tough experiments”: novel approaches to the hydration behavior of oxyanions

Abstract

We explore the deconvolution of correlations for the interpretation of the microstructural behavior of aqueous electrolytes according to the neutron diffraction with isotopic substitution (NDIS) approach toward the experimental determination of ion coordination numbers of systems involving oxyanions, in particular, sulfate anions. We discuss the alluded interplay in the title of this presentation, emphasized the expectations, and highlight the significance of tackling the challenging NDIS experiments. Specifically, we focus on the potential occurrence of N$$2+\atop{i}$$ ...SO$$2-\atop{4}$$ pair formation, identify its signature, suggest novel ways either for the direct probe of the contact ion pair (CIP) strength and the subsequent correction of its effects on the measured coordination numbers, or for the determination of anion coordination numbers free of CIP contributions through the implementation of null-cation environments. For that purpose we perform simulations of NiSO₄ aqueous solutions at ambient conditions to generate the distribution functions required in the analysis (a) to identify the individual partial contributions to the total neutron-weighted distribution function, (b) to isolate and assess the contribution of N$$2+\atop{i}$$ ...SO$$2-\atop{4}$$ pair formation, (c) to test the accuracy of the neutron diffraction with isotope substitution based coordination calculations and X-ray diffraction based assumptions, and (d) to describe the water coordination around both the sulfur and oxygen sites of the sulfate anion. In conclusion, we finally discuss the strength of this interplay on the basis of the inherent molecular simulation ability to provide all pair correlation functions that fully characterize the system microstructure and allows us to “reconstruct” the eventual NDIS output, i.e., to take an atomistic “peek” (e.g., see Figure 1) at the local environment around the isotopically-labeled species before any experiment is ever attempted, and ultimately, to test the accuracy of the “measured” NDIS-based coordination numbers against the actual values by the “direct” counting.

Authors:

Chialvo, Ariel A.  ^[1];

• Search DOE PAGES for author "Chialvo, Ariel A."
• Search DOE PAGES for ORCID "0000-0002-6091-4563"

Vlcek, Lukas  ^[1]

• Search DOE PAGES for author "Vlcek, Lukas"
• Search DOE PAGES for ORCID "0000-0003-4782-7702"

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division

Publication Date:

Thu Jan 21 00:00:00 EST 2016

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1324062

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Pure and Applied Chemistry

Additional Journal Information:

Journal Volume: 88; Journal Issue: 3; Conference: 34. International Conference on Solution Chemistry (ICSC-34), Prague (Czech Republic), 30 Aug-3 Sep 2015; Journal ID: ISSN 0033-4545

Publisher:

IUPAC

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; computer simulation; electrolytes; hydration; ICSC-34; neutron diffraction; speciation