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Ion Distributions at the Nitrobenzene-Water Interface Electrified by a Common Ion

Guangming Luo·Sarka Malkova·Jaesung Yoon·David G. Schultz·Binhua Lin·Mati Meron·Ilan Benjamin·Petr Vanysek·Mark L. Schlossman
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Abstract

Synchrotron x-ray reflectivity is used to study ion distributions at the liquid-liquid interface between a nitrobenzene solution of tetrabutylammonium tetraphenylborate (TBATPB) and a water solution of tetrabutylammonium bromide (TBABr). The concentration of TBABr is varied to alter the ion distribution. Our x-ray measurements are inconsistent with several commonly used theories of ion distributions, including Gouy-Chapman, modified Verwey-Niessen, and the MPB5 version of the Poisson-Boltzmann equation. These structural measurements are described well by ion distributions predicted by a version of the Poisson-Boltzmann equation that explicitly includes a free energy profile for ion transfer across the interface when this profile is described by a simple analytic form or by a potential of mean force from molecular dynamics simulations. These x-ray measurements from the liquid-liquid interface provide evidence for the importance of interfacial liquid structure in determining interfacial ion distributions.

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Guangming Luo, Sarka Malkova, Jaesung Yoon, David G. Schultz, Binhua Lin, Mati Meron, Ilan Benjamin, Petr Vanysek, Mark L. Schlossman. 2006-04-06. Ion Distributions at the Nitrobenzene-Water Interface Electrified by a Common Ion. https://arxiv.org/abs/cond-mat/0604182

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