Elucidation of the Structure of Organic Solutions in Solvent Extraction by Combining Molecular Dynamics and X‐ray Scattering

Abstract

This research was supported by the CEA (DSOE/RBPCH) and the scientific committee of the University of Montpellier II, as well as through national funding (ANR 12-BS08-0021; ILLA). We thank Eric Pellegrini for fruitful discussions on the simulation of the structure factors from MD simulations, as well as Bruno Corso for technical support with the SWAXS apparatus.Supporting information for this article is available on the WWW under http://dx.

Depletion of water-in-oil aggregates from poor solvents: Transition from weak aggregates towards reverse micelles

“…A newly published study shows that the combination of small angle scattering experiments with molecular dynamic simulations offers new key insight into the complex organic fluid structure for both the molecular and the supramolecular levels, without preliminary hypothesis on the aggregate shapes, or organization [12]. This methodology has been successfully applied for the aggregation characterization of organic phases containing two different amide extractants in n-heptane, contacted with an aqueous phase, and forming small reverse aggregates, without a strongly organized system containing a well defined curved surfactant layer as in the classical reverse micelle organization.…”

“…The value of the area per molecule immediately gives the area per surfactant molecule present [9] and the amount of monomers coexisting in dynamic equilibrium is experimentally difficult to determine and is roughly in the order of 10 −3 M for all cases described up to now [10]. -"No" because there are recent experimental reports by Rodrigues [11] and Ferru [12] about well determined w/o aggregates, with four to height molecules per aggregate, that do not show a measurable Porod limit decay in scattering. These aggregates are in dynamic equilibrium with monomers of extractant dispersed in the solvent.…”

Radiochemical analysis of protactinium speciation

“…The interfacial and bulk properties of these systems were investigated using a combination of physical measurements, synchrotron small angle X-ray scattering (SAXS), and atomistic molecular dynamic (MD) simulations. 138,139 The results presented in this manuscript supplement recent reports and provide a detailed account of the occurrence of nano-scale domains formed in the organic phase of oil/water systems containing an alcohol. We also provide further discussion of the chemical equilibration necessary for understanding the energetics of aggregate formation involving alcohols 1-octanol and 2-ethyl-hexanol in solutions of water and dodecane.…”

“…156 Note that nMoldyn actually calculates the atomic number weighted structure factor for SAXS. 157,158 The atomic form factor is related to the atomic number (Z) via Equation 27;…”

New Insights into the Recovery of Strategic and Critical Metals by Solvent Extraction

“…Tributyl phosphate (TBP) is an industrially relevant solvating extractant used to separate plutonium and uranium from nuclear fuel waste and is prone to form third phases under high acid and metal concentrations due to its amphiphilic nature and propensity to form reverse micelles [49]. While the study of these colloidal systems by X-ray and neutron scattering techniques is increasingly common [50], pulsed-field-gradient NMR spectroscopy has only recently been used to study the shape and size of metal-containing aggregates [51]. This diffusion NMR method is complementary to small-angle scattering techniques and was used to study the interactions between TBP aggregates containing uranium or zirconium cations and HNO3 in a dodecane diluent.…”