Understanding the Effect of the Phase Modifier n-Octanol on Extraction, Aggregation, and Third-Phase Appearance in Solvent Extraction

Abstract

Phase modifiers are often added to solvent extraction processes to avoid the third-phase formation. While this important issue was attributed to sticky interactions between reverse aggregates, structural effects of phase modifiers remain ambiguous. As they are similar to reverse hydrotropes, phase modifiers may act as cosurfactants or cosolvents in the organic phase in a solvent extraction system. We therefore applied an innovative small-angle scattering approach coupled with surface tension measurements on the industrially applied AMEX process to evaluate how phase modifiers repel the third phase and affect the extraction properties. We first confirmed that adding 1-octanol has a small influence on the extraction performance. By varying the scattering contrast of the solution with deuterated 1-octanol, we found that 1-octanol is located both in the solvent, acting as a cosolvent and diluting the aggregates, and in an outer shell of the aggregates. Further surface tension measurements demonstrated that instead of penetrating till the core of the aggregates as a cosurfactant, 1-octanol only penetrates their shell and forms a shielding barrier avoiding the coalescence of aggregates.

Impact of Water Extraction on Malonamide Aggregation: A Molecular Dynamics and Graph Theoretic Approach

“…Based on the composition analysis of the hydrogen bonded clusters, we find that the water-in-oil aggregates in this system are far from monodisperse and lack a characteristic malonamide aggregate number. This, in conjunction with the background amphiphilic self-association dominating the scattering profiles, indicates that standard colloidal model fitting approaches to quantifying organic phase aggregation − should be re-evaluated. We find large populations of the water-centered clusters with small numbers of water molecules.…”

From Water Solutions to Ionic Liquids with Solid State Nanopores as a Perspective to Study Transport and Translocation Phenomena

“…Upon adsorption to solid surface, aliphatic alcohols can sterically weaken ILs interactions with nanopore surface. Also, their amphiphilic character (in particular, aliphatic alcohols are more hydrophobic than ILs ions) will cause a diversity of self‐assembly which are difficult to manage experimentally, [ 170 ] and even more difficult to predict theoretically. [ 171 ] If the idea is to slow down the flow of ions between the two compartments, then ILs ordering at nanopore walls should not be prevented completely.…”

Role of diluent in the unusual extraction of Am3+ and Eu3+ ions with benzene-centered tripodal diglycolamides: local structure studies using luminescence spectroscopy and XAS

“…35 Alcohols are known to form different structural units in an aliphatic solvent with different solvation properties; more details can be found in the literature. 36,37 The addition of IDA increases the overall polarity of the organic phase, which may facilitate the solubility of the relatively polar metal-ligand solvate in the organic phase [38][39][40][41][42][43] and, hence, favour the extraction of the trivalent Ln 3+ /An 3+ by L I compared with L II . Typically, the extraction of Am 3+ increased upon increasing the IDA content in n-dd, suggesting a better solvation of the Am 3+ -L I solvate compared with that in pure n-dd.…”