Investigation of Inner and Outer Phase Formation in Tube Radial Distribution Phenomenon Using Various Types of Mixed Solvent Solutions

Abstract

When mixed solvent solutions, such as ternary water-hydrophilic/hydrophobic organic solvents, water-surfactant, water-ionic liquid, and fluorous-organic solvents are delivered into a microspace under laminar flow conditions, the solvent molecules are radially distributed in the microspace, generating inner and outer phases. This specific fluidic behavior is termed "tube radial distribution phenomenon" (TRDP). In this study, the factors influencing the formation of inner and outer phases in the TRDP using the above-mentioned mixed solvent solutions were investigated. We examined phase diagrams, viscosities of the two phases (upper and lower phases in a batch vessel), volume ratios of the phases, and bright-light or fluorescence photographs of the TRDP. When the difference in viscosities between the two phases was large (> approximately 0.73 mPa·s), the phase with the larger viscosity formed an inner phase regardless of the volume ratios, whereas when the difference was small (< approximately 0.42 mPa·s), the phase with the larger volume formed an inner phase. The TRDP using a water-surfactant mixed solution was also investigated in capillary chromatography based on TRDP.

Distribution Equilibria of Amphoteric 8-Quinolinol between 1-Alkyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imide and Aqueous Phases and Their Effect on Ionic Liquid Chelate Extraction Behavior of Iron(III)

“…ILs are also used in analytical chemistry, including electroanalytical chemistry 2,3 and separation chemistry. [4][5][6][7] Solvent extraction of metal cations is a separation technique using large amounts of hydrophobic organic solvents for the extraction phase materials.…”

Tube Radial Distribution Flow Separation in a Microchannel Using an Ionic Liquid Aqueous Two-Phase System Based on Phase Separation Multi-Phase Flow

“…8 When there is a viscosity difference of over 0.7 mPa·s between the two phases, the phase with the highter viscosity forms the inner phase and the phase with the lower viscosity forms the outer phase, like water-[C4mim]Cl-KOH and water-[C2mim]MP-K2HPO4. 8,14 The configuration pattern was confirmed based on the viscous dissipation principle. On the other hand, when there was a viscosity difference of less than 0.7 mPa·s between the two phases, the larger volume phase formed an inner phase; that is, the phase configuration depended on the volume ratios, like water-[C4mim]Cl-K2HPO4.…”

“…8,14 In the present study, the phase diagram, viscosity, and TRDF image of the water-[C4mim]Cl-NaOH system was additionally examined. Figure 2 shows the phase diagram for this system, including solubility curves at 15 and 20 C. Transformation from the homogeneous to heterogeneous phases occurred upon changing the temperature from a high to low value.…”

“…2. The NaOH system was checked and considered regarding the following things, compared to the KOH system: 1) the appearance of salt precipitation in a batch vessel, as the KOH system showed precipitation at high concentrations of ionic liquid, 14 and 2) the effect of the difference in the hydration behavior between hydrophobic ion (K + ) and hydrophilic ion (Na + ) on the phase diagrams. As a result, we could not observe salt precipitation in the experimental area for the NaOH system, and there was little difference in the solubility curve position on the phase diagrams between the systems.…”

“…1,[10][11][12][13] Ionic liquid aqueous systems separate into two distinct phases, namely an ionic liquid-rich phase and ionic liquid-poor phase, when cooled below a certain temperature. 13 In our previous study, 8,14 the TRDP and TRDF behavior of ionic liquid aqueous two-phase systems (e.g., water-1-butyl-3-methylimidazolium chloride ([C4mim]Cl)-KOH, water-[C4mim]Cl-K2HPO4, and water-1-ethyl-3-methylimidazolium methylphosphonate ([C2mim]MP)-K2HPO4) showing phase separation characteristics were examined by feeding into a capillary tube. However, there has been no information on the distribution behavior of a solute in the TRDF with ionic liquid aqueous two-phase systems.…”