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Ionic liquids (ILs) have been proposed as extractants for separation of metals, including rare earth elements. In particular, protonated betaine bis(trifluoromethylsulfonyl)imide ([HBet][TFSI]) exhibits liquid–liquid phase behavior with water that can be tuned by complexation with various metals. Here we show that previously undetected neutral zwitterionic betaine formed during the IL synthesis can affect the phase behaviour. [ABSTRACT FROM AUTHOR]

Separation of olefins from their paraffin analogs relies on energy‐intensive cryogenic distillation. Facilitated transport‐based membranes that reversibly and selectively bind olefins, but not paraffins, could save considerable amounts of energy. However, the chemical instability of the silver ion olefin‐binding carriers in such membranes has been a longstanding roadblock for this approach. We discovered long‐term carrier stability against extended exposure to hydrogen, a common contaminant in such streams. Based on UV/Vis absorption and Raman spectroscopy, along with XRD analysis results, certain ionic liquids solubilize silver ions, and anion aggregates surrounding the silver ion carriers greatly attenuate their reduction by hydrogen. Here, we report the stability of olefin/paraffin separation properties under continuous exposure to high pressure hydrogen, which addresses a critical technical roadblock in membrane‐based olefin/paraffin separation. [ABSTRACT FROM AUTHOR]

A study to examine the solubility of gases in ionic liquids (ILs) is conducted. Findings reveal a several fold increase in carbon dioxide solubility due to the use of fluoro-alkyl chains.

The ability of C[O.sub.2] to induce liquid/liquid-phase separation in mixtures of ionic liquids and organics is examined. The ability of C[O.sub.2] to act as an antisolvent has depended on the solubility of the C[O.sub.2] in the ionic liquid/organic mixture and strong hydrogen bonding between the ionic liquid and the organic has made it difficult for C[O.sub.2] to induce a liquid/liquid-phase secarbon compoundsparation.

The solvent strength of IL/organic mixtures is reported using Reichardt's dyes 30 and 33, Kamlet-Taft parameters and phenol blue. The results shows that the polarity of ILs is largely unaffected by the organic consolvent that is the probes are preferentially solvated by the ILs.

A report on the solubilities of a variety of gases in several different ionic liquids is presented. It is concluded that the nature of the anion has the most significant influence on the gas solubilities.

The influence of anion, cation alkyl chain length, and additional alkyl substituents on the cation ring and on the solubility of CO2 in ILs at pressures to 150 bar is investigated. The results suggest that the solubility of carbon dioxide is strongly dependent on the choice of anion.

The bimolecular rate constants of the addition reaction between hydroxyl radical and nitrobenzene are determined in subcritical and supercritical water (SCW) at temperatures between ambient and 390 degree celsius. The measured bimolecular rate constants reported distinctly non-Arrhenius behavior from ambient to 350 degree celsius but increased in the slightly subcritical and supercritical region between 350 and 390 degree celsius.

A study of the ability of subcritical water to support ionic chemistry from the successful generation of (-R-xanthenium (R = H and C6H5) carbocations at temperatures up to 330 degrees Celsius from their respective alcohol precursors. The results show that for ion/neutral isoCoulombic reactions, require low-temperature Arrhenius parameters to predict the rate constants in water at higher temperatures and that the effect of pressure on the bimolecular rate constants in the temperature range of 22-330 degrees Celsius was negligible.

A study investigated the triplet-triplet annihilation of anthracene in supercritical water at temperatures ranging from 375 degrees to 450 degrees C and pressures of 50-350 bar. The experiment aimed to determine whether the conclusions about diffusion-controlled reactions in lower temperature supercritical fluids also apply to reactions in supercritical water. Observed rate constant and anthracene triplet extinction coefficient data were taken to determine the bimolecular rate constants as a function of temperature and pressure.

Investigation of local solvation effects during fluorescence quenching of anthracene in supercritical CO2 as the reaction is varied from diffusion controlled to kinetically controlled found that reaction rates depend on donor energy levels and acceptor electron affinities. Results indicate that a large pressure effect is exerted on reaction rate by local composition enhancement of the quencher molecules in the anthracene solute. Fluorescence spectra and solvatochromic shift data indicate both local density augmentation and local composition increases around the anthracene.

The absolute reactivity of triplet benzophenone and benzyl free radicals towards molecular oxygen in supercritical CO2 and CHF3 is measured using laser flash photolysis, absolute reaction kinetics and integral equation theory in order to investigate preferential consolvent solvation in ternary supercritical fluid mixtures. The bimolecular rate constants increase slightly with increase in pressure and are consistent with the preferential solvation of the solute.

Investigations of the possibility of diffusion-controlled mechanisms being obstructed or enhanced in supercritical fluids or fluid mixtures, draw on the findings of the triplet-triplet annihilation process of benzophenone (Ph2C double bond O) and the self-termination reaction of benzyl radical, PhCh2. Both reactions occur basically at the diffusion-control limit in supercritical fluoroform and carbon dioxide doped with 1 mol % acetonitrile when spin statistical factors are considered.

A study was done on the effects of pressure on the absolute kinetics of benzophenone photoreduction in supercritical CO2. Results show that the highest rate constants occur at lower pessures near the critical point of the solution despite the decrease in activation volume during lowering to the critical pressure. These findings show the effects of increasing the local concentration of substrate in the compressible region near the critical point.