The dynamic process of atmospheric water sorption in [BMIM][Ac]: quantifying bulk versus surface sorption and utilizing atmospheric water as a structure probe

Condensable Gases Capture with Ionic Liquids

Condensable gases are the sum of condensable and volatile steam or organic compounds, including water vapor, which are discharged into the atmosphere in gaseous form at atmospheric pressure and room temperature. Condensable toxic and harmful gases emitted from petrochemical, chemical, packaging and printing, industrial coatings, and mineral mining activities seriously pollute the atmospheric environment and endanger human health. Meanwhile, these gases are necessary chemical raw materials; therefore, developing green and efficient capture technology is significant for efficiently utilizing condensed gas resources. To overcome the problems of pollution and corrosion existing in traditional organic solvent and alkali absorption methods, ionic liquids (ILs), known as "liquid molecular sieves", have received unprecedented attention thanks to their excellent separation and regeneration performance and have gradually become green solvents used by scholars to replace traditional absorbents. This work reviews the research progress of ILs in separating condensate gas. As the basis of chemical engineering, this review first provides a detailed discussion of the origin of predictive molecular thermodynamics and its broad application in theory and industry. Afterward, this review focuses on the latest research results of ILs in the capture of several important typical condensable gases, including water vapor, aromatic VOCs (i.e., BTEX), chlorinated VOC, fluorinated refrigerant gas, low-carbon alcohols, ketones, ethers, ester vapors, etc. Using pure IL, mixed ILs, and IL + organic solvent mixtures as absorbents also briefly expanded the related reports of porous materials loaded with an IL as adsorbents. Finally, future development and research directions in this exciting field are remarked.

Polyimide/Ionic Liquid Composite Membranes for Middle and High Temperature Fuel Cell Application: Water Sorption Behavior and Proton Conductivity

Four water insoluble room-temperature protic ionic liquids (PILs) based on the N-alkylimidazolium cation with the alkyl chain length from 1 to 4 and bis(trifluoromethylsulfonyl)imide anion were synthesized and their chemical structure was confirmed by the 1H NMR and 19F NMR analysis. PILs were revealed to be thermally stable up to 360 and 400 °C. At the same time, the proton conductivity of PILs was found to be dependent mostly on the temperature and, to a less extent, on the type of the cation, i.e., the increase of the conductivity from ~3 × 10-4 S/cm at 25 °C to 2 × 10-2 S/cm at 150 °C was observed. The water vapour sorption capacity of PILs was evaluated as a function of relative humidity and the influence of the alkyl chain length on the phase behaviour in the PIL-water system was discussed. The composite polyimide/PILs membranes were prepared by the PIL immobilization in the porous polymer (Matrimid® 5218) film. The composite membranes showed a high level of proton conductivity (~10-3 S/cm) at elevated temperatures (up to 160 °C). The obtained results reveal that the elaborated composite polyimide/PIL membranes are promising candidates for the application as proton exchange membrane at middle and high temperatures.

Water absorption by deep eutectic solvents

Deep eutectic solvents are found to be highly hygroscopic when exposed to the atmosphere.

The dynamic evaporation process of the deep eutectic solvent LiTf2N:N-methylacetamide at ambient temperature

The dynamic evaporation process of the lithium-based deep eutectic solvent LiTf₂N:NMA under ambient conditions can be divided into three stages.

Surface enhancement of water at the ionic liquid-gas interface of [HMIM][Cl] under ambient water vapor

The ionic liquid-gas interface of 1-hexyl-3-methyl-imidazolium chloride, [HMIM][Cl], was examined in the presence of water vapor using lab-based ambient pressure x-ray photoelectron spectroscopy (APXPS) at room temperature. The interfacial water uptake was measured quantitatively in the pressure range of high vacuum up to a maximum of 5 Torr (27% RH) and back to high vacuum in a systematic manner. Water mole fractions in the interface determined from APXPS were compared to previously published tandem differential mobility analysis results on [HMIM][Cl] nanodroplets. Our findings show that water constitutes a significantly larger mole fraction at the interface when compared to the bulk. Additionally, the reverse isotherms showed that the uptake of water at the interface of [HMIM][Cl] is a reversible process.

Adventitious Water Sorption in a Hydrophilic and a Hydrophobic Ionic Liquid: Analysis and Implications

The sorption of water in ionic liquids (ILs) is nearly impossible to prevent, and its presence is known to have a significant effect on the resulting mixtures' bulk and interfacial properties. The so-called "saturation" water concentrations have been reported, but water sorption rates and mixing behaviors in ILs are often overlooked as variables that can significantly change the resulting mixtures' physical properties over experimental time frames of several minutes to hours. The purpose of this work is to establish a range of these effects over similar time frames for two model ILs, protic ethylammonium nitrate (EAN) and aprotic butyltrimethylammonium bis(trifluoromethylsulfonyl)imide (N1114 TFSI), as they are exposed to controlled dry and humid environments. We report the water sorption rates for these liquids (270 ± 30 ppm/min for EAN and 30 ± 3 ppm/min for N1114 TFSI), examine the accuracy and precision associated with common methods for reporting water content, and discuss implications of changing water concentrations on experimental data and results.

The dynamic process of radioactive iodine removal by ionic liquid 1-butyl-3-methyl-imidazolium acetate: discriminating and quantifying halogen bonds versus induced force

The halogen bonds vs. induced force of the dynamic process of iodine removal by ionic liquid is discriminated and quantified.