Supported ionic liquid membranes for water and volatile organic compounds separation: Sorption and permeation properties

Novel Poly(ionic liquid) Augmented Membranes for Unconventional Aqueous Phase Applications in Fractionation of Dyes and Sugar

Poly(ionic) liquid (PIL) augmented membranes were fabricated through self-polymerization of 2-vinyl pyridine and 4-vinyl pyridine followed by dopamine triggered polymerization and bridging with inert polyamide support. The resulting membranes acquired a positive surface charge with a high degree of hydrophilicity. Fourier transformed Infra-red (FTIR) and Energy dispersive X-ray (EDX) spectroscopic investigation revealed the successful augmentation of PIL surface layer, whereas surface morphology was investigated through scanning electron microscopy (SEM) imaging. This manuscript demonstrates pi electron-induced separation of dyes with the trend in permeability: Coomassie Brilliant Blue G (CBBHG) > Remazol Brilliant Blue R (RBBR) > Eichrome Black T (EBT) > Congo Red (CR). CBBG exhibited extended conjugation over large aromatic domain. RBBR and EBT were associated withtheelectron-donating -NH2 group and electron-withdrawing -NO2 group, respectively, hence pi electron density on aromatic ring varied. The steric repulsion between two pairs of ortho hydrogens (Hs) in biphenyl moieties of CR resulted in deviation of planarity and hence aromaticity leading to the lowest permeability. The sugar fractionation followed the trend: Galactose > Mannose > Fructose > Glucose > Xylose. More hydroxyl (-OH) groups in sugars and their conformational alignment in the same direction, exhibited more lone pair of electrons leading to more interaction with PIL and hence better permeability. Pentose showed poorer permeation than hexose, whereas aldose showed better permeation than ketose.

WITHDRAWN: Sustainable liquid membrane separation using interfacial engineering of deep eutectic solvent and cellulose acetate

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Effects of Operating Parameters on Ionic Liquid Membrane to Remove Humidity in a Green Continuous Process

Membrane processes are promising methods to separate gases from feed streams without phase changing. A hybrid process, the combination of ionic liquids with a ceramic membrane (ILM), has been developed for humidity removal in a green continuous process. This new concept provides a more efficient and available ionic liquid (IL)-based membrane regeneration process, which just switches the moist feed stream to dry air. Furthermore, the ILM presents high stability and mechanical resistance during long-time operation. In addition, the influences of several operating parameters, including flow rate, temperature, absolute pressure, and feed concentration on process efficiency were investigated. The lower inlet flow rate was found to be favorable for drying humid air. Moreover, when the pressure increased, the mass of absorbed water was increased, while the feed concentration had no significant effects on the membrane separation performance. However, the operating temperature had a great effect on humidity removal. It is necessary to note that the processes at room temperature can limit the energy consumption. The absorbing process of ILM remained efficient after several absorption desorption cycles. Therefore, the new ILM hybrid process that has been developed has great potential for consecutive humidity removal processes.

Selective Recovery of n-Butanol from Aqueous Solutions with Functionalized Poly(epoxide ionic liquid)-Based Polyurethane Membranes by Pervaporation

In this study, hydroxyl-terminated polybutadiene-poly(epoxide ionic liquid)-poly(urethane urea) (HTPB-PEIL-PU) membranes, HTPB-PEIL1-PU and HTPB-PEIL2-PU, were prepared by the reaction of functionalized PEIL, poly(1-methylimidazole-3-methyl-ethyloxy)hexafluorophosphate or poly(1-methylimidazole-3-methyl-ethyloxy)bistrifluoromethanesulfonimidate, respectively, with HTPB using 4,4'-diphenylmethane diisocyanate (MDI) as the chain extender. The HTPB-PEIL-PU and HTPB membranes were investigated for the selective recovery of n-butanol from aqueous solutions by pervaporation. PEIL was confirmed to be successfully embedded in the PU membranes by ¹H NMR, Fourier transform infrared, and differential scanning calorimetry measurements. According to our mechanical measurements, the HTPB-PEIL-PU membranes retain the mechanical properties of the original PU membrane. PEIL was shown to enhance the diffusion rate of n-butanol significantly based on swelling behavior tests. The pervaporation flux through the HTPB-PEIL1-PU membrane increased with increasing feed temperature and feed concentration. In contrast, the separation factor of the HTPB-PEIL1-PU membrane increased with increasing feed temperature but decreased with increasing feed concentration. In addition, the HTPB-PEIL2-PU membrane exhibited an optimal separation factor of up to 29.2 at a feed concentration of 3% and a feed temperature of 70 °C, which is superior to that (22.7) through pure HTPB membranes. Furthermore, the HTPB-PEIL1-PU and HTPB-PEIL2-PU membranes show better long-term stability than other supported ionic liquid membranes.

A Bibliometric Analysis of Research on Supported Ionic Liquid Membranes during the 1995-2015 Period: Study of the Main Applications and Trending Topics

A bibliometric analysis based on Scopus database was performed to identify the global research trends related to Supported Ionic Liquid Membranes (SILMs) during the time period from 1995 to 2015. This work tries to improve the understanding of the most relevant research topics and applications. The results from the analysis reveal that only after 2005 the research efforts focused on SILMs became significant, since the references found before that year are scarce. The most important research works on the four main application groups for SILMs defined in this work (carbon dioxide separation, other gas phase separations, pervaporation and liquid phase separations) were summarized in this paper. Carbon dioxide separation appeared as the application that has received by far the most attention according to the research trends during the analysed period. Comments about other significant applications that are gaining attention, such as the employment of SILMs in analytical tasks or their consideration for the production of fuel cells, have been included.

Application of polymer-based membranes containing ionic liquids in membrane separation processes: a critical review

The interest in ionic liquids, particularly in polymerizable ionic liquids, is motivated by their unique properties, such as good thermal stability, negligible vapor pressure, and wide electrochemical window. Due to these features ionic liquids were proposed to be used in the membrane separation technology. The utilization of conventional ionic liquids is, however, limited by their release from the membrane during the given separation process. Therefore, the incorporation of polymerizable ionic liquids may overcome this drawback for the industrial application. This work is a comprehensive overview of the advances of ionic liquid membranes for the separation of various compounds, i.e. gases, organic compounds, and metal ions.

Water sorption properties of room-temperature ionic liquids over the whole range of water activity and molecular states of water in these media

The water sorption behavior for various RTILs ([C₄C₁im][BF₄], [C₄C₁im][PF₆], [C₆C₁im][PF₆], [C₄im][DBP], [C₄im][BEHP] and [Et₃HN][CF₃SO₃]) was studied over the whole range of water activity using a continuous gravimetric method and ATR-IR measurements.