Insights into the effect of CO 2 absorption on the ionic mobility of ionic liquids

Magnetic Reson in Chemistry

Azancheev

Gibaydullin

et al. 2017

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We used 1H pulsed field gradient nuclear magnetic resonance to study the self‐diffusion of polyethylene glycol (PEG) with average molecular mass of 200 and ions in mixtures of PEG with imidazolium bis(mandelato)borate (BMB) and imidazolium bis(oxalato)borate ionic liquids (ILs). The IL was mixed with PEG in the concentration range of 0–100 wt%. Within the temperature range of 295 to 353 K, the diffusion coefficient of BMB is slower than that of the imidazolium cation. The diffusion coefficients of PEG, as well as the imidazolium cation and BMB anions, differ under all experimental conditions tested. This demonstrates that the IL in the mixture is present in at least a partially dissociated state. Generally, increasing the concentration of PEG leads to an increase in the diffusion coefficients of PEG and both the ions and decreases their activation energy for diffusion. Nuclear magnetic resonance chemical shift alteration analysis showed that the presence of PEG changes the chemical shifts of both ions but in different directions. Impedance spectroscopy was used to measure the ionic conductivity of the ILs mixed with PEG. Copyright © 2017 John Wiley & Sons, Ltd.

“…Temperature dependences of D for ILs often follow the Vogel–Fulcher–Tamman (VFT) equation for diffusivity, which is described by the following equation:

D = D_{0} exp ((), \frac{- B}{((), T - T_{0})})

where D 0 , T 0 , B are adjustable parameters. Energy of activation for diffusion is related with B as E D = B ⋅ R .…”

Section: Resultsmentioning

confidence: 99%

“…Temperature dependences of D for ILs often follow the Vogel-Fulcher-Tamman (VFT) equation for diffusivity, which is described by the following equation [11,21,25] :…”

Section: Diffusion Of Neat Ionic Liquids Peg and Il/peg Mixturesmentioning

confidence: 99%

Dynamic properties of imidazolium orthoborate ionic liquids mixed with polyethylene glycol studied by NMR diffusometry and impedance spectroscopy

Magnetic Reson in Chemistry

Azancheev

Gibaydullin

et al. 2017

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“…ILs are regarded as designer solvents due to their tunability of physical and chemical properties based on the molecular design of the cation and anion structures. 4,5 1-Ethyl-3-methyl-imidazolium acetate ([EMIM] [OAc]) is one of the most commonly used ILs for processing cellulose and chitin fibers and films, 6-8 aerogels 9,10 and for biomass pretreatment. 11 [EMIM][OAc] is used also as a medium for performing chemical reactions, in particular, for derivatisation of polysaccharides.…”

Section: Introductionmentioning

confidence: 99%

Rapid carbene formation increases ion diffusivity in an imidazolium acetate ionic liquid confined between polar glass plates

Phys. Chem. Chem. Phys.

Antzutkin

Shah

2019

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“…[10][11][12]37 Absorption of gases is another type of association that also effects the diffusivity of ions. 13 Nuclear magnetic resonance (NMR) spectroscopy is an appropriate technique for the investigation of the diffusion of ions and sorbent additives in the ILs. 14 Because of the prevalent industrial applications of ILs, they are also regarded as promising CO 2 sorbents.…”

Section: Introductionmentioning

confidence: 99%

“…16 Also by replacing amino acid anions with N-heterocyclic anions, the viscosity of the ILs decreased significantly with improved CO 2 capture capacity. 13 In addition, it was observed that most of the amino acid based ILs become highly viscous or solidified after CO 2 absorption. However, aprotic N-heterocyclic anion (AHA) based ILs remained liquid with much faster ionic mobility after reaction with CO 2 molecules.…”

Section: Introductionmentioning

confidence: 99%

High CO₂absorption capacity by chemisorption at cations and anions in choline-based ionic liquids

Bhattacharyya

Phys. Chem. Chem. Phys.

Shah

2017

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The effect of CO absorption on the aromaticity and hydrogen bonding in ionic liquids is investigated. Five different ionic liquids with choline based cations and aprotic N-heterocyclic anions were synthesized. Purity and structures of the synthesized ionic liquids were characterized by H andC NMR spectroscopy. CO capture performance was studied at 20 °C and 40 °C under three different pressures (1, 3, 6 bar). The IL [N][4-Triz] showed the highest CO capture capacity (28.6 wt%, 1.57 mol of CO per mol of the IL, 6.48 mol of CO per kg of the ionic liquid) at 20 °C and 1 bar. The high CO capture capacity of the [N][4-Triz] IL is due to the formation of carbonic acid (-OCOH) together with carbamate by participation of the -OH group of the [N] cation in the CO capture process. The structure of the adduct formed by CO reaction with the IL [N][4-Triz] was probed by using IR, C NMR andH-C HMBC NMR experiments utilizing C labeled CO gas. H andC PFG NMR studies were performed before and after CO absorption to explore the effect of cation-anion structures on the microscopic ion dynamics in ILs. The ionic mobility was significantly increased after CO reaction due to lowering of aromaticity in the case of ILs with aromatic N-heterocyclic anions.