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In this work, CO₂ absorption capacities in a series of aqueous N-alkyl-N-methylmorpholinium-based ILs with acetate as the counterpart anion were investigated. Among these ILs, N-butyl-N-methylmorpholinium acetate ([Bmmorp][OAc]) with the highest CO₂ absorption capacity was screened for thermodynamic modeling. The non-random two-liquid model and the Redlich–Kwong equation of state (NRTL-RK model) were used to describe the phase equilibria. The CH₄ absorption capacity in the aqueous [Bmmorp][OAc] was also measured in order to verify the results predicted from the thermodynamic modeling, and the comparison shows the reliability of the model prediction. The parameters were embedded into the commercial software Aspen Plus. After that, the aqueous [Bmmorp][OAc] solutions with 30–40 wt % of water were selected to carry out process simulation for CO₂ separation from biogas, and it was found that using these aqueous [Bmmorp][OAc] gave rise to lower energy usage and smaller size of equipment than other physical solvents. The results suggest that aqueous [Bmmorp][OAc] solution can be used as an alternative to organic solvents and has the potential to decrease the cost of CO₂ separation.

A critical analysis of the role of Hammett basicity (H−) and aqueous basicity (pKa) in CO2 uptake in deep-eutectic solvents (DESs) suggests that neither H− nor pKa correlates with the CO2 w/w% capacity in the studied DESs. Instead, strong “synergistic interactions” between donor and acceptor moieties satisfactorily relate to the w/w% of CO2 in DESs.

Ionic liquids (ILs) have been receiving much attention as solvents in various areas of biochemistry because of their various beneficial properties over the volatile solvents and ILs availability in myriad variants (perhaps as many as 10(8)) owing to the possibility of paring one cation with several anions and vice-versa as well as formulations as zwitterions. Their potential as solvents lies in their tendency to offer both directional and non-directional forces toward a solute molecule. Because of these forces, ionic liquids easily undergo intermolecular interactions with a range of polar/non-polar solutes, including biomolecules such as proteins and DNA. The interaction of genomic species in aqueous/non-aqueous states assists in unraveling their structure and functioning, which have implications in various biomedical applications. The charge density of ionic liquids renders them hydrophilic and hydrophobic, which retain intact over long-range of temperatures. Their ability in stabilizing or destabilizing the 3D-structure of a protein or the double-helical structure of DNA has been assessed superior to the water and volatile organic solvents. The aptitude of an ion in influencing the structure and stability of a native protein depends on their ranking in the Hofmeister series. However, at several instances, a reverse Hofmeister ordering of ions and specific ion-solute interaction has been observed. The capability of an ionic liquid in terms of the tendency to promote the coiling/uncoiling of DNA structure is noted to rely on the basicity, electrostatic interaction, and hydrophobicity of the ionic liquid in question. Any change in the DNA's double-helical structure reflects a change in its melting temperature (T-m), compared to a standard buffer solution. These changes in DNA structure have implications in biosensor design and targeted drug-delivery in biomedical applications. In the current review, we have attempted to highlight various aspects of ionic liquids that influence the structure and properties of proteins and DNA. In short, the review will address the issues related to the origin and strength of intermolecular interactions, the effect of structural components, their nature, and the influence of temperature, pH, and additives on them.

The nonvolatility, structure-tunability and high CO2 uptake capacity render ionic liquids (ILs) the most exciting materials for the carbon dioxide (CO2) capture and fixation to value-added chemicals. The aim of this mini-review is to give a brief idea about the development of the potential ILs for CO2 capture, the mechanism involved in the CO2 binding and the application of ILs in the conversion of CO2 to useful chemicals. The mechanisms and nature of interactions in between IL-CO2 have been discussed in terms of the nature of cation, anion, presence of functional group and the extent of interaction between the components of ILs. The fixation of CO2 to linear and cyclic carbonates and electroreduction of CO2 to carbon-rich fuels in ILs has been accounted in detail. At the end, future challenges in terms of commercializing the ILs for CO2 capture and utilization technology are discussed.

Herein, we have studied the potential of lutidinium-based ILs (1-allyl-3,5-dimethylpyridinium chloride [3,5-ADMPy]Cl and 1-allyl-3,4-dimethylpyridinium chloride [3,4-ADMPy]Cl) in the dissolution of cellulose, and their structures were confirmed by 1H and 13C NMR spectra, respectively. [3,5-ADMPy]Cl exhibited the highest capacity in cellulose dissolution. In fact, it dissolved 20 wt% of cellulose within 12 min and 26 wt% of cellulose in 35 min at 118 °C. The crystallinity and morphology of native and regenerated cellulose were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and CP/MAS 13C NMR spectroscopy. These techniques clearly suggest that the crystallinity of cellulose is reduced upon treatment in lutidinium-based ILs. The thermogravimetric analysis (TGA) showed that regenerated cellulose had thermal stability close to that of native cellulose.

A series of novel ethylenediamine(EDA)-based deep-eutectic solvents (DESs) gave rise to unexpectedly large carbon dioxide (CO2) capturing capacity at higher temperatures owing to the “synergetic interaction” between the donor and acceptor moieties.

Herein we report the CO₂ uptake in potential deep-eutectic solvents (DESs) formed between hydrogen bond acceptors (HBAs) such as monoethanolammonium chloride ([MEA·Cl]), 1-methylimidazolium chloride ([HMIM·Cl]) and tetra-n-butylammonium bromide ([TBAB]) and hydrogen bond donors (HBDs) like ethylenediamine ([EDA]), diethylenetriamine ([DETA]), tetraethylenepentamine ([TEPA]), pentaethylenehexamine ([PEHA]), 3-amino-1-propanol ([AP]) and aminomethoxypropanol ([AMP]) and analyzed the outcome in terms of the specific polarity parameters. Among various combinations of HBAs and HBDs, [MEA·Cl][EDA]-, [MEA·Cl][AP]-, [HMIM·Cl][EDA]- and [HMIM·Cl][AP] showed excellent CO₂ uptake which was further improved upon increasing the mole ratio of HBA : HBD from 1 : 1 to 1 : 4. The lowest CO₂ uptake in [MEA·Cl][PEHA] (12.7 wt%) and [HMIM·Cl][PEHA] (8.4 wt%) despite the highest basicity of [PEHA] infers that the basicity is not the sole criteria for guiding the CO₂ uptake but, in reality, CO₂ capture in a DES relies on the interplay of H-bonding interactions between each HBA and HBD. The role of HBAs in guiding CO₂ uptake was more prominent with weak HBDs such as [TEPA] and [PEHA]. The speciation of absorbed CO₂ into carbamate, carbonate, and bicarbonate was favorable in DES characterized by comparable hydrogen bond donor acidity (α) and hydrogen bond acceptor basicity (β) values, whereas the conversion of carbamate to carbonate/bicarbonate was observed to depend on α. The addition of water in DES resulted in lower CO₂ uptake due to the decreased basicity (β).