CO2 removal with ‘switchable’ versus ‘classical’ ionic liquids

A New Trend and Future Perspectives of the Miniaturization of Conventional Extraction Methods for Elemental Analysis in Different Real Samples: A Review

Sample preparation is one of the viable procedures to be used before analysis to enhance sensitivity and reduce the matrix effect. The current review is mainly emphasized the latest outcome and applications of microextraction techniques based on the miniaturization of the classical conventional methods based on liquid-phase and solid-phase extraction for the quantitative elemental analysis in different real samples. The limitation of the conventional sample preparation methods (liquid and solid phase extraction) has been overcome by developing a new way of reducing size as compared with the conventional system through the miniaturization approach. Miniaturization of the sample preparation techniques has received extensive attention due to its extraction at microlevels, speedy, economical, eco-friendly, and high extraction capability. The growing demand for speedy, economically feasible, and environmentally sound analytical approaches is the main intention to upgrade the conventional procedures apply for sample preparation in environmental investigation. A growing trend of research has been perceived to quantify the trace for elemental analysis in different natures of real samples. This review also recapitulates the current futuristic scenarios for the green and economically viable procedure with special overemphasis and concentrates on eco-friendly miniaturized sample-preparation techniques such as liquid-phase microextraction (LPME) and solid-phase microextraction (SPME). This review also emphasizes the latest progress and applications of the LPME and SPME approach and their future perspective.

Theoretical and Economic Evaluation of Low-Cost Deep Eutectic Solvents for Effective Biogas Upgrading to Bio-Methane

This paper presents the theoretical screening of 23 low-cost deep eutectic solvents (DESs) as absorbents for effective removal of the main impurities from biogas streams using a conductor-like screening model for real solvents (COSMO-RS). Based on thermodynamic parameters, i.e., the activity coefficient, excess enthalpy, and Henry’s constant, two DESs composed of choline chloride: urea in a 1:2 molar ratio (ChCl:U 1:2), and choline chloride: oxalic acid in a 1:2 molar ratio (ChCl:OA 1:2) were selected as the most effective absorbents. The σ-profile and σ-potential were used in order to explain the mechanism of the absorptive removal of CO2, H2S, and siloxanes from a biogas stream. In addition, an economic analysis was prepared to demonstrate the competitiveness of new DESs in the sorbents market. The unit cost of 1 m3 of pure bio-methane was estimated to be in the range of 0.35–0.37 EUR, which is comparable to currently used technologies.

Novel Amino-Functionalized Ionic Liquid/Organic Solvent with Low Viscosity for CO2 Capture

To achieve low regeneration energy consumption and viscosity, a novel amino-functionalized ionic liquid [TEPAH][2-MI] combined with organic solvents has been proposed for CO₂ capture in this work. The results demonstrated that the absorption loading of [TEPAH][2-MI]/N-propanol (NPA)/ethylene glycol (EG) was 1.72 mol·mol^-1 (28 wt %, 257 g·L^-1), which was much higher than that of monoethanolamine/water, and the regeneration efficiency was maintained at 90.7% after the fifth regeneration cycle. The viscosities of the solution were only 3.66 and 7.65 mPa·s before and after absorption, respectively, which were significantly lower than those of traditional nonaqueous absorbents. The reaction mechanism investigated via ¹³C NMR and quantum calculations summarized that CO₂ first reacted with the amino group of [TEPAH]⁺ to form the carbamates through the zwitterion formation and protonation process, while CO₂ reacted with the N atom of [2-MI]^- to directly form the carbamate. Then, some of them further reacted with NPA and EG to form the carbonates. Moreover, N^π and N^τ tautomers of [TEPAH][2-MI] could convert into each other continuously when CO₂ was absorbed. During CO₂ desorption, the carbamates and carbonates reacted with AFILH⁺ to decompose and released CO₂ directly.

A smart friction control strategy enabled by CO2 absorption and desorption

Intelligent control of friction is an attractive but challenging topic and it has rarely been investigated for full size engineering applications. In this work, it is instigated if it would be possible to adjust friction by controlling viscosity in a lubricated contact. By exploiting the ability to adjust the viscosity of the switchable ionic liquids, 1,8-Diazabicyclo (5.4.0) undec-7-ene (DBU)/ glycerol mixture via the addition of CO₂, the friction could be controlled in the elastohydrodynamic lubrication (EHL) regime. The friction decreased with increasing the amount of CO₂ to the lubricant and increased after partial releasing CO₂. As CO₂ was absorbed by the liquid, the viscosity of the liquid increased which resulted in that the film thickness increased. At the same time the pressure-viscosity coefficient decreased with the addition of CO₂. When CO₂ was released again the friction increased and it was thus possible to control friction by adding or removing CO₂.

Two coexisting liquid phases in switchable ionic liquids

Switchable ionic liquids are attractive in gas capture, separations, and nanomaterial synthesis.

Screening of deep eutectic solvents (DESs) as green CO2 sorbents: from solubility to viscosity

35 novel DESs are synthesized and screened in terms of their CO₂ solubility and viscosity.

CO2-responsive polymeric materials: synthesis, self-assembly, and functional applications

CO2 is an ideal trigger for switchable or stimuli-responsive materials because it is benign, inexpensive, green, abundant, and does not accumulate in the system. Many different CO2-responsive materials including polymers, latexes, solvents, solutes, gels, surfactants, and catalysts have been prepared. This review focuses on the preparation, self-assembly, and functional applications of CO2-responsive polymers. Detailed discussion is provided on the synthesis of CO2-responsive polymers, in particular using reversible deactivation radical polymerization (RDRP), formerly known as controlled/living radical polymerization (CLRP), a powerful technique for the preparation of well-defined (co)polymers with precise control over molecular weight distribution, chain-end functional groups, and polymer architectural design. Self-assembly in aqueous dispersed media is highlighted as well as emerging potential applications.

Active chemisorption sites in functionalized ionic liquids for carbon capture

Carbon capture with site-containing ionic liquids is reviewed with particular attention on the activation and design of the interaction sites.

Ionic liquids derived from organosuperbases: en route to superionic liquids

This is a comprehensive review of various task-specific ionic liquids derived from TMG, TBD, DBU, DBN and other organosuperbases.

Elucidation of molecular interactions between a DBU based protic ionic liquid and organic solvents: thermophysical and computational studies

Energy profile of 1,8-diazabicyclo[5.4.0]undec-7-en-8-ium trifluoroacetate [DBUTFA].

Efficient and reversible CO2 capture by amine functionalized-silica gel confined task-specific ionic liquid system

Simple, efficient and practical CO₂ capture method is reported using task-specific ionic liquid (IL) supported onto the amine-functionalized silica gel. The results have been shown that both the capacity and rate of the CO₂ absorption notably increase in the supported IL/molecular sieve 4 Å system in comparison of homogeneous IL. Additionally, it has shown that the prepared material is capable for reversible carbon dioxide absorption for at least 10 cycles without significant loss of efficiency. The presence of the amine-based IL and the surface bonded amine groups increase the capacity of CO₂ absorption even in a CO₂/CH₄ gas mixture through the formation of ammonium carbamate onto the surface of mesoporous material.