Deep eutectic solvents (DESs) are an emerging class of mixtures characterized by significant depressions in melting points compared to those of the neat constituent components. These materials are promising for applications as inexpensive "designer" solvents exhibiting a host of tunable physicochemical properties. A detailed review of the current literature reveals the lack of predictive understanding of the microscopic mechanisms that govern the structure-property relationships in this class of solvents. Complex hydrogen bonding is postulated as the root cause of their melting point depressions and physicochemical properties; to understand these hydrogen bonded networks, it is imperative to study these systems as dynamic entities using both simulations and experiments. This review emphasizes recent research efforts in order to elucidate the next steps needed to develop a fundamental framework needed for a deeper understanding of DESs. It covers recent developments in DES research, frames outstanding scientific questions, and identifies promising research thrusts aligned with the advancement of the field toward predictive models and fundamental understanding of these solvents.

Deep Eutectic Solvents: A Review of Fundamentals and Applications.

The inherent structure tunability, good affinity with CO2, and nonvolatility of ionic liquids (ILs) drive their exploration and exploitation in CO2 separation field, and has attracted remarkable interest from both industries and academia. The aim of this Review is to give a detailed overview on the recent advances on IL-based materials, including pure ILs, IL-based solvents, and IL-based membranes for CO2 capture and separation from the viewpoint of molecule to engineering. The effects of anions, cations and functional groups on CO2 solubility and selectivity of ILs, as well as the studies on degradability of ILs are reviewed, and the recent developments on functionalized ILs, IL-based solvents, and IL-based membranes are also discussed. CO2 separation mechanism with IL-based solvents and IL-based membranes are explained by combining molecular simulation and experimental characterization. Taking into consideration of the applications and industrialization, the recent achievements and developments on the t...

Ionic-Liquid-Based CO2 Capture Systems: Structure, Interaction and Process

Ionic liquids synthesis and applications: An overview

Global warming due to the emission of greenhouse gases, especially carbon dioxide (CO2), has a significant effect on the climate change and has become a widespread concern in the recent years. Carbon capture, utilization, and sequestration (CCUS) strategy appears to be effective in decreasing the carbon dioxide level in the atmosphere. Despite a great progress in this field, there are still major limitations in commercialized the CO2 capture methods that rely on absorption phenomena. High capital costs of for the CO2 capture, low absorption and desorption rates (which require large facilities), solvent losses due to evaporation, and the use of corrosive solvents are among main obstructions. Recently, CO2 capture with ionic liquids (ILs) has appreciably attracted researchers’ attention. The distinct properties of ILs such as negligible vapor pressure and their affinity to capture the CO2 molecules make them a feasible alternative for currently available solvents including, different amines. This paper covers a brief review of previous engineering and research works on various CO2 capture techniques, the description of CO2 capture process using ILs, mechanisms of the CO2 capture with ILs at molecular level, CO2 and ILs properties, characterization of the CO2/IL systems, impacts of operating and fluids conditions on CO2 absorption capacity by ILs, and CO2 solubility and selectivity in ILs. Moreover, the technical and economic aspects of the CO2 capture with ILs, screening criteria for ILs/CO2 systems, and important results obtained from previous studies will form the last parts of this manuscript. This review offers a proper/systematic guideline that assists researchers and engineers to comprehensively understand and to effectively design the CO2/ILs processes, focusing on the thermodynamic and mass transfer aspects.

A systematic review on CO2 capture with ionic liquids: Current status and future prospects

Ionic liquids (ILs) and deep eutectic solvents (DESs) have been suggested as eco-friendly alternatives to organic solvents. A trace amount of water is often unavoidable as impurity, and water is also added on purpose to reduce their problematically high viscosity and lower their high price. Understanding the distinct effects of water on the properties of ILs/DESs is highly important. In this review, we collect published experimental and theoretical results for IL/DES–H2O systems at varied water concentrations and analyze them. Results from mechanistic studies, thermodynamic modelling and advanced experiments are collected and critically discussed. Six commonly studied IL/DES–H2O systems were selected to map experimental observations onto microscopic results obtained in mechanistic studies. A great variety of distinct contours of the excess properties can be observed over the entire compositional range, indicating that the properties of IL/DES–H2O systems are highly unpredictable. Mechanistic studies clearly demonstrate that the added H2O rapidly changes the heterogeneous 3D structures of pure ILs/DESs, leading to very different properties and behaviour. There are similarities between aqueous electrolytes and IL/DES solutions but the bulky and asymmetric organic cations in ILs/DESs do not conform to the standard salt dissolution and hydration concepts. Thermodynamic modelling previously assumes ILs/DESs to be either a neutral ion-pair or completely dissociated ions, neglecting specific ion hydration effects. A new conceptual framework is suggested for thermodynamic modelling of IL/DES–H2O binary systems to enable new technologies for their practical applications.

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The peculiar effect of water on ionic liquids and deep eutectic solvents

Techno-economic analysis and performance comparison of aqueous deep eutectic solvent and other physical absorbents for biogas upgrading

To study the effects of type and content of cosolvent as well as temperature on the properties of two well-known deep eutectic solvents (DESs), i.e., ChCl/EG (choline chloride + ethylene glycol at ...

Chunyan Ma

Papers

The peculiar effect of water on ionic liquids and deep eutectic solvents

Techno-economic analysis and performance comparison of aqueous deep eutectic solvent and other physical absorbents for biogas upgrading

Thermodynamic Study of Choline Chloride-Based Deep Eutectic Solvents with Water and Methanol

Modeling, simulation and evaluation of biogas upgrading using aqueous choline chloride/urea

Molar enthalpy of mixing and refractive indices of choline chloride-based deep eutectic solvents with water