Treatment and Resource Utilization of Gaseous Pollutants in Functionalized Ionic Liquids

With the rapid development of science, technology, and the economy of human society, the emission problem of gas pollutants is becoming more and more serious, which brings great pressure to the global ecological environment. At the same time, the natural resources that can be exploited and utilized on Earth are also showing a trend of exhaustion. As an innovative and environmentally friendly material, functionalized ionic liquids (FILs) have shown great application potential in the capture, separation, and resource utilization of gaseous pollutants. In this paper, the synthesis and characterization methods of FILs are introduced, and the application of FILs in the treatment and recycling of gaseous pollutants is discussed. The future development of FILs in this field is also anticipated, which will provide new ideas and methods for the treatment and recycling of gaseous pollutants and promote the process of environmental protection and sustainable development.

Tuning Functionalized Ionic Liquids for CO2 Capture

The increasing concentration of CO₂ in the atmosphere is related to global climate change. Carbon capture, utilization, and storage (CCUS) is an important technology to reduce CO₂ emissions and to deal with global climate change. The development of new materials and technologies for efficient CO₂ capture has received increasing attention among global researchers. Ionic liquids (ILs), especially functionalized ILs, with such unique properties as almost no vapor pressure, thermal- and chemical-stability, non-flammability, and tunable properties, have been used in CCUS with great interest. This paper focuses on the development of functionalized ILs for CO₂ capture in the past decade (2012~2022). Functionalized ILs, or task-specific ILs, are ILs with active sites on cations or/and anions. The main contents include three parts: cation-functionalized ILs, anion-functionalized ILs, and cation-anion dual-functionalized ILs for CO₂ capture. In addition, classification, structures, and synthesis of functionalized ILs are also summarized. Finally, future directions, concerns, and prospects for functionalized ILs in CCUS are discussed. This review is beneficial for researchers to obtain an overall understanding of CO₂-philic ILs. This work will open a door to develop novel IL-based solvents and materials for the capture and separation of other gases, such as SO₂, H₂S, NOx, NH₃, and so on.

Formation and Properties of Poly(Ionic Liquid)-Carbene Nanogels Containing Individually Stabilized Silver Species

Imidazolium-based ionic liquids have the ability to undergo a variety of chemical reactions through an N-heterocyclic carbene (NHC) intermediate, which has expanded the chemical toolbox for new applications. Despite their uses and exploration, the carbene-forming properties and applications of their polymeric congeners, poly(ionic liquid)s (PILs), is still underdeveloped. Herein, we explore the NHC-forming properties of a theophylline-derived PIL for nanogel synthesis. Using silver oxide as both the carbene-forming reagent and cross-linker, nanogels containing individually stabilized ions can be created with different sizes and morphology, including large "galaxy-like" superstructures. Using high-resolution TEM techniques, we directly observed the sub-nanometer structure of these constructs. These features combined exemplify the unique chemistry of poly-NHCs for single-metal-ion-stabilization nanogel design.

Amino-Functional Ionic Liquids as Efficient Catalysts for the Cycloaddition of Carbon Dioxide to Yield Cyclic Carbonates: Catalytic and Kinetic Investigation

Various amino-functional ionic liquids were developed as homogeneous catalysts for the cycloaddition of carbon dioxide to different epoxides yielding the corresponding cyclic carbonates under metal- and solvent-free conditions. The effects of reaction temperature, reaction time, CO2 pressure, and the amount of catalyst on the cycloaddition reaction were investigated. The catalysts could be easily recovered after the reaction and then reused at least eight times without noticeable loss of activity and selectivity. Reaction kinetic studies were undertaken, the reaction was apparently first order with respect to the concentration of epoxide and catalyst. Furthermore, the rate constants were determined over a temperature range of 100–130°C and the activation energy was determined to be 45.9 kJ mol−1. Finally, a possible reaction mechanism was proposed. The amino-functional ionic liquids showed the advantage of high catalytic activity and were easily recyclable for CO2 chemical fixation into valuable chemicals.

Organocatalyzed coupling of carbon dioxide with epoxides for the synthesis of cyclic carbonates: catalyst design and mechanistic studies

The coupling of carbon dioxide (CO₂) with epoxides with the formation of cyclic carbonates is a highly attractive 100% atom economic reaction. It represents a greener and safer alternative to the conventional synthesis of cyclic carbonates from diols and toxic phosgene.

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.

Amine-rich ionic liquid grafted graphene for sub-ambient carbon dioxide adsorption

The present study describes the synthesis of the triazolium based amine-rich ionic liquid (ARIL), namely, 3,5-diamino-1-methyl-1,2,4-triazolium tetrafluoroborate grafted graphene (HEG/ARIL), and its application in carbon dioxide adsorption.

Ionic liquid functionalization – an effective way to tune carbon dioxide adsorption properties of carbon nanotubes

In this research, the influence of non-covalent functionalization by ionic liquids on carbon dioxide (CO₂) adsorption–desorption properties of multi-walled carbon nanotubes (MWNTs) and partially exfoliated MWNTs (PEMWNTs) has been studied.

The electronegativity equalization method fused with molecular mechanics: a fluctuating charge and flexible body potential function for [Emim][Gly] ionic liquids

Recently, experimental and theoretical studies on amino acid ionic liquid (AAIL) systems have attracted much attention. A transferable intermolecular potential approach that includes fluctuating charges and a flexible body based on a combination of the electronegativity equalization method and molecular mechanics (EEM/MM), and its application to an AAIL system containing 1-ethyl-3-methylimidazolium ([Emim](+)) and glycine ([Gly](-)) are explored and tested in this study. A consistent integration of EEM with MM requires the input of the EEM charges of all atoms into the MM intermolecular electrostatic interaction term. Compared with ionic liquid (IL) force fields, the EEM/MM model has an outstanding feature: the EEM/MM model not only presents the electrostatic interaction of atoms and their changes in response to different ambient environments but also introduces "the H-bond interaction region" in which a new parameter kHB(RHB) is used to describe the electrostatic interaction of hydrogen atoms in [Emim](+) and oxygen atoms in [Gly](-), which can form hydrogen bonds. The EEM/MM model gives quite accurate predictions for gas-phase state properties of [Emim](+), [Gly](-), and ion pairs, such as optimized geometries, dipole moments, vibrational frequencies, and cluster interaction energies. Due to its explicit description of charges and hydrogen bonds, the EEM/MM model also performs well for the liquid-phase properties of [Emim][Gly] under ambient conditions. The calculated properties, such as density, heat of vaporization, the self-diffusion coefficient, and ionic conductivity, are fairly consistent with available experimental results.