Tuning organic carbon dioxide absorbents for carbonation and decarbonation

Acidity Scale in a Choline Chloride- and Ethylene Glycol-Based Deep Eutectic Solvent and Its Implication on Carbon Dioxide Absorption

An equilibrium acidity (pK_a) scale that comprises 16 Brönsted organic acids, including phenols, carboxylic acids, azoles, and phenylmalononitriles, was established in a choline chloride/EG-based deep eutectic solvent (DES) ([Ch][Cl]:2EG) by ultraviolet-visible (UV-Vis) spectroscopic methods. The established acidity scale spans about 6 pK units in the DES, which is similar to that for these acids in water. The acidity comparisons and linear correlations between the DES and other solvents show that the solvent property of [Ch][Cl]:2EG is quite different from those of amphiphilic protic and dipolar aprotic molecular solvents. The carbon dioxide absorption capabilities as well as apparent absorption kinetics for a series of anion-functionalized DESs ([Ch][X]:2EG) were measured, and the results show that the basicity of comprising anion [X] of choline salt is essential for the maximum carbon dioxide absorption capacity, i.e., a stronger basicity leads to a greater absorption capacity. The possible absorption mechanisms for carbon dioxide absorption in these DESs were also discussed based on the spectroscopic evidence.

Biomaterials for CO2 Harvesting: From Regulatory Functions to Wet Scrubbing Applications

A new series of 2-aminoethyl-benzene-based biomaterials, namely, dopamine (DOP), tyramine (TYR), phenylethylamine (PEA), and epinephrine (EPN), dissolved in dimethylsulfoxide (DMSO) have been investigated for CO2 capture upon activatiing their hydhydrochloride salts  with a NaOH pellet. Spectroscopic measurements, including ex situ ATR-FTIR, 1D and 2D NMR experiments have been applied to verify the formation of the sodium carbamate adducts (RR'N-CO2 - Na+). The emergence of new peaks in the IR spectra ranging between 1702 and 1735 cm-1 together with the chemical shift within 157-158 ppm in the 13C NMR, as well as with cross-peaks obtained by 1H-15N HSQC measurements at ca. 84 and 6.6 ppm verified the formation of RR'N-CO2 - Na+ products upon the chemical fixation of CO2. The CO2 sorption capacity of the examined biomaterials was evaluated volumetrically, with a maximum value of 8.18 mmol CO2·g-1 sorbent (36.0 (w/w)%, including both chemisorption and physisorption), for 5 (w/v)% solutions measured at 5 bar CO2 and 25 °C, for TYR and PEA. DFT calculations indicated that the intramolecular hydrogen bonding within the structural motif of EPN-N-CO2 - Na+ adduct provides an exceptional stability compared to monoethanolamine and other structurally related model compounds.

Inedible saccharides: a platform for CO2 capturing

The economic viability of eco-friendly and renewable materials promotes the development of an alternative technology for climate change mitigation. Investigations reported over the past few years have allowed understanding the mechanism of action for a wide spectrum of saccharides toward carbon dioxide (CO2), in terms of reactivity, reversibility, stability and uptake. Exploiting bio-renewables, viz., inedible saccharides, to reduce the anthropogenic carbon footprint upon providing a sustainable and promising technology that is of interest to different groups of scientists, to overcome demerits associated with the current state-of-the-art aqueous amine scrubbing agents, following a "green chemistry guideline", by employing materials with properties relevant to the environment toward sustainable development. The interdisciplinary nature of research in this area provides a large body of literature that would meet the interest of the broad readership of different multidisciplinary fields. Although many reports emphasize the use of biomass in various industrial products ranging from pharmaceutics, medical preparations, soaps, textiles, cosmetics, household cleaners, and so on, to our knowledge there is no focused article that addresses the application of saccharides for CO2 sequestration. In this review, we highlight the recent advances on the use of oligo-, poly- and cyclic saccharides to achieve a reversible binding of CO2. The future research directions are discussed to provide insight toward achieving sustainable development through implementing bio-renewables.

New insights into the chemistry of ionic alkylorganic carbonates: a computational study

A library of hydrogenated, perfluorinated aliphatic and aromatic alcohols are selected together with a combination of superbases and metal hydrides to understand the thermodynamics of the binary mixtures once serving as sorbents for the capture of CO₂via ionic organic alkylcarbonate formation.

Bis-tris propane in DMSO as a wet scrubbing agent: carbamic acid as a sequestered CO2 species

We report the chemisorption of CO₂ by bis-tris propane dissolved in DMSO via carbamic acid formation.

Substituent dependence of imidazoline derivatives on the capture and release system of carbon dioxide

The imidazoline having a cyclic guanidine moiety only captured CO₂ quantitatively, and then the cyclic guanidine derivative gave the guanidinium bicarbonate by CO₂ fixation together with a slight amount of water.