Amino acid ionic liquids (ILs) are the most interesting and effective for CO2 capture due to their low toxicity, biodegradability, and fast reactivity toward CO2. The ionic nature of amino acid ILs can raise an environmental issue if the cation counterpart becomes toxic to the aquatic ecosystems, and they can become potential atmospheric pollutants. In this regard, choline based ILs are known to be promising scaffolds for the development of less toxic amino acid ILs. However, the existing choline amino acid ILs are highly viscous, limiting their applicability as solvents. Ether functionalized choline based amino acid ILs with a novel series of less toxic green ILs were explored with reduced viscosity and high CO2 capture capacity. A simple, economic, clean, and environmentally benign method was utilized for the synthesis of novel choline based amino acid ILs using a commercially available and economical starting material, 2-(dimethylamino)­ethanol (deanol, a human dietary food supplement). These ILs have low viscosity with high CO2 capture capacity (1.62 mol of CO2 /mol of IL, 4.31 mol of CO2/kg of IL, 19.02 wt % of CO2). The mechanism of [N1,1,6,2O4]­[Lys] + CO2 reaction and adduct structure was proposed by using DFT calculations, and IR and NMR spectroscopic techniques.

We investigate a comparative effect of CO absorption on the ionic mobility of two choline based ionic liquids comprising two different anions such as threonine and imidazole. The synthesized ionic liquids were characterized using H andC NMR and other spectroscopic techniques. By keeping a common cation and changing the anion from threonine to imidazole both the viscosity and density reduced drastically. We found that [N][Imi] exhibits the highest CO capture capacity at 20 °C of 5.27 mol of CO per kg of ionic liquid (1.27 mol of CO per mol of ionic liquid, 23.26 wt% of CO) whereas [N][Threo] exhibits 3.6 mol of CO per kg of ionic liquid (1.05 mol of CO per mol of ionic liquid, 15.87 wt% of CO). The activation energy for diffusion is calculated using the Vogel-Fulcher-Tamman (VFT) equation in the form of diffusivity. It was found that the activation energy for the diffusion of [N][Threo] is ∼10 times higher than that of [N][Imi]. H diffusion NMR data revealed that the diffusivity of [N][Imi] is increased after CO absorption whereas a decrease in diffusivity was observed in the case of [N][Threo]. This anomalous behavior of [N][Imi] was further explained by using DFT calculations.

A shift towards an economically viable biomass biorefinery concept requires the use of all biomass fractions (cellulose, hemicellulose, and lignin) for the production of high added-value products. As lignin is often underutilized, the establishment of lignin valorization routes is highly important. In-house produced organosolv as well as commercial Kraft lignin were used in this study. The aim of the current work was to make a comparative study of thermoplastic biomaterials from two different types of lignins. Native lignins were alkylate with two different alkyl iodides to produce ether-functionalized lignins. Successful etherification was verified by FT-IR spectroscopy, changes in the molecular weight of lignin, as well as 13C and 1H Nuclear Magnetic Resonance (NMR). The thermal stability of etherified lignin samples was considerably improved with the T2% of organosolv to increase from 143 °C to up to 213 °C and of Kraft lignin from 133 °C to up to 168 °C, and glass transition temperature was observed. The present study shows that etherification of both organosolv and Kraft lignin with alkyl halides can produce lignin thermoplastic biomaterials with low glass transition temperature. The length of the alkyl chain affects thermal stability as well as other thermal properties.

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