Understanding the Interaction of Boric Acid and CO2 with Ionic Liquids in Aqueous Medium by Multinuclear NMR Spectroscopy

Document identifier: oai:DiVA.org:ltu-77093
Access full text here:10.1021/acssuschemeng.9b06068
Keyword: Natural Sciences, Chemical Sciences, Physical Chemistry, Naturvetenskap, Kemi, Fysikalisk kemi, Aqueous functionalized choline-based ionic liquids, Boric acid, Diffusivity of molecules, NMR spectroscopy, NMR relaxation, CO2 absorption, Chemistry of Interfaces, Gränsytors kemi
Publication year: 2020
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Abstract:

Boric acid is known to enhance the kinetics of CO2 absorption by some active aqueous solutions. However, the mechanism of interaction of boric acid with CO2 in the presence of active molecules is not yet fully understood. In this work, the interaction and dynamics of ions in aqueous solutions of functionalized choline-based ionic liquids [N1,1,5,2OH][Threo] and [N1,1,5,2OH][Tau] in the presence of boric acid and CO2 was thoroughly investigated using a multinuclear NMR approach: 13C and 11B NMR spectroscopy, 11B NMR transverse relaxation, and 1H and 11B NMR diffusometry. 13C and 11B NMR spectroscopy revealed the formation of borate-based complexes as a result of a reaction between boric acid and the anions of the ILs at ionic liquid/boric acid molar ratios larger than ca. 0.15. The formation of these complexes and their dynamics were further investigated using 11B relaxation and 1H and 11B pulse-field-gradient (PFG) NMR. Plausible reaction mechanisms of boric acid with the anions of the ILs, formation of the borate complexes, and dissociation of these complexes facilitated by CO2 molecules are suggested.

Authors

Andrei Filippov

Luleå tekniska universitet; Kemiteknik; Kazan State Medical University, Kazan, Russia; Chemistry of Interfaces
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Oleg Antzutkin

Luleå tekniska universitet; Kemiteknik; Department of Physics, Warwick University, Coventry, U.K
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Faiz Ullah Shah

Luleå tekniska universitet; Kemiteknik
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