A new low transition temperature mixture (LTTM) formed by choline chloride + lactic acid: Characterization as solvent for CO2 capture

A new low transition temperature mixture (LTTM) formed by lactic acid and choline chloride is evaluated in this work as solvent for separation of CO2. The new liquid solvent is prepared by mixing two natural and readily available solid starting materials showing strong hydrogen bond interactions. The physical and phase behaviour of these mixtures can be tailored as a function of the nature and ratio of the constituents, temperature and water content. A complete characterization of physical properties (density, viscosity, surface tension, glass transition temperature) is carried out. The phase behaviour and Henry's constant for the pseudo-binary system composed of LTTM (lactic acid:choline chloride = 2:1) and CO2 are also studied. This work opens room for further optimization of a possible CO2 capturing process using LTTMs.

Graphical abstractFrom left to right, the pictures taken at room temperature for lactic acid (melting point 326 K), lactic acid:choline chloride at molar ratio 2:1 (melting point 206 K) and choline chloride (decomposition temperature lower than the melting point).Figure optionsDownload full-size imageDownload as PowerPoint slide