Separation of Lactic Acid Based on Amide-Based Hydrophobic Deep Eutectic Solvents: Insights from Experiments and Molecular Dynamics Simulations

Nowadays, the development of appropriate technologies is of great significance for society. To avoid the negative impact of traditional separation methods on the environment, novel biodegradable amides were used for the separation of lactic acid (LA) by the in situ formation of deep eutectic solvents (DESs). The formation mechanism was explained by quantum chemical calculations and FT-IR analysis. In addition, the stripping of LA was performed by hydrophobic DESs interacting with water, and the amide in DESs was regenerated and reused. Meanwhile, the classical molecular dynamics simulations were adopted to describe the complex mixture of the amide–LA–water system structures and properties in depth. The essence of interaction between hydrophobic DESs and water is a dynamic reversible phase equilibrium process. This study provides a new direction for the development of clean technology such as carboxylic acid separation and also provides guidance for the design of hydrophobic DESs.