Study on the Mechanism of Ionic Liquids Improving the Extraction Efficiency of Essential Oil Based on Experimental Optimization and Density Functional Theory: The Fennel (Foeniculi fructus) Essential Oil Case

Abstract

In this work, microwave-assisted ionic liquids treatment, followed by hydro-distillation (MILT-HD), as an efficient extraction technology, was used to extract essential oil. The purpose for this was to use multivariate analysis (MVA) models to investigate the effects of potential critical process parameters on the extraction efficiency of essential oil, and explore the mechanism of ionic liquids (ILs). According to the design of experiment (DoE), under optimal process conditions, the extraction efficiency of essential oil was dramatically enhanced, and had low energy demands. Since little is known regarding those mechanisms, according to the non-covalent interaction analysis, the underlying mechanism for ILs improving extraction efficiency was explored based on the density functional theory (DFT). The results showed that ILs could form intense non-covalent bond interaction with cellulose. It helped destroy the network hydrogen bond structure of cellulose in plant cells and caused the essential oils in the cells to be more easily exposed to the extraction solution, thereby accelerating extraction efficiency. Based on this work, it is conducive to understand the MILT-HD process better and gain knowledge of the mechanism of ILs.

Ionic liquids revolutionizing biomedicine: recent advances and emerging opportunities

“…The process of interaction between ILs and cellulose had also been emphasized, wherein non-covalent interactions (H-bonds and van der Waals forces) between the ILs and cellulose lead to the breakdown of the H-bonds' cellulose structure. 185 IL-based UAE extraction has been identified as an efficient technique to facilitate natural product extraction and increased yield. Compared with traditional extraction, UAE-assisted extraction has less solvent consumption and shorter extraction time.…”

“…The process of interaction between ILs and cellulose had also been emphasized, wherein non-covalent interactions (H-bonds and van der Waals forces) between the ILs and cellulose lead to the breakdown of the H-bonds’ cellulose structure. 185…”