Monoethanolamine deep eutectic solvent on isolation of cardanol from cashew nutshell liquid

Abstract

BACKGROUND

Monoethanolamine-based deep eutectic solvent (MEADES) at different molar ratios (1:2, 1:3, 1:4, 1:5, 1:6, and 1:7) was prepared and used for the isolation of cardanol from cashew nutshell liquid (CNSL).

RESULTS

In this work, the density of MEADES at different molar ratios (1:2, 1:3, 1:4, 1:5, 1:6, and 1:7), isobutyl methyl ketone (IBMK), ethyl acetate (EtAc), acetone, hexane, methanol, ethanol, and butanol was measured at different temperatures (293.15–343.15 K). Subsequently, the density of the binary mixture of IBMK with EtAc over the whole composition range was measured at different temperatures (293.15–343.15 K). Further, the pH of all the prepared MEADES was determined and functional group analysis was carried out using Fourier transform infrared (FTIR) spectroscopy. Finally, the experimental isolation of cardanol was conducted with feed:ternary mixtures at different solvent ratios (50:150, 50:125, 5:100, and 50:75 mL) and characterized using FTIR spectroscopy and gas chromatography–mass spectrometry.

CONCLUSION

It was observed that all the prepared deep eutectic solvents have strong hydrogen bonds between choline chloride (ChCl) and monoethanolamine (MEA) at all the studied molar ratios when the wavenumbers of individual compounds with mixtures of ChCl and MEA were compared. All the prepared MEADES used for isolation of cardanol from CNSL by varying the feed:ternary solvent ratios. It was concluded that the percentage of cardanol isolation was strongly dependent on the molar ratio of ChCl and MEA, and the volume of IBMK and EtAc as cosolvent in their mixtures. 98.93% cardanol isolation was achieved when using a 50 mL CNSL:75 mL mixture of solvents (i.e., 25 mL MEADES:25 mL IBMK:25 mL EtAc). © 2025 Society of Chemical Industry (SCI).