Key words: supercritical CO2, hydrothermal fractionation, lignin, coconut fiber, extraction
A new approach to fractionation of coconut fiber by the hydrothermal method using ethanol and supercritical (SC) CO2 as co-solvents is proposed. The efficiency of the method for isolating valuable components due to the synergistic effect of hydrothermal treatment and increased solubility of biomass in the ethanol—water—SC CO2 system is demonstrated. During the 15 minute treatment at 110 °C, 12 MPa, and a fiber-to-ethanol mass ratio of 1 : 20, the maximum lignin yield (65 %) was reached, which is more than 2 times higher than during hydrothermal extraction with ethanol addition (26 %). The conservation of carbonyl groups and the native ratio of G (guaiacil) and S (syringyl) structural units in isolated lignin in accordance with the literature data has been shown by IR- and NMRspectroscopy.
doi:10.34984/SCFTP.2025.20.4.006