THE EFFECTIVENESS OF USING DEEP EUTECTIC SOLVENT ON DELIGNIFICATION OF WHEAT STRAW

The research is dedicated to study the efficiency of lignin extraction using deep eutectic solvent (DES) composed of choline chloride and oxalic acid (0.75 : 1). The experiment was conducted in the temperature range 80–110 °С. The cellulose-enriched fraction (technical cellulose), as well as lignin and hemicellulose fractions were isolated from the treatment products. Evaluation of the effectiveness was carried out by the yield of lignin fraction and degree of delignification. It was found that increasing the temperature up to 110 °С caused the increase of delignification of wheat straw degree to 83%, and yield of lignin fraction up to 15.5% dry mass. Along with delignification, removal of hemicellulose from straw biomass in this temperature range and, as a consequence, an increase in the cellulose content of the technical cellulose fraction was observed. The structural changes of the technical cellulose were analyzed using IR-spectroscopy and scanning electron microscopy methods. The obtained SEM-images allowed to clearly trace morphological changes of structure and to draw conclusions about the effectiveness using DES on breaking the bonds between the biopolymers of the lignocarbohydrate complex of wheat straw.