The Effectiveness of Using a Deep Eutectic Solvent in Delignification of Wheat Straw

Objective: The research aims to study the efficiency of lignin extraction using a deep eutectic solvent (DES) composed of choline chloride and oxalic acid (0.75 : 1), and to evaluate its effectiveness in wheat straw delignification. Methods: The experiment was conducted within a temperature range of 80–110°C at atmospheric pressure. The cellulose-enriched fraction (technical cellulose), as well as the lignin and hemicellulose fractions, were isolated from the product mixture. Structural changes in the technical cellulose were analyzed using IR spectroscopy and scanning electron microscopy (SEM). Results and Discussion: Increasing the temperature to 110°C resulted in a 83% degree of delignification of wheat straw and a lignin yield of 15.5% dry mass. Alongside delignification, there was a removal of hemicellulose, which led to an increase in cellulose content in the technical cellulose fraction. The SEM images revealed clear morphological changes in the biomass, suggesting that DES effectively cleaved the bonds between the lignin-carbohydrate complex. Conclusions: The study concluded that DES composed of choline chloride and oxalic acid is efficient for delignifying wheat straw, increasing the cellulose content in the technical cellulose fraction and providing insights into the structural changes through SEM analysis.