Development of the lignin extraction method from para rubber wood sawdust with choline chloride-lactic acid deep eutectic solvent

Abstract

This work investigated the extraction of lignin from para rubber wood sawdust by deep eutectic solvent extraction (DES) using choline chloride-lactic acid (ChCl-LA). The DES extraction was operated using ChCl/LA with molar ratio of 1:10, and the lignin was extracted with good yields. To determine the optimal conditions for lignin extraction by this technique, various factors were studied, including extraction temperature (90-150 °C), extraction time (6-24 h), the amount of water required for lignin precipitation (150-300 mL), and precipitation time (24-48 h). The optimized conditions were achieved at 150 °C, 24 h, 300 mL of DI water and 48 h of precipitation time, and the highest extracted lignin content was 17.54%. Moreover, excessive water in the extracted solution can be recovered with evaporation, and it was discovered that similar extracted lignin content could be obtained (16.85%) by only using 150 mL of DI water during lignin precipitation but extending the precipitation time to 48 h. This study provides a simple, inexpensive, and environmentally friendly lignin extraction technique.