LIGNIN EXTRACTION METHOD AS AN ANTIOXIDANT FOR BIODIESEL USING MICROWAVE AND DEEP EUTECTIC SOLVENT

Abstract

LIGNIN EXTRACTION METHOD AS AN ANTIOXIDANT FOR BIODIESEL USING MICROWAVE AND DEEP EUTECTIC SOLVENT This invention is a method for extracting lignin from empty oil palm fruit bunches (OPEFB) as a natural antioxidant for biodiesel using a combination of microwave and deep eutectic solvent (DES) based on choline chloride and lactic acid. This method was developed to overcome the instability of biodiesel oxidation and the limited efficiency of conventional isolation methods. The extraction process is carried out by mixing OPEFB powder and DES (molar ratio of 1:1 to 1:5) at an OPEFB-DES ratio of 1:5 to 1:15. The mixture is extracted using a microwave with a power of 300-500 watts for 1-3 minutes, followed by separation of lignin using water as an antisolvent. This method is able to produce depolymerized lignin with a yield of 75-85%, purity ≥80%, and high antioxidant activity (IC50 ≤1,000 μg / mL) which effectively increases the oxidation stability of biodiesel.