Recycling of deep eutectic solvent in the extraction of ferulic acid from oil palm empty fruit bunch

The study explored ferulic acid extraction from palm empty fruit bunch (EFB) fiber using deep eutectic solvent (DES) of chlorine chloride-acetic acid as the extraction medium and the way to recover and recycle the DES thereafter. Antisolvent was added to selectively precipitate the ferulic acid, which was recovered by filtration thereafter. Recycling the DES without further purification led to increased ferulic acid yield with each subsequent extraction, likely due to retained ferulic acid. The retained ferulic acid and other impurities could be removed by precipitation brought upon by the addition of a second antisolvent. 1H nuclear magnetic resonance revealed that there was no excess ferulic acid in the recycled DES-treated with two types of antisolvents (ethanol and water). The yield of ferulic acid increased from 0.1367-0.1856 g/g when treated with only one antisolvent to 0.1368-0.2897 g/g with two antisolvent treatments. Oil droplets were also observed in the DES upon the addition of antisolvent 2, with recovered oil ranging from 0.6% to 3%. The study emphasized the significance of using DES as an extraction medium for ferulic acid from oil palm EFB fiber and the method to recycle the DES for subsequent processes.