Extraction of ferulic acid from oil palm pressed fiber by a choline chloride based deep eutectic solvent

Abstract

AbstractResults on the extraction of ferulic acid from palm pressed fiber using deep eutectic solvent (DES) of choline chloride‐acetic acid (ChCl‐AA) and choline chloride‐citric acid (ChCl‐CA) are reported. Acetic acid was found to be a better hydrogen bond donor to choline chloride than citric acid for the extraction of ferulic acid. Influence of water content in both DES was investigated whereby ChCl‐AA and ChCl‐CA experienced a drop in viscosity from 9.678 to 1.429 and 22.658 ± 1.655 mm2/s, respectively as the water content in the DES increased from 0 to 50 wt%. The drop in viscosity contributed to higher extraction efficiency in which 41,155 ± 940 mg/kg ferulic acid was obtained after 6 h reflux when ChCl‐AA with 30 wt% water was used for the extraction compared to 30,940 ± 621 mg/kg when neat ChCl‐AA was used. Further increase in water content in the DES however, did not lead to higher extraction efficiency. Although viscosity of the DES could be improved with the addition of water, there is a threshold where the DES could tolerate the presence of water without changing its solvent behavior. Surface response model revealed that interaction between heating duration and water content in DES, as well as second order effect of both heating duration and water content in DES played important roles in the extraction of ferulic acid from oil palm pressed fiber. The optimum condition for extraction of ferulic acid from palm pressed fiber was heating for 6 h with DES containing 30 wt% water.