Effect of Temperature on Lignin Isolation by Using Organosolv Method from Oil Palm Empty Fruit Bunch

Abstract

Lignin is the second most abundant biopolymer on the earth as promising raw material for various valuable products. In terms of biorefinery, the organosolv method promotes elevate satisfy isolation due to its ease of purification and environmental friendliness. This study aimed to determine the effect of temperature on lignin isolation from palm oil empty fruit bunch (EFB) obtained through the organosolv method. The isolation was using acetic acid, formic acid, and water (30:60:10( v/v/v)) as the solvent and 0,1% of HCl as a catalyst at various temperatures (60°C, 85°C, 100°C, and 121°C). The heating temperature had significant effect on the yield, purity and pH of lignin. The lignin yield roses when the temperature increase from 60°C to 85°C but starts to decrease at 100°C. The highest yield of 15.87% was obtained at 85°C. However, the purity is inversely proportional to the yield. The higher the yield, the lower the purity correspond to condensation reaction at temperature above 85°C. The highest purity of 94.49% was obtained at the lowest yield at temperature 121°C. The heating temperature also affected pH. The pH is increase with increasing temperature. Functional groups analysis using FT-IR indicated that lignin isolates obtained at a temperature of 60°C, 85°C, 100°C, and 121°C had similar functional groups, consist of ether linkage, aromatic rings, C-H methyl linkage, guaiacyl rings, and syringyl rings indicated that the lignin of oil palm empty fruit bunch classified as SGH-type lignin.