Lignin Isolation from Wood by Organosolv Method
The growing awareness of the environmental concerns in the subsequent decade has brought attention to the importance of having efficient and renewable processes. Lignin represents the second most abundant natural polymer on earth and might play an important role as an alternative in petrochemical industry. Also, it may be considered as an aromatic renewable source. Kraft, lignosulfonate and Organosolv are the main three methods are usually used for lignin isolation from wood. In this project, lignin from sawdust was isolated by using Organosolv method. Two different mixtures; ethanol-water (50 vol %) with 1.0 wt. % H2SO4 as a catalyst, and formic acid-acetic acid (85 vol. %) were investigated. Furthermore, the effect of the reaction time on the lignin yield using 50 vol. % ethanol-water solution was also conducted in this current study. Also, the amount of total lignin in wood sample was measured using Klason method for calculating the acid insoluble residue (AIR) in addition to UV-spectrophotometer for acid soluble lignin (ASL) amount. According to the results, the percentage of lignin in the wood sample was 30 wt. %. The research has also shown that the yield of lignin using ethanol-water mixture obviously increased with increasing the reaction time which accounted the maximum for 16.87 wt. % of the total amount of lignin present after 5 hours of heating process. For a certain amount of wood sample, it was found that the lignin yield using formic acid-acetic acid mixture was higher than the lignin yield obtained from ethanol-water mixture. Other factors such as safety, environmental issues and economic must be considered in the final selection of method recommended for lignin extraction from wood.