Palm Oil By-Product can be Converted to Sugar for Biomass Production, Researchers Reveal

Scientists from Singapore's Agency for Science, Technology and Research (A*STAR) have found ways to convert residues from palm oil extraction, also known as empty fruit bunch (EFB) into useful sugar for biomass production. EFB contains xylan, a carbohydrate made up of units of xylose. Xylan is very susceptible to being broken down to individual sugar molecules in the presence of mild acid. Known as hydrolysis, this process is not widely applied to EFB — despite its well-established use for converting sugarcane bagasse and corn stover — because of difficulties in making it cost effective.

Thus, scientists used the combination of acids they selected for hydrolyzing EFB: sulfuric (H₂SO₄) and phosphoric acid (H₃PO₄), as the combined use of both acids has a synergistic effect in improving sugar yields. Since the elements sulfur and phosphorus are essential for the fermentation of xylose using microbes, the researchers' combination of acids will play a fundamental role in the further conversion of xylose into other useful chemicals, such as the sugar substitute xylitol, lactic acid and ethanol. After hydrolysis and neutralization, these acid components can be used directly in a microbial fermentation.

After discerning the right combination of mild acids, the research team used computer modeling followed by supporting experiments to find the optimal conditions for hydrolysis. They obtained xylose yields of 80–90%. The conditions they optimized included the concentrations of the two acids, the reaction temperature, the dilution of the solution and the size of the EFB particles.

View A*STAR's news release at http://www.research.a-star.edu.sg/research/6586.