Environmental Protection

Sugar Created from Palm Oil Extraction Waste

A research team in Singapore has used plant waste matter from palm oil extraction to make a useful sugar.

Palm oil extraction is responsible for more than 13 million tons of waste plant matter each year. The resulting by-product, empty fruit bunch (EFB), can be used to produce heat and electricity, but can now also be converted into sugar as demonstrated by a research team led by Jin Chuan Wu from the Institute of Chemical and Engineering Sciences.

EFB contains xylan, a carbohydrate made up of units of xylose, and is very susceptible to being broken down to these individual sugar molecules in the presence of mild acid. Known as hydrolysis, this process is not widely applied to EFB because it is not very cost effective.

In order to successfully make the sugar, Wu and his team used the combination of acids selected for hydrolyzing EFB: sulfuric (H2SO4) and phosphoric acid (H3PO4).The acids play a large role in the 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 discovering the right combination of mild acids, Wu and his team used computer modeling and supporting experiments to find the optimal conditions for hydrolysis, which 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.

"Next, we will convert the sugars into lactic acids by microbial fermentation using lactic acid bacteria," explains Wu. “This lactic acid will be used for producing polylactic acid: a renewable and completely biodegradable biopolymer that is stable at high temperatures and has broad applications.”

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