Rice Hulls Separation for Biofuels

Interest in homegrown sustainable biofuels has fluctuated directly with the price of non-renewable fuels. However, using potential food or feed, such as corn, to produce bioenergy seems unethical in a world of limited caloric resources. As a non-food renewable resource, lignocellulosic biomass from food processing could be used as an important starting point to produce biofuels indefinitely.

Rice hulls are a secondary agricultural residue that must be transported to processing centers with the rough grain for separation. Thus, costs for low density transportation for the biomass are negligible and unavoidable, unlike primary agricultural residues like corn stover. Rice hulls high silica content makes them unsuitable for animal feed, so they are often burned or landfilled. One way to valorize them is separation with deep eutectic solids (DES).

DES can separate rice hulls into a lignin-rich product with many potential uses, such as in solid fuel or in binders, as well as a cellulose-rich product with potential for enzymatic hydrolysis to produce sugars for fermentation to biofuels. We have separated these biofuels using DES.