There are two major methods of converting lignocellulosic materials to sugars using acid hydrolysis: dilute acid treatment and concentrated acid treatment. In addition, dilute acid pretreatment is often used to solubilizehemicellulose and at least partially swell the cellulose prior to enzymatic hydrolysis. Economics dictates the recovery and reuse of the acid, even at concentrations of one percent. Researchers have developed patented technology for the recovery and recycle of both hydrochloric acid (HCl) and sulfuric acid (H2SO4) by solvent extraction. This technology has been applied mainly to the recovery of acid from concentrated acid hydroly sates. This project will apply acid recovery technology to the wide range of HCl and H2SO4 concentrations used in dilute and concentrated acid hydrolysis and acid pretreatment. Solvent extraction experiments will be performed to determine the acid concentration range suitable for applying the technology. Acid recovery will then be applied in an enzymatic hydrolysis/fermentation experiment to identify any inhibitory effects of the solvent. Finally, the economics of applying acid recovery to various hydrolysis techniques will be projected. The subsequent Phase II research project will optimize the technology for ongoing acid hydrolysis/enzymatic hydrolysis processes. Anticipated Results/Potential Commercial Applications as described by the awardee: The development of this simple and effective acid recovery technology should greatly improve the economics for biomass conversion to ethanol. The technology has wide spread application for both concentrated acid and dilute acid processes, as well as for acid pretreatment prior to enzymatic hydrolysis. The technology should find widespread application and therefore should have significant commercial appeal.
