1Department of Chemical Engineering

The Ohio State University

Columbus, OH 43210

Phone: (614)292-6611

Fax: (614)292-3769

E-mail: yangst@che.eng.ohio-state.edu

²Environmental Energy Inc.

P.O. Box 15, 1253 N. Waggoner Rd.

Blacklick, OH 43004

Lactic acid is an important specialty chemical that can be used to synthesize biodegradable polymers and green solvents, such as polylactic acid (PLA) and lactate esters. Lactate esters in many situations can replace toxic solvents. Extractive fermentation with on-line product removal can eliminate product inhibition and greatly improve the fermentation efficiency. In this study, on-line extraction of lactic acid from the fermentation broth was demonstrated by using Alamine 336 in oleyl alcohol contained in a hollow-fiber membrane extractor. With simultaneous stripping the solvent with ammonia water or sodium hydroxide in another membrane extractor, ammonium lactate or sodium lactate was produced in high concentrations. With Rhizopus oryzae immobilized in a rotating fibrous bed bioreactor, the extractive fermentation process produced a high lactate concentration of ~300 g/L with 92% lactate yield from starch. Lactic acid in organic solvent can be used directly to produce lactate esters by reacting with alcohols (e.g., ethanol) in an immobilized lipase reactor under ambient conditions. The extractive fermentation coupled with esterification with immobilized lipase reactor provides an energy-efficient green process for production of lactate esters from biomass.