Final Report: Separation Process for Biobased Lactic AcidEPA Contract Number: 68D03027
Title: Separation Process for Biobased Lactic Acid
Investigators: Dunuwila, Dillum D.
Small Business: Lec Tech Inc.
EPA Contact: Manager, SBIR Program
Project Period: April 1, 2003 through September 1, 2003
Project Amount: $69,966
RFA: Small Business Innovation Research (SBIR) - Phase I (2003) RFA Text | Recipients Lists
Research Category: Nanotechnology , SBIR - Nanotechnology , Small Business Innovation Research (SBIR)
Lactic acid (CAS No. 50-21-5, 2-hydroxypropanoic acid) is the most widely occurring hydroxycarboxylic acid and is distributed in normal food. Lactic acid is used primarily in food and food-related applications, and a small amount is used in medicine and cosmetics. More recently, because of the demand for "greener" chemicals for use in chemistry and engineering technologies, the scope for lactic acid has broadened. Particularly, very large volume opportunities have materialized in biodegradable polymer feedstocks. Consequently, several agriprocessing and chemical companies, such as Archer Daniels Midland, Cargill Dow LLC, and PURAC either have announced plans to produce lactic acid from carbohydrate fermentation, or have production underway. These developments are expected to boost the fermentation-derived lactic acid capacity. The most formidable challenge facing the industry is the development of an efficient separation process for the recovery and purification of biobased lactic acid. An economically viable process that does not generate waste byproducts does not exist at present. This research project was aimed at providing a highly efficient, economically viable, and environmentally friendly separation process for biobased lactic acid that eliminates the generation of waste or byproducts.
All commercially viable, lactic acid-producing microorganisms presently require
neutralization during fermentation to ensure that the pH does not become low
enough to kill the microbes. To obtain the acid, a cation elimination process
is necessary, wherein the base cation needed to neutralize the acid during
fermentation is replaced by protonation. Previously, several strategies have
been pursued by a number of researchers:
· The gypsum process, wherein sulfuric acid is used to acidify the calcium salt of lactic acid (calcium lactate is produced by neutralizing the fermentation broth with lime), results in stoichiometric production of calcium sulfate (gypsum), which has low quality and limited commercial value. Both the acid and the base are irreversibly consumed during the associated chemical processes.
· Electrodialysis, which uses a conventional concentrating electrodialysis step followed by watersplitting electrodialysis to convert the salt to acid and base, is an alternative. Numerous economic studies have indicated that this process is costly in both capital (membranes) and operating costs (electrical power), and probably is not feasible for commodity chemical production.
· Extraction of lactic acid by polar organic solvents, water-soluble trialkyl amines, and water-immiscible long-chain trialkyl amines in the presence of pressurized carbon dioxide have been studied. None of these techniques is commercially viable because of long residence times and large processing volumes.
The proposed separation process was designed to overcome the limitations of the existing technologies. Furthermore, the technical challenges associated with the unit operations of the proposed separation process were identified. Plausible solutions for investigation during Phase II will be proposed.
LEC Tech, Inc., contends that the proposed separation process for biobased lactic acid is conceptually sound and meets the industry needs. Phase I results suggest that the project will lead to a highly efficient, economically viable, and environmentally friendly separation process for biobased lactic acid that eliminates the generation of waste or byproducts.