TECHNOLOGICAL AND ECONOMIC-POTENTIAL OF POLY(LACTIC ACID) AND LACTIC-ACID DERIVATIVES

Lactic acid has been an intermediate-volume specialty chemical (world production similar to 40,000 tons/yr) used in a wide range of food pro cessing and industrial applications. Lactic acid has the potential of becoming a very large volume, commodity-chemical intermediate produced from renewable carbohydrates for use as feedstocks for biodegradable polymers, oxygenated chemicals, plant growth regulators, environmental ly friendly ''green'' solvents, and specialty chemical intermediates. The recent announcements of new development-scale plants for producing lactic acid and polymer intermediates by major U.S. companies, such a s Cargill, Ecochem (DuPont/ConAgra), and Archer Daniels Midland, attes t to this potential. In the past, efficient and economical technologie s for the recovery and purification of lactic acid from crude fermenta tion broths and the conversion of lactic acid to the chemical or polym er intermediates had been the key technology impediments and main proc ess cost centers. The development and deployment of novel separations technologies, such as electrodialysis (ED) with bipolar membranes, ext ractive distillations integrated with fermentation, and chemical conve rsion, can enable low-cost production with continuous processes in lar ge-scale operations. The use of bipolar ED can virtually eliminate the salt or gypsum waste produced in the current lactic acid processes. T hus, the emerging technologies can use environmentally sound processes to produce environmentally useful products from lactic acid. The proc ess economics of some of these processes and products can also be quit e attractive. In this paper, the recent technical advances in lactic a nd polylactic acid processes are discussed. The economic potential and manufacturing cost estimates of several products and process options are presented. The technical accomplishments at Argonne National Labor atory (ANL) and the future directions of this program at ANL are discu ssed.