PROPOSAL OF A NEW L-LACTATE PURIFICATION PROCESS USING CHITOSAN

Abstract

 Optically pure lactate is a raw material for biodegradable polylactic resin. Such lactate is produced by fermentation, and lactate purification from cultivation broth remains a critical issue for reducing the production cost of polylactic resin. Crystallization of calcium lactate is a popular process for its purification; however, the process requires condensed calcium lactate solution, and calcium sulfate is produced as waste in the final step for liberation of lactic acid. This study investigated the purification process via chitosan lactate. Chitosan L-lactate was made using chitosan as a neutralizer in lactate fermentation. Anti-solvent crystallization was applied to recover chitosan lactate, and acetone was worked as an anti-solvent to precipitate chitosan lactate. Finally, ammonium lactate and chitosan were obtained separately by adding chitosan lactate into aqueous ammonia. The recovery ratio of lactate and chitosan was almost 100% when using high molecular chitosan. Recovered chitosan would use as a neutralizer in lactate fermentation again.