METHOD FOR REGENERATING LACTIC ACID-BASED BIODEGRADABLE PLASTIC

摘要

PROBLEM TO BE SOLVED: To regenerate highly-purified lactic acid from a lactic acid-based biodegradable plastic waste without loosing quality due to the incorporation of impurities.

SOLUTION: The regeneration method comprises hydrolysis treatment and supercritical extraction treatment. The hydrolysis treatment is a treatment for reacting an object to be treated containing a biodegradable plastic derived from lactic acid with water under saturated steam pressure of about 140°C to hydrolyze the biodegradable plastic to form an aqueous lactic acid solution. The supercritical extraction treatment is a treatment for maintaining the aqueous lactic acid solution obtained by the hydrolysis treatment under a supercritical environment of carbon dioxide, that is, at a temperature of about 60°C and pressure of about 8 MP, removing a supercritical fluid of carbon dioxide in which the aqueous lactic acid solution is melted, and bringing the supercritical fluid back to ordinary temperature to form a purified lactic acid separated from carbon dioxide.

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