Recycling of poly lactic acid into lactic acid with high temperature and high-pressure water

The converting of poly L-lactic acid into its monomer (lactic acid) was performed using high temperature and high pressure water at the temperature range of 250-350 degrees C and for a period of 30 minutes. The results show that temperature and reaction time affected the recycling efficiency and optical selectivity. Under the tested conditions, the highest amount of lactic acid (yield of 90.7-92.5%) was obtained at temperature of 250 degrees C and reaction time of 10-20 min. The remains were an un-harmful byproduct. A study on the effect of temperature on the optical purity of lactic acid product demonstrated L-lactic acid was predominant at a low range temperature of 250-260 degrees C. At higher temperature, racemic mixture was observed. Based on our experimental results, the method was found to be simple and promising for recycling of poly lactic acid into its monomer, lactic acid.