Steam treatment of waste Polylactid acid (PLA) based products for lactic acid recovery

Published in: Engineering Innovations for Global Sustainability: Proceedings of the 14th Latin American and Caribbean Conference for Engineering and Technology
Date of Conference: July 20-22, 2016
Location of Conference: San Jose, Costa Rica
Authors: César M. Moreira
Abhay Koppar
Pratap Pullammanappillil
Bruce A. Welt
Refereed Paper: #354

Abstract:

Thermal treatment of 2.5 grams (dry weight) and 7.5 grams (dry weight) batches of PLA-product was carried out at 121 oC and 160 oC and exposed to different treatment time periods. Molecular weight reduction was not affected by the amount of PLA material loaded. Rate of molecular weight reduction was about six times faster at 160 oC than at 121 oC. Complete depolymerization of the PLA-product was not possible at the temperatures used here. A maximum recovery (yield) of lactic acid of 35% was obtained at a loading of 7.5 g, temperature at 121 °C and exposure time of 720 min. At 160°C , recovery was 25% but obtained within 120 minutes. Results suggest that PLA-product waste behaviour will differ from pure PLA pellet. With PLA-product waste, complete lactic acid recovery was not possible and other by-products like acetic and propionic acids were produced from thermal treatment.