Approach for the Low Carbon Footprint of Biodegradable Plastic PBAT: Complete Recovery of Its Every Monomer via High-Efficiency Hydrolysis and Separation

Abstract

Biodegradable plastics are considered one of the solutions to solve the environmental pollution caused by plastic waste. However, on easy-to-collect occasions, recovery of biodegradable plastics is a preferable option rather than biodegradation, since it can fully utilize carbon resources and reduce carbon emissions. Herein, efficient and eco-friendly recycling of widely used biodegradable plastic, polybutylene adipate terephthalate (PBAT), was demonstrated by alkaline hydrolysis in the solution of ethanol and H2O. The degradation ratio of PBAT was achieved above 99% at 80 °C for 50 min. Diacid salts were self-precipitated out from the reaction solution, followed by acidification to obtain diacid monomers. The reaction solution after filtrating away the diacid salts can be recycled several times without sacrificing the degradation ratio of PBAT, while 1,4-butanediol monomer can be further recovered by the two-step mild distillation at 80 °C. The carbon emission of the whole recycling process was evaluated, and it was only half of that of the biodegradation. The work provides new insight into the recycling of biodegradable plastics.