Improved biodegradability of low-density polyethylene using plasma pretreatment and plastic-degrading bacteria

Abstract

Polyethylene is widely used and is a major cause of serious environmental problems because it is non-biodegradable and difficult to recycle. To overcome these environmental problems, in this study, low-density polyethylene (LDPE) was treated with low-temperature plasma at atmospheric pressure, an eco-friendly technology. After inducing oxidation on the LDPE film by plasma treatment, a method for improving the biodegradation efficiency of LDPE-degrading bacteria was identified, and the underlying mechanism was investigated. Fourier-transform infrared and X-ray photoelectron spectroscopy analyses showed that the plasma treatment resulted in the formation of new peaks corresponding to the C–O and –CC– bonds and stronger –CO– bond groups than the –C–O– bond groups, showing that the oxidation of LDPE film was strong. Additionally, the –C–H– bond ratio on LDPE surfaces inoculated with Pseudomonas putida increased by 13–25.5% compared to that on untreated controls. Pseudomonas putida reduced the thermal stability by forming a biofilm on the oxidized LDPE film during the plasma treatment. The weight of untreated LDPE film was reduced by 50%, while that of treated LDPE film was reduced by 80%, confirming more efficient degradation. Thus, LDPE decomposition efficiency can be improved using a short plasma treatment to increase the adhesion and fixation of LDPE-degrading bacteria on the surface of oxidized LDPE films. Therefore, plasma pretreatment technology could be used to reduce plastic contamination in agricultural environments.