Characterization of Potential Pollutants from Poly(lactic acid) after the Degradation Process in Soil under Simulated Environmental Conditions

Abstract

In recent years, the amount of produced petrochemical plastic waste has been growing at an alarming rate. According to the Plastics Europe Market Research Group (PEMRG)/Conversio Market & Strategy GmbH, in 2018 the global production of plastics amounts to 359 million tons, and in Europe—61.8 million tons. More than 80% of all marine litter is plastic, which accumulates in the environment due to its durability. Due to the growing problem, biodegradable polymer products are introduced to the market. Therefore, it is necessary to conduct research on degradation products in order to estimate the risk arising from their presence in the environment. This paper discusses research on compounds that may potentially remain in the soil after the degradation of the double green PLA polymer. The aim of the research was to prove whether products made of PLA, e.g., packaging, films and other waste can release substances harmful to the environment. Therefore, soil was selected as a medium to characterize the substances potentially released from the polymer under conditions simulating the degradation process in the environment. The soil was always used from the same producer. Before the polymer biodegradation process, it was additionally checked for pH, C and N content, number of microorganisms, etc. PLA degradation in soil was carried out in a laboratory accredited by the Polish Accreditation Center (PCA). During the research, soil samples at various stages of the degradation process under laboratory conditions were subjected to both extraction in an aqueous environment and organic solvent extraction The studies used the gas chromatography coupled with mass spectrometry (GC/MS), as well as pyrolysis gas chromatography (Py-GC/MS). In addition, the study used the gel permeation chromatography (GPC/SEC) allowing to determine the distribution of molar masses, average molar masses and polydispersity, and the infrared spectroscopy (FTIR).

Influence of the microstructure in the biodegradability process of eco‐friendly materials based on polylactic acid and mango seed for food packaging to minimize microplastic generation

“…The samples in the soil were in contact with water, oxygen, microorganisms, and PLA should decompose in lactic acid and then H 2 O, CO 2 , and nontoxic compounds. Nonetheless, it is considerably persistent in soil, which could be considered a pollutant material 77 . The addition of mango seed material would accelerate the degradation rate.…”

Biodegradable Nonwoven Materials with Antipathogenic Layer

“…The degradation of plastics depends on many factors, including properties of the polymer, chemical structure, molar mass, glass transition temperature, melting point, polydispersion, crystallinity, sample surface, etc. [98][99][100]. A study on the biodegradation of PLA showed that the higher the degree of crystallinity, the molar mass and the melting point, the slower is its degradation.…”

“…A study on the biodegradation of PLA showed that the higher the degree of crystallinity, the molar mass and the melting point, the slower is its degradation. While in the first stage hydrolytic degradation can be observed, the second stage is related to the activity of microorganisms activity [98]. Liu et al [101] investigated biodegradation of PLA/PHB-blended nonwovens in the presence of microbial communities and indicated the role of Proteobacteria and Firmicutes in the process in a soil environment.…”

Bioplastics: A new analytical challenge

“…Spectroscopic techniques such as FT-IR, UV-Vis, and Fluorescence, are mostly used to highlight variations in the building blocks of the polymer structure (Han 2016). Spectrometric approaches such as NMR and massspectrometry are widely used for the qualitative and quantitative determination of several classes of substances including low molecular weight pollutants, high molecular weight polymers up to supramolecular aggregates (Banerjee 2012;Indelicato 2016;Biale 2021;Krawczyk-Walach 2021) Therefore, all these analytical approaches can be very informative in synergy when it comes to evaluating a material undergoing various stresses or degradative processes (Kumar 2017;Akdoğan 2018;Falkenstain 2021;Ghasemlou 2022).…”