The Reactivity of Polyethylene Microplastics in Water under Low Oxygen Conditions Using Radiation Chemistry

Abstract

Polyethylene (PE) is an intensely utilized polymer, which has consequently led to it becoming a common environmental contaminant. PE and other plastic waste are known to be highly persistent in surface waters; however, chemical and physical changes do take place over time, dependent mostly on highly variable natural conditions, such as oxygen (O2) availability. Gamma radiation was used to generate reactive oxygen species, namely hydroxyl radicals, in initially aerated aqueous solutions to simulate the natural weathering of microplastics in waters where there are fluctuations and often depletions in dissolved O2. The headspace of the irradiated PE-containing solutions was probed for the formation of degradation products using solid-phase microextraction (SPME) fibers in combination with gas chromatography mass spectrometry (GCMS). The major species detected were n-dodecane, with trace levels of tridecane, 2-dodecanone, and hexadecane, which were believed to be predominately adsorbed in the PE microplastics in excess of their aqueous solubility limits. Surface characterization by Raman spectroscopy and light and dark field microscopy indicated no change in the chemical composition of the irradiated PE microplastics under low O2 to anaerobic conditions. However, morphological changes were observed, indicating radical combination reactions.

Effects of Gamma Irradiation on Polyethylene Terephthalate and Detection of Microplastic Particles Down to 1 μm

“…Radiation sterilization is also used for medical products and their packaging, which are made of both thermoplastics and thermosets, with a typical dose of 25 kGy . On the other hand, the doses used for experimental purposes can be much higher. ,,− Here, the doses have been chosen so that they do not deviate significantly from the radiation doses used in food and medical devices, but are still large enough to demonstrate the effects of γ-irradiation on the formation of PET microparticles.…”

Distribution and Fate of Polyethylene Microplastics Released by a Portable Toilet Manufacturer into a Freshwater Wetland and Lake

“…Most recently, the testing of at least 130 residential properties near the facility and areas of George Lake showed elevated lead levels [42]. The presence of these contaminants may influence the physical and chemical changes of the more recently emitted plastic pollution over time [44,45].…”