Sorption and desorption kinetics of PFOS to pristine microplastic

Bettie Cormier,Flora Borchet,Leo W Y Yeung,Marta Szot,Anna Kärrman,Steffen H Keiter

doi:10.1007/s11356-021-15923-x

Abstract

The sorption processes of persistent organic pollutants on microplastics particles are poorly understood. Therefore, the present study investigated the sorption processes of perfluorooctanesulfonate (PFOS) on polyethylene (PE) microplastic particles (MPs) which are representing a prominent environmental pollutant and one of the most abundant microplastic polymers in the aquatic environment, respectively. The focus was set on the investigation of the impact of the particle size on PFOS sorption using four different PE MPs size ranges. The sorption kinetics for 6 months was studied with one selected size range of PE MPs. Besides, the desorption of PFOS from PE MPs under simulated digestive conditions was carried out by using artificial gut fluid mimicking the intestinal juice of fish. The investigation of the size effects of particles over 6 months demonstrated a linear increase of PFOS concentration sorbed onto PE with a decrease of the particle size. Thus, our findings implicate efficient sorption of PFOS onto PE MPs of different sizes. The results showed that PFOS desorbed from the PE MPs into the artificial gut fluid with a rate of 70 to 80%. Besides, a longer exposure of PE MPs to PFOS leads to a higher concentration adsorbed by PE MPs, which may favor the ingestion of higher concentration of PFOS, and thus represents a higher risk to transfer relevant concentrations of PFOS during digestion.

Highlights

The use of plastic has become unavoidable in our society which is directly related with an increasing global plastic production (Geyer et al 2017)
PFOS and other per- and polyfluoroalkyl substances (PFAS) possess a great chemical stability and specific surface properties (Paul et al 2009); these compounds were used in numerous products, e.g., varnishes, waxes, firefighting foams, metal plating and cleaning, coating formulations, lubricants, and as a repellent for leather, paper, and textiles (Ahrens and Bundschuh 2014; Paul et al 2009)
We detected a background contamination of PFOS on PE microplastic particles (MPs) that originated from methanol and the different equipment used in both laboratory rooms

Summary

Introduction

The use of plastic has become unavoidable in our society which is directly related with an increasing global plastic production (Geyer et al 2017). Besides numerous benefits of plastic products, it becomes obvious that plastics have. Polyethylene (PE; -(-CH2-CH2-)n-) represents the polymer with the greatest global production for plastic manufacturing (PlasticsEurope 2018). The use of PE as passive sampler demonstrated the ability of PE to concentrate chemicals (Huckins et al 1990). Besides its extensive use as passive samplers for hydrophobic organic pollutants, PE has been commonly studied as one of the reference polymers to investigate chemical sorption to MPs (Lee et al 2014; Hüffer and Hofmann 2016; Li et al 2018; Xu et al 2018)

Methods

Results

Conclusion