Producing fragmented micro- and nano-sized expanded polystyrene particles with an accelerated mechanical abrasion experiment

Abstract

Microplastics are world widely found from beach to open ocean and from sea surface to deep-sea bed. They are manufactured as small plastic particles (primary microplastics) to produce resin pellets, scrubbers for cosmetics, or blasting materials or they are generated by the fragmentation of larger plastic products (secondary microplastics). Fragmented secondary microplastic particles account for the majority of microplastics and have various origins, which makes proper control difficult. Photo-oxidation and mechanical abrasion on beaches and (or) sea surface are thought to be major weathering and fragmentation process for generating secondary microplastic particles. None of scientific information is, however, available where and how secondary microplastics are produced. Fragmentation of expanded polystyrene (EPS), one of top three polymer types in marine debris monitoring study was done with an accelerated mechanical abrasion experiment in a laboratory. Forty EPS spherules detached from a EPS float were placed in an amber bottle with glass bead (3 mm in diameter) or natural sand (pre-combusted at 450 °C), respectively. The bottles were rotated with a tumbler for a month at 113 rpm. Fragmented EPS particles were extracted by density separation with deionized water and identified with microscopic FT-IR, SEM and fluorescence microscope after Nile Red staining. After mechanical abrasion, apparent surface damage of EPS srials or they are generated by the fragmentation of larger plastic products (secondary microplastics). Fragmented secondary microplastic particles account for the majority of microplastics and have various origins, which makes proper control difficult. Photo-oxidation and mechanical abrasion on beaches and (or) sea surface are thought to be major weathering and fragmentation process for generating secondary microplastic particles. None of scientific information is, however, available where and how secondary microplastics are produced. Fragmentation of expanded polystyrene (EPS), one of top three polymer types in marine debris monitoring study was done with an accelerated mechanical abrasion experiment in a laboratory. Forty EPS spherules detached from a EPS float were placed in an amber bottle with glass bead (3 mm in diameter) or natural sand (pre-combusted at 450 °C), respectively. The bottles were rotated with a tumbler for a month at 113 rpm. Fragmented EPS particles were extracted by density separation with deionized water and identified with microscopic FT-IR, SEM and fluorescence microscope after Nile Red staining. After mechanical abrasion, apparent surface damage of EPS s