Nano-fragmentation of expanded polystyrene exposed to sunlight

Abstract

Fragmentation of micro- and nano-sized particles was qualitatively and quantitatively determined from the expanded polystyrene (EPS) exposed to sunlight for 9 months. The exposed EPS cubes (3x3 cm surface area) were sampled in duplicate at 2 (2M), 5 (5M) and 9 month (9M).The mass of >10 μm EPS particles produced per EPS cube surface area (g/m2) significantly (p<0.05) increased according to exposure time 0.1±0.1 g/m2 for control, 2.6±0.3 g/m2 for 2M, 3.9±0.4 g/m2 for 5M and 7.2±0.2 g/m2 for 9M. The mean and median size of >10 μm EPS particles measured by laser diffraction was 26-29 μm and 18-20 μm, respectively. The hydrodynamic diameter of the EPS particles in the filtrates of <0.8 μm pore filter-paper was 532 nm for 2M, 530 nm for 5M and 752 nm for 9M by dynamic laser scattering. Their particle abundances measured by nanoparticle tracking analysis were 1.8x109 particles/ml for 2M and 3.2x109 particles/ml for 2M and 9M. Two months of outdoor exposure of EPS were enough to produce a large number of micro- as well as nano-sized plastics.t 2 (2M), 5 (5M) and 9 month (9M).The mass of >10 μm EPS particles produced per EPS cube surface area (g/m2) significantly (p<0.05) increased according to exposure time 0.1±0.1 g/m2 for control, 2.6±0.3 g/m2 for 2M, 3.9±0.4 g/m2 for 5M and 7.2±0.2 g/m2 for 9M. The mean and median size of >10 μm EPS particles measured by laser diffraction was 26-29 μm and 18-20 μm, respectively. The hydrodynamic diameter of the EPS particles in the filtrates of <0.8 μm pore filter-paper was 532 nm for 2M, 530 nm for 5M and 752 nm for 9M by dynamic laser scattering. Their particle abundances measured by nanoparticle tracking analysis were 1.8x109 particles/ml for 2M and 3.2x109 particles/ml for 2M and 9M. Two months of outdoor exposure of EPS were enough to produce a large number of micro- as well as nano-sized plastics.