Strong Sorption of PCBs to Nanoplastics, Microplastics, Carbon Nanotubes, and Fullerenes

The presence of microplastic and carbon-based nanoparticles in the environment may have implications for the fate and effects of traditional hydrophobic chemicals. Here we present parameters for the sorption of 17 CB congeners to 10-180 mu m sized polyethylene (micro-PE), 70 nm polystyrene (nano-PS), multiwalled carbon nanotubes (MWCNT), fullerene (C-60), and a natural sediment in the environmentally relevant 10(-5)-10(-1) mu g L-1 concentration range. Effects of salinity and sediment organic matter fouling were assessed by measuring the isotherms in fresh- and seawater, with and without sediment present Sorption to the "bulk" sorbents sediment organic matter (OM) and micro-PE occurred through linear hydrophobic partitioning with OM and micro-PE having similar sorption affinity. Sorption to MWCNT and nano-PS was MWCNT and C-60 was 3-4 orders of magnitude stronger than to OM and micro-PE. Sorption to nano-PS was 1-2 orders of magnitude stronger than to micro-PE, which was attributed to the higher aromaticity and surface-volume ratio of nano-PS. Organic matter effects varied among sorbents, with the largest OM fouling effect observed for the high surface sorbents MWCNT and nano-PS. Salinity decreased sorption for sediment and MWCNT but increased sorption for the polymers nano-PS and micro-PE. The exceptionally strong sorption of (planar) PCBs to C-60, MWCNT, and nano-PS may imply increased hazards upon membrane transfer of these particles.