Increasing production and application of nanomaterials will inevitably lead to environmental release and subsequent human and ecological exposures. Anticipated production and use of graphene family nanomaterials (GFN) have raised concerns about their potential release into the environment. Graphene oxide (GO) is one of the most highly studied members of the GFN due to its comparatively inexpensive synthesis relative to graphene and its role as a precursor in the synthesis of other graphene-based nanomaterials. Like graphene, GO exists as 2-D sheets, but GO is much more readily dispersible in water due to the presence of basal plane hydroxyl and epoxy groups, and edge carboxyl groups. Environmental studies have indicated that GO is stable in the water column even at relatively high ionic strengths and that GO may be phototransformed to yield both reduced GO products (rGO) as well as oxygenated PAHs. In this report, an approach for modeling the environmental fate of graphene oxide, rGO, and oxygenated PAHs in surface waters is presented. GO and rGO transport and mass distribution in the water column and in sediments is modeled using the newly updated Advanced Toxicant module of the Water quality Analysis Simulation Program (WASP8). WASP8 is parameterized for particle transport using an experimentally measured, system specific, first-order heteroaggregation rate constant for particle attachment to naturally occurring water body particulates (ex. sediments). The heteroaggregation rate constants and calculated particle collision frequencies are then used to determine GO and rGO particle attachment efficiencies. The interaction of the oxygenated PAH fraction with water body particulates is modeled using classic equilibrium partitioning theory. Simulated water body GO concentrations are assessed for their potential ecological effects using model membrane systems: GO interactions with phospholipid supported bilayers, as well as bilayers derived from fathead minnow (<i>Pimephales promelas</i>) cell membrane extracts, are quantified using quartz crystal microbalance deposition techniques.

Modeling the environmental fate of graphene oxide and its transformation products in surface waters

253rd National Meeting (2017)

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