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Fate and transformation of graphene oxide in marine systems
Citation:
Adeleye, A., K. Ho, AND R. Burgess. Fate and transformation of graphene oxide in marine systems. Sixth Sustainable Nanotechnology Organization Conference, Marina del Rey, California, November 05 - 07, 2017.
Impact/Purpose:
In recent years, nanotechnology has developed into a major industry in the United States and around the world. Nanomaterials are extremely small objects that show great promise for a variety of industrial and consumer applications but our understanding about their fate and effects in the environment is limited. Graphene oxide is a member of the graphene family nanomaterials (GFNs), which are being developed for use in functional coatings, anti-corrosion applications, antifouling applications, water treatment filtration membranes, conductive inks, etc. These applications may lead to release of these nanomaterials into the environment, and there is need to understand the fate of graphene oxide (and the other GFNs) in the environment. This study focused on the fate and transformation of graphene oxide in seawater, which is predicted to be a major sink for many engineered nanomaterials. The influences of important environmental parameters—such as salinity, solar irradiation, and natural organic matter—on the fate of GO in seawater were investigated.
Description:
Graphene oxide (GO) may be released into natural waters at different phases of its life cycle. Currently, there is no study on the fate of GO in seawater, which is predicted to be a major sink for many engineered nanomaterials. In this study, the influences of salinity (0-50 ‰), aging (0 and 28 d), solar irradiation (12 and 24 h), and natural organic matter or NOM (algal exudates and humic acid) on the fate of GO in seawater were investigated using techniques such as dynamic light scattering, electron microscopy, and X-ray photoelectron spectroscopy. The critical coagulation salinity of GO was determined as 1.5 ‰ but the settling velocity of GO increased with salinity up to 10 ‰. Settling velocity of GO decreased thereafter from 0.145 m/d at 10 ‰ to 0.108 m/d at 50 ‰. Stability of GO increased with increased NOM concentrations and its transformation decreased with increased salinity. Carbon to oxygen ratio increased under ambient light from 1.61 in pristine GO to 2.18, 1.98, and 1.71 after 28 d in 0, 1, and 30 ‰ media, respectively. Although solar irradiation caused more rapid reduction of GO, the stability of irradiated GO did not change significantly in seawater.