Superfund Research Program

Nanomaterial Design for Environmental Health and Safety

Project Leader: Robert H. Hurt
Grant Number: P42ES013660
Funding Period: 2009-2021

Project-Specific Links

Final Progress Reports

Year:   2020  2014 

Studies and Results

During the past year, work continued within Nanomaterial Design for Environmental Health and Safety on managing exposure to vapor toxicants through exploration of graphene as an ultrathin vapor barrier. Researchers used their experience with mercury vapor containment to build a general-purpose diffusion cell for studying the permeation of other vapor toxicants through multilayer graphene films and validated its operation using water vapor as a simple model permeant. During the course of this work, they also observed that graphite oxide, a key intermediate in graphene synthesis, was capable of explosive decomposition upon mild heating. Because this has important safety implications, researchers engaged in a study of the kinetics and molecular mechanisms of this explosive decomposition and their dependence on material composition and environmental conditions.

Work also continued in collaboration with the Toxicity of Metallic Nanoparticles and Carbon Nanotubes project on the potential toxicity of nanomaterials and their safe design principles (Aims 1 and 2) with emphasis on the graphene-based materials being used for the development of vapor barriers. Researchers studying reactive oxygen species generation from graphene surfaces discovered that graphene also can exhibit free radical scavenging activity. They developed sensitive chemical and spectroscopic methods to characterize the antioxidant activity of these graphene materials and found them to be highly active for the scavenging of hydroxyl radical because of their ultrahigh surface area and extended conjugated structure. As an example application, researchers found that graphene coatings on titania particles were effective at suppressing photo-oxidative damage normally associated with titania in the presence of sunlight.

Significance

Researchers published five peer-reviewed papers in the past year, including one on the antioxidant chemistry of graphene materials and one on explosive decomposition described above. They published the first report in the literature on antioxidant behavior in graphene materials that has relevance for the interpretation of nanotoxicity data. This research also has potential applications in the use of graphene to mitigate oxidative damage from other chemical substrates or materials when formulated as mixtures or hybrids. The work on explosive decomposition is continuing in 2015 and has clear implications for worker safety in the manufacture, processing, storage, and transportation of graphite oxide. The graphite-oxide route is emerging as one of the most commercially attractive methods to produce graphene, and ongoing work seeks to define the material purification and processing conditions that will ensure worker safety.