Fate and Toxicity of CuO Nanospheres and Nanorods
used in Al/CuO Nanothermites Before and After Combustion
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Abstract
Although nanotechnology
advancements should be fostered, the environmental
health and safety (EHS) of nanoparticles used in technologies must
be quantified simultaneously. However, most EHS studies assess the
potential implications of the free nanoparticles which may not be
directly applicable to the EHS of particles incorporated into in-use
technologies. This investigation assessed the aquatic toxicological
implications of copper oxide (CuO) nanospheres relative to CuO nanorods
used in nanoenergetic applications to improve combustion. Particles
were tested in both the as-received form and following combustion
of a CuO/aluminum nanothermite. Results indicated nanospheres were
more stable in water and slowly released ions, while higher surface
area nanorods initially released more ions and were more toxic but
generally less stable. After combustion, particles sintered into larger,
micrometer-scale aggregates, which may lower toxicity potential to
pelagic organisms due to deposition from water to sediment and reduced
bioavailability after complexation with sediment organic matter. Whereas
the larger nanothermite residues settled rapidly, implying lower persistence
in water, their potential to release dissolved Cu was higher which
led to greater toxicity to <i>Ceriodaphnia dubia</i> relative
to parent CuO material (nanosphere or rod). This study illustrates
the importance of considering the fate and toxicology of nanoparticles
in context with their relevant in-use applications