Page 24 - PR 2014 2016 03 Applications of Ionizing Radiations

66 Application of Ionizing Radiations | Progress Report

and composting in natural environment. In
Figure 38a. Micrograph of
order to assess the effects of the polymer graphene oxide prepared
by the modified Hummers
coatings on the degradation process of the
method.
specimens, only the yellow and black sam-
ples were exposed to a controlled compost-
ing environment via respirometry, reducing
to 16 the number of samples. The organic
compound generated by the biodegradation
process was analyzed by the ecotoxicity tests.
It was observed that the coating layer acted
as a barrier that inhibits degradation of the
plastic when exposed to weathering. The
addition of pro-degrading agents accelerat-
ed the degradation process, promoting the Figure 38b. Image by electron microscopy transmission coupled to
an energy dispersive spectrometer shows silver nanoparticles (dark
migration of the metal ion to the medium spots) incorporated to graphene oxide.
without affecting the final quality of the
organic compost/soil.

Synthesis of metal/graphene based
composites using electron beam
for electrochemical applications

Graphene is an allotrope of carbo obtained
in a monolayer form from graphite. This Figure 38c. Image by electron microscopy scan coupled to an energy
dispersive spectrometer shows nickel nanoparticles incorporated to
nanomaterial has exceptional chemical, elec- graphene oxide.
trical and mechanical properties: a precise
surface area of 2,630 m /g per monolayer,
2
excellent electrical and thermal conductiv- Graphene oxide as adsorbent for
ities and high mechanical resistance and Cesium ions removal from aqueous
chemical stability. The existence of metallic solution and radioactive liquid waste.
nano-particles augments the surface through
which the electric current passes, thus in - Graphene Oxide (GO) is a graphene-based
creasing the electrical conductivity of the nanomaterial that has enticed attention on
nanocomposites. Ionizing radiation (electron account of its functionalized surface which
beam and gamma radiation) was utilized to comprises hydroxyl, epoxy, carbonyl and car-
synthesized and combine nickel, copper, pal- boxyl groups, and has a robust complexation
ladium and silver nanoparticle on graphene- ability with ion metal. GO has shown high
based material. This methodology requires sorption competence to eliminate cesium
neither toxic reagents nor generates toxic ion from aqueous solution. The trials were
wastes. These new nano-composites have performed in batch and the following param-
several applications in the electrochemical eters were considered: contact time, pH and
field, such as components for supercapaci- cesium ion concentration in aqueous solution.
tors, solar cells, sensors, electro catalysis and An equilibrium was reached after 60 minutes
lithium batteries. contact in neutral solution. The percentage of

Instituto de Pesquisas Energéticas e Nucleares