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Explora: Environment
and Resource Experimental application of GQDs for nuclear materials removal

2.3.3. Atomic force microscopy: topography and A
phase imaging
Atomic force microscopy was performed using a
Bruker Multimode 8 (Bruker Corporation, Germany
Manufacturer, Country) with Nanoscope Analysis 1.50
software in tapping mode. This facilitated the acquisition
of topographic and phase images to ascertain particle B
diameter, height, and phase composition. The cantilever
had a spring constant of 0.24 N/m and a nominal tip radius
of 2 nm. The particle solutions, diluted to approximately 10
9
to 10 particles/cm , were applied to freshly cleaved mica
3
10
and dried in a vacuum chamber. The scanning resolution
was 256 × 256 lines at a frequency of 0.5 Hz.
2.3.4. Optical property assessment Figure 1. Diagram illustrating the experiment conducted on plastic and
metal plates. Both surfaces were contaminated with the radioisotopes
Optical characteristics of the GQD dispersion were 99mTc and 131I at different times, followed by the application of graphene
evaluated using a Cary 60 UV-Vis spectrophotometer quantum dots. (A) Rigid PVC surface (plastic); (B) Aluminum, Monel,
(Agilent, Califórnia) for absorbance and an Ocean Optics and Zinc surfaces.
HR2000 (Ocean Insight, Germany) for fluorescence
spectroscopy. Fluorescence was analyzed using LED as zinc oxide, which is used in paints. Aluminum is a
excitation at an emission wavelength of 395 nm. lightweight, silvery-white metal known primarily for its low
density and ability to resist corrosion. It is the most abundant
2.3.5. Powder X-ray diffraction (PXRD) analysis metal in the Earth’s crust and the third most abundant
GQDs were characterized using PXRD with a Bruker element after oxygen and silicon. It is used in a wide range of
AXS D8 Advance diffractometer (Bruker Corporation, applications, including transportation (aircraft, automobiles,
Germany Manufacturer, Country), featuring a CuKα bicycles, and spacecraft), construction (windows, doors, and
radiation source at 40 mA and 40 kV. PXRD measurements siding), packaging (cans and foil), consumer electronics,
encompassed high angle (2θ = 15 – 68°) and low angle and many others.
(2θ = 1.3 – 8.3°) ranges. For the study, a 3 cm area was marked on each surface
2
2.3.6. Surface contamination with 99mTc and 131-I where the radioactive materials were applied as a liquid
solution with a specific activity of 100 microCi. One minute
For this study, we have used four different surfaces, following the dispersion of the radioactive substances, a
intentionally contaminated with technetium 99m and precise quantity of 20 mg of GQDs (in powder form) was
131-I (Figure 1). The surfaces used were: (i) rigid PVC, evenly spread over the same area and gently rubbed in.
(ii) monel, (iii) zinc, and (iv) aluminum.
Subsequently, the GQDs were gathered and weighed, and
The rigid form of PVC is used in construction for pipes their radioactivity was quantified using a gamma counter
and in profile applications such as doors and windows. (Hidex Oy, Finland).
Monel is a group of nickel alloys, primarily composed
of nickel (up to 67%) and copper, with small amounts of After application, the gentle friction applied to an area
iron, manganese, carbon, and silicon. Due to its robust contaminated with radioactive materials easily allowed for
properties, monel is used in various applications, including their chemical interaction, promoting adequate contact
marine engineering, chemical and hydrocarbon processing between the GQDs and the radioisotopes present. In this
equipment, valves, pumps, shafts, fittings, fasteners, and way, the spreading action on the contaminated surface
heat exchangers. It is also used in aerospace applications did not cause any changes to the metallic and PVC/plastic
for its resistance to high-temperature environments. Zinc’s structure of the surface. The idea behind this method is to
most notable property is its ability to resist corrosion. allow the GQDs to adsorb the radioisotopes present on the
When exposed to air, it forms a protective layer of zinc contaminated surface, facilitating their removal.
carbonate by reacting with carbon dioxide. This layer helps 2.4. Statistical analysis
protect the metal from further corrosive elements. Beyond
galvanization and alloys, zinc is used in die-casting, as a All experiments were performed in triplicate, and the
component in batteries, and in various compounds such t-student test assay was performed with a P < 0.05.

Volume 1 Issue 1 (2024) 4 doi: 10.36922/eer.3403