Publication: Performance of graphene oxide and coconut shell activated carbon for 131i isolation from delay tank202
Date
2023-07
Authors
Hadzuan, Fara Hana Mohd
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Abstract
Iodine-131, with a half-life of 8 days and about 971 keV excess energy, is the
well-known radionuclide used for hyperthyroidism and thyroid cancer. Due to its
considered low-medium half-life, differentiated thyroid cancer (DTC) patients
administered with high energy 131I need to be isolated until at least minimal radiation
exposure is achieved. An underground system known as a delay tank is used to
withhold the 131I and other clinical wastewater until a non-hazardous level is
achieved and discharged into the main sewage system. The Nuclear Medicine
Department, HUSM has only two isolation wards for the DTC patients and the delay
tank of the department has a limited capacity hence linked to the restriction of
patients’ admissions. Thus, an alternative technique using graphene oxide (GO) and
coconut shell activated carbon (CSAC) was proposed for isolating the 131I clinical
wastewater from the delay tank. The synthesized GO and CSAC were mixed with
radioactive clinical wastewater with varying concentrations and filtered using
membrane filter paper to collect the sediment. The decay rate of 5 mg/mL for both
carbon-based materials was significantly higher than the concentrations 1, 2, 3, and 4
mg/mL, which indicates active interaction has occurred. The synthesized carbonbased
materials, along with the sediments, were analyzed in several characterization
studies; via Field Emission Scanning Electron Microscopy (FESEM), GO and CSAC
were found appeared wrinkled-like tissue and had micropores on the surface,
respectively; X-ray Diffraction (XRD) of GO, GO:131I, CSAC and CSAC:131I
obtained 2-theta () peak values of 11.8, 31.7, 24.68 and 28.28 respectively that are collateral with previous studies. The d-spacing (Å) and the crystallinity index (%)
of each material were also obtained; X-ray Photoelectron Spectroscopy (XPS) was
used for the composition study of the samples, which shows binding energy of
283.95, 284.27, 285.29 and 287.10 eV on C1s spectra that indicate the existence of
C-C, C=C, C-O, C=O bonds respectively. The UV-Vis Spectrophotometry was used
to analyze the sorption capability of GO, GO:131I, CSAC, and CSAC:131I; showing
results of a 230, 210, 205, and 223 respectively, dominated by -* transition of
aromatic C-C. Based on the results and underlining the unique features of both
carbon-based materials, it is proven that these two materials can be used as an
alternative method for the isolation of Iodine131 clinical wastewater from delay tanks.