Sorption Profile of Low Specific Activity 99Mo on Nanoceria-Based Sorbents for the Development of 99mTc Generators: Kinetics, Equilibrium, and Thermodynamic Studies.

99Mo/99mTc generators play a significant role in supplying 99mTc for diagnostic interventions in nuclear medicine. However, the applicability of using low specific activity (LSA) 99Mo asks for sorbents with high sorption capacity. Herein, this study aims to evaluate the sorption behavior of LSA 99Mo towards several CeO2 nano-sorbents developed in our laboratory. These nanomaterials were prepared by wet chemical precipitation (CP) and hydrothermal (HT) approaches. Then, they were characterized using XRD, BET, FE-SEM, and zeta potential measurements. Additionally, we evaluated the sorption profile of carrier-added (CA) 99Mo onto each material under different experimental parameters. These parameters include pH, initial concentration of molybdate solution, contact time, and temperature. Furthermore, the maximum sorption capacities were evaluated. The results reveal that out of the synthesized CeO2 nanoparticles (NPs) materials, the sorption capacity of HT-1 and CP-2 reach 192 ± 10 and 184 ± 12 mg Mo·g-1, respectively. For both materials, the sorption kinetics and isotherm data agree with the Elovich and Freundlich models, respectively. Moreover, the diffusion study demonstrates that the sorption processes can be described by pore diffusion (for HT-synthesis route 1) and film diffusion (for CP-synthesis route 2). Furthermore, the thermodynamic parameters indicate that the Mo sorption onto both materials is a spontaneous and endothermic process. Consequently, it appears that HT-1 and CP-2 have favorable sorption profiles and high sorption capacities for CA-99Mo. Therefore, they are potential candidates for producing a 99Mo/99mTc radionuclide generator by using LSA 99Mo

Developing a Chromatographic 99mTc Generator Based on Mesoporous Alumina for Industrial Radiotracer Applications: A Potential New Generation Sorbent for Using Low-Specific-Activity 99Mo.

The commercial low-pressure column chromatographic 99Mo/99mTc generator represents a reliable source of onsite, ready-to-use 99mTc for industrial applications. These generators use fission-produced 99Mo of high specific activity, posing serious production challenges and raising proliferation concerns. Therefore, many concepts are aimed at using low-specific-activity (LSA) 99Mo. Nonetheless, the main roadblock is the low sorption capacity of the used alumina (Al2O3). This study investigates the feasibility of using commercial alumina incorporated with LSA 99Mo to develop a useful 99Mo/99mTc generator for industrial radiotracer applications. First, the adsorption profiles of some commercial alumina sorbents for LSA 99Mo were tested under different experimental conditions. Then, the potential materials to develop a 99Mo/99mTc generator were selected and evaluated regarding elution yield of 99mTc and purity. Among the sorbents investigated in this study, mesoporous alumina (SA-517747) presented a unique sorption-elution profile. It demonstrated a high equilibrium and dynamic sorption capacity of 148 ± 8 and 108 ± 6 mg Mo/g. Furthermore, 99mTc was eluted with high yield and adequate chemical, radiochemical, and radionuclidic purity. Therefore, this approach provides an efficient and cost-effective way to supply onsite 99mTc for radiotracer applications independent of fission-produced 99Mo technology

Speciation Gamma-Spectrometry: the Fate of Environmental Radio-Nuclides in Hard-Water Lakes

Abstract A sequential fractionation method for simultaneous and absolute measurement of environmental radio-nuclides, 241 Am, 210 Pb, 226 Ra, 137 Cs, 40 K and 234 Th/ 238 U, by gamma-spectrometry was tested and applied to hard-water lake-sediments. The carbonate, fulvic, humic and mineral insoluble fractions were extracted from the sediments. Correction of self-absorption and geometrical effects, arising from the conditioning of bulk and fractionated sediments, were done using Monte Carlo simulations. This "non-destructive" fractionation procedure allows further analysis of other chemical species in the same fractions thus creating possibilities to study the dynamics of self-cleaning mechanism in lakes. The results demonstrate that the procedure is quantitative and suitable for the determination of environmental key radio-tracers in different fractions. Unlike other fresh-water sediments the major part of the environmental radio-nuclides is associated with "mineral" fractions. This speciation gamma-spectrometry procedure was supplemented by isotope-dilution alpha-spectrometry 210 Po ( 210 Pb), for determining the acid-soluble organic fractions in fresh-water lakes. The overall speciation procedure demonstrated that carbonate fractions, extracted from hard-water lake sediments, could be separated either free from, or associated with, fulvic-compounds. This speciation procedure can be applied to other aquatic deposits, however supplementary steps can be added if other data are required

Uppsala Natural Radiocarbon Measurements XII

This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Evaluating the Sorption Affinity of Low Specific Activity 99Mo on Different Metal Oxide Nanoparticles

99Mo/99mTc generators are mainly produced from 99Mo of high specific activity generated from the fission of 235U. Such a method raises proliferation concerns. Alternative methods suggested the use of low specific activity (LSA) 99Mo to produce 99mTc generators. However, its applicability is limited due to the low adsorptive capacity of conventional adsorbent materials. This study attempts to investigate the effectiveness of some commercial metal oxides nanoparticles as adsorbents for LSA 99Mo. In a batch equilibration system, we studied the influence of solution pH (from 1–8), contact time, initial Mo concentration (from 50–500 mg∙L−1), and temperature (from 298–333 K). Moreover, equilibrium isotherms and thermodynamic parameters (changes in free energy ΔG0, enthalpy change ΔH0, and entropy ΔS0) were evaluated. The results showed that the optimum pH of adsorption ranges between 2 and 4, and that the equilibrium was attained within the first two minutes. In addition, the adsorption data fit well with the Freundlich isotherm model. The thermodynamic parameters prove that the adsorption of molybdate ions is spontaneous. Furthermore, some investigated adsorbents showed maximum adsorption capacity ranging from 40 ± 2 to 73 ± 1 mg Mo∙g−1. Therefore, this work demonstrates that the materials used exhibit rapid adsorption reactions with LSA 99Mo and higher capacity than conventional alumina (2–20 mg Mo∙g−1)

Evaluating the Sorption Affinity of Low Specific Activity ⁹⁹Mo on Different Metal Oxide Nanoparticles

99Mo/99mTc generators are mainly produced from 99Mo of high specific activity generated from the fission of 235U. Such a method raises proliferation concerns. Alternative methods suggested the use of low specific activity (LSA) 99Mo to produce 99mTc generators. However, its applicability is limited due to the low adsorptive capacity of conventional adsorbent materials. This study attempts to investigate the effectiveness of some commercial metal oxides nanoparticles as adsorbents for LSA 99Mo. In a batch equilibration system, we studied the influence of solution pH (from 1–8), contact time, initial Mo concentration (from 50–500 mg∙L−1), and temperature (from 298–333 K). Moreover, equilibrium isotherms and thermodynamic parameters (changes in free energy ΔG0, enthalpy change ΔH0, and entropy ΔS0) were evaluated. The results showed that the optimum pH of adsorption ranges between 2 and 4, and that the equilibrium was attained within the first two minutes. In addition, the adsorption data fit well with the Freundlich isotherm model. The thermodynamic parameters prove that the adsorption of molybdate ions is spontaneous. Furthermore, some investigated adsorbents showed maximum adsorption capacity ranging from 40 ± 2 to 73 ± 1 mg Mo∙g−1. Therefore, this work demonstrates that the materials used exhibit rapid adsorption reactions with LSA 99Mo and higher capacity than conventional alumina (2–20 mg Mo∙g−1)

The use of 137-cs in marine and lacustrine sediment dating

En este trabajo, la técnica de datación 137 Cs con precisión mejorada se muestra como una herramienta poderosa para establecer cronologías en diferentes depósitos acuáticos jóvenes (lacustres, marinos). El método tiene especial importancia cuando el método de 210 Pb da resultados parciales o poco claro