Methyl ethyl ketone extraction of technetium species from aqueous solutions of neutron irradiated ammonium molybdate crystals was studied; the two species extracted were separated by high voltage paper electrophoresis. The one was the99mTcO
ion and the other, a99mTc non-charged immobile species, probably TcO2.aq, which concentrated at the point of application on the electrophoresis paper strip.
The sorption behavior of 235U fission fission products 99Mo and 132Te was studied through batch and dynamic experiments when they were dissolved in 1 to 7M HNO3 solutions. It was found that 99Mo is always totally adsorbed on hydrated SnO2, while 132Te is rather weakly adsorbed, therefore they can be separated from each other although 132Te in the solution still remains contaminated with other radionuclides as well as 99Mo does in the solid.
Electrophoresis followed by neutron activation analysis was utilized to determine chromium(III) and (VI) in mixed solutions.
These solutions proceeded from Cr(VI) adsorbed hydrotalcites heated at 800 °C to partially immobilize Cr in the Mg-Al oxide
solid solution. Immobilization was studied by Cr lixiviation with NaCl solutions through the heated hydrotalcites. The results
have shown that Cr lixiviated was in the form of CrO42- ions, mainly because some Cr(VI) was not completely reduced to Cr(III) during heating. Chromium lixiviated from HT-Cr sample,
heated at 800 °C and γ-irradiated at 1000 kGys, was found, as well, in the form of CrO42- ions. Although γ-irradiation increases Cr immobilization in the solid, it does not reduce completely all CrO42- ions present in the solid and, therefore, some Cr is lixiviated through the solid in the form of CrO42- ion.
Natural bentonite clay was treated in order to remove impurities to increase the cation exchange capacity of the montmorillonite
and to obtain a more effective radioactive cesium sorption. It was found that the treatment of the clay determines the amount
of sorbed cesium. On the other hand it was shown that montmorillonites may retain cesium through several mechanisms which
provide strongly retained cations occupying cationic sites into the clay structure or sorbed cesium which may be lost by purification
Authors:F. Ramírez, M. Jiménez-Reyes, and S. Bulbulian
The35S products formed in irradiated CCl4, CHCl3 and C2HCl3 were analysed. In CCl4 no trace of C35SCl2 was found whereas35SO2 was identified. In CHCl3, CCl335SCl was an important product and after saturation with oxygen CCl335SO2Cl became a major product. In C2HCl3,35S product appeared as compound of low volatility.
Authors:C. Beltrán, S. Bulbulian, and C. Archundia
The products formed during thermal neutron irradiation of diphenyl selenium have been analyzed by gas chromatography. Possible reaction mechanisms are discussed to explain the principal reaction product observed. The organic yields of75Se,83Se and81mSe formed have been determined. The retention values obtained were 9.7±2.0, 8.3±1.1 and 10.4±2.1, respectively. These low values indicate that in all three cases most of the molecules are broken after the /n, / process. No isotope effect was observed.
Authors:J. Jiménez-Becerril, D. Estévez, and S. Bulbulian
Fluorine-18 has been determined in neutron irradiated lithium aluminosilicate. This compound was obtained by a high temperature thermal transformation of Li-exchanged Y zeolite. Fluorine-18 formed in neutron irradiated lithium aluminosilicates was swept with a gas mixture of Ar with 0.1% hydrogen.
The potential uses of hydrous oxides in the treatment of radioactive wastes may be affected by the physical-chemical properties
of these materials. The sorption behavior of trace level (less than 10-14 g/ml) 235U fission products in aqueous solutions was studied under static conditions on TiO2, MnO2 and SnO sorbents. A variety of anions, cations and neutral species of 132Te,95Zr, 99Mo and 103Ru in aqueous solutions at 1, 3, 5, 7 and 10 pH values were identified and their retention values were calculated. High voltage
electrophoresis was used to establish the chemical species of these radioisotopes formed in the solution.
Calcined hydrotalcite packed columns were utilized to sorb 235U fission products and their decay products. The elution behavior of some radionuclides was studied after washing the columns, either with distilled water or 0.5% NaCl solution. Afterwards, fission products and their decay products were eluted using 0.5% NaCl solution. It was found that no matter the washing process, 99mTc, the b--decay product of 99Mo, was easily separated from 99Mo which was strongly retained on the hydrotalcite. 132I, the b--decay product of 132Te, was eluted slowly and was separated from 132Te which was retained on the column. 131I and 140Ba were eluted together with 99mTc and 132I, although in smaller proportions.
Authors:V. Martínez-Miranda, S. Martínez-Gallegos, M. Esteller, and S. Bulbulian
A method based on neutron activation analysis was developed for the determination of fractions of milligrams of 2,4-D (2,4-dichlorophenoxy
acetic acid) in aqueous solution in laboratory tests. The indirect determination of 2,4-D was based on the quantification
of chlorine,38Cl, produced by neutron activation. The range of application was 0.01–100 mg l−1. No loss of38Cl by chemical effects of the nuclear reaction was found. The advantages of the proposed method include high precision and
sensitivity of determination. Results were compared with those obtained by UV-Vis spectrophotometry, where concentrations
less than 1 mg·l−1 were not detected.