Authors:M. Inoue, H. Kofuji, M. Yamamoto, H. Sasagawa, and K. Komura
In the usual measurements of radionuclides in the environmental samples by g-ray spectrometry, Compton scattering of 1461 keV g-rays from 40K severely interferes with the detection of artificial radionuclides in marine and agricultural products. In order to eliminate the interference of 40K, we have developed a simple and convenient water leaching treatment method applicable to seaweed (sargasso) samples. By this treatment, over 98% of the potassium in seaweed samples is removed without notable losses of artificial and/or natural radionuclides. In combination with the low-level g-ray counting in the Ogoya underground laboratory, the detection limit could be improved by ~1 order of magnitude.
Authors:T. Oi, Y. Kikawada, T. Honda, T. Ossaka, and H. Kakihana
Determination of the lanthanoids, thorium and uranium in silicate rocks has been investigated by neutron activation analysis (NAA). Seven or eight lanthanoids and thorium and uranium were determined by non-destructive instrumental NAA. The numbers of the lanthanoids determined were increased and errors on the final values were reduced by pre-irradiation treatments, which included a coprecipitation process with aluminium as collector to remove the alkali metals and halogens and a solvent extraction process to eliminate iron. The necessity of scandium removal was indicated.
Some physico-chemical properties and reactivity in their reduction with hydrogen of NiO—Y2O3 mixed oxides prepared in a dry way have been studied using isothermal thermogravimetry in the range of 320–410°C and temperature-programmed reduction. It was found that addition of small amounts of chloride and acetate anions retarded the reduction of nickel oxide and accelerated the reduction of mixed oxides. The presence of oxalate and formate ions manifests itself by a small positive effect. Introduction of platinum activator or heat treatment of the samples in various atmospheres led to a pronounced increase in the reduction rate. The efficiency of the spill-over effect increases with increasing proportion of non-reducible Y2O3. The pre-irradiation of the samples by accelerated electrons and gamma rays at a dose of 1 MGy results in a negative kinetic effect only with the samples containing an excess of nickel oxide.
The interactions between MoO3 and Sb2O3 or α-Sb2O4 taking place in the solid state in air during high-temperature as well as mechanochemical treatments have been investigated.
The high-energy ball milling of MoO3 with Sb2O3 converts α-Sb2O3 to β-Sb2O3 and leads to formation of Sb2MoO6 and Sb4Mo10O31 phases. They are the final products of thermal synthesis in an inert atmosphere but not in air. The solid solution of MoO3 in β-Sb2O4 was obtained in high-temperature reaction of MoO3 with Sb2O3 or α-Sb2O4 as well as by milling of mixture MoO3/α-Sb2O4 for 14 h. The milling resulted in higher than 3 mol% solubility of MoO3 in β-Sb2O4. The constructed phase diagram of MoO3–α-Sb2O4 system is presented.
Authors:A. S. Al-Hobaib, D. M. Al-Dhayan, K. M. Al-Sulaiman, and A. A. Al-Suhybani
Sand filters are used as a filter bed in many ground water treatment plants to remove the physical contaminants and oxidation
products. A build-up of radioactivity may take place on the granules, where iron and manganese oxides are deposited and form
thin films on the surface of sand filter. The oxides of iron and manganese play an important role in adsorbing radium from
ground water. The disposal of those granules makes a significant problem. A batch technique is used for solubilization of
radium from sand filters in the presence of some organic acids, which act as reducing agents. These acids are formic acid,
acetic acid, benzoic acid, succinic acid, oxalic acid, phthalic acid, and adipic acid. The data were obtained as a function
of acidity, temperature, contact time and liquid/solid ratio particle size and shaking speed. It was found that oxalic acid
was the best for radium removal. The effectiveness of these acids on radium removal was as follows: oxalic acid > phthalic
acid > adipic acid > succinic acid > formic acid > acetic acid. The maximum removal obtained was 69.9% at 1M oxalic acid at
8 ml/g ratio. Reaction kinetics and mechanism parameters of the dissolution process were studied and compared with other published
Radiometric X-ray fluorescence analysis was used for the determination of Mn, Fe, Cu, Zn and Pb in wastewater and sludges from three wastewater treatment plants in Bratislava (SR). Metals were determined in wastewaters after preconcentration by 8-hydroxyquinoline and in sludges by drying and pressing to pellets.238Pu and109Cd was used for excitation of fluorescence radiation.
Authors:S. Khalameida, J. Skubiszewska-Zięba, V. Zazhigalov, R. Leboda, and K. Wieczorek-Ciurowa
Mechanochemical treatment (MChT) in various media (water, air, ethanol) of the V2O5/ammonium dimolybdate composition at the ratio V:Mo = 0.7:0.3 has been carried out. Physicochemical transformations in this
system have been studied by means of X-ray powder diffraction (XRD) and thermal analysis as well as FTIR spectroscopy. Ammonium
dimolybdate undergoes hydration with formation of 4-aqueous ammonium paramolybdate during the MChT in water. Changes of phase
and chemical composition at activation are determined first of all by nature of medium in which milling was carried out. Maximal
interaction of components occurs during modification of the studied system in water.