Among the crystalline matrices being developed for immobilization of 137 Cs and 90 Sr are framework aluminosilicates like feldspars and feldspathoids. A novel approach to obtain mineral-like aluminosilicate forms of 137 Cs and 90 Sr with using porous materials based on hollow aluminosilicate microspheres of coal fly ash (cenospheres) has been demonstrated. Two modifications of microspherical porous materials have been developed, (i) moulded porous matrices based on consolidated cenospheres and (ii) zeolite sorbents obtained by hydrothermal zeolitization of cenospheres. The first includes impregnation of Cs-or Sr-containing solutions into porous matrices, drying and calcining at temperatures (700-900°С) lower than the softening point of the porous matrix material, at which solid phase crystallization takes place with formation of framework aluminosilicates, such as Cs-nepheline, pollucite or Sr-anorthite. Using zeolite sorbents, immobilization of Cs + and Sr 2+ proceeds through the step of trapping ions from the solution followed by drying and thermochemical solid-phase transformation of saturated zeolites into pollucite or Sr-anorthite over the same temperature range. Cenosphere-derived porous matrices and zeolite sorbents were tested in fixation of 137 Cs using spiked simulants of actual radioactive waste. The durability of crystalline aluminosilicate 137 Cs -forms obtained was shown to satisfy Russian (GOST P 50926-96) and international standards.
Abstract-Essential oil has been isolated from the above-ground part of the lemon balm growing in the neighborhood of Krasnoyarsk by the method of exhaustive water and steam distillation. Forty seven components, each with a content of more than 0.1% of whole oil, have been identified by GC-MS. The main oil components are citronellol (36.71%) and geraniol (27.20%). The oil also contains ten components with a content of more than 1% of the sum of all oil components: benzyl alcohol (1.67%), linalool (1.75%), citronellal (1.44%), neral (3.33%), geranial (4.39%), caryophyllene (3.73%), caryophyllene oxide (1.40%), dibutyl phthalate (1.36%), butylisobutyl ester of phthalic acid (2.45%), and phytol (2.55%). The composition of lemon balm oils from different regions of the world has been compared.
This paper describes the results of a joint research program of Russian institutes at St. Petersburg, Krasnoyarsk and Zheleznogorsk and the Idaho National Engineering and Environmental Laboratory to develop a new material for stabilizing radioactive solutions and other uses, such as high-temperature catalysis. An open-cell glass crystalline porous material, Gubka, or “sponge” in Russian, having an open-cell porosity of up to 90 %, was produced from hollow glass crystalline microspheres (cenospheres) formed in fly ash from coal combustion. The cenospheres were separated into fractions based on grain size, density, magnetic properties, and whether or not they were perforated. Selected fractions were molded and agglomerated by sintering with or without a binder at high temperatures. Depending on the cenosphere fractions selected, sintering conditions and additional treatments, Gubka was formed with an open-cell porosity ranging from 40-90 %. The porous material has a bulk density of 0.3-0.6 g/cm3, and two types of porous openings: 0.1-30 micrometer flow-through pores in the cenosphere walls and 20-100 micrometer interglobular pores between the cenospheres. Examples of Gubka application described in this paper include stabilization of different surrogate radioactive waste solutions containing 0.0001 to 0.7 M nitric/hydrochloric acid and 0 to 1.2 M sodium nitrate. Waste solid loadings of 46-55 wt.% nitrate salts, or 26-37 wt.% oxides after calcination, were achieved in those tests.
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