Concentrating Radiocesium with Selective Sorbents

The dynamic characteristics of ¹³⁷Cs sorption with the sorbent based on NaX zeolite and copper(II) and antimony(V) ferrocyanides were studied. At a rate of filtration of active solution (2 ×10⁵ Bq l^{- 1 137}Cs) of 50-200 column volumes per hour, the degree of sorption (S) was 95.0-99.8%. The optimum filtration rate of the solution containing radioactive cesium was determined to be 75 column volumes per hour. Up to 6000 column volumes with the specific activity of 6.2 Bq l^{- 1} with respect to ¹³⁷Cs was passed. In this case, the sorption was 96.0-98.0%. At the optimum filtration rate, the initial activity of the solution does not affect the point of ¹³⁷Cs localization in the column volume. An increase in the filtration rate to 200 column volumes per hour results in smearing of the sorption front, with a decrease in the ratios of the sorbent activities at the top and bottom parts of the column from 15.4 to 3.9.     

Sorbents based on modified polysiloxanes

Organic-inorganic hybrid sorbents based on a polysiloxane modified with amino and thiourea groups have been synthesized for the first time by a sol-gel process. The structure of the sorbents has been determined by X-ray photoelectron spectroscopy and IR spectroscopy. Their thermal stability has been assessed and the mechanism of their degradation has been elucidated. The structural and adsorption parameters of the sorbents have been evaluated. The results demonstrate that the introduction of amino groups into the structure of the polysiloxane yields an effective sorbent for Pb(II) extraction and enables Cu(II) and Zn(II) separation from Co(II) and Ni(II). The thiourea-modified polysiloxane selectively sorbs Bi(III) (0.1–2 M HCl), Pt(IV) (pH 2), and Pb(II) (pH > 3). Divalent Co, Ni, Cu, and Zn can be sorbed from alkaline solutions.     

Crystalline Host Phases for Actinides,Obtained by Self-Propagating High-Temperature Synthesis

Host matrices for actinides prepared by self-propagating high-temperature synthesis are studied. The matrices consist of a pyrochlore or fluorite phase and metallic molybdenum. The factor determining the structural type of the crystal lattice of the target phase is the ionic radius ratio. When the difference in the ionic radii is insignificant, as in the case of Y^{3 +} (r 0.102 nm) and Zr^{4 +} (r 0.084 nm), the oxide Zr_{1 - x}Y_xO_{2 - 0 . 5 x} with a fluorite structure is formed, in which the cations occupy the eight-coordinate sites. This structure permits incorporation of heavy lanthanides and tetravalent actinides: U^{4 +} (r 0.10 nm), Np^{4 +} (r 0.098 nm), and Pu^{4 +} (r 0.096 nm). When the difference in the ionic radii is more considerable, as in the case of Y^{3 +} and Ti^{4 +} (r 0.061 nm), a pyrochlore-related structure is realized. In this case the cations occupy different (eight- or six-coordinate) sites. The pyrochlore structure is preserved if the radii of ions occupying different structural sites change in parallel. This structure is typical of zirconates of trivalent actinides and light REEs. The decision on the major host phase for actinides is determined by the waste composition. At low content of light REEs and americium an oxide with a fluorite-related structure shows promise. At high content of these elements, zirconates and titanates with the pyrochlore structure are more stable.     

Coolers Based on Solid Sorbents

A cooler based on solid sorbents, in which an activated carbon fiber (pure) and an activated carbon fiber impregnated with CaCl₂ are used, has been designed. Results of an experimental investigation of the time dependence of the change in the heat flux are presented.     

Chelating scintillation fibers for measurements of 137Cs

Solid scintillating fibers, coated with a dual-mechanism bifunctional polymer shown to bind Cs(I) in alkaline solutions, were developed for measurement of 137Cs. The effect of the epoxy-polymer coating thickness on attenuation of the signal from 137Cs was evaluated. After optimal coating conditions were determined, both scintillation fiber and resin functions were retained, producing stable field-ready fibers. Temporal studies were performed to examine the kinetics of 137Cs uptake into the resin. Calibration curves of the fiber response were generated by beta-emission from solutions of 137Cs dissolved in 1 M sodium hydroxide. The plots exhibited a linear response over a range of 4-3200 nCi/mL (3.4 x 10(-10)-2.7 x 10(-7) M 137Cs), with a limit of detection of 3.65 nCi/mL (approximately 42 parts per trillion 137Cs). The distribution coefficient of Cs was determined to be 490 +/- 50 mL/g from these measurements. Selectivity studies of the resin were performed in the presence of 100 fold excess of Sr(II), Al(III), and nonradioactive Cs(I). Linear calibration plots were obtained in the presence of these potential interferences, but at a reduced sensitivity. The fibers were also used to evaluate the 137Cs content of a mock tank waste sample to show the potential of the fibers in complicated matrixes.     

Compounds of Xenon in the Chemistry of Actinides

Radiochemistry - Published evidence on the reactions of XeF2, Na4XeO6, and XeO3 with ions of uranium, neptunium, plutonium, and americium in aqueous acid, carbonate, and alkaline solutions is...     

Emanation-Thermal Analysis of Fibrous Basalt Sorbents

Structural changes in basalt sorbents in the course of thermal treatment were studied by complex emanation-thermal analysis. Sorbent was prepared by two-stage treatment of staple basalt fibers with hydrochloric acid. The sorption isotherms of liquid nitrogen vapor on these new sorbents were obtained, the open surface areas were determined, and the porosity and pore size distribution of leached fibers were evaluated. The data of thermostimulated gas liberation method showed that water sorbed on porous basalt fibers occurs in two energy-different states: the main fraction of water is desorbed at 90-110°C, and the remainder, at 300-320°C. The sorbent is completely regenerated on heating to 550°C. Degradation of the fiber pore structure begins at 700°C, and fiber sintering, at temperatures greater than 1150°C. A mathematical model of emanation of the porous systems in the sintering mode was proposed, and the activation energies of emanation of the initial and porous fibers were calculated. It was found that leaching, along with formation and development of the mesopore system, generates numerous point defects. Due to significant sorption activity and high thermal stability, fibrous basalt sorbents can be recommended to prepare sorption filters for treatment of radiochemical production wastes.     

Magnetic Sorbents for Removing U(VI) from Aqueous Media

Sorption of U(VI) onto magnetic sorbents from aqueous media was studied. The limiting value of the U(VI) adsorption onto magnetite and magnetic potassium zinc hexacyanoferrate(II) at pH 5.0, calculated from the Langmuir equation, is 125 and 102 μmol g^–1, respectively. Natural components of waters, namely, Na⁺ and Ca²⁺ ions and fulvic acids at concentrations of up to 200 mg dm^–3, do not noticeably influence the U(VI) sorption onto magnetic sorbents. Owing to high selectivity (degree of recovery 87–91%) and possibility of separating the solid phase by magnetic separation, these sorbents show promise for removing U(VI) from mineralized mine water.     

Structure and Properties of Carbon Fiber Sorbents

The surface properties of carbon fiber adsorbents prepared from different starting materials and by different procedures were investigated with the aim of optimizing their pore structure. The best results were obtained with carbonized fibers: at 900°C in flowing CO₂, their specific surface was increased from 0.5 to 2000 m²/g.     

储热型吸附式空气取水器吸附剂与储热材料的选择

本文针对太阳能储热型吸附式空气取水器吸附剂和储热材料的选择,分别研究了以膨胀硫化石墨(ENG-TSA)和以活性炭纤维(ACF)毡为基质的复合吸附剂的导热系数和吸附性能,硬脂酸/膨胀硫化石墨(ENG-TSA-SA)复合相变储热材料的导热系数与DSC测试。结果表明:ENG-TSA-LiCl复合吸附剂的导热系数最大可达5.67 W/(m·K),吸水量最大可达1.54 g/g。真空浸渍法获得的ACF-LiCl复合吸附剂的吸水量比大气浸渍法高。ASLi40固化吸附剂的吸水量为1.59 g/g,适用于大批量生产。ENG-TSA-SA的径向导热系数为22.2 W/(m·K),相变温度区间为65.9~77.1℃,适用于太阳能等低品位热能。储热器的添加明显延缓了解吸温度降低的趋势。     

偕胺肟基螯合树脂的研究进展

偕胺肟螯合树脂对重金属离子有高的选择性和较大的吸附量,可用于污水处理和回收利用废矿、废液中的重金属离子。本文介绍了偕胺肟螯合树脂的合成方法,阐述了偕胺肟基螯合树脂的物理化学性质及其表征手段,对偕胺肟螯合树脂作为吸附分离材料的研究现状进行了评述,展望了偕胺肟螯合树脂的应用前景。     

吹响“结集号” 迎接新曙光——2010年上海包装新思路

2010年经济虽有回暖,但金融危机的阴霾尚未完全退去。去年底召开的上海经济工作会议,明确提出上海要在率先转变经济方式上取得实质性的新突破、新发展,特别强调要大力发展服务经济,要在继续扩大开放中推动经济转型,在改革创新中实现转变,走出具有上海自身优势和特色的发展道路。上海包装行业在为经济建设配套服务中,必须洞察市场、转变观念、扎     

“老字号”吹响了集结号

"老字号"是近年来经常出现在报端的名字,"老字号"的企业和产品也是上了年纪的人群难以忘怀的记忆。随着市场经济的繁荣,商业竞争的加剧,许多"老字号"品牌逐渐淡出了人们的视线,有的销声匿迹,有的步履艰难。面对这严峻的现实,上海九百集团充分发挥品牌地域的优势,重兵出击,强强联手,先后选址华山路和西康路二     

蛋白质溶液浓缩分离用高分子水凝胶研究进展

蛋白质溶液的浓缩过程是蛋白质应用研究的关键步骤,智能水凝胶浓缩分离蛋白质具有工艺简单、耗能少、产品活性高等优点,近年得到了广泛重视。综述了传统高吸水凝胶、交联葡聚糖凝胶、温敏型水凝胶、pH敏感型水凝胶等用于蛋白质溶液浓缩的研究进展,并提出蛋白质溶液浓缩用智能水凝胶的研究新思路。     

Modified Cu+-Containing Zeolites as Sorbents for Localization of Radioiodine and Radiocesium Aerosols

New sorbents for efficient sorption of radioiodine and radiocesium from aqueous solutions and vapor-gas phase were prepared by treatment of Cu⁺-containing NaX and NaA zeolites with acetylene in aqueous solution. The modified zeolites sorb radioiodine and radiocesium from aqueous solution with the distribution coefficient more than 10⁴ and from a vapor-gas flow with the decontamination factor higher than 10² and 10³, respectively.     

Nanostructured Magnetic Sorbents for Selective Recovery of Uranium(VI) from Aqueous Solutions

Direct sol-gel, novel template, and additional high-temperature reduction procedures for preparing iron oxides and their composites, showing promise for selective sorption of dissolved U(VI) from aqueous media of various acidities, are described. The sorption activity of the materials was studied, the kinetic curves of the sorption were obtained, and the efficiency of the selective recovery of U(VI) from aqueous solutions with different pH values using the new sorbents was compared. The probable mechanism of the U(VI) sorption onto the sorbents studied was suggested on the basis of SEM, XPS, emf, and BET data. The quantitative sorption of U(VI) is determined to a greater extent by the composition of the sorbent solid phase, rather then by the specific surface area of the sorbents, which ranges from 0.1 to 47.3 m² g^?1 depending on the synthesis procedure. The crystalline Fe⁰ phase in the sorbents prepared using additional high-temperature reduction plays the key role in the U(VI) sorption by the reducing deposition mechanism. The saturation magnetization for this type of sorbents can reach 133–140 emu g^?1, which is an additional advantage allowing magnetic separation of the spent sorbents from the treated solutions.