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41.
The hollandite Ba1Cs0.28Fe0.82Al1.46Ti5.72O16, which has been proposed for the cesium-specific conditioning, can be synthesized either by an alcoxyde or a dry route. In both cases, a two-step protocol is applied, i.e., a calcination at 1000 °C followed by a sintering at 1200 °C. After sintering, both synthetic processes lead to a tetragonal form. According to the X-ray diffraction (XRD) patterns collected at the barium and the cesium K absorption edges, the different positions of these two elements have been evidenced with a more centered position in the oxygen cubic site of the tunnel for Ba than for Cs. On the contrary, after calcination, the two synthetic routes yield different products. The alcoxyde route gives rise to a mixture of the aforementioned Cs- and Ba-containing tetragonal I4/m hollandite, a Cs-only-containing monoclinic I2/m hollandite and an unidentified phase with a weak coherence length containing only Ba. The dry route yields a single tetragonal hollandite material containing Ba and Cs slightly different in composition from the targeted compound. 相似文献
42.
The heat capacities of potassium, rubidium, cesium, and thallium azides were determined from 5 to 350 K by adiabatic calorimetry. Although the alkali-metal azides studied in this work exhibited no thermal anomalies over the temperature range studied, thallium azide has a bifurcated anomaly with two maxima at (233.0±0.1) K and (242.04±0.02) K. The associated excess entropy was 0.90 calth K?1 mol?1. The thermal properties of the azides and the corresponding structurally similar hydrogen difluorides are nearly identical. Both have linear symmetrical anions. However, thallium azide shows a solid-solid phase transition not exhibited by thallium hydrogen difluoride. At 298.15 K the values of Cpo, So, and , respectively, are 18.38, 24.86, and 12.676 calth K?1 mol?1 for potassium azide; 19.09, 28.78, and 15.58 calth K?1 mol?1 for rubidium azide; 19.89, 32.11, and 18.17 calth K?1 mol?1 for cesium azide; and 19.26, 32.09, and 18.69 calth K?1 mol?1 for thallium azide. Heat capacities at constant volume for KN3 were deduced from infrared and Raman data. 相似文献
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固体基质室温燐光法(SS-RTP)的检出限依赖于固体基质的RTP背景的高低。本文考察了七种国产滤纸在重原子存在时和不存在时的RTP背景。研究了各种降低滤纸背景的处理方法。研究结果表明,采用NaOH、β-环糊精、EDTA、乙醇和丙酮浸泡或煮沸滤纸,都能不同程度的降低滤纸背景,最大降低率为88%。KI、NaAc、Pb(Ac)_2、TlNO_3和Cscl等重原子可使滤纸背景有较大幅度的增强,而经处理的滤纸,RTP背景较未处理滤纸背景降低一倍以上,最大可降低94.5%。用NaOH溶液处理滤纸,不仅能有效地降低背景,而且能提高分析物的RTP信号。研究表明纤维素伴生物质——木素,可能是产生燐光背景的杂质之一。 相似文献
45.
1 INTRODUCTION The reactivity of activated alumina adsorbent is closely related to its specific surface area: the larger the specific surface area, the better its activity and adsorbent capability are. However, in reality, the prac- tically available specific surface area or effective spe- cific area has relationship with its pore structure[1]. Since many reactant molecules are difficult to enter the pores to react with whose radius is shorter than certain critical value, the increase of p… 相似文献
46.
垃圾在流化床中焚烧NO排放特性研究 总被引:2,自引:3,他引:2
在Ф150 mm流化床上,研究了六类典型组分垃圾NO转化率与床温和过量空气系数(excess air简称EA)的关系。研究发现,纸渣与木块NO转化率最高,橡胶与塑料最低;织物、纸张、厨余、木块、塑料NO均具有中温生成特性,一般在800 ℃~850 ℃时即接近最大值,之后温度升高对NO的生成影响不大;橡胶与无烟煤由于含N化合物结构稳定,其NO转化率随床温升高而增大;由于挥发分析出的相互影响,较低的火焰温度,混合垃圾NO转化率一般低于单组分垃圾的线性叠加;少量水分不会对垃圾NO转化率造成很大影响,相反还会促进NO的转化,但过量水分会抑制NO的生成。 相似文献
47.
A.?H.?Naik N.?V.?Thakkar S.?R.?DharwadkarEmail author K.?D.?Singh Mudher V.?Venugopal 《Journal of Thermal Analysis and Calorimetry》2004,78(3):707-713
Sodium zirconium phosphate [NaZr2P3O12], a potential ceramic matrix for fixation of high level nuclear waste, was synthesized by heating the mixture of sodium carbonate [Na2CO3], zirconyl nitrate hydrate [ZrO(NO3)2·5H2O] and ammonium dihydrogen phosphate [NH4H2PO4] in air, in a resistance heated furnace and a microwave heating system respectively in the temperature range 450 to 650°C. The mixture heated for 1 h in a resistance furnace at 450°C yielded a poorly crystalline NaZr2P3O12 [NZP]. Increasing the temperature to 650°C produced a highly crystalline product. The same mixture heated in a microwave oven at 450°C for 1 h however, yielded the most crystalline NZP.In an alternate method, the mixture of sodium dihydrogen phosphate (NaH2PO4), zirconium dioxide (ZrO2) and diammonium hydrogen phosphate [(NH4)2HPO4] heated in resistance furnace at 650°C for the same period did not react in air. It also did not yield the pure product at 450°C when heated in microwave assembly for 1 h.The authors thank the Board of Research in Nuclear Sciences (BRNS) of the Department of Atomic Energy (DAE) for the financial support for this work under the project No. 2000/37/19/BRNS/1959 dtd09-02-02. 相似文献
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V. Bruder-Hubscher F. LagardeM.J.F. Leroy C. CoughanowrF. Enguehard 《Analytica chimica acta》2002,451(2):285-295
The release of five elements (Cr, Cu, Mn, Pb and Zn) from a municipal solid waste incineration bottom ash (BA) under different extraction conditions has been investigated by performing the three-step sequential extraction procedure proposed by the Standards, Measurements and Testing Program of the European Union. A fourth step (strong acid attack) has been added in order to calculate the mass balance. The results of this study provide information on the potential mobility of the studied elements. Almost all of the Cr and part of the Mn are extracted with strong acid which indicates low potential mobility in the environment. Most of the Cu is extracted under oxidizing conditions. Pb and Zn are released under acidic condition, indicating the possibility of their mobilization by changes in pH. The reproducibility of the sequential extraction procedure is also discussed. 相似文献
50.