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1.
采用电导法测定了水溶液中298.15 K时VOSO4·n H2O(s)的电导率,通过Origin数据拟合求出极限摩尔电导;采用改进的Ostwald稀释定律和改进的Davies方程求解活度系数,进而求得溶液的真实离子强度;采用Shedlovsky方法求解硫酸氧钒离子对的解离常数。经过数据处理得到了298.15 K时硫酸氧钒极限摩尔电导率Λ0为209.205 020 9S·dm2/mol,硫酸氧钒离子对的解离常数Kd为0.001 756 218,进而可以研究其他相关热力学性质。 相似文献
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多聚磷酸钠对牛背最长肌盐溶蛋白质热诱导凝胶保水性和超微结构的影响 总被引:11,自引:4,他引:11
本文以牛背最长肌为材料,采用L25(5^6)正交设计研究了焦磷酸二氢二钠、三聚磷酸钠和六偏磷酸钠对牛背最长肌盐溶蛋白质热诱导凝胶保水性和凝胶超微结构的影响。结果表明,在相同的离子条件下,添加的酸性焦磷酸钠或焦磷酸二氢二钠和三聚磷酸钠对热诱导凝胶保水性有极显著的影响(p<0.0001和p<0.0071),而六偏磷酸钠的影响则不显著(p>0.05)。值得注意的是,焦磷酸二氢二钠与六偏磷酸钠的交互作用、焦磷酸二氢二钠与三聚磷酸钠的交互作用、三聚磷酸钠与六偏磷酸钠的交互作用对热诱导凝胶保水性的影响极显著(p<0.0001),且比三聚磷酸钠的方差贡献大。Duncan多重比较显示,在盐溶蛋白质提取过程中,添加0.3%焦磷酸二氢二钠可使凝胶的保水性平均达到98.375%,比焦磷酸二氢二钠添加量为0.1%、0.15%和0.2%的凝胶保水性(分别为81.652%、84.384%和78.987%)高,差异显著(p<0.05)。扫描电镜研究结果显示,保水性不同的凝胶其超微结构表现出很大的差异。保水性为99.5%的凝胶其凝胶结构致密,均匀,网格细小,而且线条较纫,边缘平滑。而保水性为90%的凝胶则结构粗糙,表现为线条较粗,不均匀,蛋白质交联较少,网格大且不一致。线条多呈平行排列,或以聚集状态存在。 相似文献
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Engineering Morphologies of Cobalt Pyrophosphates Nanostructures toward Greatly Enhanced Electrocatalytic Performance of Oxygen Evolution Reaction
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Herein, a surfactant‐ and additive‐free strategy is developed for morphology‐controllable synthesis of cobalt pyrophosphate (CoPPi) nanostructures by tuning the concentration and ratio of the precursor solutions of Na4P2O7 and Co(CH3COO)2. A series of CoPPi nanostructures including nanowires, nanobelts, nanoleaves, and nanorhombuses are prepared and exhibit very promising electrocatalytic properties toward the oxygen evolution reaction (OER). Acting as both reactant and pseudo‐surfactant, the existence of excess Na4P2O7 is essential to synthesize CoPPi nanostructures for unique morphologies. Among all CoPPi nanostructures, the CoPPi nanowires catalyst renders the best catalytic performance for OER in alkaline media, achieving a low Tafel slope of 54.1 mV dec−1, a small overpotential of 359 mV at 10 mA cm−2, and superior stability. The electrocatalytic activities of CoPPi nanowires outperform the most reported non‐noble metal based catalysts, even better than the benchmark Ir/C (20%) catalyst. The reported synthesis of CoPPi gives guidance for morphology control of transition metal pyrophosphate based nanostructures for a high‐performance inexpensive material to replace the noble metal‐based OER catalysts. 相似文献
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本文研究了焦磷酸锰引发淀粉与丙烯腈接枝共聚及淀粉—丙烯腈接枝共聚物(SPAN)水解制备高吸水性树脂(HSPAN),研究了影响 HSPAN 吸水率和吸液率的因素,结果表明:SPAN 的接枝效率>95%,接上百分数为55~65%:HSPAN吸去离子水522ml/g、自来水302ml/g,吸合成血88ml/g、合成尿86ml/g、0.9NaCl%溶液88ml/g. 相似文献
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Mesoporous zirconium phosphate pyrophosphate of composition Zr(P2O7)0.81(O3POH)0.38 was obtained by calcination at 600°C of a mesoporous zirconium phosphite diphosphonate, Zr[(O3P-C6H4-PO3)0.54 (O3P-C6H4-PO3H2)0.13(O3PH)0.79]. The surface area of this completely inorganic material (215 m2/g) was lower than that of its inorgano-organic precursor (350 m2/g); however, both materials exhibited the same pore distribution, with an average pore diameter of 4 nm, and similar values of the mesopore volume (0.21 and 0.28 cm3/g, respectively). These results showed that the thermal treatment at 600°C leaves nearly unaltered the mesoporous structure of the precursor. 31P solid state NMR and TEM investigations were also carried out and discussed. The material obtained represents a considerable advancement in the preparation of zirconium phosphates with high surface area. Due to the good thermal stability of its surface acid groups (700–800°C), it is of interest for potential uses as an acid catalyst at high temperature. 相似文献
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TiAl samples were dipped in a low-concentrated phosphoric acid solution, air dried, then heated to 800 °C under argon gas before oxidation under reconstituted air at this temperature. At the end of the heating ramp, sample surfaces were covered by a titanium pyrophosphate (TiP2O7) layer, well adhered to the substrate. This pyrophosphate was shown to be detectable from 400 °C. Chemical reactions have been proposed for the formation of this compound. TiP2O7 coating strongly increased the oxidation resistance of TiAl at 800 °C for 100 h. After 100 h, a transition period occurred leading to the change of TiP2O7 into TiO2, which was achieved after 230 h, total mass gain always remaining below that of raw substrate. This evolution was demonstrated not resulting from a thermal decomposition of pyrophosphate compound. 相似文献
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The reoxidability of vanadyl pyrophosphate is studied by thermal analysis and by temporal analysis of product (TAP). The samples
differ by surface area, oxidation state of vanadium, crystallite size, and degree of crystallinity. The morphology ranges
from platy to prismatic and the microstructure from mosaic crystals exhibiting {100} faces to bulky crystals. The reactivity
of these samples during oxidation as well as their catalytic reactivity studied in flow reactor is accounted for by the microstructure.
The highest reoxidation capability and the best catalytic properties in oxidation of n-butane to maleic anhydride are obtained with mosaic crystals.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献