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排序方式: 共有87条查询结果,搜索用时 15 毫秒
1.
为了明确微波对制备高岭石插层的作用,采用乙酰胺对高岭石的微波熔融插层和油浴熔融插层进行了对比实验.借助于XRD、FTIR等分析测试手段,通过对比不同时间段2种插层环境下的插层率,分析了微波对插层反应的影响,进而探讨了微波对插层反应的作用机理.研究发现在反应初期微波对插层反应起促进作用,但随着时间的延长这种促进作用减弱,并呈现出一定的阻碍作用,认为是微波对乙酰胺的热作用和极化作用综合作用的结果. 相似文献
2.
Ananta Kumar MishraSaswata Bose Tapas KuilaNam Hoon Kim Joong Hee Lee 《Progress in Polymer Science》2012,37(6):842-869
Proton-exchange membrane fuel cells have emerged as a promising emission free technology to fulfill the existing power requirements of the 21st century. Nafion® is the most widely accepted and commercialized membrane to date and possesses excellent electrochemical properties below 80 °C, under highly humidified conditions. However, a decrease in the proton conductivity of Nafion® above 80 °C and lower humidity along with high membrane cost has prompted the development of new membranes and techniques. Addition of inorganic fillers, especially silicate-based nanomaterials, to the polymer membrane was utilized to partially overcome the aforementioned limitations. This is because of the lower cost, easy availability, high hydrophilicity and higher thermal stability of the inorganic silicates. Addition of silicates to the polymer membrane has also improved the mechanical, thermal and barrier properties, along with water uptake of the composite membranes, resulting in superior performance at higher temperature compared to that of the virgin membrane. However, the degrees of dispersion and interaction between the organic polymer and inorganic silicates play vital roles in improving the key properties of the membranes. Hence, different techniques and solvent media were used to improve the degrees of nanofiller dispersion and the physico-chemical properties of the membranes. This review focuses mainly on the techniques of silicate-based nanocomposite fabrication and the resulting impact on the membrane properties. 相似文献
3.
在2-硝基-4-乙酰胺基苯甲醚(NMA)催化加氢合成2-氨基-4-乙酰胺基苯甲醚(AMA)反应中,规整纳米Pd/C催化剂表现出很好的催化活性和选择性。但Pd/C催化剂在反应的套用过程中表现出反应活性逐渐降低。通过XRD、BET、EDS、XPS等物性表征以及Na2S滴定法和原子吸收法测定Pd含量的研究表明,钯微晶的长大、钯流失、催化剂中毒等不是引起Pd/C催化剂失活的主要原因,而Pd/C催化剂表面金属钯活性位在反应后被2-氨基-4-乙酰胺基苯甲醚产物等有机物覆盖可能是导致其性能逐渐降低的关键。使用酸洗法可以去除反应后Pd/C催化剂表面覆盖的2-氨基-4-乙酰胺基苯甲醚等有机物,释放金属钯活性位,实现Pd/C催化剂的性能有较大程度的恢复;而其他方法对Pd/C催化剂活性恢复的效果不明显。 相似文献
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M. R. Ganjali P. Norouzi F. Faridbod S. Riahi M. R. Yaftian A. Zamani D. Matt 《Journal of Applied Electrochemistry》2007,37(7):827-833
A Th4+ ion-selective membrane sensor was fabricated from poly (vinyl chloride) (PVC) matrix membrane containing 2-(diphenylphosphorothioyl)-N′,N′-diphenyl acetamide (DPTD) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of the membrane composition, pH and additive
anionic influence on the response properties were investigated. The sensor, comprising 30% PVC, 63% solvent mediator, 4% ionophore
and 3% anionic additive demonstrates the best potentiometric response characteristics. It displays Nernstian behavior (15.2 ± 0.5 mV
per decade) over the concentration range 1.0 × 10−2–1.0 × 10−6 M. The detection limit of the electrode is 6.3 × 10−7 M (∼140 ng/ml). The response time of the electrode is 30 s .The sensor can be used in the pH range 3.0–9.0 for about 6 weeks.
The membrane sensor was used as an indicator electrode in the potentiometric titration of Th4+ ions with EDTA. It was successfully applied to the determination of thorium ions in binary mixture. 相似文献
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A simple and fast method for the TMS derivatization of phenolic acids in a closed vial using microwave irradiation followed by GC/MS analysis is proposed. A full factorial design was used to investigate the effects of two independent variables, namely, time and power of microwave irradiation, on the yield of silylation reaction. The optimal conditions were tested against the classical heating derivatization procedure. No significant differences were found between the classical heating and microwave-assisted derivatization. Chromatographic separation of the nine phenolic acids examined was achieved in 16 min. The mass spectral fragmentation patterns of the derivatives obtained by the proposed method were identical to those from the classical heating. Four different batches of brewer’s spent grain were extracted and analyzed for the total phenolic acid content. Significant differences between the batches of spent grains were found for all analytes. The total phenolic acid content varied between 2688 and 4884 μg/g. 相似文献
10.
研究了流加操作与稀释添加耦合辅助高浓度变性还原溶菌酶的复性,建立了相关的过程动力学模型.利用三态复性的过程模型对实验数据进行了拟合,获得了较好的拟合效果.利用模型分析了复性过程的动力学特性,结果表明,两者耦合可在较低的盐酸胍浓度(1 mol8226;L-1)存在下使较高浓度的(5 mg8226;ml-1)变性溶菌酶获得80%以上的复性收率;并且发现添加剂乙酰胺的辅助复性作用与盐酸胍相同,降低盐酸胍浓度,适当提高乙酰胺浓度即可使聚集体生成速率常数最小,酶的复性收率最大;但甘油与盐酸胍具有协同作用,只有在适当的盐酸胍浓度下添加甘油才可获得理想的复性效果. 相似文献