Physicochemical investigation of the decomposition products of ammonium metal carboxylates: ammonium ferric citrate hydrate

The thermal decomposition up to 400 °C of ammonium ferric citrate hydrate, of unknown structure and formula weight, was studied by thermogravimetry, differential thermal analysis, infrared (IR) spectroscopy and X-ray diffractometry. The possible identities of the formula weight and the intermediate products of calcination are discussed. The results revealed that the parent material is amorphous and contains two moles of water and two moles of ammonia. Decomposition takes place via six weight-loss processes, three endothermic (90–230 °C) and three exothermic (240–298 °C), leading eventually to the formation of Fe₂O₃. The intermediate solid products are mainly unstable amorphous oxycarbonates, as indicated by X-ray and IR spectroscopies. The gas-phase decomposition products identified by IR spectroscopy are NH₃, CO₂, CO, CH₃COCH₃, CH₄ and NH₄OH. Surface area measurement and scanning electron microscopy showed that Fe₂O₃, the final product at 400 °C, hada surface area of 40 m²/g and good crystalline and porous character.     

柠檬酸根对纳米Fe_3O_4/PVA磁性复合膜性能的影响

采用化学共沉淀法制备了添加柠檬酸根前后的纳米Fe_3O_4粉体材料,用流延成膜法制备了添加柠檬酸根前后的Fe_3O_4/聚乙烯醇(PVA)复合膜。用红外光谱分析仪、古埃磁天平法、振动样品磁强计、自制磁致变形设备、发射扫描电子显微镜对添加柠檬酸根前后的纳米Fe_3O_4/PVA复合膜的结构及性能进行了表征和分析。结果表明:添加柠檬酸根纳米Fe_3O_4制备的Fe_3O_4/PVA复合膜磁化率更大、磁性能更好、磁致变形性能更大、分散性好。     

Liquid–liquid equilibria of aqueous two-phase systems composed of TritonX-100 and sodium citrate or magnesium sulfate salts

Liquid–liquid phase diagrams of surfactant-based aqueous two-phase systems (ATPS) composed of TritonX-100, as a non-ionic surfactant, and two different salts have been studied at 298.15 K. The salts used were an inorganic salt, magnesium sulfate (MgSO₄), and an organic salt, sodium citrate (Na₃C₆H₅O₇). The results show that the salt MgSO₄ is more capable of inducing ATPS formation than the salt Na₃C₆H₅O₇. The experimental liquid–liquid equilibrium data were correlated using a modified virial model. Good agreement was obtained with the experimental data.     

柠檬酸根辅助电沉积制备铂纳米粒子及其制备条件的优化

以氧化铟锡（ITO）透明导电玻璃为基体,在柠檬酸根存在下,采用恒电位电化学沉积法制备铂纳米粒子,并通过改变施加电位、柠檬酸钠浓度、前驱体浓度和电解质浓度来优化铂纳米粒子的制备条件.利用X射线衍射（XRD）表征在ITO表面沉积的Pt颗粒的晶相结构,并运用循环伏安法（CV）测定Pt/ITO电极在酸性介质中的电催化氧化性能.实验结果表明,在施加电位为-0.3V、H2PtCl6浓度为0.8mmol/L、柠檬酸钠浓度为20mmol/L和电解质HClO4浓度为0.1mol/L的条件下,制备出的铂纳米粒子的电催化性能较好.     

pH值对胶体金制备的影响

研究了不同的溶液pH值对胶体金颜色、粒径的影响。在不同pH值下通过柠檬酸三钠法制备胶体金溶液,利用紫外/可见光吸收分光光度计对胶体金进行扫描,得到最大吸收峰波长及峰宽;通过透射电镜观察其颗粒直径及分布,再将二者结果进行比较分析。结果显示:随着溶液pH值变小,胶体金颜色由红→蓝→黑,粒径变大。     

基于光纤光谱的二恶烷浓度检测方法研究

为了准确、快速、低成本地检测二恶烷浓度,实验制备了二恶烷紫外光谱检测试剂——柠檬酸稳定银纳米粒子(Ci-AgNPs)试剂,搭建了光纤光谱测量系统。利用光纤光谱测量系统,实验研究了二恶烷检测试剂浓度、温度、p H对二恶烷浓度检测性能的影响。在此基础上,测试了检测剂对二恶烷的选择响应特性。实验研究发现,当Ci-AgNPs试剂浓度为15μmol/L,温度为55oC,p H为7时,Ci-AgNPs试剂对二恶烷的响应灵敏度达到0. 001 6 L/g,响应时间为10 min。该检测试剂对甲醇、无水乙醇、丙酮、乙腈、四氢呋喃、N-二甲基甲酰胺、三氯甲烷、二甲基亚砜均不响应,表明该检测试剂对二恶烷具有较好的选择敏感性。     

打造我国主体能源(煤炭)升级版面临的主要问题与对策探讨

为了研究阻化剂对煤燃烧特性的影响,选取柠檬酸钠和聚磷酸铵进行复配,开展复合阻化剂优选的实验研究。采用锥形量热仪在45 kW/m²的热辐射强度下, 分析阻化煤样的燃烧行为和阻化效果。结果表明,在选取的实验比例中,当柠檬酸钠与聚磷酸铵的质量比为3∶1时,煤燃烧的热释放速率和总热释放量明显降低,烟气持续生成时间有效缩短,抑制了烟气的产生,体现出优良的阻燃抑烟效果;在煤炭的燃烧效率方面,提高了体系的火灾性能指数,降低了火灾增长指数,有效抑制了煤炭的燃烧,表现出复合阻化剂良好的协效作用。

     

凝血酶分离纯化方法的研究进展

血浆中凝血酶是近年开发的一种新型止血剂。对其分离纯化的等电点沉淀法、柠檬酸钡吸附法和氢氧化镁吸附法做了综述。     

盐对勾兑牛奶酒体系稳定性的影响

试验了不同浓度的柠檬酸三钠对于勾兑牛奶酒体系的影响,结果表明随着柠檬酸三钠浓度的增大,勾兑牛奶酒体系的pH值和粘度也随之增大,当柠檬酸三钠的浓度由0.002mol/L增大到0.02mol/L,酒精质量分数大于20%时,其体系的pH值表现出了几乎相同的增加值;而对所有体系来讲,随着酒精质量分数的增大,粘度的增加值却越来越小.试验结果还发现,加入0.008mol/L柠檬酸三钠能够使得牛奶蛋白在乙醇存在下达到最好的稳定效果.