【作者】 张智平；

【导师】 梁鑫淼；

【作者基本信息】 中国科学院研究生院（大连化学物理研究所） ， 分析化学， 2007， 博士

【摘要】 色谱柱是色谱分离分析的核心，而色谱固定相的研究则是各种高效液相色谱赖以建立和发展的基础，因此研制、开发新型色谱固定相便成为色谱技术中一个长久不衰的研究课题。通过喷雾-干燥技术合成出了不同Mg／Al比的氧化物，利用线性溶剂化能关系考察了这些Mg／Al氧化物的色谱保留性质，发现相对于Al₂O₃、Mg／Al=0.1的氧化物，Mg／Al=5、10的氧化物和MgO有利于溶质保留值增加的贡献项不仅包括偶极／极化项、氢键供体酸性项和氢键受体碱度项，且包括分子体积项。经过对文献中不同色谱固定相线性溶剂化能回归常数的分析，建立了一种用来关联溶质在Mg／Al=5、10的氧化物及MgO上容量因子对数值与常用正相、反相柱上容量因子对数值间的新关系。系统考察了不同反应条件下，利用K₂CO₃和Mg（NO₃）₂溶液共沉淀反应制备氧化镁前驱体水合碳酸镁的变化规律。发现在较低的温度和pH值条件下，产物容易生成针状的MgCO₃·χH₂O，而在较高的温度和pH值条件下，产物容易生成片状或由片状颗粒自组装而成具有规则形状的Mg₅（CO₃）₄（OH）₂·4H₂O颗粒。同时深入研究了Mg₅（CO₃）₄（OH）₂·4H₂O微球的生成过程，发现当K₂CO₃和Mg（NO₃）₂溶液迅速混合后，所得产物容易生成由细小粒子组成的块状（MgCO₃）_0.8(（Mg（OH）₂）_0.2·1.3H₂O颗粒；随着反应的进行，这些细小颗粒会逐步组装成针状的MgCO₃·χH₂O或其它形貌的颗粒，而后者会进一步地转变为类球形的Mg₅（CO₃）₄（OH）₂·4H₂O颗粒。在以上研究的基础上，发展了一种制备单分散氧化镁微球的新方法—晶种诱导共沉淀法，并发现氧化镁微球前驱体的形貌极大地依赖于Mg₅（CO₃）₄（OH）₂·4H₂O品种加入的顺序和量，磷酸盐加入的种类、量和顺序以及反应溶液的陈化时间。通过对氧化镁微球色谱性能的评价，发现相对于商品硅胶固定相，不同类型的碱性化合物和多环芳烃化合物在氧化镁微球上表现出较好的分离效果。更多还原

【Abstract】 The core of chromatography for the separation and analysis is based on the chromatographic column, whereas the development of all kinds of high-performance liquid chromatography modes is dependent on the stationary phases. Therefore, the development and exploitation of new types of stationary phases is a never-gone research topic in the chromatographic field.The chromatographic retention behaviors of the Mg/Al oxides with various Mg/Al ratios obtained by spray dried techniques, have been investigated by linear solvation energy relationships. The results demonstrate that in comparison with the contribution of these characteristic interactions for the increase of solutes’ retention on Al₂O₃ and the oxide of Mg/Al=0.1, the ones for the increase of solutes’ retention on the oxides of Mg/Al=5、10 and MgO, include not only dipolarity/polarizability, the solute hydrogen bond donating and accepting abilities, but also the intrinsic molar volume. By analysis of the regression constants on various normal-phase （NP） and reversed-phase （RP） columns reported in the literature, a new model has been developed to correlate the solute logarithmic retention factors on Mg/Al = 5, 10 and MgO columns with the data of NP and RP columns.The changes of MgO precursors, magnesium carbonate hydrates, obtained via the precipitation of K₂CO₃ and Mg（NO₃）₂ solutions with the variation of reaction conditions, have been systemically investigated. The results indicate that at lower temperatures and lower pH values, magnesium carbonate hydrates are prone to display needlelike morphology; whereas at higher temperatures and higher pH values, the crystallites tend to assemble into sheetlike particles or the regular Mg₅（CO₃）₄（OH）₂·4H₂O particles assembled by sheetlike structures. The shape evolution of spherical Mg₅（CO₃）₄（OH）₂·4H₂O has also been deeply studied, and the results illustrate that the formation of spherical particles are via a complex process, in which the agglomerates （MgCO₃）_0.8 （Mg（OH）₂）_0.2·1.3H₂O built by many fine grains are first produced after the "burst" mixture of K₂CO₃ and solutions. Then the fine grains tend to assemble into needlelike or other similar particles, and the latter will further transfer into spherical Mg₅（CO₃）₄（OH）₂·4H₂O particles.On the basis of above investigation, a new method, seed-induced precipitation, has been developed for synthesis of monodisperse MgO microspheres, and the reaction parameters, such as the sequence and amount of introduction of Mg₅（CO₃）₄（OH）₂·4H₂O seeds, the kinds, amount and sequence of introduction of phosphate salts, and aging time of reaction solution, have great effects on the morphologies of MgO precursors. The chromatographic properties of as-synthesized MgO microspheres have also been investigated, and the results demonstrate that in comparison with the commercial silica, as-synthesized MgO microspheres exhibit excellent properties on the separation of various basic compounds and polycyclic aromatic hydrocarbons.更多还原