MgFe-Cl-LDHs的合成、结构及其插层组装性能研究

合成出了层间含Cl-的MgFe型层状双羟基氢氧化物（MgFe-Cl-LDHs），通过X射线衍射(XRD)、红外光谱(FT-IR)、热重及差热分析(TG-DTA)和元素分析等手段对其组成和结构特征进行了分析。研究表明：在共沉淀条件下，可制得晶体结构规整的MgFe-Cl-LDHs，且其结构规整性随组成中Mg²⁺/Fe³⁺物质的量比的增大而增强；LDHs层板六配位的金属离子与层板羟基层、层板羟基层与层间结构水的相互作用不随Mg²⁺/Fe³⁺物质的量比的改变而改变，而层板主体与层间客体阴离子之间的静电引力随Mg²⁺/Fe³⁺物质的量比的增大而降低。另外，其超分子结构特征使层间Cl^-能与有机阴离子CH₂CHC₆H₄SO₃^-和CH₃(CH₂)₁₁SO₃^-发生离子交换，形成以双分子层垂直于层板的交错有序的排布结构模式。

Study on Preparation,Structure and Intercalation Assembly of MgFe-CI Layered Double Hydroxides

Layered double hydroxides containing Mg²⁺ and Fe³⁺ in the brucite-like layers and interlayer chloride ions with an Mg²⁺/Fe³⁺ ratio of 2 to 4 were prepared through coprecipitation and characterized by elemental analysis, X-ray diffraction, FT-IR and thermal analysis. By increasing the Mg²⁺/Fe³⁺ ratio, a well-crystallized hydrotalcite can be obtained. In the case of the material prepared with Mg²⁺/Fe³⁺=4, the interlayer chloride ions may be replaced by either vinylbenzenesulfonate or dodecyl sulfonate ions suggesting that these materials may be useful precursors to MgFe-LDHs intercalated with a variety of organic anions. The interactions between the metal cations and hydroxyl groups in the brucite layer, and between the brucite layers and water in gallery spaces were not affected by Mg²⁺/Fe³⁺ molar ratio. The electrostatic interaction between the brucite layers and anions in gallery spaces was reduced by increasing the Mg²⁺/Fe³⁺ molar ratio.