Mg-Fe-LDHs纳米颗粒的合成及其阴离子交换容量的研究

采用液相共沉淀法合成了镁铁型层状双氢氧化物(简称Mg-Fe-LDHs)纳米颗粒,考察了粒子形貌、化学组成、晶体结构、阴离子交换容量及原料配比的影响.结果表明,所合成样品为片状纳米颗粒,化学组成与原料配比基本一致.在所研究的原料配比范围内,产品中n(Mg):n(Fe)在2:1～4:1范围内,产品具有水滑石层状六方晶系结构.随n(Mg):n(Fe)从2:1增大到4:1,粒径增大(从37.9nm增大到61.2nm),六方晶格参数a降低(变化范围为0.317～0.310nm),而六方晶格参数c增大(变化范围为2.380～2.412nm),层间距增大(从0.793nm增大到0.804nm),阴离子交换容量增大(从0.52mmol/g增大到1.28mmol/g).

Studies on Preparation and Anion Exchange Capacity of Mg-Fe-LDHs Nanoparticles

The nanoparticles of magnesium ferric layered double hydroxides(Mg-Fe-LDHs) were synthesized by coprecipition method, and their shape, chemical composition, crystal structure, anion exchange capacity and the effects of the n(Mg): n(Fe) in raw material on these properties were studied by transmission electron microscope, chemical analysis and X-ray diffraction etc.. It was found that the Mg-Fe-LDHs particles were plate like nanoparticles, and their chemical compositions are basically consistent with the compositions of raw materials. In the range of n(Mg): n(Fe) of 2:1～4:1, the Mg-Fe-LDHs has the same layered crystal structure as hydrotalcite which belongs to the hexagonal system. With increasing of n(Mg): n(Fe) in the chemical compositions of the samples from 2:1 to 4:1, the particle size of the samples increases from 37.9 nm to 61.2 nm. The lattice constant, a, of hexagonal cell decreases from 0.317 nm to 0.310 nm and the lattice constant, c, of hexagonal celLIncreases from 2.380 nm to 2.412 nm. The basal spacing of the Mg-Fe-LDHs increases from 0.793 nm to 0.804 nm. The anion exchange capacity of the Mg-Fe-LDHs increases from 0.52 mmol/g to 1.82 mmol/g.