Mg-Fe-LDHs纳米颗粒的合成及其阴离子交换容量的研究

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

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）

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 cell increases 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.