硅酸盐学报2011，Vol.39Issue(2)：365-370,6.
尿素法合成镁铁水滑石的制备机理
Preparation Mechanism of the Mg-Fe Hydrotalcite with Urea Method
摘要
Abstract
Mg-Fe hydrota1cite with uniform and high crystallinity was prepared using an improved urea method. The structure, morphology and composition of Mg-Fe hydrotalcite were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer. The preparation mechanism is discussed, and the effect of mole ratio of urea to Fe3+ in the reaction system on the precipitation of the Mg-Fe hydrotalcite was investigated. The results show that the coprecipitation of Mg2+ and Fe3+ to form the Mg-Fe hydrotalcite crystal could occur when the pH value is between 8.48 and 9.35. The nucleation mechanism of the Mg-Fe hydrotalcite is as follows: Fe3+ formed Keggin structure Fe13 cluster(polyoxocation [Fe1304(OH)24(OH2)12]7+), andMg2+ formed amorphous Mg(OH)2 in the reaction system. On one hand, the brucite-like sheets of Mg-Fe hydrotalcite with positive charges are formed after the Fe13 cluster was adsorbed rapidly on the surface of amorphous Mg(OH)2. On the other hand, this net positive charge can be compensated by CO23- anions through coulomb forces, which lay in the interlayer region between brucite-like sheets for the balance of the potential valence. At last, the nucleation of Mg-Fe hydrotalcite with electrical neutrality is quickly finished. When the mole ratio of urea to Fe3+ is 12, the optimal relative yield of the Mg-Fe hydrotalcite that possessed well-crystalline structures is obtained.关键词
镁铁水滑石/尿素/制备机理/pH值Key words
magnesium-iron hydrotalcite/ urea/ preparation mechanism/ pH value分类
化学化工引用本文复制引用
黄炎,曾虹燕,王亚举,杨永杰,魏英民,赵策..尿素法合成镁铁水滑石的制备机理[J].硅酸盐学报,2011,39(2):365-370,6.基金项目
国家重大科技专项(2009ZX07212-001-03) （2009ZX07212-001-03）
湖南省研究生科研创新项目(CX2010B268) （CX2010B268）
湖南省高校科技创新团队项目资助. （）
