MgSiF_6对铝硅酸溶胶凝胶化的影响及其机理

STUDY OF EFFECT OF MgSiF_6 ON GELLING OF ALUMINOSILICATE SOL

实验研究了ＭｇｓｉＦ６对铝硅酸溶胶凝胶化的影响，并用２７Ａｌ、２９Ｓｉ核磁共振和ＸＲＤ研究了铝硅酸溶胶－ＭｇＳｉＦ６凝胶的物相组成及Ａｌ、Ｓｉ在其中所处的结构状态。结果表明：在铝硅酸溶胶中加入ＭｇＳｉＦ６会导致Ａｌ３＋离子从溶胶胶粒中溶出，溶胶胶粒结构的破坏，从而引起溶胶胶粒中Ａｌ／Ｓｉ比和Ａｌ、Ｓｉ所处结构状态的变化。ＭｇＳｉＦ６与从溶胶胶粒溶出的Ａｌ３＋、Ｎａ＋离子作用形成水溶性很低的ＮａＭｇＡｌＦ６，从而降低了液相中Ａｌ３＋离子的浓度，减弱了Ａｌ３＋对溶胶的絮凝作用，同时使得铝硅酸溶胶－ＭｇＳｉＦ６系统的Ｎａ、Ｆ溶出率降低。

The effect of MgSiF6 on the gelling of aluminosilicate sol was experimentally studied, andthe phase composition and structural saltes of Al, St in the aluminosilicate sol-MgSiF6 gel system werealso studied by means of 27 Al and 29 St NMR and XRD measurements. The results showed that addingMgSiF6 into aluminosilicate sol would result in the dissolution of A13+ from the sol particles, accompanied by the break of the structure of the particles, so as to lead to the changes of Al/Si ratio and thestructural state of Al and St in the particles. NaMgAlF6 with very low solubility was formed throughthe reaction between the MgSiF6 added and the A13+ and Na+ ions dissolved from sol particles, so as toreduce the concentration of A13+ ions in the solution. As a result, the effect of A13+ as a flocculantand the amount of Na+ and F- dissolved were reduced.