硅溶胶对钙基膨润土性能影响

Effects of Silica Sol on Properties of Ca-Bentonite

对硅溶胶改性钙基膨润土的研究结果表明:硅溶胶/膨润土(质量比)小于1/8时,膨润土的吸附性和悬浮性随着硅溶胶加入量的增加而提高,进一步增加硅溶胶的加入量反而下降,膨胀性持续降低;pH值对硅溶胶改性效果影响不大;随焙烧温度的升高,膨润土的吸附性和膨胀性呈先上升后下降的趋势,悬浮性提高,500 C焙烧土综合性能最佳;硅溶胶改性500C焙烧后膨润土的性能更好.差热分析表明,600～700C焙烧膨润土失去晶格羟基,综合性能降低;扫描电镜观察说明,硅溶胶改性后膨润土颗粒分散性较好;X-射线衍射和透射电镜分析证实了带负电的硅溶胶主要结合在蒙脱石端面上.

Effects of the silica sol on Ca-bentonite have been studied. Results indicate that when the quality ratio of the silica sol to the bentonite is less than 1/8, the adsorption and the suspended ability of the bentonite increase with increasing the addition of the silica sol, but decrease with further increasing the addition of the silica sol, the dilatability is reduced all the time. Effects of the pH value to modified bentonite properties are small. With the increasing of the temperature, the absorbing and the dilatability increase first and then decrease, the suspended ability is improved all the time, and the comprehensive properties of the bentonite calcined at 500℃ are the best. Modification effects of the silica sol on the bentonite calcined at 500℃ are better. The differential thermal analysis （DTA） indicates that when the bentonite is calcined between 600℃ and 700 ℃, the dehydroxylation can be happened, and the comprehensive properties reduced. The scanning electron microscopy （SEM） observation shows that dispersive capacity of the bentonite modified with the silica sol is better than that of the raw bentonite. The X-ray diffraction （XRD） and the transmission electron microscopy （TEM） analyses verify that the silica sol with negative charges is mainly adsorbed on the montmorillonite edge.