钠基膨润土-NaAlO_2-NaOH水体系合成方钠石的条件与机理

Synthesis Conditions and Mechanism of Sodalite in Na-Bentonite-NaAlO_2-NaOH-H_2O System

基于钠蒙脱石良好的剥离分散和反应活性,采用钠基膨润土为原料,在常压下碱性水体系中合成方钠石。探讨了Na2O/SiO2物质的量比、反应时间、反应温度、SiO2/Al2O3物质的量比对合成方钠石的影响。结果表明,Na2O/SiO2物质的量比对合成方钠石物相的纯度影响最大,反应温度次之;反应时间和SiO2/Al2O3物质的量比在最佳条件附近对方钠石的合成影响很小;在反应过程中,钠蒙脱石、方石英和钠长石发生"碱溶",所形成的产物与溶液中的偏铝酸钠反应形成方钠石。后期形成的方钠石围绕先期形成的方钠石生长,形成了方钠石球形聚集体。

Based on good dispersion and reaction activity of Na-montmorillonite, sodalite was synthesized from Na-bentonite as a raw material in the alkaline water system under the atmospheric pressure. This paper focuses on the effect of SiO2/Al=O3 molar ratio, Na20/SiO2 molar ratio, reaction temperature, reaction time on the formation sodalite. The results show that the Na20/SiO2 molar ratio has a great influence on the synthesis of pure sodalite phase, and the reaction temperature comes second, but the impact of reaction time and SiO2/AI203 molar ratio is the least when the synthesis conditions were near the optimized. In the reaction process, Na-montmorillonite, quartz and albite were occurring “ alkali dissolution”, and the reaction products can react with sodium aluminate in the solution to form sodalite. The formation of the later sodalite around the early formed sodalite to growth, forming spherical aggregates.