高岭石水化作用和离子吸附的微量热研究

Microcalorimetry of hydration and ion adsorption of kaolinite

黏土矿物是最常见的地表矿物,其水化和吸附行为有着重要的地质工程和环境工程应用意义.为了研究不同金属阳离子溶液在不同温度下对高岭石水化能力的影响,利用微量热仪测定不同温度条件下高岭石与水、不同盐溶液作用产生的反应热.结果表明:离子浓度越高,吸附量越大,高岭石与溶液混合产生的释热量越高;碱金属阳离子与高岭石的作用强度与离子半径有关,具有Cs^+>K^+>Na^+强度顺序.温度对高岭石-碱金属离子相互作用强度有着重要影响.相对高温条件下的释热量明显升高,可能与高岭石羟基面反应性增强、碱金属离子与羟基氢的交换反应加强有关.由此可知,黏土矿物-流体相互作用与温度、离子半径和离子浓度呈正相关关系.

Clay minerals are the most common minerals in nature,and its hydration and adsorption play critical roles in engineering geologies and environmental applications. In order to study the effect of different metal cation solutions on the hydration of kaolinite at different temperature,we use microcalorimeter to measure the heat generated by the mixing of kaolinite and water as well as different salt solutions at different temperature. The results show that the heat release derived from the mixing of kaolinite with salt solution increases with the ion concentration as well as adsorption amount. The intensity of interactions between alkali metal cations and kaolinite is closely related to the ionic radius,and present the order of Cs^+>K^+>Na^+ in strength. Temperature plays an important role to determine the interaction strength. The heat release at relative high temperature obviously increases,which may be attributed to the enhanced reactivity of kaolinite hydroxyl surface and the exchange reaction between alkali metal ions and hydroxyl hydrogen. Therefore,the clay mineral-fluid interactions are positively correlated with temperature,ionic radius and ionic concentration.