Osman MA, Moor C, Caseri WR, Suter UW
Swiss Federal Laboratories for Materials Testing and Research, Dübendorf, CH-8600, Switzerland
J Colloid Interface Sci. 1999 Jan 1;209(1):232-239. doi: 10.1006/jcis.1998.5878.
The lithium surface ions of a muscovite, which was partially delaminated with a hot saturated lithium nitrate solution, exchange readily with sodium, potassium, rubidium, and cesium ions. The remaining potassium ions in the interlayers of the muscovite do not exchange at ambient conditions. The surface ion exchange is quite fast but can be followed by measuring the change in conductivity of the reaction mixture. In dilute systems, an initial drop in conductivity due to the exchange of the alkali metal ions with Li+ was observed, which was followed by a slow increase over a long period of time. That increase in conductivity is attributed to the formation of alkali bicarbonates due to the CO2 omnipresent in water. The surface Li+ was exchanged almost quantitatively by K+, Rb+, or Cs+ until a saturation value was nearly reached, while the Li+/Na+ exchange was less quantitative. The equilibrium constants (K) of these reactions as well as the ion exchange capacity were calculated by nonlinear least-squares fits. For the Na+/Li+ exchange K was found to be 4, while those of the K+, Rb+, and Cs+ exchange were too high for an accurate determination. The affinity of the alkali metal ions to muscovite decreased in the order K+, Rb+, Cs+ > Na+ > Li+. Copyright 1999 Academic Press.
用热饱和硝酸锂溶液部分剥离的白云母的锂表面离子能与钠、钾、铷和铯离子迅速发生交换。白云母层间剩余的钾离子在环境条件下不发生交换。表面离子交换相当快，但可以通过测量反应混合物电导率的变化来跟踪。在稀溶液体系中，观察到由于碱金属离子与Li⁺的交换导致电导率最初下降，随后在很长一段时间内缓慢上升。电导率的增加归因于水中普遍存在的CO₂导致碱金属碳酸氢盐的形成。表面Li⁺几乎被K⁺、Rb⁺或Cs⁺定量交换，直到几乎达到饱和值，而Li⁺/Na⁺交换的定量程度较低。通过非线性最小二乘法拟合计算了这些反应的平衡常数（K）以及离子交换容量。对于Na⁺/Li⁺交换，发现K为4，而K⁺、Rb⁺和Cs⁺交换的K值太高，无法准确测定。碱金属离子对白云母的亲和力按K⁺、Rb⁺、Cs⁺＞Na⁺＞Li⁺的顺序降低。版权所有1999年学术出版社。
