Ishida T, Makino T
Faculty of Agriculture, Kagawa University, Ikenobe 2393, Miki, Kagawa, 761-0795, Japan
J Colloid Interface Sci. 1999 Apr 1;212(1):152-161. doi: 10.1006/jcis.1998.6030.
Dielectric measurements were performed on montmorillonite, allophane, and imogolite suspensions under various pH conditions, using time domain reflectometry over the frequency range 10 kHz-20 GHz. A dielectric relaxation peak due to bound water could be observed for all the clays. Allophane has two peaks, indicating that its peaks are very similar to those of silica-alumina gels. Although imogolite has a similar chemical composition, only one peak was found. The relaxation strength of montmorillonite is greater than that of the other two clays. For all the clays, the relaxation strength depended on the pH. A change in the relaxation strength according to a change in pH is explained in terms of the different network structures of the clay particles. It is suggested that bound water influences the network structure formation. In montmorillonite, a great relaxation process detected at low frequency is caused by surface polarization of counterions. The change in measure of the structural unit with the pH, identified from Schwartz's theory, has a tendency similar to that postulated by other experimental techniques, and surface charge densities identified are close to those estimated from CEC. Copyright 1999 Academic Press.
在不同pH条件下，使用时域反射仪在10 kHz至20 GHz频率范围内对蒙脱石、水铝英石和伊毛缟石悬浮液进行了介电测量。对于所有粘土，均可观察到由结合水引起的介电弛豫峰。水铝英石有两个峰，表明其峰与硅铝凝胶的峰非常相似。尽管伊毛缟石具有相似的化学成分，但仅发现一个峰。蒙脱石的弛豫强度大于其他两种粘土。对于所有粘土，弛豫强度取决于pH值。根据pH值变化导致的弛豫强度变化可通过粘土颗粒不同的网络结构来解释。有人认为结合水会影响网络结构的形成。在蒙脱石中，低频下检测到的较大弛豫过程是由抗衡离子的表面极化引起的。根据施瓦茨理论确定的结构单元测量值随pH值的变化趋势与其他实验技术所假设的趋势相似，并且所确定的表面电荷密度与根据阳离子交换容量估算的值接近。版权所有1999年，学术出版社。
