Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennnoudai, Tsukuba-shi, Ibaraki 305-8572, Japan.
J Colloid Interface Sci. 2013 Oct 1;407:109-15. doi: 10.1016/j.jcis.2013.05.080. Epub 2013 Jun 13.
We have investigated the electrokinetic responses of two different kinds of clay particles, kaolinite and montmorillonite. The dielectric permittivity of kaolinite suspensions is linearly proportional to volume fraction up to volume fractions of 20%, whereas that of montmorillonite is deviating from a linear relationship, for volume fractions below 0.5%. This indicates that the montmorillonite particles experience a particle-particle interaction at these low volume fractions. The complex dipole coefficients of both clays estimated by experimental data are, however, within experimental error in good approximation independent on volume fraction and agree with the theoretical predictions. The relaxation frequency in clay-water system at low ionic strength is almost determined by the relaxation of the double layer for both kaolinite and montmorillonite. For volume fractions larger than 0.5% for montmorillonite, we find that the zeta potential measured by electroacoustic methods starts to depend strongly on volume fraction. It is expected that for these high volume fractions, the dipole coefficients will also become volume-fraction dependent.
我们研究了两种不同类型的粘土颗粒（高岭石和蒙脱石）的电动响应。高岭石悬浮液的介电常数与体积分数呈线性比例关系，直至 20%的体积分数，而蒙脱石的介电常数则偏离线性关系，体积分数低于 0.5%。这表明在这些低体积分数下，蒙脱石颗粒会发生颗粒间相互作用。然而，通过实验数据估算出的两种粘土的复偶极系数在实验误差范围内几乎独立于体积分数，并且与理论预测相符。在低离子强度下，粘土-水体系的弛豫频率几乎完全由双电层的弛豫决定，对于高岭石和蒙脱石都是如此。对于蒙脱石的体积分数大于 0.5%，我们发现通过电动声学方法测量的 ζ 电位开始强烈依赖于体积分数。预计对于这些高体积分数，偶极系数也将变得依赖于体积分数。
