蒙脱石分散体系中用Zeta电位修正静电作用能的计算

针对扩展DLVO理论的静电作用能计算中表面电位难以测定,讨论以Zeta电位代替表面电位进行静电作用能计算的可行性。计算了蒙脱石表面电位,运用扩展的DLVO理论分别用Zeta电位和表面电位计算蒙脱石悬浮液的临界硬度,并通过蒙脱石悬浮液的临界硬度试验进行验证。试验结果表明:(1)悬浮液中蒙脱石颗粒表面与滑动面之间的水和电解质离子起到屏蔽表面电位的作用,表面电位计算的静电势能并不能反映颗粒间的静电作用;用Zeta电位代替表面电位计算颗粒间静电作用能,与实验结果更相符;(2)颗粒间滑动层开始接触时,水化作用能开始增大,电解质离子不仅减小了颗粒间的静电斥力,还减小了滑动层厚度,使水化作用距离缩短,颗粒更容易接近从而发生凝聚;(3)随电解质浓度的增加,蒙脱石颗粒Zeta电位和表面电位的绝对值均表现为减小的趋势,且表面电位的变动幅度要远高于Zeta电位的变动;双电层与滑动层厚度均呈指数减小。

Calculation of electrostatic interaction energy by using Zeta potential in montmorillonite dispersion system

For the extended DLVO theory，the surface potential is difficult to be measured.In this paper，the feasibility of using Zeta potential instead of surface potential to calculate the electrostatic potential was discussed.The surface potential of montmorillonite was calculated，and the critical hardness of montmorillonite suspension was calculated by Zeta potential and surface potential based on the extended DLVO theory.The results show that：① The water and electrolyte ions between the surface of montmorillonite particles and the shear surface can shield the surface potential，and the electrostatic potential energy calculated from the surface potentials does not reflect the potential energy of interaction between particles.The electrostatic potential energy of particles can be calculated by Zeta potential instead of surface potential，and the result is in good agreement with the experimental results.② When the interparticle shear layer starts to contact，the hydration energy begins to increase.Electrolyte ions not only reduce the electrostatic repulsion between particles，but also reduce the thickness of the sliding plane，reduce the distance of hydration，the particles are more easily accessible and coagulation occurs.③ With the increase of electrolyte concentration，the fluctuation of surface potential is much larger than the change of Zeta potential.The thickness of double layers and shear layer decreases exponentially.