不同酸碱条件下胶体迁移对含水介质渗透性的影响

Effect of Colloid Transport on Porous Medium Permeability in Different Acidic and Basic Environment

文章通过室内土柱实验,研究胶体在迁移过程中对含水介质渗透性的影响以及不同酸碱条件下含水介质渗透性变化的特征,并从胶体的动电性质、粒径分布以及胶体与含水介质的空间排斥效应等方面对含水介质渗透性变化的微观机理进行探讨。研究结果表明,胶体溶液的酸碱度对含水介质的渗透性影响很大,中性和碱性条件下,胶体容易迁移,含水介质渗透性变化小。不同酸碱度条件下胶体粒度、表面动电性质不同:在酸性环境下出水胶体表面zeta电势和淌度为正,由于胶体带正电荷与含水介质表面所带负电荷的电性相反,电荷之间的吸引作用使胶体沉积作用加大,随着胶体聚沉在含水介质表面上渗透性急剧降低;在碱性环境中出水胶体表面zeta电势和淌度为负,电荷间的排斥作用将极大地促进胶体在含水介质中的迁移。

Experiments were conducted to study the effect of colloids mobility as well as different acidic and basic conditions on permeability of porous medium in columns. Colloidal particle size, surface zeta potential and blocking effect between porous /nedium and colloids were discussed to study microscopic mechanism of permeability change. Results showed that the pH value of solutions had great influence on permeability of porous medium. The transport of colloids in sand columns was facilitated in neutral and basic conditions, and the decrease of permeability was comparatively small. Different pH in the influent may result in different colloidal properties in the effluent. When in acid condition, surface zeta potential and mobility of colloid in the effluent was positive, which the strong electrostatic attraction between the surface of solid particle and colloids increased the deposition of colloids. With colloids depositing on the porous medium, the permeability decreased dramatically. In the alkaline environment, surface zeta potential and mobility of colloid was negative, which the electrostatic repulsive between the surface of solid particle and colloids facilitated greatly the transport of colloids in sand columns.