镉溶液污染黏土微观结构演化规律

镉溶液在压实黏土中迁移会引起黏土微观结构的变化。通过一系列扫描电子显微镜与低温氮吸附实验,观察了镉溶液污染黏土的表面微观形貌与孔隙结构的演化规律。扫描电子显微镜观察结果显示,受镉溶液污染严重的土柱上表面孔隙明显,土颗粒之间主要以点-点排列方式为主;而受镉溶液污染较弱的下表面,土颗粒之间主要以片-片状排列为主。低温氮吸附实验结果表明,Z=0 cm、Z=10 cm、Z=20 cm、Z=30 cm处,污染黏土吸附量分别为682.65、631.72、583.25和523.36 cm3/g。随土柱中土层深度的增大,黏土颗粒间微孔增多,二次孔减少,孔隙体积与比表面积减小。镉溶液污染黏土孔隙主要集中在10 nm以下。

Microstructure evolution of clay polluted by Cd2+ chemical solution

The microstructure of compacted clay was changed by the migration of cadmium solution.In order to observe the surface microtopography and pore structure of polluted clay by Cd²⁺ solution,a series of scanning electron microscope(SEM) and low temperature N₂ adsorption testing were performed in laboratory.The results of SEM testing showed that the pores of upper surface samples in soil column were obvious,and the soil particle appeared point-point arrangement.However,the lower surface soil particle appeared piece-piece arrangement.The results of N₂ adsorption testing showed that adsorption capacities were 682.65,631.72,583.25 and 523.36 cm³/g at Z=0 cm,Z=10 cm,Z=20 cm and Z=30 cm,respectively.The amount of secondary pore,pore volume and specific surface area decreased with increasing of soil layer depth in soil column,but the amount of micropore increased.The main concentration of pore was less than 10 nm.