Microstructural Changes in Sand-Bentonite Soils when Exposed to Aniline

Abstract

Bentonite was exposed to aniline through batch experiments and flexible wall conductivity tests. The mineralogy and microstructure of the samples were studied using X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and mercury intrusion porosimetry, before and after aniline exposure. Results indicated that the mineralogical structure of the clay mineral was unaffected by the exposure to aniline, despite evidence that aniline adsorbed onto bentonite upon contact. Tests on sand-bentonite composites showed that the sample with a larger fraction of clay had a greater proportion of fine pores ( <50 μm), thus a lower conductivity to aniline. This is attributed to the phenomenon of the two phase immiscible flow. The conductivity of sand-bentonite composites to aniline appears to be controlled by the soil's pore structure; the amount of bentonite controls the pore size distribution of the sample.