MICROSTRUCTURAL CHANGES IN SAND-BENTONITE SOILS WHEN EXPOSED TO ANILINE

Bentonite was exposed to aniline through batch experiments and flexibl e wall conductivity tests. The mineralogy and microstructure of the sa mples were studied using X-ray diffraction, infrared spectroscopy, sca nning electron microscopy, and mercury intrusion porosimetry, before a nd after aniline exposure. Results indicated that the mineralogical st ructure of the clay mineral was unaffected by the exposure to aniline, despite evidence that aniline adsorbed onto bentonite upon contact. T ests on sand-bentonite composites showed that the sample with a larger fraction of clay had a greater proportion of fine pores (<50 mu m), t hus a lower conductivity to aniline. This is attributed to the phenome non of the two phase immiscible flow. The conductivity of sand-bentoni te composites to aniline appears to be controlled by the soil's pore s tructure; the amount of bentonite controls the pore size distribution of the sample.