Permeability of earthen liners containing organobentonite to water and two organic liquids

The intrinsic permeabilities of compacted specimens containing sand and bentonite and specimens containing sand, bentonite, and either of two organobentonites (hexadecyltrimethylammonium or benzyltriethylammoniumbentonite) have been measured for three permeant liquids (water, nitrobenzene, and heptane) with dielectric constants ranging from 80.2 to 1.92. When the permeant liquid was changed from water to heptane, the intrinsic permeability of sand/bentonite specimens increased by a factor of about 100. Conversely, when the permeant liquid was changed from water to heptane for sand/bentonite/organobentonite specimens, the intrinsic permeabilities of the specimens showed no significant change. Results of tests for nitrobenzene, which has a dielectric constant intermediate to water and heptane, showed uniformly low permeabilities for all specimens. X-ray diffraction and contact-angle measurements were used to explain these results in terms of the interlayer expansion/compression and the dispersion/flocculation of the bentonite and organobentonites when exposed to the different permeant liquids. The addition of organobentonites to conventional sand/bentonite compacted earthen liners can help prevent failure of the liner following the release of nonpolar organic liquids.