LABORATORY STUDIES OF THE FLOW OF SOME ORGANIC-SOLVENTS AND THEIR AQUEOUS-SOLUTIONS THROUGH BENTONITE AND KAOLIN CLAYS

A laboratory study was undertaken to evaluate the flow of the following organic solvents and their aqueous solutions through bentonite and kaolin clays: benzene, toluene, p‐xylene, nitrobenzene, trichloroethylene, tetrachloroethylene, ethyl acetate, 2‐butanone, and phenol. In each experiment, one pore volume of a 0.005 N CaSO4 solution (water) flowed through the clays, followed by several pore volumes of an aqueous solution of one of the organic solvents, and then by about three pore volumes of the neat organic solvent. The hydraulic conductivity for the aqueous organic solutions was not significantly different from those for water, and ranged from 4.6 × 10‐7 to 14.4 × 10‐7 and from 0.6 × 10‐7 to 0.8 × 10‐7 cm/sec through the kaolin and bentonite clays, respectively. The flow of the neat solvents through either the bentonite or kaolin clay increased by up to two orders of magnitude. The aqueous solutions did not change the physical appearance of the clays. In general, the more hydrophobic solvents caused the clays to shrink, producing distinct large vertical cracks. The hydrophilic solvents typically caused the clays to aggregate and fracture, forming a network of cracks. The kaolin clay appeared to aggregate more readily than the bentonite clay. The higher swelling of the clays in water than in the neat organic solvents likely caused the physical changes in the clays and the rapid flow of the neat solvents through them. Copyright © 1990, Wiley Blackwell. All rights reserved