Filtration experiments with bentonite and kaolinite samples compacted under pressure of up to 10,000 psi (703 kg/sq cm) were carried out at temperatures of 25 to 85°C, using chloride solutions of alkali and alkaline earth metals.

The hydraulic-conductivity values obtained confirm and extend the trends showing conductivity decreasing with increasing compaction pressures, but increasing with increasing hydraulic-pressure gradients and temperatures. The increase in the conductivity with temperature is equal to that expected from the decrease in the kinematic viscosity of water.

The retardation sequences obtained with bentonite at ambient laboratory temperatures are the same at experimental (much higher) and field-flow rates; they are: Li < Na < K < Rb < Cs and Mg < Ca <= Sr < Ba. The membrane efficiencies for monovalent and divalent cations generally decrease and increase, respectively, with decreasing flow rates; Ca and other divalent cations are retarded with respect to Na and other monovalent cations at field-flow rates.

The retardation selectivity of bentonite decreases with increasing temperatures. Divalent cations are retarded with respect to monovalent cations and the retardation of Cs, Rb, and K with respect to other cations is decreased greatly at the higher temperatures.

The membrane efficiencies obtained with kaolinite are small.