Imbibition-displacement of an aqueous interstitial liquor by an organic fluid containing a surfactant

Imbibition was investigated as a method of assisting the removal of interstitial liquor from the salt cake contained in the Hanford underground storage tanks. In this application, imbibition would be the displacement of the interstitial liquor from the salt cake by a heavy organic containing a surfactant. Preliminary studies with a salt cake liquor system formed from NaNO₃ alone indicated that a surfactant-tetrachloroethylene system could displace 75 percent of the interstitial liquor. Further investigations were carried out with a sale cake--liquor system containing NaNO₃, NaNO₂, NaAlO₂, and NaOH. Twenty-seven surfactants and two heavy organics, carbon tetrachloride and tetrachloroethylene, were tested. In one test, an anionic surfactant and tetrachloroethylene gave promising results with the latter salt cake; however, these results could not be duplicated. All other surfactants tested gave unsatisfactory results. The presence of NaOH in the salt cake recipe seems to increase the interfacial tension of the interstitial liquid-organic fluid system. Investigations of chemical and radiation stability, corrosion aspects, and ease of removability from the tanks of the heavy organic systems revealed tat tetrachloroethylene and carbon tetrachloride are chemically stabilized with additives. It is recommended that a theoretical analysis be made on the application of imbibition to the waste tanks, that experiments be carried out to test the theoretical considerations, and that other promising surfactants such as amphoterics be tested. (author).