Use of Polyethers in the Treatment of Acidic High-Activity Nuclear Wastes. Final Report, May 31, 1975-August 31, 1980

摘要

A solvent extraction system has been developed which will reversibly extract Cs exp +1 from 3M HNO sub 3 . The organic phase consists of a matrix solution of 27 vol% TBP, and 68 vol% kerosene. The complexing agents consist of (.076M) 5 vol% didodecylnaphthalene sulfonic acid (DNS) and .02M Bis (4,4'(5') (1-hydroxyheptyl)benzo) 18-crown-6. This is a synergistic system since both complexing agents are necessary to extract the cesium. The data indicate that one crown molecule is involved in the organic complex while the number of DNS molecules is at least one to satisfy the valence requirements but may be more since surfactants of the DNS type tend to form small aggregates in the organic phase. This lack of extraction is probably due to steric effects around the extracted metal atom when two or three ionized DNS molecules are required for valence adjustment. Radiation stability studies of this extraction system at 10 exp 7 rad delivered over a one hour period show a decrease in the cesium distribution coefficient (D org/aq) of a factor of two with the pure radiation D org/aq = 1 about or = 2 and the post radiation D org/aq) = .5 about or = 1 (ideal for a solvent extraction system). Whatever the degradation products were, they did not interfere with the reversibility of the extraction. From an hydraulic viewpoint, the phases settled very quickly with little entrainment although mixer settler runs have not been made. The one serious problem with this extraction system is the low solubility of the crown compound (.02M) and therefore its low metal carrying capacity. The Parish Chemical Company of Provo, Utah was asked to hydrogenate the benzene rings attached to the crown which always results in a large increase in the organic and aqueous solubilities. Tests of the extraction capability of this new compound have not yet been undertaken. (ERA citation 06:028267)