SUBSTITUENT EFFECTS IN THE EXTRACTION OF CESIUM FROM ACIDIC NITRATE MEDIA WITH MACROCYCLIC POLYETHERS

A variety of dibenzocrown ethers have been evaluated for the extractio n of cesium from acidic nitrate media. Compounds incorporating a 21-cr own-7 moiety are shown to exhibit greater cesium/sodium selectivity, s uperior functional stability, and better compatibility with PUREX-like diluents than dibenzocrown ethers with other ring sizes. The cesium d istribution ratios obtained with these compounds, however, are general ly not large enough to be of practical value. Higher D-C5 values are a chieved with several dibenzo-18-crown-6 derivatives. Of these, the bes t results are achieved with (5')-di[(1-hydroxy-2-ethylhexyl)benzo]-18- crown-6. The distribution ratios obtained with this compound in undilu ted tri-n-butyl phophate (TBP) compare favorably with those reported f or synergistic systems combining a crown ether with the anion of a lip ophilic organic acid.