Radium Separation Through Complexation by Aqueous Crown Ethers and Ion Exchange or Solvent Extraction*

Abstract

The effect of three water-soluble, unsubstituted crown ethers (1 5-crown-5 (1 5C5), 18-crown-6 (18C6) and 21-crown-7 (21C7)) on the uptake of Ca, Sr, Ba and Ra cations by a sulfonic acid cation exchange resin, and on the extraction of the same cations by xylene solutions of dmonylnaphthalenesulfonic acid (HDNNS) from aqueous hydrochloric acid solutions has been investigated. The crown ethers enhance the sorption of the larger cations by the ion exchange resin, thereby improving the resin selectivity over calcium, a result of a synergistic interaction between the crown ether and the ionic functional groups of the resin. Similarly, the extraction of the larger alkaline earth cations into xylene by HDNNS is strongly synergized by the presence of the crown ethers in the aqueous phase. Promising results for intra-Group IIa cation separations have been obtained using each of the three crown ethers as the aqueous ligands and the sulfonic acid cation exchange resin.Even greater separation factors for the radium -calcium couple have been measured with the crown-ethers and HDWS solutions in the solvent extraction mode. The application of the uptake and extraction results to the development of radium separation schemes is discussed and a possible flowchart for the determination of 226Ra/22sRa in natural waters is presented.

Competitive Solvent Extraction of Ra(II) and Ba(II) from Aqueous Solutions with Lipophilic, Acyclic, Di‐ionizable Polyethers

“…A number of reports have appeared on the separation of alkaline earth cations by ion exchange (9)(10)(11), solvent extraction (9)(10)(11), and membrane systems (19)(20)(21). Some of them involve radium (9)(10)(11)(12)(13)(14)(15)(16)18), while only three studies of competitive separation of radium from magnesium, calcium, strontium, and barium by liquid-liquid extraction have been published (12,16,18).…”

“…Some of them involve radium (9)(10)(11)(12)(13)(14)(15)(16)18), while only three studies of competitive separation of radium from magnesium, calcium, strontium, and barium by liquid-liquid extraction have been published (12,16,18). The ion carriers employed were crown ethers, both ionizable (12)(13)(14) and neutral (9)(10)(11)(12)15), as well as ionizable calixarene-crown ethers (16).…”