IEC 124 |
| Lætitia H. Delmau, Cara L. Johnston, Jennifer L. Rumppe, Viktor N. Pastushok, and Bruce A. Moyer. Chemical Sciences Division, Oak Ridge National Laboratory, P.O. BOX 2008 MS 6119, Oak Ridge, TN 37831-6119 |
| Several synthesized aza-analogs of the dioctyloxy-calix[4]arene oxocrown-6 family were studied for their cesium, and more generally, alkali metal extraction performance. This study is part of an ongoing effort to clean up DOE tank-stored nuclear waste at sites such as Hanford and Savannah River. Selective removal of 137Cs is of major importance as this radionuclide, along with 90Sr, contributes the bulk of the gamma radiation and heat generation of the waste. The new extractants contain one or two aza-substituents respectively at the 3- position and at the 3,4- or the 2,5- positions of the crown in either the free base form (NH) or the substituted form (NCH2CH2NHTs). Cesium extraction performance of the compounds was measured as a function of pH, diluent, and anions present in the system and compared with that of the oxo analog. Overall results show an increase of the cesium extraction with pH. Diluent effects were consistent with the expected trends based on their properties. Cesium extraction from different sodium salt media followed the usual bias based on the anion free energies of partitioning. Interestingly, mixtures of dioctyloxy-calix[4]arene oxocrown-6 with each substituted aza-compound showed a marked preference for hydroxide. Selectivity was on the order of 1000 for Cs over Na and on the order of 100 for Cs over K. Hydrogen bonding effects were revealed by using a diaza derivative where the two protons were replaced by methyl groups. |
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Advanced Technologies for Decontaminating and Managing Radioactive Wastes
1:00 PM-5:00 PM, Tuesday, March 25, 2003 Convention Center -- Room 394, Oral
Division of Industrial and Engineering Chemistry |