Enhancement of the Mutual Separation of Lanthanide Elements in the Solvent Extraction Based on the CMPO-TBP Mixed Solvent by Using a DTPA-Nitrate Solution

概要

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The mutual separation behavior of rare earth elements was studied in the system based on the neutral extractant CMPO (n-octyl(phenyl)-N, N-diisobutylcarbamoyl methylphosphine oxide) and aminopolyacetic acid DTPA (diethylenetriamine pentaacetic acid). The extractability of lanthanides decreased monotonously with increasing of atomic number in the system of 0.2M CMPO-1.0M TBP-n-dodecane (TRUEX solvent) and 0.05M DTPA-NaNo3 or hydroxylamine nitrate (HAN) solution. The separation factor of La/Lu was 6, 600 using 0.05M DTPA-3M NaNO3 solution (initial pH=2.0). The mutual separation of lanthanides in the CMPO/DTPA system was greatly improved when compared with the general TRUEX system. The separation factor was not affected by the initial pH of the solution (1.8-2.2), the salting out reagent (NaNO3 and HAN), or its concentration (2, 3M). The experimentally obtained separation factors of lanthanide elements were reproduced by a simple model based on the distribution ratios in the TRUEX extraction system and the stability constants of DTPA-metal complex. The mutual separation between light lanthanides is attributed to the selectivity of DTPA, while CMPO mainly influences the separation of heavy lanthanides.
社団法人日本原子力学会の論文
1999-10-25