Extraction chromatography in the DHDECMP—HNO3 system

Studies on solubility of uranyl complexes in supercritical carbon dioxide and its controlling factors using UV-visible and17O- and19F-NMR spectroscopy

“…DMSO and CH 2 Cl 2 (Kanto Chemical Co., Inc.) were stored over 4A molecular sieves before use. The Cu(hfa) 2 , Cr(hfa) 3 , and Zr(hfa) 4 O phase to CH 2 Cl 2 phase. After the CH 2 Cl 2 phases were evaporated, the yellow precipitates were obtained and re-crystallized from n-hexane.…”

“…In this way, scCO 2 samples containing each b-diketonato complex were prepared inside a high-pressure NMR cell. 4 is colorless, the solubility of Zr(hfa) 4 in scCO 2 was examined using NMR spectrometer. The sample for NMR measurements was prepared in a similar manner to that used in the UV-visible spectrophotometric method.…”

“…The sample for NMR measurements was prepared in a similar manner to that used in the UV-visible spectrophotometric method. The scCO 2 sample containing the Zr(hfa) 4 complex was prepared in a high-pressure NMR cell, and the concentrations of Zr(hfa) 4 complex dissolved into scCO 2 were determined by measuring the area ratios of the 19 F-NMR peak of samples to that of CF 3 COOH.…”

“…Furthermore, the effect of the number of fluorine atoms in the ligands on the solubility of b-diketonato complexes in scCO 2 were examined by comparing the solubility of Cu(hfa) 2 , Cr(hfa) 3 , and Zr(hfa) 4 complexes. The solubility of Cu(hfa) 2 , Cr(hfa) 3 , and Zr(hfa) 4 3.0 6 10 72 M, and 4.4 6 10 72 M, respectively (see Table 1).…”

“…N,N,N 0 ,N 0 -tetraoctyl-3-oxapentanediamide (TODGA) being the tridentate ligand containing three oxygen donors has a powerful ability to separate tri-and tetra-valent metal ions and a high extraction capability compared with other representative extractants [3]. Extraction chromatography that combines the favorable characteristics of solvent extraction and ion exchange has been widely recognized as very promising separation technique, because this method provides the decontamination of small quantities of actinide elements in liquid wastes [1,4]. Recently, novel thermo-responsive polymer gels including poly-N-isopropylacrylamide and N,N,N 0 ,N 0 -tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) derivatives were synthesized as extraction chromatographic agents, and adsorption-desorption separation processes of MA(III) and Ln(III) ions were realized onto silica beads immobilizing the polymer gels by only changing temperatures [5].…”