TALSPEAK EXTRACTION SYSTEM UNDER VARIABLE LOADING CONDITIONS - PART 2: SPECIATION STUDIES

Abstract

The reported investigation was performed to gain structural information on the organic phase complex species in the Trivalent Actinide-Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes (TALSPEAK) process under various loading conditions. In conjunction with the distribution studies of the TALSPEAK system constituents, presented in Part 1 of this investigation, loaded bis(2-ethylhexyl) phosphoric acid (HDEHP)/isooctane was evaluated using various spectroscopic techniques including NMR, FTIR and visible absorbance spectroscopy. Liquid-liquid distribution and vapor pressure osmometry (VPO) aggregation results correlate with observed changes in the spectroscopic signatures as a function of organic phase loading and water partitioning. Explicit FTIR spectral interpretation of the HDEHP spectra is complex due to overlapping phosphorus absorbance bands, and in this work a combination of the spectroscopic techniques was utilized to elucidate the phosphorus-lanthanide complex structure and changes in speciation due to aggregation. The results from this research will benefit an overall improved prediction of the TALSPEAK process performance under flow conditions.