A PRELIMINARY EVALUATION OF MICROPOROUS HOLLOW-FIBER MEMBRANE MODULES FOR THE LIQUID-LIQUID-EXTRACTION OF ACTINIDES

Microporous hollow fiber (MI-IF) membrane modules provide an inexpensive, low-maintenance, and dispersion-free approach to continuous-flow liquid-liquid extraction processes. This work involves analyzing the potential for using these modules for process-scale metal separations such as radioactive waste stream cleanup and environmental remediation. In this work, MHF modules are used to remove neodymium (a surrogate for americium) from 2 M nitric acid using DHDECMP [dihexyl N,N-diethylcarbamoylmethylphosphonate] and CMPO [n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide] as extractants in diisopropylbenzene. The modules are also used to concentrate the neodymium from the organic by back-extracting it into 0.01 M nitric acid. The performance of this technology is discussed in terms of the number of theoretical equilibrium extraction stages provided by each module, as well as how the module's extraction and back-extraction capabilities are affected by different aqueous and organic flow rates, and by the different extractants.