Separation of uranium from nitric- and hydrochloric-acid solutions with extractant-coated magnetic microparticles

The magnetically assisted chemical separation (MACS) process utilizes selec tive magnetic microparticle composites to separate dissolved metals from so lution. In this study, MACS particles were coated with neutral and acidic o rganophosphorus extractants, octyl(phenyl)-N,N-diisobutylcarbamoylmethyl ph osphine oxide (CMPO), tributyl phosphate (TBP), trioctylphosphine oxide (TO PO), and bis(2-ethylhexyl)phosphoric acid (D(2)EHPA or HDEHP) and were eval uated for the separation of uranyl ions from nitric- and hydrochloric-acid solutions. The results suggest that a synergistic interaction between the p article surface and solvent coating may explain why the particles display, in some cases, orders of magnitude of higher partitioning coefficients than are estimated from solvent-extraction measurements. Particles coated with TBP and those coated with a combination of TOPO and D(2)EHPA displayed the most desirable characteristics for removing uranium from dilute acid enviro nments typical of contaminated groundwater. Uranium separation from moderat e to highly acidic waste streams typical of Department of Energy (DOE) nucl ear wastes is best accomplished using particles coated with a combination o f CMPO and TBP.