Kinetics of the coupled transport of uranium(VI) across supported liquid membranes containing bis(2-ethylhexyl)phosphoric acid as a mobile carrier

Abstract

Kinetics of the coupled transport of uranium(VI) from nitric acid solutions containing 1.52 x 10/sup -4/ to 1.8 x 10/sup -3/ mol/dm/sup 3/ of uranium(VI) through a supported liquid membrane (SLM) containing 0.0025-0.025 mol/dm/sup 3/ of dimeric bis(2-ethylhexyl)phosphoric acid in kerosene as a mobile carrier was investigated. Rate equations describing the transport of uranium(VI) were derived taking into account the resistances of aqueous film diffusion, chemical reaction, and membrane phase diffusion. The relative resistance of each transfer step was evaluated. The transport rate of uranium(VI) was found to be controlled by chemical reaction and aqueous film diffusion, both of which occur at the source-side interface, and is in agreement with that estimated by the derived rate equation including a membrane factor.