Studies on membrane stability and recovery of uranium (VI) from aqueous solutions using a liquid emulsion membrane process

An extensive study on separation and recovery of uranium (VI) from dilute aqueous solutions using a liquid emulsion membrane (LEM) technique is presented. The study has highlighted the importance of emulsion stability for maximizing uranium recovery. The emulsion constitutes tri-n-octylphosphine oxide (TOPO) as a carrier, paraffin as organic diluent, an emulsifying agent, and stripping phase. The residence time required for adequate pertraction of uranium has been evaluated. The important variables affecting the LEM permeation process such as the concentrations of surfactant, extractant, internal strip phase, and effect of speed of agitation, aqueous feed phase pH, and the presence of iron were systematically investigated. Using suitable values, an attempt was made to recover uranium from a synthetic process plant stream. It was found that strip phase sodium carbonate concentration of 0.5 M gives maximum recovery of uranium. The feed phase pH has been found to be critical for uranium recovery by this technique. (C) 2002 Published by Elsevier Science B.V.