Simultaneous extraction and stripping of uranium ions via multi-dropped liquid membrane system

Abstract

An investigation on the separation of U(VI) from aqueous solutions via a multi dropped liquid membrane (MDLM) and its model is presented. A new method that is more advantageous than other liquid membrane techniques is applied. Di(2-ethylhexyl) phosphoric acid was used as a highly selective carrier for the transport of U(VI) ions through the MDLM. Maximum percentages of U(VI) extraction and stripping achieved were 98.9 % using 1.459 × 10-3 M D2EHPA as the extractant, 1 M NH4HCO3 as the stripping solution. The influences of pH and temperature on donor and acceptor phases, the influence of carrier phase concentrations and membrane's flow velocity were investigated. For the description of relationships of U(VI) concentration in particular phases with time, a model based on the assumption of consecutive first-order reactions was proposed. The kinetic parameters (k 1, k 2, R m max, t max, J d max, J a max) were calculated for the interface reactions assuming two consecutive, irreversible first-order reactions. The activation energy value was calculated as 10.2 kcal mol-1 for extraction. The value of calculated activation energy indicates that the process is chemically controlled by U(VI) ions. The experiments have demonstrated that D2EHPA derivative is a good carrier for U(VI) transport through MDLM in the study. © 2015 Pleiades Publishing, Ltd.