An attempt for the stabilization of supported liquid membrane

As a part of the investigation on the treatment of low-level radioactive wa stewater using supported liquid membranes, a method for stabilizing a suppo rted liquid membrane (SLM) is proposed. Aqueous Ce(III) solutions containin g sodium nitrate and nitric acid were used as the simulated low level radio active wastewater. The SLM consisted of octyl(phenyl)-N,N-diisobutylcarbamo ylmethylphosphine oxide (CMPO) as a carrier of Ce(III), tributyl phosphate (TBP) as a modifier and dodecane as a solvent. The strip solutions were aqu eous solutions of chelating agents such as trisodium citrate and disodium h ydrogen citrate. A small plate-and-frame type SLM module was used and circu lation mode for both the feed and the strip solutions was adopted. The SLM was unstable and water permeation through the SLM occurred, suggesting repl acement of the organic membrane solution in the pores of a support membrane by the aqueous feed solution. However, the SLM was stabilized by adding an organic membrane solution to the reservoir of the strip solution and by ci rculating the membrane solution through the strip side of the SLM module so that the SLM could frequently contact the membrane solution dispersed as d roplets in the strip solution. By this method, the SLM was not degraded by repeated replacements of both the feed and the strip solutions. The effect of chelating agent in the strip solution on the permeation rate of Ce(III) was also investigated. (C) 2000 Elsevier Science B.V. All rights reserved.