Abstract
Many problems must be worked out for practical use of the surfactant liquid membrane process. Among them, the following subjects are very important : (1) the selection of proper combination of extractant, surfactant and diluent as membrane liquid, and their concentrations ; and (2) the choice of species and concentrations of elution reagent in internal aqueous phase, and of adjuvant in external aqueous feed. solution. This paper deals with the recovery and concentration of chromium contained in aqueous sulfuric acid solution, and investigates the proper condition of the surfactant liquid membrane process and the possibility of recycle use of the organic phase as the membrane phase.
Tertiary amines such as tridodecyl or trioctyl amines diluted in kerosene, which are familiar as extractants for chromium, were found to form gel-like chromium complex in the presence of surfactant such as Span 80 or polyamine. The extracted chromium, therefore, was not transported to the internal aqueous phase through the organic phase. Chromium in the external aqueous phase was successfully transported and concentrated into the internal aqueous phase containing lithium hydroxide solution through the organic phase with 2-ethylhexyl alcohol and polyamine in kerosene. Further, it was found that recycle use of the organic phase did not affect the function of the surfactant liquid membrane.
