Transport of manganese(II) across supported liquid membranes (SLM)

In our efforts to understand the behavior of the transport of metals across supported liquid membranes (SLM), a new phenomenon called the solubility and viscosity mechanism was observed experimentally and explained theoretically. The study utilized a new model developed earlier, which incorporated the solubility and viscosity effects of the diluent and carrier immobilized in a supported liquid membrane. It was found that these effects influenced the system significantly. At first, the solubility mechanism helped to explain the non-monotonic behavior of the flux with respect to the carrier concentration, as opposed to the linear behavior observed by past theories, which ignored this phenomenon that occurs simultaneously with the carrier-metal reaction. The metal distribution within the organic phase inside the membrane was a function of both carrier and diluent viscosity. Secondly, the negative effect of increased viscosity on diffusivity, accounted for in the theoretical development, was found to give better predictions of the measured fluxes. It was observed that the concentration of the organic carrier and the structure of the membrane had a marked effect on the metal flux across the membrane. The flux increased with increasing concentration of the carrier in the membrane, reaching a maximum value at about 30 % carrier concentration (v/v), above which the flux decreased.