Stability and Effect of Diluents in Supported Liquid Membranes for Cr(III), Cr(VI), and Cd(II) Recovery

Some results obtained with the aim of optimizing the permeation fluxes, separation factors, and stability of SLM's are described. A flat sheet polypropylene membrane was used in all the experiments. The ions on which the SLM's were tested were Cr(III), Cr(VI), and Cd(II). The carriers were dinonyl-naphthalene sulfonic acid (DNNSA), Aliquat 336, and Alamine 336. The diluents were o-xylene, kerosene, n-heptane, and their mixtures. Among the various mixtures tested for membrane impregnation, a maximum separation factor of 15.0 by using the SLM 50% v/v DNNSA + 25% v/v o-xylene + 25% v/v kerosene was obtained. The stability of this membrane was greater than 70 hours of continuous operation. The effect of temperature in the 25-35°C range was also investigated.