Selective facilitated transport of benzene across supported and flowing liquid membranes containing silver nitrate as a carrier

Separation of benzene from cyclohexane was performed using two types of liquid membranes, i.e., a supported liquid membrane and a flowing liquid membrane. Silver nitrate was used as the carrier of benzene. The permeation rate of benzene increased with increasing carrier concentration, and the separation factor, which is defined as the ratio of permeability of benzene to that of cyclohexane, was about 630 when the supported liquid membrane prepared by immobilizing 4 mol/L aqueous silver nitrate solution in cellulose filter paper was used. Compared with the supported liquid membrane, the flowing liquid membrane, where a liquid membrane solution was forced to flow in a thin compartment between two microporous membranes, showed one order of magnitude higher permeation rate at high flow rate of the membrane solution. The flowing liquid membrane was very stable and no noticeable decrease in both the flux and the selectivity was observed during 11 days operation. The mechanisms of the facilitated transport of benzene through both types of liquid membrane were proposed. The permeation rate and the selectivity were quantitatively simulated by the proposed model.