PHOTOPUMPING IN LIQUID MEMBRANES CONTAINING PHOTOACTIVE CARRIERS

A steady-state model describing photofacilitated transport in liquid m embranes is used to consider photoactive carriers with a wide range of thermodynamic and kinetic properties in order to investigate active t ransport against a concentration gradient (photopumping). Most experim ental and theoretical studies have focused on systems in which strongl y binding forms of the carrier and carrier-solute complex absorb light to convert to weakly binding forms. For such systems, absorption of l ight can result in transport against a concentration gradient greater than a factor of 5. However, the maximum photoefficiencies are less th an 0.01%. Membranes containing carriers in which the weak forms of the carrier and complex are photoactive exhibit similar photopumping perf ormance with an order of magnitude higher photoefficiencies. This stud y provides guidelines for the selection of carriers for future experim ental investgations of photofacilitated liquid membranes.