Membrane Separation of Structural Isomers by Selective Inclusion Binding.

Structural isomers o-, m-and p-nitrophenols (NPs) were separated by applying selective inclusion binding of cyclodextorin (CD) and selective permeability of ultrafiltration (UF) membrane. Three-component systems are composed of two guest molecules (NPs) and one host molecule (CD). Two-component systems are composed of one guest molecule and one host molecule. UF experiments were carried out for the two systems and the following conclusions were obtained.1. The molecule with stronger inclusion binding in the two-component system have larger relative rejection in three-component systems.2. This means that the separation ability in three-component systems is greater than the one calculated from two-component systems.3. The rise ratio of rejection (η) becomes higher when pH becomes higher, but the selectivity (Si/j) defined by ηi/ηj is nearly constant with pH or both two-and three-component systems.