POLYAMPHOTERIC MEMBRANE STUDY .2. PIEZODIALYSIS IN WEAKLY AMPHOTERIC POLYMER MEMBRANES

Piezodialysis in weakly amphoteric polymer membranes is discussed from the viewpoint of non-equilibrium thermodynamics. Succinyl chitosans w ere used as the weak polyampholytes. With varying pH in the outer solu tion, the apparent isoelectric point of the membrane was defined as th e point of zero membrane potential, where solute permeation is much en hanced. Piezodialysis was confirmed from the phenomenological hydrauli c permeability coefficients, reflection coefficients and solute permea bility coefficients of the membrane, which were based on non-equilibri um thermodynamics. Permeation experiments with mixed ion systems were also performed. The permeation behaviour was in accordance with that e xpected for the interactions of ions with polyampholytes in aqueous so lutions. (C) 1996 Elsevier Science Ltd.