Hafnia ceramic nanofiltration membranes - Part II. Modeling of pressure-driven transport of neutral solutes and ions

We use the hindered transport theory for neutral solutes and the macroscopi c homogeneous electro-transport theory for ions to predict without any adju stable parameters the limiting rejection of, respectively, four neutral mol ecules and five binary electrolytes by granular porous hafnia nanofilters. Membrane parameters entering into the theory, namely the membrane effective pore size and effective charge density, are estimated from independent mea surements performed on the membrane material. The theory is in reasonably g ood overall agreement with the rejection measurements performed on hafnia n anofilters using uncharged sucrose and PEG (400, 600, 1000) molecules and 1 0(-3) M electrolytes (NaCl, NaNO3, CaSO4, CaCl2, and Na2SO4) at acidic, neu tral, and basic pH values (3, 6, and 9). (C) 2000 Elsevier Science B.V. All rights reserved.