Abstract

Ions transport in nanofiltration (NF) membranes was investigated by means of extended Nernst–Planck (ENP) equation
and Donnan relationship using as main variables, ions strength, membrane charge density, membrane thickness, and with a
permeation flux range of 10−6–10−5 m/s. Four different salt solutions were considered: NaCl, Na2SO4, NaF, and MgSO4. Salt
rejection coefficient is the main index used for analyzing NF performance for both positive and negative charged membranes.
The model calculation showed an excellent agreement with experimental data and high rejection coefficient for Na2SO4 has been
obtained. Donnan effect was the major mechanism of rejection for different salt solutions.