Abstract: Nanofiltration separation has become a popular technique for removing large organic
molecules and inorganic substances from water. It is achieved by a combination of three
mechanisms: electrostatic repulsion,sieving and diffusion. In the present work, a model
based on irreversible thermodynamics is extended and used to estimate rejection of
inorganic salts and organic substances. Binary systems are modeled, where the feed contains
an ion that is much less permeable to the membrane as compared with the other ion. The two
model parameters are estimated by fitting the model to the experimental data. Variation of
these parameters with the composition of the feed is described by an empirical correlation.
This work attempts to describe transport through the nanofiltration membranes by a simple
model.

Key words: diffusion, Donnan equilibrium, electrostatic repulsion, ion adsorption, irreversible thermodynamics, nanofiltration

摘要： Nanofiltration separation has become a popular technique for removing large organic
molecules and inorganic substances from water. It is achieved by a combination of three
mechanisms: electrostatic repulsion,sieving and diffusion. In the present work, a model
based on irreversible thermodynamics is extended and used to estimate rejection of
inorganic salts and organic substances. Binary systems are modeled, where the feed contains
an ion that is much less permeable to the membrane as compared with the other ion. The two
model parameters are estimated by fitting the model to the experimental data. Variation of
these parameters with the composition of the feed is described by an empirical correlation.
This work attempts to describe transport through the nanofiltration membranes by a simple
model.

关键词: diffusion;Donnan equilibrium;electrostatic repulsion;ion adsorption;irreversible thermodynamics;nanofiltration;polymeric membranes;steric hindrance;surface charge , steric hindrance, surface charge