Nanofiltration (NF) is a pressure-driven, porous membrane separation process. NF membranes have a pore size on the order of one nanometer and a typical molecular weight cut-off of 300−500 Da. NF membranes are either positively or negatively charged depending on the feed chemistry and the functional groups forming the surface, and their separation performance is governed by the interplay of steric effects (size exclusion), electrostatic effects (Donnan exclusion), and dielectric exclusion. NF membranes are particularly valuable for water softening applications, in which divalent ions are to be removed from polyelectrolytes.

Our group has focused on modeling transport and separation for various NF membranes, in order to learn how to better design and use NF for selective separation processes. Some of these studies have been done in collaboration with membrane fabricators at the Singapore Membrane Technology Center.

Selected Papers on Nanofiltration

Y. Roy and J.H. Lienhard V, “A framework to analyze sulfate versus chloride selectivity in nanofiltration,” Environmental Science: Water Research & Technology, online 21 January 2019, 5(3):585-598, 2019. (OPEN ACCESS) (preprint)

Y. Roy and J.H. Lienhard V, “Factors contributing to the change in permeate quality upon temperature variation in nanofiltration,” Desalination, online 11 January 2019, 455:58-79, 1 April 2019. (doi link) (preprint)

O. Labban, T.H. Chong, J.H. Lienhard V, “Design and Modeling of Novel Low-Pressure Nanofiltration Hollow Fiber Modules for Water Softening and Desalination Pretreatment,” Desalination, online 14 April 2018, 439:58-72, 1 August 2018. (doi link) (preprint)

Predicted effect of pore size on a nanofiltration membrane's ion rejection.

Predicted effect of pore size on a nanofiltration membrane’s ion rejection from a synthetic seawater solution. Negative rejection of Na+ results from requirement of electroneutrality in the permeate (Labban et al., 2018)

O. Labban, C. Liu, T.H. Chong, J.H. Lienhard V, “Relating Transport Modeling to Nanofiltration Membrane Fabrication: Navigating the Permeability-Selectivity Tradeoff in Desalination Pretreatment,” J. Membrane Science, online 6 March 2018, 554:26-38, 15 May 2018. (doi link) (preprint)

Y. Roy, D. Warsinger, and J.H. Lienhard V, “Effect of temperature on ion transport in nanofiltration membranes: diffusion, convection, and electromigration,” Desalination, online 9 Aug. 2017, 420:241–257, 15 Oct. 2017. (doi link) (preprint)

O. Labban, C. Liu, T.H. Chong, J.H. Lienhard V, “Fundamentals of Low-Pressure Nanofiltration: Membrane Characterization, Modeling, and Understanding the Multi-Ionic Interactions in Water Softening,” J. Membrane Sci., online 31 August 2016, 521:18-32, 1 January 2017. (doi link) (preprint)

Y. Roy, M.H. Sharqawy, and J.H. Lienhard V, “Modeling of Flat-Sheet and Spiral-Wound Nanofiltration Configurations and Its Application in Seawater Nanofiltration,” J. Membrane Sci., online 24 June 2015, 493:630-642, 1 Nov. 2015. (doi link) (preprint)