Effect of Nanopatterning on Concentration Polarization during Nanofiltration

Membranes used for desalination still face challenges during operation. One of these challenges is the buildup of salt ions at the membrane surface. This is known as concentration polarization, and it has a negative effect on membrane water permeance and salt rejection. In an attempt to decrease concentration polarization, a line-and-groove nanopattern was applied to a nanofiltration (NF) membrane. Aqueous sodium sulfate (Na2SO4) solutions were used to test the rejection and permeance of both pristine and patterned membranes. It was found that the nanopatterns did not reduce but increased the concentration polarization at the membrane surface. Based on these studies, different pattern shapes and sizes should be investigated to gain a fundamental understanding of the influence of pattern size and shape on concentration polarization.

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Enhancement of concentration polarization due to gel accumulated at membrane surface

Journal of Membrane Science ◽

10.1016/j.memsci.2006.08.007 ◽

2006 ◽

Vol 285 (1-2) ◽

pp. 96-101 ◽

Cited By ~ 9

Author(s):

Sergey P. Agashichev

Keyword(s):

Concentration Polarization ◽

Membrane Surface

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Temperature and Velocity Effects on Mass and Momentum Transport in Spacer-Filled Channels for Reverse Electrodialysis: A Numerical Study

Energies ◽

10.3390/en11082028 ◽

2018 ◽

Vol 11 (8) ◽

pp. 2028 ◽

Cited By ~ 5

Author(s):

Zohreh Jalili ◽

Jon Pharoah ◽

Odne Stokke Burheim ◽

Kristian Einarsrud

Keyword(s):

Mass Transfer ◽

Pressure Drop ◽

Concentration Polarization ◽

Numerical Study ◽

Membrane Surface ◽

Lower Pressure ◽

Low Flow ◽

Fluid Temperature ◽

Reverse Electrodialysis ◽

Flow Velocities

Concentration polarization is one of the main challenges of membrane-based processes such as power generation by reverse electrodialysis. Spacers in the compartments can enhance mass transfer by reducing concentration polarization. Active spacers increase the available membrane surface area, thus avoiding the shadow effect introduced by inactive spacers. Optimizing the spacer-filled channels is crucial for improving mass transfer while maintaining reasonable pressure losses. The main objective of this work was to develop a numerical model based upon the Navier–Stokes and Nernst–Planck equations in OpenFOAM, for detailed investigation of mass transfer efficiency and pressure drop. The model is utilized in different spacer-filled geometries for varying Reynolds numbers, spacer conductivity and fluid temperature. Triangular corrugations are found to be the optimum geometry, particularly at low flow velocities. Cylindrical corrugations are better at high flow velocities due to lower pressure drop. Enhanced mass transfer and lower pressure drop by elevating temperature is demonstrated.

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The Self-diffusion Coefficients of the Ions in Aqueous Sodium Chloride and Sodium Sulfate at 25°

Journal of the American Chemical Society ◽

10.1021/ja01122a050 ◽

1952 ◽

Vol 74 (2) ◽

pp. 446-451 ◽

Cited By ~ 31

Author(s):

Julian M. Nielsen ◽

Arthur W. Adamson ◽

James W. Cobble

Keyword(s):

Sodium Chloride ◽

Diffusion Coefficients ◽

Sodium Sulfate ◽

The Self ◽

Aqueous Sodium ◽

Self Diffusion

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Role of membrane surface in concentration polarization at cation exchange membranes

Journal of Membrane Science ◽

10.1016/j.memsci.2003.12.032 ◽

2004 ◽

Vol 239 (1) ◽

pp. 119-128 ◽

Cited By ~ 79

Author(s):

R Ibanez ◽

D.F Stamatialis ◽

M Wessling

Keyword(s):

Cation Exchange ◽

Concentration Polarization ◽

Membrane Surface

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The Effect of Flow Pulsation on Ultrafiltration System Limiting Flux Behavior

Volume 7B: Fluids Engineering Systems and Technologies ◽

10.1115/imece2013-62514 ◽

2013 ◽

Author(s):

Chyouhwu Brian Huang ◽

Hung-Shyong Chen

Keyword(s):

Membrane Filtration ◽

Concentration Polarization ◽

Membrane Separation ◽

Membrane Surface ◽

Paper Industry ◽

Surface Concentration ◽

Permeate Flux ◽

Filtration Time ◽

Protection Systems ◽

Oil Water

Ultrafiltration (UF) is an important industrial operation and is found in the food industry, separation of oil-water emulsions, treatment effluents from the pulp and paper industry, and environmental protection systems. Despite being widely used in these areas, UF systems exhibit a limiting flux behavior caused by concentration polarization on the membrane surface. Concentration polarization can be severe in macromolecular solutions due to low diffusivity on membrane separation and both mechanical and chemical methods have been used to reduce this phenomenon. This study introduces a new mechanical method that improves the performance of membrane separation and decreases concentration polarization. It involves pulsing the feed flow discontinuously and based on our results, feed flow velocity and solution bypass/membrane filtration time ratio are two vital factors when it comes to improving permeate flux. The proposed method is expected to find wide application, particularly in the processing of macromolecular solution.

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