Effect of Nanopatterning on Concentration Polarization during Nanofiltration.

Lauren M Ward,Steven T Weinman,Barbara G Fickling

doi:10.3390/membranes11120961

Abstract

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.

Highlights

Water scarcity is a challenge that the world is facing and will continue to face as more countries become industrialized [1]
The polyamide NF270 membranes were directly patterned with silicon stamps by thermal embossing, which causes the active and support layers to deform into the pattern shape [10,11]
An established method was used to imprint a line-and-groove nanosized pattern onto a commercial NF membrane to test the hypothesis that nano-sized line-and-groove

Summary

Introduction

Water scarcity is a challenge that the world is facing and will continue to face as more countries become industrialized [1]. Membranes are semi-permeable barriers that are used to purify water in a variety of applications. Many different types of membrane processes are used to purify water. NF and RO membranes, called thin-film composite membranes, are comprised of a polyamide active layer, a support layer, and a non-woven fabric support, and are used to desalinate water. These membranes have different usages due to the differences in their polyamide network structures, and differences in what they reject. Their pore sizes are larger than RO membranes, yet smaller than

Methods

Results

Conclusion