274454 Hydrophilic Electrospun Nanofibrous Mat: An Effective Support for High Osmotic Water Flux Thin-Film-Composite Membrane

Wednesday, October 31, 2012: 2:10 PM
408 (Convention Center )
Ngoc Bui, Chemical, Materials & Biomolecular Engineering, University of Connecticut, Storrs, CT and Jeffrey R. McCutcheon, Department of Chemical and Biomolecular Engineering, University of Connecticut, Storrs, CT

Hydrophilic electrospun nanofibrous mat: An effective support for high osmotic water flux thin-film-composite membrane

Nhu-Ngoc Bui, Jeffrey R. McCutcheon*

áDepartment of Chemical, Materials & Biomolecular Engineering and Center for Environmental Sciences and Engineering; University of Connecticut; Storrs, Connecticut, USA

Abstract

Electrospun nanofibers supported polyamide composite membranes have been recently found to be an effective candidate for the next generation of engineered osmosis (EO) membranes [1]. The highly porous nanofibrous supports with interconnected pores structures play a critical role in minimizing the internal concentration polarization effect occurring inside the support layer during osmosis processes. It enables the capability of producing high osmotic water flux using EO technology. In this study, robust thin film composite membranes supported by hydrophilic nanofibers electrospun from blends of polyacrylonitrile (PAN) and cellulose acetate (CA) at different weight ratios were reproducibly fabricated and investigated. These membranes exhibited two to three times higher osmotic water flux than the standard commercial forward osmosis membrane made by Hydration Technology Innovation (HTI). Results shown that the nanofibrous mat is more hydrophilic when more PAN was blended. The contact angles of PAN and CA nanofibrous mats were 69.86▒15.83o and 107.43▒5.60o, respectively. The hydrophilicity of the electrospun nanofibrous supports was found to correlate well with the flux performance of TFC membranes. The more hydrophilic PAN-supported TFC membranes performs the highest average osmotic water flux of 55 L/m2h in pressure-retarded osmosis mode and about 30 L/m2h in forward osmosis mode when using 1.5M NaCl as the draw solution at 25oC. The corresponding reverse salt flux ranged from 0.5 to 2 g/m2h. To the best of our knowledge, these membranes outperformed almost all forward osmosis flat sheet membranes have been reported in open literature. These results suggest that electrospun nanofibrous supported polyamide composite membranes may effectively enable applications like forward osmosis where internal concentration polarization is the performance-limiting factor.

Figure 1. Cross-sectional SEM image of polyamide thin-film-composite (TFC) membrane supported on a polyacrylonitrile (PAN) nanofibrous mat.

Figure 2. Osmotic water fluxes (a) and reverse salt fluxes (b) of TFC membranes supported on nanofibrous mats electrospun from blends of cellulose acetate and polyacrylonitrile at different weight ratios: 80/20, 50/50, 20/80 and pure PAN. Experimental conditions: 1.5M NaCl draw solution, deionized water feed solution, measured volumetric flow rateá of the feed and draw solution were 0.5 lpm, temperature of both feed and draw solution was 25.0▒0.5 oC.

References

[1] N.N. Bui, M.L. Lind, E.M.V. Hoek, J.R. McCutcheon, Journal of Membrane Science, 385-6, 10-19, (2011).


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