(715c) Analysis of Zeolite Contribution to Thin Film Nanocomposite Membrane Reverse Osmosis Performance

Hydrophilic zeolite nanoparticles have been incorporated into polyamides to form thin film nanocomposite (TFN) membranes, which studies show impact their performance and transport properties for reverse osmosis applications¹.  This work has focused on the use of Linde type A zeolite nanocrystals because of their hydrophilicity and ideal pore size (ca 4 angstroms), which is appropriate to allow water molecules but not hydrated ions to pass.  Recent studies of these thin film nanocomposite membranes have shown an increase in permeability while maintaining similar solute rejection levels to their corresponding thin film composites^1-4.  Various hypotheses have been proposed about the mechanism by which zeolites impact TFN membrane performance^1-4; these include that zeolites may act as preferential flow channels for water, zeolites may create defects through the thin film, and that zeolites may alter the structure of the polyamide.

            In this study, we systematically evaluate zeolite loading of TFN membranes.  In particular, we present both TFN seawater performance along with rigorous characterization and quantification of the thin film surface chemistry and structure.  Precise quantification of the zeolite loading of the thin films has been performed with thermal and imaging techniques.  We then compare the results of the TFN membranes with quantified nanoparticle loading to that of the individual components and what is expected theoretically.

References

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A.K., and Jawor, A. (2007). Interfacial polymerization of thin film

nanocomposites: a new concept for reverse osmosis membranes. J. Memb. Sci, 294 (1).

2. Lind, M.L., Ghosh, A.K., Jawor, A., Huang, X., Hou, W., Yang, Y., and Hoek, E.M.

(2009). Influence of zeolite crystal size on zeolite-polyamide thin film

nanocomposite membranes. Langmuir, 25 (17), 10139-10145.

3. Lind, M.L., Jeong, B., Subramani, A., Huang, X., and Hoek, E.M. (2009). Effect of

mobile cation on zeolite-polyamide thin film nanocomposite membranes. J.

Mater. Res., 24 (5), 1624-1631.

4. Lind, M.L., Suk, D.E., Nguyen, T.V. et al. (2010). Tailoring the Structure of Thin Film

Nanocomposite Membranes to Achieve Seawater RO Membrane Performance.

Env. Sci. Tech., 44 (21), 8230-8235.