Zeolite-polyamide thin film nanocomposite membranes: Towards enhanced performance for forward osmosis

Zeolite-polyamide thin film nanocomposite (TFN) membranes were prepared on a polysulfone (PSf) porous substrate tailored for forward osmosis (thin thickness, high porosity, and straight needle-like pores). The TFN membranes were characterized and evaluated in comparison with a thin film composite (TFC) membrane. The incorporation of NaY zeolite nanoparticles in the polyamide rejection layer significantly changed its separation properties. In the range of 0.02-0.1 wt./v% zeolite loading, the incorporation of zeolite-polyamide exhibited enhanced water permeability of membrane likely due to the porous nature of zeolite. However, further increase in zeolite loading led to a reduction in water permeability, possibly as a result of the formation of a thicker polyamide layer. The most permeable TFN membrane (TFN0.1, with 0.1 wt./v% zeolite loading) had a water permeability approximately 80% higher compared to the baseline TFC membrane. The FO water flux followed a similar trend to that of the membrane water permeability. Under all cases evaluated in the current study (0.5-2.0 NaCl draw solution, DI water and 10 mM NaCl feed solution, and both membrane orientations), the membrane TFN0.1 exhibited highest water flux (up to 50% improvement over the TFC membrane). To the best knowledge of the authors, this is the first report on zeolite-polyamide based TFN membranes for FO applications. (C) 2012 Elsevier B. V. All rights reserved.