Thin film membranes with additives for forward and pressure retarded osmosis

Abstract

A thin film composite or TFC membrane formed by interfacial polymerization of an organic and aqueous phase on a support membrane with nanoparticles in the discrimination layer and / or the support membrane, optimized by the selection of nanoparticles for membrane flux, hydrophilicity and to minimize thickness of the support membrane while maintaining the strength and ruggedness characteristics required for forward osmosis (FO) and / or pressure retarded osmosis (PRO) so that the flux flow paths are less tortuous than conventional support membranes and thereby provide increased flux flow.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application claims the priority of provisional application 61 / 050,572, filed May 5, 2008 and Ser. No.12 / 424,533 filed Apr. 15, 2009, incorporated in herein in full and attached hereto as Appendix A for that purpose.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention is related to thin film composite membranes, which may be called TFC membranes, and more particularly to such membranes used for forward osmosis or FO, for example to purify water, or for pressure retarded osmosis or PRO, for example to generate power from the mixing of salt water and pure water.[0004]2. Description of the Prior Art[0005]RO membranes are often made by interfacial polymerization or IFP of a monomer in a nonpolar (e.g. organic) phase together with a monomer in a polar (e.g. aqueous) phase on a porous support membrane. The support membrane is used for structural support of the IFP membrane during manufacturing and during ope...

AI Technical Summary

Benefits of technology

[0008]The increased pressure in the draw solution resulting from transport of the feed solution across the discrimination membrane into the draw solution may be used. Contaminants from the feed solution may be removed resulting from transport of the contaminants across the discrimination membrane into the draw solution.

Problems solved by technology

However, when IFP RO membranes are used for FO or PRO, the solvent, typically water, and the solute, typically water diluted with inorganic or organic salts, or other soluble molecules, tend to dilute each other and reduce membrane efficiency.

Further, the support membrane, which is used primarily for structural support, reduces water flux to some degree, and the solvent and solute become mixed in solution in the thickness of the support membrane structure including a fabric, further reducing membrane efficiency for both FO and PRO processes.

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