Design and Performance of Thin Film Composite (TFC) Membrane for Forward Osmosis (FO) and Pressure Retarded Osmosis (PRO) Applications

A systematic approach used to design and fabricate HTI’s TFC forward osmosis membrane and the resulting performance of the membrane will be discussed.  This design approach resulted in increased flux performance of the FO membranes. Membrane was supported by incorporating an embedded woven support material into the ultrafiltration (UF) support structure prior to the PA deposition.  This design facilitates a reduced thickness of the porous support layer while providing sufficient mechanical stability to utilize existing manufacturing tools and protocols commonly used in the reverse osmosis (RO) industry, which increase the likelihood of its adoption on a large scale.  Overall, the thinner membrane minimizes internal concentration polarization (ICP) and ultimately produces a higher flux membrane while retaining exceptional salt rejection properties comparable to HTI’s commercially available cellulose triacetate membranes.  This membrane design also withstands the applied pressure required for PRO power generation applications and is tolerant to a wide range of pH conditions.

Thorough analysis of membrane characterization coupled with aspects of membrane morphology that lead to optimal performance will be presented along with the relevant FO and PRO performance of the membranes. Pure water permeability (PWP) and molecular weight cut-off (MWCO) of the base UF membrane are determined by normal flow experiments. Dextran of wide molecular distribution is used to determine the MWCO of the base membranes support structure.