A statistics-based forward osmosis membrane characterization method without pressurized reverse osmosis experiment

A simple forward osmosis (FO) membrane characterization method was developed based on the combination of a single FO test and a statistical approach to avoid the pressurized reverse osmosis (RO) test, which may damage the tested FO membrane or misread the membrane characteristics. The single FO test measures water and reverse solute flux (Jw and Js, respectively) in the active layer facing feed solution (AL-FS) mode using deionized water as feed and sodium chloride as draw solute. The statistical approach finds the most appropriate water permeability (A), salt permeability (B), and the resistance to salt diffusion within the support layer (KICP) of the tested FO membrane to predict Jw and Js using both internal concentration polarization (ICP) and external concentration polarization (ECP) models. Verifications using various experimental results in this work and other literatures reveal that the developed FO membrane characterization method determines more reliable parameters (A, B, and KICP) than the conventional characterization method based on the RO experiment to predict the experimental Jw and Js in FO processes. Consideration of ECP helps to determine more accurate FO membrane parameters (especially KICP), but it is difficult to properly model ECP suitable for the tested FO membrane channel.