Researchers at Korea University have developed a novel method to determine reverse draw and forward feed solute fluxes in a forward osmosis (FO) membrane, in order to analyse FO performance more accurately.
Specifically, the apparent draw solute permeability Bd and feed solute permeability Bf are proposed, instead of relying just on the solute permeability B.
The results clearly demonstrate that neither draw nor feed fluxes are well predicted with the solute permeability B measured in a reverse osmosis (RO) mode experiment, as typically employed in FO membrane characterisation.
In this study, the draw and feed solute permeabilities were evaluated independently by experimental protocols which simulated actual FO operation more closely. Much better agreement between experimental observations and theoretical predictions was obtained when both Bd and Bf were applied for the analysis of draw and feed solute flux, respectively.
Thus, the utilisation of apparent draw and feed solute permeabilities provides more precise assessment of draw solute loss and permeate water quality, which are very important for FO membrane process design and operation.