Mass transport of various membrane configurations in pressure retarded osmosis (PRO)

Recent development of high performance membranes and advanced modeling have moved the pressure retarded osmosis (PRO) technology closer to commercialization. Nevertheless, a PRO model, that combines the aforementioned two aspects for mathematical quantification and comprehensive assessment of the multi-configured membranes, is still lacking. For the first time, we build a universal platform to analytically evaluate the mass transport of various membrane configurations (i.e., flat sheet (FS), single- and double-skinned hollow fibers (HFs)) for PRO processes. The FS model is found to be applicable for single-skinned HF membranes under laboratory testing conditions. The HF curvature effect needs to be removed when comparing the experimentally determined structural parameter among different membrane configurations. For the double-skinned HF membrane particularly of antifouling interest, the high pressure applied in the fiber lumen side deteriorates the transport properties of its additional skin on the shell side. By considering the foulant build-up as an external cake layer, the advantages of the double-skinned configuration can be mathematically confirmed than the single-skinned one when fouling occurs.