(231g) Effect of Membrane Structure on the Performance of Nanofiltration Hollow Fiber Membrane Used in Forward Osmosis

Based on the natural diffusion of water that permeating through a semi-permeable membrane from a solution with low osmotic pressure to another solution with high osmotic pressure, forward osmosis (FO) employs the osmotic pressure gradient to induce a net flow of water through the membrane into the draw solution (with high osmotic pressure), which can effectively separate the water from dissolved solutes. FO can be realized under low pressure and low temperature instead of employing high hydraulic pressure as the driving force for separation in the reverse osmosis process or high temperature in distillation. The main advantages of using FO in seawater/brine desalination are that FO membrane has high rejection to a wide range of contaminants, and it may have a lower membrane fouling propensity than other pressure-driven membrane processes together with the low energy cost. The membranes used in FO process play a vital role on the FO performance of separation and productivity. Up to now, the membranes used in almost all FO processes are available commercial reverse osmosis membranes. It is necessary to develop special FO membranes that can adapt for the forward osmosis application. Nanofiltration membranes may have potential applications in the realization of FO for their tunable molecular-size pores on the selective layer to reject larger molecules, such as salts, sugars, starches, proteins, viruses, bacteria, and parasites. In this study, hydrophilic polybenzimidazole hollow fiber membranes through dry-jet wet phase inversion and its modified patterns were fabricated with different structures, for instances, wall thickness, microstructure and porosity in order to investigate the effects of membrane morphology on the membrane performance during FO process. It has been acknowledged that the support layer structure have the important effect on the water transport due to the serious internal concentration polarization in the porous support layer.