Studies On Preparation And Performance Of Cellulose Triacetate Forward Osmosis Membrane

Forward Osmosis (FO) is the transportation of water across a selectively permeable membrane from a region of higher water chemical potential to a region of lower water chemical potential. It is driven by a difference in solute concentrations across the membrane that allows passage of water, but rejects most solute molecules or ions. Due to its inherent advantages, such as low energy expenditure, low membrane fouling, simple configuration and equipments and so on, forward osmosis process was widely extensively studied by scientists in various disciplines of science and engineering. Now, its applications in seawater desalination, wastewater treatment, food and pharmaceuticals processing, controlling drug release, electrical power generation, etc. have showed potential values.However, less attention has been paid to forward osmosis membrane separation process in domestic research and even no report was found on the preparation of FO membranes. So, this paper focuses on the preparation of FO membranes, by phase inversion method, with cellulose triacetate as the membrane materials, in order to examine the influencing factors in the process of preparation in detail. Especially, in view of the important influences of the supporting material on the performance of FO membrane, its structure and property have been researched, such as the thickness, porosity and the hydrophilicity, in search of finding a good performance of support material to make a greater increase of water flux. The experiment showed that the best material was 180mesh polyester mesh. In addition, the effects of the additive content in casting solution and the evaporation time during the process of preparation on the membrane performance were investigated. The result showed that the optimal additive content was 6.6%, the best evaporation time was the longer the better. Meanwhile, the paper compared with the influence factors on the process of RO membrane preparation, in order to provide a reference for FO membrane preparation.Furthermore, the effect of membrane orientation, draw solution concentration and solution flow rate on the performance of FO membrane separation process had been studied. In this study the optimized experimental conditions were the draw solution faced the support layer,4mol/L glucose and the flow rate for the peristaltic pump speed was 100r/h respectively.Finally, the application in desalination of brackish water with different concentrations and the artificial seawater has been studied after determining the suitable operating conditions, with the purpose of providing valuable information for the practical desalination process. At last, this paper investigated the fouling of FO membrane in presence of humic acid, and compared with the fouling of pressure-driven membranes to explore the mechanism of contamination of FO membrane.