Effects Of Dreparation Condition On Forward Osmosis Membrane And Investigation Of Its Application

Reverse osmosis (RO) has played a significant role in solving the water shortage and pollution and been applied to the various walks of life with the benefit of its easily acceptable and stable membranes. Recently, forward osmosis (FO), an osmosis pressure-drived process, has become an alternative technology for water treatment due to the lower energy consumption and characteristic of environmental friendly.In this paper, forward osmosis (FO) membranes based on cellulose triacetate (CTA) were prepared via a Non-solvent Induced Phase separation (NIPS) method. In preparation, acetone, dioxane and N-Methyl pyrrolidone were used as solvents. Methanol, phosphoric acid, TEP and lactic acid were used as additives respectively, and pure water was used as the coagulation medium. Then, membrane structure were optimized by different coagulation conditions.Firstly, casting solution condition was studied, and best solute proportion was obtained. Besides, different ratios of different additives on the preparation of CTA membrane were also investigated. All is to make sure the casting solution uniformity and to knife a flat membrane. Secondly, influence of coagulation conditions were investigated to obtain membranes with best performance. Through these tests, it can be safely concluded that membrane was favoured for FO process at the evaporation time of 15 s and evaporation temperature of 25 ℃ and coagulation temperature of 10 ℃. Under this conditions, membrane has relatively high water flux and salt rejection. Besides, the mean pore size of membrane surface decreased at the annealing temperature of 60-70 ℃. Finally, several draw solutions were investigated to discuss the effects on forward osmosis and the application of removing microcystin. Different draw solutions have different osmotic pressures in FO system. In MgCl2 solution draw solution system, higher water flux was obtained when compared to NaCl and glucose solutions. While, larger salt rejection was obtained in glucose solution. Furthermore, with a bright and promising prospect, the microcystin in daily water usage could be removed by the CTA-based FO process.