Forward osmosis membrane and method of preparing same

A method of preparing for a forward osmosis membrane, comprising:

• (a) preparing an antibacterial modified support mesh:
• the support mesh is hydrophilic non-woven fabrics or polyester screens;
• the polyester mesh is modified by nano-Ag and nano-TiO2;
• the method of preparing is adding nano-Ag 0.1-0.5 wt. % (by weight) and nano TiO2 0.2-1 wt. % (by weight) into a 2-8 wt. % polyvinyl alcohol aqueous solution by weight, performing ultrasonic dispersion to obtain a modified suspension, immersing the support mesh into the suspension, and then drying naturally;
• (b) preparing a casting solution:
• adding hydrophilic polymers into a water-soluble solvent system mixing well to obtain the casting solution;
• (c) coating the casting solution prepared in step (b) on the surface of a glass board covered with the antibacterial modified support mesh made at the step (a) to obtain an initial forward osmosis membrane with a certain thickness;
• (d) treating an external layer of the initial forward osmosis membrane by removing the solvent, and forming a dense skin layer on the external layer to obtain a second initial forward osmosis membrane;
• (e) performing phase separation film formation or interfacial film formation with the second initial forward osmosis membrane to obtain the forward osmosis membrane;
• the average particle size of the nano-Ag is 20 nm;
• the average particle size of nano-TiO2 is 5-10 nm;
• when using a 0.5 mol/L sodium chloride solution by volume as a draw solution, and using a 0.01 mol/L magnesium sulfate solution by volume as a feed solution, the membrane flux can reach 8-13 L/(m2*h), the rejection of the magnesium sulfate is above 97%, the antibacterial rate is above 90%, and the performances of the membrane is not affected even after 10 days of immersion in a eutrophication-rich raw water, after washing to test, its antibacterial capability is still above 90%.