Method for preparing a novel guanidine-based composite nanofiltration flat-sheet membrane

A method for preparing a guanidine-based composite nanofiltration (NF) flat-sheet membrane, comprising the following steps:

• 1) pretreatment of a polyethersulfone (PES) ultrafiltration membrane:
• a wet PES membrane is sonicated and then soaked in deionized water for at least 12 hours, and visible moisture on the surface is removed by using a rubber roller;
• 2) preparation of reaction solutions:
• an aqueous phase solution is prepared by using 2-2.5 wt % of 1,3-diaminoguanidine hydrochloride, and an oil phase solution is prepared by using 0.1-0.3 wt % of trimesoyl chloride;
• and
• 3) preparation of a guanidine-based composite NF membrane:
• the aqueous phase solution obtained in step 2) is placed on the surface of said PES ultrafiltration membrane obtained in step 1) and shaken well, the solution pH is promptly adjusted to 11.2-11.5, after 1 minute, the solution is poured out and visible moisture on the membrane surface is wiped, the oil phase solution obtained in step 2) is added rapidly and uniformly, after reacting for 1-2 minutes, the oil phase solution is poured out, the membrane is placed in an oven for drying, the membrane is cooled down at room temperature, then the surface of the guanidine-based composite NF membrane is rinsed with deionized water, and thus the guanidine-based composite NF flat-sheet membrane is obtained.