Preparation, regeneration and application of a chelating microfiltration membrane

A preparation method of a chelating microfiltration membrane, comprising:

• A. preparing a polyvinylidene fluoride flat sheet membrane:
• adding 70-90 parts of a solvent into a reactor, then adding 4-22 parts of a pore-forming agent and 6-16 parts of polyvinylidene fluoride, then dissolving completely to form a casting membrane solution;
• stirring and reacting the casting membrane solution for 1-44 h in the reactor, wherein the reaction temperature is controlled at 50-100° C.;
• wherein the casting membrane solution, after being settled and defoamed, is shaped as a diaphragm by employing a thermally induced phase separation process;
• soaking the diaphragm in distilled water for 1-3 h, and finally drying to produce a polyvinylidene fluoride PVDF flat sheet membrane;
• B. defluorination:
• adding the polyvinylidene fluoride flat sheet membrane obtained in step A and a low concentration alkaline potassium permanganate solution to the reactor, wherein a mass ratio of the flat sheet membrane and the alkaline potassium permanganate solution is 1:20-1:50, with a temperature controlled at 10-100° C., performing the reaction for 1-25 h, and then washing and drying to obtain a defluorinated flat sheet membrane;
• C. grafting glycidyl methacrylate:
• adding the deflourinated flat sheet membrane obtained in step B and a solution of glycidyl methacrylate at a concentration of 0.5-5% to the reactor, wherein a mass ratio of the deflourinated flat sheet membrane and the solution of glycidyl methacrylate is 1:20-1:50, then adding an initiator and a polymerization inhibitor, wherein the temperature is controlled at 10-120° C., and the reaction is performed for 1-25 h, and then washing and drying to obtain a grafted flat sheet membrane;
• D. melamine modification:
• adding the grafted flat sheet membrane obtained in step C and a solution of melamine at a concentration of 0.1-5.0% to the reactor, wherein a mass ratio of the grafted flat sheet membrane and the solution of melamine is 1:20-1:50, with the temperature controlled at 10-120° C., performing the reaction for 1-36 h, and then washing and drying.