Acid-resistant positive charge nanofiltration composite membrane and preparation method thereof

The invention belongs to the technical field of water treatment polymer separation membranes, and particularly relates to an acid-resistant positive charge nanofiltration composite membrane and a preparation method thereof. Immersing the surface of the polysulfone ultrafiltration base membrane into a water phase solution containing polyamine and urea compounds, standing, and removing redundant water phase; then dip-coating an oil phase solution containing multi-element acyl chloride, standing and then drying; and immersing the obtained membrane into a coating solution, standing, washing and drying to obtain the nanofiltration membrane, the total mass concentration of the polyamine and the urea compound is 1%-4%, the polyamine is one or more of diethylenetriamine, triethylene tetramine, tetraethylenepentamine and polyethyleneimine, and the mass concentration of the polyamine is 0.9%-3.9%; the urea compound is one or more of mesylate bicyclic urea, 4-chlorphenyl urea, 1, 3-bis (4-chlorphenyl) thiourea and pheny