The invention relates to a preparation method of a
nanofiltration membrane with an adjustable
desalination rate. The preparation method is characterized by comprising the following steps: (1) preparing a membrane
casting solution; (2) preparing a hollow
fiber base membrane, namely metering the membrane
casting solution and a core solution, pumping the membrane
casting solution and the core solution into a
spinning nozzle, extruding feed liquid from the
spinning nozzle, enabling the extruded feed liquid to pass through an air gap and enter a coagulating bath, forming hollow membrane filaments through
phase inversion in the coagulating bath, and winding the hollow membrane filaments for later use; and (3) preparing a hollow
fiber nanofiltration composite membrane, namely soaking the wound membrane filaments with pure water, then soaking the membrane filaments in a water phase solution of
polyamine, and carrying out
polymerization reaction on an
oil phase containing a polyacyl
chloride monomer and a water phase
monomer on the surface of the membrane on a
coating machine to form a compact separation
skin layer so as to finally obtain the
nanofiltration membrane. Poly(N-vinylcaprolactam) gel is introduced in the preparation of the base membrane, so that the pore structure of the
ultrafiltration base membrane can be adjusted through temperature, and the surface
pore diameter of the base membrane and the
interfacial polymerization reaction rate in the preparation process of the composite nanofiltration membrane can be adjusted and controlled while the water-phase temperature is realized.