The invention discloses a preparation method and application of a cross-
basement membrane back-
diffusion in-situ growth ZIF modified polyvinyl
polyamide positively charged
nanofiltration membrane. The preparation method comprises the following steps: firstly,
coating a support membrane by using an organic phase solution containing a trimesoyl
chloride monomer; the preparation method comprises the following steps: preparing a supporting
basement membrane, pouring a mixed
aqueous solution of polyethyleneimine and
zinc nitrate hexahydrate on the supporting
basement membrane to carry out
interfacial polymerization, overturning the supporting
basement membrane after
polymerization, pouring a 2-methylimidazole
aqueous solution on the surface, carrying out cross-
basement membrane in-situ growth of ZIF, and carrying out heat treatment and
alcohol activation on the membrane after growth. According to the method disclosed by the invention, ZIF particles can be more uniformly generated in the membrane, interface gaps caused by MOF agglomeration are avoided, a high-positive-
electricity layer can be prepared by combining a reverse-phase interface
polymerization method in which polyethyleneimine is used as a water-phase
monomer, and the water
permeation flux is greatly improved while high interception of
magnesium ions is maintained; the problem of mutual restriction of permeability and selectivity is solved, the process is simple, and preparation conditions are mild.