abstract |
A composite semipermeable membrane includes a porous support membrane made of a substrate and a porous support layer and a polyamide separation-functional layer disposed on the porous support layer, wherein the zeta potential of the separation-functional layer at pH 6 is −20 mV or lower, and the zeta potential difference between potentials of the separation-functional layer at pH 10 and pH 3 is 25 mV or smaller, and has high water permeability and high salt rejection performance and high acid/alkali durability. |