Preparation method of water and alcohol separating membrane

The invention relates to a preparation method of a water and alcohol separating membrane, and aims to solve the problems that the existing water and alcohol separating technology is complicated in production technology, high-solubility water and alcohol are difficultly separated and a polyvinylamine membrane has low strength and is easy to break in a membrane separation method. The preparation method comprises the following steps: dissolving natural protein fiber to obtain a protein polymer solution, adjusting the pH value of the protein polymer solution with an acid solution, and adding a dispersing agent; and then blending the protein polymer solution and a polyvinylamine solution, performing a crosslinking reaction under a low-temperature condition, and finally performing drying treatment to obtain the water and alcohol separating membrane. The preparation method is very simple; in addition, the water and alcohol separating membrane can separate the high-solubility water from alcohol and can concentrate an