The invention belongs to the field of membrane
pollution control, and particularly relates to a modification method for prolonging the service life and performance of a
pervaporation membrane in
seawater. According to the method, the
pervaporation membrane is soaked in deionized water for treatment, so that anticorrosive substances on the surface of the membrane are stripped, the soaked
pervaporation membrane is pasted in a membrane
assembly, then the membrane
assembly is soaked in a
tannic acid solution for 60 s, and after soaking is finished, the membrane
assembly is taken out. The membrane assembly is taken out, the surface of the membrane is washed with deionized water and then moved into a
ferric chloride solution to be soaked for 60 s, finally, the surface of the membrane is washed with deionized water, so that the
polyphenol coating is successfully attached to the surface of the membrane, and the unique property of the
polyphenol coating becomes the key for prolonging the service life of the membrane; when the PH is lower than 3, most-OH groups in the
tannic acid are protonated, so that the
polyphenol coating is disintegrated and separated from the
pervaporation membrane, and pollutants accumulated on the surface of the membrane are removed at the same time. And subsequently. The surface of the
pervaporation membrane is coated with a new polyphenol coating again, so that the service life of the
pervaporation membrane is prolonged, and the method also has important significance in reducing the treatment cost of desalinated
seawater.