Azine-linked covalent organic framework-modified GO membrane for high-efficiency separation of aqueous dyes and salts in wastewater

Dyes, salts, microorganisms, and other pollutants found in wastewater can be harmful to the environment and are difficult to treat. To address this problem, we designed and prepared a graphene oxide (GO) membrane that was modified with an azine-linked covalent-organic framework via dipping and polymerization. This membrane could efficiently remove dyes with molecular weight from 319.85 to 1355.37 (removal efficiency greater than 90%), inorganic salts (greater than 80%), and microorganisms (nearly 100%). The maximum flux of the composite membrane can reach 47 L m −2 h −1 bar −1 . The developed membrane was able to carry out its removal effect by utilizing a combination of sieving and electrostatic interactions, showing promising future application prospects. The removal mechanism of the developed membrane is also briefly discussed. Through the sieving action of the membrane, the interaction of ions and the polarity effect, the dye, salt and microorganisms wastewater can be separated efficiently. • A dense GO membrane encapsulated by azine-linked covalent organic framework. • Remarkable performance on the separation of dyes, salts and microorganisms. • Better separation effect and better stability. • Close combination of azine-linked covalent organic framework and GO.