The invention discloses a functionally gradient
covalent organic framework membrane. The functionally gradient
covalent organic framework membrane is prepared from polyethersulfone and a
covalent organic framework. Preparation steps comprise the following steps: taking 1,3,5-triformylphloroglucinol and hydrazine
hydrate as monomers; carrying out condensation
polymerization reaction in 1,3,5-trimethylbenzene and an
ethanol solvent; washing a product through
tetrahydrofuran,
acetone and
dichloromethane in sequence; then carrying out wet-phase
grinding to obtain the covalent organic framework TpHZ; dispersing the covalent organic framework TpHZ into N,N-
dimethylformamide and mixing with the polyethersulfone to form a membrane
casting solution; adding a certain amount of the volatile
solvent tetrahydrofuran; carrying out steps including scraping, non-
solvent induced phase separation, surface segregation, immersion,
drying and the like on the membrane
casting solution to obtain the functionally gradient covalent organic framework membrane. The functionally gradient covalent organic framework membrane has the advantages of simple and convenient preparation process, strong
controllability, easiness for obtaining the raw materials and
common method. The prepared membrane is used for realizing pervaporization of an
ethanol-water
solution system and has high
permeation flux and
high selectivity on water molecules; the
composite membrane has good operation stability at high temperature.