Impacts of coating condition on composite membrane performance for CO2 separation

Poly (N,N-dimethylaminoethyl methacrylate)–poly (ethylene glycol methyl ether acrylate) (PDMAEMA–PEGMEA) containing ether oxygen groups and amino groups was synthesized by radical polymerization method. A composite hollow fiber membrane used for CO2 separation was prepared by coating a layer of PDMAEMA–PEGMEA onto a porous polysulfone (PSf) substrate. Three types of PSf hollow fibers from dopes with different polymer concentrations were prepared by phase-inversion method. Their permeances were tested and a fit one with smallest mean pore size was selected as the support substrate of composite membrane. The permeance of the prepared composite membranes to H2, N2, CH4 and CO2 was tested. Coating condition including the polymer concentration of coating solution and number of sequential coatings largely influenced the composite membrane performance for CO2 separation. Their effects on the permselectivity of composite membrane were explored. For the composite membrane prepared under optimal fabrication condition, its CO2 permeance was about 25 GPU with CO2/N2, CO2/CH4 and CO2/H2 selectivities were 45, 20 and 4.1, respectively.