CO2 separation membranes with high permeability and CO2/N2 selectivity prepared by electrostatic self-assembly of polyethylenimine on reverse osmosis membranes

Abstract

CO₂ separation membranes prepared by green, simple, and efficient methods have faced great challenges. In this work, a facilitated transport membrane with high CO₂ permeance and CO₂/N₂ selectivity was prepared by an aqueous self-assembly method using commercially available polyethylenimine (PEI) and reverse osmosis (RO) membranes as the assembled molecule and substrate, respectively. When the PEI concentration was 50 mg L⁻¹, the prepared membranes showed excellent permeability and selectivity. The effects of PEI concentration, pH of electrostatic-assembly and operating conditions on the membrane performance were systemically studied. The prepared membrane was also analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements to determine the adsorption and assembly kinetics of PEI. For CO₂, the facilitated transport mechanism was dominant because of the presence of amine groups from PEI molecules, while N₂ transport was accomplished by a simple solution-diffusion mechanism.