Boosting pervaporation performance by promoting organic permeability and simultaneously inhibiting water transport via blending PDMS with COF-300.

Abstract Recently much endeavor has been devoted to improving pervaporation performances of polydimethylsiloxane (PDMS) membranes for organic aqueous solutions by doping hydrophobic porous particles. However, the strategy generally promotes water permeation as well, which is contrary to the separation purpose but has not caused researchers' attention. Here, a novel strategy was proposed to improve pervaporation performance by promoting organic permeation and simultaneously inhibiting water permeation via doping organophilic porous particles that have hydrogen bonding interaction sites in pore channels. To test this strategy, COF-300 was synthesized and blended with PDMS to form mixed matrix membranes (MMMs). Pore size distribution, FT-IR, XPS and water adsorption results demonstrated the presence of hydrophilic amino and aldehyde groups in COF-300. Meanwhile, the COF-300 exhibited ultrahigh affinity toward furfural with a maximum adsorption capacity of 525.3 mg g−1 at 80 °C. Pervaporation experiments showed that COF-300 promoted permeations of furfural and other organics including aniline, butanol, ethanol and phenol but inhibited water transport. The reduced water permeability was attributed to the hydrogen bonding between water molecule and COF-300, which increased the mass transfer resistance of water molecules. Compared to the pure PDMS membrane, the 8 wt% COF-300/PDMS MMM displayed an increment of 14.1% in furfural permeability but a diminution of 20.0% in water permeability when separating a 1.0 wt% furfural aqueous solution at 80 °C. As a result, an increase of 42.7% in the furfural selectivity was obtained, demonstrating the feasibility of the proposed strategy and the high potential of COF-300 in fabricating MMMs for pervaporation separation of organic aqueous solutions. Graphical abstract Image 1 Highlights • PDMS/COF-300 matrix mixed pervaporation membranes were prepared. • COF-300 greatly enhances furfural solubility in mixed matrix membranes. • PDMS/COF-300 membranes show high permeabilities to organics due to high organo-affinity and open pore channels of COF-300. • Water transport is limited because of hydrogen bonding between water and COF-300. • COF-300 increases furfural/water selectivity by 42.7% of the pristine PDMS. [ABSTRACT FROM AUTHOR]