Enhanced performance of polyimide hybrid membranes for benzene separation by incorporating three-dimensional silver–graphene oxide

Abstract

Graphene oxide-Ag nanoparticle composites were prepared through impregnation reduction using different reactants. Transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy analyses were performed to characterize differences in the morphologies of three different Ag–GO composites. Scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry analyses were also applied to evaluate the morphology and thermal stability of the hybrid membranes. Swelling–sorption and pervaporation experiments of benzene and cyclohexane were conducted to evaluate the separation performance of hybrid membranes containing different Ag–GO composites. Results demonstrated that small Ag nanoparticles generated through impregnation reduction using Ag(NH3)2+ and PEG were homogeneously distributed in the hybrid membranes because of moderate reduction rate. The polymide (PI) hybrid membrane exhibited high separation performance. Increase in Ag content in the Ag–GO samples led to the formation of Ag particles on the GO surface; these particles enhanced the separation performance of the hybrid membranes. When Ag-GO samples with 15 mass percent added, the hybrid membrane showed the highest separation performance and its maximum separation factor in the pervaporation experiments reached 35. It is more than three times higher than that of the GO/PI hybrid membrane. Moreover, large Ag particles were formed and aggregated during the preparation and polymerization of Ag–GO samples with high Ag contents; these particles reduced the separation performance of the hybrid membranes.