CO2/CH4 mixed gas separation using graphene oxide nanosheets embedded hollow fiber membranes: Evaluating effect of filler concentration on performance

Abstract

Graphene oxide (GO) nanosheets-based composite polymeric membranes are being explored for the effective separation of gases owing to hydrophilic nature and abundant oxygen moieties on their surface that attracts the polar gases. In this study, the effect of GO nanosheets concentration on the CO2/CH4 mixed gas separation performance of polysulfone (Psf) hollow fiber mixed matrix membranes (HFMMMs) was examined. The different concentration of GO, i.e., 0.25, 0.5, and 0.75 wt% of the polymer dope solution, was used. Hollow fiber membranes (HFMs) were prepared using dry/wet quench method with water as non-solvent, and physicochemical properties were evaluated. Morphological changes were observed in the Psf/GO HFMMMs. The gas separation performance study of the HFM samples was carried out using pure CO2 and CH4 gases at 1–5 bar transmembrane pressure and 25 ± 2 °C. It was found that HFMMMs with 0.25 wt% GO nanosheets (PG25) showed 137% higher ideal CO2/CH4 selectivity than the pristine HFMs. In case of the mixed gas permeation studies using feed consisting of 50:50 vol% of CO2 and CH4, the PG25 HFMMMs showed 201% higher CO2/CH4 selectivity than that of the pristine HFMs. Moreover, the PG25 HFMMMs showed separation performance stability when they were applied for the long-term stability study. These results indicate that 0.25 wt% GO nanosheets in Psf is the optimum concentration which gives improved CO2/CH4 mixed gas separation performance.