fabrication and performance evaluation of mixed matrix membrane comprising pebax and graphene hydroxyl in olefin/paraffin separation

Propylene is a widely used compound in various industrial applications, but its separation from propane, which is often associated with it, remains a significant challenge. among the separation methods, membrane technology, particularly polymeric membranes, offers an attractive solution due to its relatively low cos t and simplicity. in this study, hydroxyl-functionalized graphene (g─oh) nanosheets were used as an additive in a pebax 1657 matrix. the results from fourier transform infrared spectroscopy (ftir) revealed that the interaction between pebax and g─oh is physical, characterized by a shift in some peaks due to hydrogen bonding. the proper dispersion of g─oh in the pebax matrix was confirmed by differential scanning calorimetry (dsc), which also showed an increase in the glass transition temperature (tg), indicating the rigidity of pebax chains in the presence of g─oh. thermogravimetric analysis (tga) results demonstrated that the degradation temperatures (td) of pebax/ g─oh 1 wt.% and pebax/g─oh 2 wt.% membranes were 335°c and 330°c, respectively. a comprehensive gas permeation study, including pure and mixed gas tests at feed pressures of 2, 6, and 10 bar, as well as a long-term stability test, was conducted on the membranes. among all the mmms, pebax/g─oh 1.5 wt.% demonstrated the best gas separation performance, achieving a propylene permeability of 89.8 barrer and a c3h6/c3h8 selectivity of 9.8. additionally, under mixed gas permeation tests (50:50 v/v of c3h6 and c3h8), this membrane exhibited a propylene permeability of 76.3 barrer and a c3h6/c3h8 selectivity of 8.8. finally, the performance of the mmms in c3h6/c3h8 separation was benchmarked against the robeson upper bound curve.