Advanced toluene/n-heptane separation by pervaporation: investigating the potential of graphene oxide (GO)/PVA mixed matrix membrane

The separation and purification of aromatic/aliphatic hydrocarbon mixtures from petroleum feedstocks is a significant industrial undertaking that poses several challenges. This task is commonly encountered during the production of ultralow-sulfur gasoline and naphtha reforming processes, both of which are critical for various industries. Recently, membrane pervaporation for separating aromatic/aliphatic mixtures is regarded as a promising option compared to conventional methods due to its energy efficiency. The preparation of a cross-linked polyvinyl alcohol (PVA) membrane with varying molecular weights, is aimed at effectively separating toluene/n-heptane. To further enhance the separation efficiency, mixed matrix membranes (MMMs) were fabricated by incorporating graphene oxide (GO) at different loadings. The PVA membrane with a molecular weight of 130,000 was utilized as the polymer phase, as it exhibited a permeation flux of 24.8 g/m2h and a separation factor of 5.5. Increasing the GO loading from 0.5 to 1.5 wt% increased total flux; however, further increments in GO content led to a decrease in flux. Notably, the PVA-1.5GO sample demonstrated optimum performance, with a total permeation flux of 30.6 g/m2h, separation factor of 11.9. For this sample, pervaporation separation index (PSI) of 333.54 was obtained, indicating a 199% increase compared to that of pure PVA membrane (111.4).