(730g) Fabrication of Graphene Oxide (GO) Composite Membranes for Organic Solvent Nanofiltration (OSN)

An ultrathin graphene oxide (GO) laminar composite membrane has been fabricated in-house via pressure-assisted filtration. The membrane substrate is a lab-fabricated Matrimid^® membrane crosslinked with 1,6-hexanediamine (HDA) to improve its chemical stability. GO dispersions are centrifuged and diluted before filtration to minimize the defects of the resultant GO selective layer. The morphologies, pore sizes as well as the microstructures of the prepared membranes are characterized by field emission scanning electron microscopy (FESEM), filtration test and position annihilation spectroscopy (PAS), respectively. When being treated with various solvents, the GO laminar composite membrane exhibits good stability in both polar and nonpolar solvents. Experimental results suggest that the Donnan exclusion is less effective in organic solvents than in aqueous system, while the size exclusion and solute-membrane affinity turn out to be the dominant factors in determining separation performance. Some active pharmaceutical ingredients (APIs) and food additives, e.g. tetracycline, roxithromycin, vitamin B12 and lecithin, are used to demonstrate the separation capability of the newly developed membrane in real-life applications. Three 7-day tests of vitamin B12 in isopropanol and ethanol as well as lecithin in hexane also confirm the membrane integrity and separation performance for continuous uses.