Researchers develop graphene oxide membrane for faster, lower-energy isopropanol purification

An international team led by researchers at KU Leuven, with contributing authors from the University of Bath, Nanjing University, Huazhong University of Science and Technology and Monash University, has developed a graphene oxide membrane that speeds up the removal of water from isopropanol (IPA), a solvent used worldwide in the pharmaceutical and electronics industries. The results offer an alternative to conventional distillation-based purification, which requires high energy input.

Separating chemical mixtures into pure components is a crucial but energy-intensive process in industrial chemistry, accounting for 10 to 15% of global energy use. IPA, produced globally at over 3.5 million metric tons a year in a market exceeding $6.3 billion, is typically purified from water-laden mixtures using heating and distillation, methods that carry a significant energy and CO2 footprint. The team turned instead to pervaporation, a membrane-based separation technique that bypasses vapor-liquid equilibrium constraints and uses only the latent heat of evaporation. The membrane, termed N-GOm, is built by co-assembling conventional graphene oxide (GO) nanosheets with a newly developed variant, nanoporous graphene oxide (NPGO), whose sheets carry smaller pores and oxygen-rich functional groups that increase water affinity. Combining the two nanosheet types creates an internal structure with two functions: narrow channels that block larger molecules, and hydrophilic regions that attract and transport water. The researchers report that this design raises the DFT-calculated water adsorption energy roughly 2.6-fold and lowers the diffusion energy barrier by about 40% compared with standard GO membranes.

Structural design of N-GOm: GO (gray) and NPGO (blue) nanosheets on a nylon substrate (yellow), forming sp2 graphitic and hydrophilic sp3 domains that create the membrane’s cavity structure. Image credit: Nature CommunicationsSeparating chemical mixtures into pure components is a crucial but energy-intensive process in industrial chemistry, accounting for 10 to 15% of global energy use. IPA, produced globally at over 3.5 million metric tons a year in a market exceeding $6.3 billion, is typically purified from water-laden mixtures using heating and distillation, methods that carry a significant energy and CO2 footprint. The team turned instead to pervaporation, a membrane-based separation technique that bypasses vapor-liquid equilibrium constraints and uses only the latent heat of evaporation. The membrane, termed N-GOm, is built by co-assembling conventional graphene oxide (GO) nanosheets with a newly developed variant, nanoporous graphene oxide (NPGO), whose sheets carry smaller pores and oxygen-rich functional groups that increase water affinity. Combining the two nanosheet types creates an internal structure with two functions: narrow channels that block larger molecules, and hydrophilic regions that attract and transport water. The researchers report that this design raises the DFT-calculated water adsorption energy roughly 2.6-fold and lowers the diffusion energy barrier by about 40% compared with standard GO membranes.

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