Researchers from the University of Bath and an international team led by KU Leuven have developed a graphene oxide membrane that could make one of the chemical industry’s most energy-intensive separation processes faster, cleaner and more efficient. The technology selectively removes water from isopropanol, a widely used solvent in pharmaceutical manufacturing, electronics production and other industrial applications, without relying on the high temperatures required by conventional distillation.
The membrane separates a mixture containing 90 per cent isopropanol and 10 per cent water, producing a permeate containing approximately 99.6 per cent water. This means that water can be extracted rapidly while most of the isopropanol remains on the original side of the membrane. The results, published in Nature Communications, point to a possible alternative to thermal purification systems that consume substantial amounts of energy and contribute to industrial carbon dioxide emissions.
Chemical separation is a largely invisible part of modern manufacturing, but it has an enormous environmental footprint. Separating mixtures into pure or highly concentrated components accounts for an estimated 10 to 15 per cent of global energy use. Distillation, the dominant method for many solvent purification processes, works by heating a mixture until its components vaporise and condense at different temperatures. Although effective, the process requires continuous heat input and can become particularly demanding when components have similar boiling points.
Isopropanol, also known as isopropyl alcohol, illustrates this challenge. The solvent is used in pharmaceutical processing, electronics cleaning, laboratory work and a wide range of commercial products. It is also increasingly relevant to efforts to develop bio-based chemicals from renewable resources. As demand grows, researchers are looking for ways to purify it with less energy while maintaining the quality required for industrial use.
The new membrane is made from graphene oxide, a carbon-based material consisting of extremely thin sheets. Graphene oxide can form layered structures containing nanoscale channels through which selected molecules move. In this study, the researchers engineered the material by combining conventional graphene oxide sheets with modified variants containing smaller pores. The resulting membrane has a more complex internal architecture than a simple layered film, allowing it to balance transport speed and molecular selectivity.
At the heart of the design is a delicate relationship between pore size, molecular interaction and transport resistance. Channels that are too narrow can restrict movement and slow the process, potentially reducing its practical value. Channels that are too large may allow unwanted molecules to pass through, lowering the purity of the separated product. The researchers therefore created a structure in which some regions provide narrow pathways capable of excluding larger molecules, while other areas interact strongly with water and help it move through the membrane.
This behaviour is linked to the chemistry of graphene oxide. Its surface contains oxygen-rich functional groups that can attract water molecules and make the material hydrophilic. When water encounters the membrane, these chemical sites help it enter and migrate through the nanoscale channels. Isopropanol, which interacts differently with the membrane and has a larger molecular structure in this environment, is preferentially held back. The result is a selective transport process driven by both physical confinement and chemical affinity.
Dr Pengrui Jin, a Prize Fellow and independent principal investigator in the Department of Chemical Engineering at the University of Bath, said the membrane efficiently removes water from the isopropanol mixture while producing a highly concentrated water stream. According to the researchers, the process is faster than existing approaches and requires less energy because it does not depend on high-temperature operation. Unlike distillation, membrane separation can operate through differences in chemical potential and selective molecular transport rather than repeated evaporation and condensation.
The technology could be especially valuable in applications where solvent purification is performed continuously or where heat-sensitive materials are present. Lower operating temperatures may also reduce equipment demands and help limit the formation of unwanted by-products. However, the researchers emphasise that the membrane is still at the development stage. Long-term stability, resistance to fouling, performance at industrial scale and the economics of manufacturing large membrane areas will all need to be assessed before commercial deployment.
The team is now exploring whether the structurally engineered graphene oxide membrane can be adapted to other chemical mixtures. Solvents vary widely in molecular size, polarity and interactions with membrane materials, so a membrane that performs well for isopropanol and water may require further redesign for different systems. If the approach can be scaled successfully, it could provide a more energy-efficient platform for solvent dehydration and contribute to the broader transition toward lower-carbon chemical manufacturing.
Subject of Research: Graphene oxide membrane technology for the energy-efficient separation of water from isopropanol.
Article Title: Solvent dehydration with structurally engineered nanoporous graphene oxide membranes
Web References: https://doi.org/10.1038/s41467-026-72660-w
References: Jiang et al., “Solvent dehydration with structurally engineered nanoporous graphene oxide membranes,” Nature Communications. DOI: 10.1038/s41467-026-72660-w.
Keywords
Graphene oxide, nanoporous membranes, isopropanol purification, solvent dehydration, chemical separation, membrane technology, sustainable chemistry, energy efficiency, chemical engineering, water separation, industrial sustainability, distillation alternatives
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