New Membrane Accelerates Purification Of Industrial Solvents

KU Leuven-led international research speeds up separation of water and isopropanol using less energy

An international team led by researchers at KU Leuven has developed a membrane technology that improves the efficiency of purifying widely-used solvents. The researchers found a more efficient way to separate water from isopropanol, a solvent used across the world in the pharmaceutical and electronics industries. The results, published in Nature Communications, offer an alternative to current purification methods that require a 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. One example is the purification of isopropanol, a widely-used solvent in the pharmaceutical and electronics sector. Current purification methods, mainly based on heating and distillation, have a significant impact on both energy consumption and CO_₂ emissions in the chemical industry.

With the growing demand for more sustainable production processes, more efficient separation techniques are essential to continue using isopropanol—also in its bio-based forms from renewable resources—on a large scale. - Professor Bart Van der Bruggen, KU Leuven

Not too small, not too large
The research team developed a new type of membrane based on graphene oxide, a material made of ultra-thin carbon layers. By combining conventional graphene oxide sheets with new variants containing smaller pores, they created an internal structure with two functions: narrow channels that block larger molecules, and regions that attract and allow water to pass through.

The main challenge is to design a structure with channels that are not too small, which would slow down the separation and require more energy, but also not too large, which would reduce the purity of the final product. The new membrane combines both efficient and high-quality separation in a single structure. - Doctoral researcher Lei Jiang of KU Leuven

‘The new membrane efficiently removes water from a mixture containing 90% isopropanol and 10% water. It selectively transports water through the membrane, leaving the isopropanol-rich mixture increasingly dehydrated and therefore more suitable for recovery and reuse. The separated permeate contains about 99.6% water, demonstrating the membrane’s high selectivity for water. In addition, the process is faster than existing techniques and requires less energy, as it does not rely on high temperatures.’ says Dr. Pengrui Jin of the University of Bath.

Broad applicability
‘The membrane delivers gains across the board: purity, energy consumption and economic efficiency,’” says Professor Van der Bruggen. ‘We are eager to test the technology on other chemical mixtures as well.’

With the combination of high levels of purity and a lower energy demand, this new membrane could support the transition toward a more climate-friendly chemical industry. The researchers are currently exploring options to scale up the technology and are assessing the possibility of filing a patent.