Evaluating permeability of VOC and greenhouse gases in dense membranes: Insights from solubility parameters and basic molecular characteristics

In our Research Group of Membrane Separations, we investigate how different membrane materials can help remove volatile organic compounds (VOCs) such as benzene, toluene, hexane, etc., from the air. These waste streams often come from fuels, paints, and industrial solvents and can negatively impact human health and the environment.

In this study, we explored various types of polymeric materials (including common barrier materials such as polyethylene and polypropylene and high-performance elastomers such as Pebax^® or silicones) to understand how well they can separate VOCs from gas mixtures using a process called vapor permeation.

To better predict how much VOCs are transported across the membrane during separation, we used physicochemical descriptors – solubility parameters, which help to characterize how organic solvents interact with polymer materials at the molecular level. We found that commonly used Hansen solubility parameters are particularly useful in estimating separation performance relating to structurally different organic compounds and the dominant molecular character of the polymer. For example, hydrophilic PVA membranes demonstrated strong selectivity for alcohols like ethanol, while hydrophobic PDMS showed favorable permeability and selectivity for aromatic VOCs like benzene and toluene.

Moreover, we described how these polymers are permeable and selective for other common gases (N₂, CO₂, CH₄, etc.), proving the critical role of molecular properties such as molecule size and polarity. This extends the predictability of membrane separation in complex gas mixtures, so this research contributes to the development of more efficient technologies for air purification and industrial VOC recovery, with broader applications in environmental protection and sustainable manufacturing.

• Stanovský P., Morávková L., Škvorová M., Hrdlička Z., Dytrych P., Izák P., Esposito E., Jansen J.C.*, Petrusová Z.*: Evaluating permeability of VOC and greenhouse gases in dense membranes: Insights from solubility parameters and basic molecular characteristics. Sep. Purif. Technol. 2025, 366 (27 August), 132697. doi.org/10.1016/j.seppur.2025.132697