Liquefaction At Nanostructured Graphitic Membranes – Unraveling Instantaneous Relocation (LANGMUIR)

• Applicant: Dr. Peter Dement
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry ; Solid State and Surface Chemistry, Material Synthesis
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 459401588

Carbon nanotubes, graphene oxide, and other nanostructured carbon materials are known to exhibit intriguing mass transfer characteristics, such as ultrafast permeation of water. The so called single-file transport in the carbon nanochannels is attributed to the frictionless flow of hydrogen-bonded molecules and has been widely addressed in separation applications. In particular, water-selective graphitic membranes appear to be promising for breaking aqueous azeotropes and dehydration of organic solvents. Vapor permeation studies have demonstrated that even gas-phase water is capable of the collective transport indicating its facile liquefaction inside the membrane pores. However, the ability of the nanocarbons to pass water vapor has been also revealed to depend on the pressure, the temperature, and the composition of the mixtures to be separated. It is assumed that adsorption and condensation of the vaporous species at the membrane surface precedes their permeation. The ‘LANGMUIR’ projects aims at studying molecular liquefaction in carbon nanomembranes (CNMs) and its impact on the transmembrane diffusion. The structural and transport properties of the model CNMs have been examined before, and in order to measure adsorption isotherms, we propose to implement a new experiment on the basis of polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). The spectral data obtained with water and alcohols will be correlated with our previous results on vapor permeation in free-standing CNMs. Temperature-dependent measurements will be further used to examine the energetics of gas-surface interactions, and experiments with mixtures are expected to shed light on the disruption of the single-file water. In addition, we plan to upgrade our originally designed permeation system to enable transport studies at low temperature. The cryogenic experiments with ammonia and propane will be conducted to show the effect of surface processes on the permeation of condensable gases. As anticipated, the proposed work will bring direct evidence for the recently advanced concept of adsorption controlled permeation (ACP) and allow for validating the kinetic models developed. The ‘LANGMUIR’ project has long-range implications for the membrane, interface, and nanofluidics research.

• DFG Programme: Research Grants