Berlin 2024 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 17: Charged Soft Matter, Polyelectrolytes and Ionic Liquids I
CPP 17.8: Vortrag
Dienstag, 19. März 2024, 11:45–12:00, H 0107
Water harvesting by thermoresponsive ionic liquids — •Robin Cortes-Huerto1, Nancy C. Forero-Martinez2, and Pietro Ballone3 — 1Max-Planck-Institut für Polymerforschung, Mainz, Deutschland — 2Johannes Gutenberg-Universität, Mainz — 3University College Dublin
Ionic liquids (ILs) whose water solutions are thermoresponsive provide an appealing route to harvest water from the atmosphere at an energy cost that can be accessed by solar heating. IL/water solutions that present a lower critical solution temperature (LCST), i.e., demix upon increasing temperature, represent the most promising choice for this task since they could absorb vapour at night when its saturation is highest and release liquid water during the day. In this talk, we present results for the kinetics of water absorption at the surface and the role of nanostructuring in this process as obtained by atomistic molecular dynamics simulations. We focus on the ionic liquid tetrabutyl phosphonium 2,4-dimethylbenzenesulfonate whose LCST in water occurs at Tc = 36 C for solutions of 50/50 wt % composition. The simulation results show that water molecules are readily adsorbed on the IL and migrate along the surface to form thick, three-dimensional islands. On a slightly longer time scale, ions crawl on these islands, covering water and recreating the original surface whose free energy is particularly low. At a high deposition rate, this mechanism allows the fast incorporation of large amounts of water, producing subsurface water pockets that eventually merge into the populations of water-rich and IL-rich domains in the nanostructured bulk.
Keywords: Water harvesting; thermoresponsive mixtures; ionic liquids