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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster 2

CPP 17.31: Poster

Dienstag, 6. September 2022, 11:00–13:00, P2

Charging of dielectric surfaces in contact with aqueous electrolyte – the influence of CO₂ — •Peter Vogel¹, Nadir Möller¹, Pravash Bista², Stefan Weber², Hans-Jürgen Butt², Benno Liebchen³, and Thomas Palberg¹ — ¹Institut für Physik, Johannes Gutenberg Universität, 55128 Mainz (Germany) — ²Max Planck Institut für Polymerforschung, 55128 Mainz (Germany) — ³Institut für Physik kondensierter Materie, Technische Universität Darmstadt, 3 64289 Darmstadt (Germany)

The charge state of dielectric surfaces in aqueous environments is of fundamental and technological importance. We use super-heterodyne light scattering in a custom-made cell to study the influence of dissolved CO₂ on the charging of three, chemically different surfaces. We compare an ideal, CO₂-free reference state to ambient CO₂ conditions. Systems are conditioned under conductometric control at different low concentrations of NaCl. As expected for constant charge densities, ζ-potentials drop upon increasing the salt concentration in the reference state. Presence of CO₂ leads to an overall lowering of ζ-potentials. Moreover, for the inorganic dielectric, the salt dependent drop is significantly weakened, and it is inversed for the organic dielectrics. We suggest that at ambient conditions, the charge state of dielectric surfaces is related to dielectric charge regulation caused by the salt concentration dependent adsorption/desorption of CO₂.