title: Hydronium-dominated ion transport in carbon-dioxide-saturated electrolytes at low salt concentrations in nanochannels.
abstract: Nanochannel ion transport is known to be governed by surface charge at low ionic concentrations. In this paper, we show that this surface charge is typically dominated by hydronium ions arising from dissolution of ambient atmospheric carbon dioxide. Taking the hydronium ions into account, we model the nanochannel conductance at low salt concentrations and identify a conductance minimum before saturation at a value independent of salt concentration in the dilute limit. Via the Poisson-Boltzmann equation, our model self-consistently couples chemical-equilibrium dissociation models of the silica wall and of the electrolyte bulk, parametrized by the dissociation reaction constants. Experimental data with aqueous KCl solutions in 165-nm-high silica nanochannels are described well by our model, both with and without extra hydronium from added HCl.
authors: Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech Building 345 East, DK-2800 Kongens Lyngby, Denmark.
authors: Kristian Lund
authors: KL
authors: Jensen
authors: Jesper Toft
authors: JT
authors: Kristensen
authors: Andrew Michael
authors: AM
authors: Crumrine
authors: Mathias Bækbo
authors: MB
authors: Andersen
authors: Henrik
authors: H
authors: Bruus
authors: Sumita
authors: S
authors: Pennathur
mesh_terms: D000465:Algorithms; D002245:Carbon Dioxide / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry*; D017136:Ion Transport; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry*; D009861:Onium Compounds / Q000737:chemistry*; D015203:Reproducibility of Results; D012492:Salts / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D009861:Onium Compounds; D012492:Salts; D002245:Carbon Dioxide; C027727:hydronium ion