Liquid Flow Reversibly Creates a Macroscopic Surface Charge Gradient

Abstract

The charging and dissolution of mineral surfaces in contact with flowing liquids are ubiquitous in nature, as most minerals in water spontaneously acquire charge and dissolve. Mineral dissolution has been studied extensively under equilibrium conditions, even though non-equilibrium phenomena are pervasive and substantially affect the mineral-water interface. Here we demonstrate using interface-specific spectroscopy that liquid flow along a calcium fluoride surface creates a reversible, spatial charge gradient, with decreasing surface charge downstream of the flow. The surface charge gradient can be quantitatively accounted for by a reaction-diffusion-advection model, which reveals that the charge gradient results from a delicate interplay between diffusion, advection, dissolution, and desorption/adsorption. The underlying mechanism is expected to be valid for a wide variety of systems, including groundwater flows in nature and microfluidic systems.

arXiv comment25 pages, 8 figures, Supplementary Information: 21 pages, 7 figures

References in corpus (4)

• The Charge of Glass and Silica Surfaces
• Water orientation and hydrogen-bond structure at the fluorite/water interface
• Liquid-solid slip on charged walls: dramatic impact of charge distribution
• Flow-induced surface charge heterogeneity in electrokinetics due to Stern-layer conductance coupled to reaction kinetics

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