2001/11/30 by René Messina, Rene Messina, Enrique Gonzalez Tovar +4 · 2 citations
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Electrostatics and Colloid Interactions #Geography #Geophysical and Geoelectrical Methods #Physics #Underwater Acoustics Research #Volume (thermodynamics) #cond-mat.soft #cond-mat.stat-mech
paper · pdf · doi:10.1209/epl/i2002-00275-y
published as Europhysics Letters, VOL 60, pp 383-389 (2002) · 7 pages, 3 figs (4 EPS files). To appear in Europhysics Letters
arxiv created 2002/08/05 · openalex publication_date 2002/11/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
In this letter we investigate the mechanism for the overcharging of a single spherical colloid in the presence of aqueous salts within the framework of the primitive model by molecular dynamics (MD) simulations as well as integral-equation theory. We find that the occurrence and strength of overcharging strongly depends on the salt-ion size, and the available volume in the fluid. To understand the role of the excluded volume of the microions, we first consider an uncharged system. For a fixed bulk concentration we find that upon increasing the fluid particle size one strongly increases the local concentration nearby the colloidal surface and that the particles become laterally ordered. For a charged system the first surface layer is built up predominantly by strongly correlated counterions . We argue that this is a key mechanism to produce overcharging with a low electrostatic coupling, and as a more practical consequence, to account for charge inversion with monovalent aqueous salt ions.