Charge Renormalization and Charge Oscillation in Asymmetric Primitive Model of Electrolytes

Abstract

The Debye charging method is generalized to study the linear response properties of the asymmetric primitive model for electrolytes. Analytic results are obtained for the effective charge distributions of constituent ions inside the electrolyte, from which all static linear response properties of system follow. It is found that, as the ion density increases, both the screening length and the dielectric constant receive substantial renormalization due to ionic correlations. Furthermore, the valence of larger ion is substantially renormalized upwards by ionic correlations, whilst that of smaller ions remains approximately the same. For sufficiently high density, the system exhibit charge oscillations. The threshold ion density for charge oscillation is much lower than the corresponding value for symmetric electrolytes. Our results agree well with large scale Monte Carlo simulations. PACS numbers:arXiv:1502.06687v2 [cond-mat.soft]

Describing screening in dense ionic fluids with a charge-frustrated Ising model

“…[23]. However, it may be possible to alter the scaling of the FI model in the overscreened regime via simple modifications such as the introduction of defects in the lattice [11], or creating asymmetry in the charge carriers, either in magnitude or shape [39]. These possibilities will be explored in future work.…”

A multiple decay-length extension of the Debye–Hückel theory: to achieve high accuracy also for concentrated solutions and explain under-screening in dilute symmetric electrolytes

“…24 The leading modes give rise to the oscillatory behavior at high ion densities in accordance with the scenery above. Many other approximate theories for electrolytes also predict such decay modes and the occurrence of the Kirkwood cross-over, for example the Mean Spherical Approximation (MSA), [25][26][27][28][29] the Linearized Modified Poisson-Boltzmann (LMPB) approximation by Outhwaite, 16,30,31 the Modified Debye-Hückel (MDH) approximation by Kjellander, 32 the closely related ''Local Thermodynamics'' (LT) approximation by Hall, 33 the Generalized Debye-Hückel (GDH) approximation by Lee and Fisher, 34,35 the Modified MSA by Varela and coworkers, [36][37][38][39] the charge renormalization theory by Ding et al 40 and the ionic cluster model approach by Avni and coworkers. 41 These theories, from GMSA onwards, are linear approximations, meaning that c i (r) and r i (r) are proportional to the ionic charge q i .…”

“…This equation for k has also been obtained in a different manner by Hall 33 in his LT approximation and recently by Ding et al in their the charge renormalization theory. 40 It can be solved numerically to give k as function of k D and when this solution inserted into eqn (31), one obtains q eff as a function of k D . For low ion densities, where k E k D , eqn (30) agrees with the Debye-Hückel expression (11) for r i , but it differs otherwise.…”

Adsorption isotherms of charged nanoparticles

“…In this sense, we can map weakly charged nanoparticles onto point particles with an effective charge. Since the PB equation works very well for point-like ions, we expect that it will also work reasonably well for our weakly charged nanoparticles which are mapped onto point-like particles with an effective charge [11,32]. Note that in this formalism, the electrostatic correlations between the nanoparticles and the ions are taken into account through the charge renormalization.…”

“…It is well known that salt can modify significantly the interaction between biomolecules in aqueous suspensions, affecting their stability [1][2][3][4][5][6][7][8][9][10][11]. The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory [12] attributes the stability of suspensions to the competition between electrostatic and dispersive, van der Waals (vdW), forces.…”