Ion size effects on the electric double layer of a spherical particle in a realistic salt-free concentrated suspension

Abstract

A new modified Poisson-Boltzmann equation accounting for the finite size of the ions valid for realistic salt-free concentrated suspensions has been derived, extending the formalism developed for pure salt-free suspensions [Roa et al., Phys. Chem. Chem. Phys., 2011, 13, 3960-3968] to real experimental conditions. These realistic suspensions include water dissociation ions and those generated by atmospheric carbon dioxide contamination, in addition to the added counterions released by the particles to the solution. The electric potential at the particle surface will be calculated for different ion sizes and compared with classical Poisson-Boltzmann predictions for point-like ions, as a function of particle charge and volume fraction. The realistic predictions turn out to be essential to achieve a closer picture of real salt-free suspensions, and even more important when ionic size effects are incorporated to the electric double layer description. We think that both corrections have to be taken into account when developing new realistic electrokinetic models, and surely will help in the comparison with experiments for low-salt or realistic salt-free systems.

12 pages, 7 figures

References in corpus (1)

• Electric double layer for spherical particles in salt-free concentrated suspensions including ion size effects

Cited by in corpus (4)

• Ultrafiltration of charge-stabilized dispersions at low salinity
• AC-field-induced Polarization for Uncharged Colloids in Salt Solution: A Dissipative Particle Dynamics Simulation
• Electric double layer of colloidal particles in salt-free concentrated suspensions including non-uniform size effects and orientational ordering of water dipoles
• DC electrokinetics for spherical particles in salt-free concentrated suspensions including ion size effects