Abstract
The structure of cylindrical double layers is studied using a modified Poisson Boltzmann theory and the density functional approach. In the model double layer, the electrode is a cylindrical polyion that is infinitely long, impenetrable, and uniformly charged. The polyion is immersed in a sea of equi-sized rigid ions embedded in a dielectric continuum. An in-depth comparison of the theoretically predicted zeta potentials, the mean electrostatic potentials, and the electrode-ion singlet density distributions is made with the corresponding Monte Carlo simulation data. The theories are seen to be consistent in their predictions that include variations in ionic diameters, electrolyte concentrations, and electrode surface charge densities, and are also capable of well reproducing some new and existing Monte Carlo results.
Highlights
Description of the interactions and correlations of large polyions with the small, more mobile ions in the surrounding ionic cloud is of significance in situations ranging from fundamental life processes such as the transport of ions, water, and various molecules across cell membranes, flocculation in colloidal systems [1], industrial polyelectrolytes [2], and the native structure of DNA and various proteins [3,4,5]
Not clearly visible at the scale of the figures, the Monte Carlo (MC), density functional theory (DFT), and modified Poisson-Boltzmann theory (MPB) reveal a non-zero potential of zero charge, which is a consequence of asymmetry in the system
We have done a comparative study of the density functional and the modified Poisson-Boltzmann theories as applied to the restricted primitive model (RPM) cylindrical double layer
Summary
Description of the interactions and correlations of large polyions with the small, more mobile ions in the surrounding ionic cloud is of significance in situations ranging from fundamental life processes such as the transport of ions, water, and various molecules across cell membranes, flocculation in colloidal systems [1], industrial polyelectrolytes [2], and the native structure of DNA and various proteins [3,4,5]. Over the past few decades the planar double layer (PDL) has become synonymous with the electric double layer as it has been the one to have been extensively investigated through theoretical approaches, numerical simulation methods, and experimental techniques (see for example, references [6, 7] for recent reviews) This notwithstanding, other double layer systems, viz., the cylindrical double layer (CDL), the spherical double layer (SDL), and ellipsoidal double layer (ESDL) have been coming under increasing scrutiny in recent years. In this paper we will explore the DFT and MPB theories for a primitive model CDL with a particular emphasis on the comparative behaviour of zeta potentials, density and mean electrostatic profiles visa-vis the Monte Carlo data. Our focus will be on DFT and MPB calculations at different physical states, we intend to do MC simulations for new states
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
