Ion transport in nanopores with highly overlapping electric double layers*

Investigation of ion transport through nanopores with highly overlapping electric double layers is exceptionally challenging. This difficulty can be attributed to the non-linear Poisson-Boltzmann (PB) equation that governs the behavior of the electrical potential distribution. In this talk, we will show how to simplify PB to a simpler and more universal equation [1], from which we derive an asymptotic solution. We leverage this new solution to address several highly debated issues. We derive the equivalent of the Gouy-Chapman equation for systems with highly overlapping electric double layers. We utilize this new relationship between the surface charge density and the surface potential to determine the power-law scaling of nanopore conductance as a function of the bulk concentrations. We derive the transport coefficients for a pore with overlapping electric double layers and compare them to the renowned uniform potential model. We show that the uniform potential model is only an approximation for the exact solution for small surface charges. The findings presented in this talk are essential to help uncover additional hidden attributes of ion transport through nanopores[2].

[1] Schnitzer and Yariv, Phys. Rev. E 87, 054301 (2013).

[2] Green, J. Chem. Phys. 154, 084705 (2021).