Impact of pH-regulated wall charge on the modulation of electroosmotic flow and transport of ionic species through slit nanochannels
Naren Bag
Том 85 №3
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The present article deals with the modulation of electroosmotic flow through narrow confinement. We consider the slit nanochannel in which the channel walls bear pH-regulated charge density, which further depends on the physicochemical properties of the microenvironment. We consider the general diffusive-electromigration-convective model for the transport of ionized liquid. The flow field is governed by the Navier-Stokes equation with an electromotive body force term. The electrostatic potential is governed by the Poisson equation. Going beyond the widely employed Debye-Hu¨ckel approximation, we developed a sophisticated numerical tool based on the finite volume method to simulate the governing non-linear equations in an iterative manner. We further derive closed form expressions for axial velocity and electrostatic potential within the Debye-Hu¨ckel framework, valid for weakly charged cases and for the entire possible range of bulk pH. Such an analytical expression is however useful for the accurate measurement of electrohydrodynamic behavior of flow characteristics across the slit nanochannel.