Electroosmotic flow and ionic conductance in a pH-regulated rectangular nanochannel

Sadeghi, M ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1063/1.4986075
  3. Abstract:
  4. Infinite series solutions are obtained for electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties of long pH-regulated rectangular nanochannels of low surface potential utilizing the double finite Fourier transform method. Closed form expressions are also obtained for channels of large height to width ratio for which the depthwise variations vanish. Neglecting the Stern layer impact, the effects of EDL (Electric Double Layer) overlap, multiple ionic species, and association/dissociation reactions on the surface are all taken into account. Moreover, finite-element-based numerical simulations are conducted to account for the end effects as well as to validate the analytical solutions. We show that, with the exception of the migratory ionic conductivity, all the physicochemical parameters are strong functions of the channel aspect ratio. Accordingly, a slit geometry is not a good representative of a rectangular channel when the width is comparable to the height. It is also observed that the distribution of the electrical potential is not uniform over the surface of a charge-regulated channel. In addition, unlike ordinary channels for which an increase in the background salt concentration is always accompanied by higher flow rates, quite the opposite may be true for a pH-regulated duct at higher salt concentrations. © 2017 Author(s)
  5. Keywords:
  6. Fourier series ; Electrical potential ; Surface reactions ; Channel aspect ratios ; Closed-form expression ; Electric double layer ; Aspect ratio ; Electroosmotic velocity ; Finite fourier transform ; Physicochemical parameters ; Physicochemical property ; Electroosmosis
  7. Source: Physics of Fluids ; Volume 29, Issue 6 , 2017 ; 10706631 (ISSN)
  8. URL: https://aip.scitation.org/doi/10.1063/1.4986075