TY - JOUR
T1 - Combined viscoelectric and steric effects on the electroosmotic flow in a microchannel under induced high zeta potentials
AU - Jimenez, E.
AU - Escandón, J.
AU - Méndez, F.
AU - Bautista, O.
N1 - Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2017/10/20
Y1 - 2017/10/20
N2 - Although the concepts of steric and the viscoelectric effects in the analysis of electrokinetic flows have been studied previously in nanochannels (Hsu et al., 2016), in the present work, their influence is extended to microchannels. The governing equations of Bikerman's Modified Poisson–Boltzmann (MPB) equation and the momentum conservation equation are solved numerically for an electroosmotic flow of a Newtonian fluid in a microchannel. Here, the excluded volume of the crowding of ions via steric factor is considered when high ionic concentration and large effective ionic size of the buffer solution are taken into account; also, the viscoelectric effect is present when high zeta potentials are induced and controlled by shielding electrodes at the walls of the microchannel. The results show a significant competition of the studied effects within the thin electric double layer, modifying the predictions from the classical velocity profiles of electroosmotic flows where the mentioned effects are not considered. It is reported that increasing the magnitude of the zeta potentials does not necessarily increase the volumetric flow rate as determined from the classical Poisson–Boltzmann (PB) theory. To validate the numerical solution, an approximate analytical solution for the velocity field for slightly high zeta potentials was determined.
AB - Although the concepts of steric and the viscoelectric effects in the analysis of electrokinetic flows have been studied previously in nanochannels (Hsu et al., 2016), in the present work, their influence is extended to microchannels. The governing equations of Bikerman's Modified Poisson–Boltzmann (MPB) equation and the momentum conservation equation are solved numerically for an electroosmotic flow of a Newtonian fluid in a microchannel. Here, the excluded volume of the crowding of ions via steric factor is considered when high ionic concentration and large effective ionic size of the buffer solution are taken into account; also, the viscoelectric effect is present when high zeta potentials are induced and controlled by shielding electrodes at the walls of the microchannel. The results show a significant competition of the studied effects within the thin electric double layer, modifying the predictions from the classical velocity profiles of electroosmotic flows where the mentioned effects are not considered. It is reported that increasing the magnitude of the zeta potentials does not necessarily increase the volumetric flow rate as determined from the classical Poisson–Boltzmann (PB) theory. To validate the numerical solution, an approximate analytical solution for the velocity field for slightly high zeta potentials was determined.
KW - Electroosmotic flow
KW - High zeta potentials
KW - Steric effect
KW - Viscoelectric effect
UR - http://www.scopus.com/inward/record.url?scp=85020868822&partnerID=8YFLogxK
U2 - 10.1016/j.colsurfa.2017.04.081
DO - 10.1016/j.colsurfa.2017.04.081
M3 - Artículo
SN - 0927-7757
VL - 531
SP - 221
EP - 233
JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects
JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects
ER -