Effect of electrolyte nature in mass transport of a neutral solute in a microtube with porous wall

Abstract

Electroosmotic flow in a microchannel is an active area in microfluidics. Microchannels with porous wall are advantageous due to selective separation and enhanced mass transport. An economic and innovative method to fabricate hollow microtubes and their application in electrokinetics are illustrated. Effects of asymmetric electrolyte on mass transport of a neutral macrosolute in the microtube with porous wall are investigated. The combined velocity profile including both pressure-driven and electroosmotic flow is modeled for different electrolytes. It is found from the study that the addition of higher valency asymmetric electrolyte (3:1) increases transport of neutral solutes across the porous wall compared to its symmetric counterpart (1:1). The developed model was validated with the experimental results, using a cartridge having hollow microtubes with porous wall. This study would be helpful to select an appropriate electrolyte, improving the design, and performance prediction of microfluidic devices.

Electro‐kinetically enhanced mass transport of charged macro‐solutes through a microchannel with porous walls

“…The above observation is established from the concentration boundary layer profile (Figure 6C) and is in corroboration with the previous reports. 30,39 On the contrary, for the electrostatic repulsion G 1 > 0 ð Þthe wall concentration is lower than the bulk leading to diffusive transport toward the wall (unlike the classical pressure driven membrane transport 40 ). In this state, as the electroosmotic flow is assisting the Poiseuille flow (blue curve, S 1 > 0), the boundary layer thickness is reduced (similar to the case of G 1 < 0).…”

Combined electroosmotic and pressure‐driven transport of neutral solutes across a rough, porous‐walled microtube

“…Several researchers have analyzed the mass transfer phenomenon in microtubes and soft nanochannels having smooth porous wall, under electroosmotic and pressure-driven flows, with both Newtonian and non-Newtonian fluids [26][27][28][29][30]. It may be noted that almost all the aforementioned studies mostly dealt with obtaining the expression of length-averaged Sherwood number and the consequent analysis of the effects of pertinent parameters like channel dimension, Debye parameter, suction velocity, PEL thickness (in the case of soft nanochannels), and so on.…”