Competition between electroosmotic and chemiosmotic flow in charged nanofluidics

摘要: In electrolyte solutions, charged nanoscale pores or channels with overlapping electrical double layers are charge selective, thereby benefiting a wide range of applications such as desalination, bio-sensing, membrane technology, and renewable energy. As an important forcing mechanism, gradient concentration along nano-confinement can drive flow without external field applied pressure difference. this paper, we numerically investigate diffusioosmotic nanoflow, particularly for dilute concentrations (0.01 mM–1 mM), calculate the corresponding fields in nanochannel connecting two reservoirs different salt concentrations—a typical fluidic configuration variety experimental applications. Under parameters, simulation results show that speed inside is linearly dependent on difference between reservoir Δc, whereas direction primarily influenced by three key parameters: length (l), height (h), surface density (σ). Through comparison chemiosmotic (due to ion-concentration difference) electroosmotic (as result induced electric field) components flow, non-dimensional number ( C = h / l λ G C) has been identified delineate directions nanochannel, where λGC characteristic (so-called Gouy–Chapman) associated inversely proportional σ. This critical dimensionless parameter, above help providing feasible strategy control nanochannel.