Development of a 3D-printed modified Scheludko-cell: Potential application for adsorption and thin liquid film study

A systematic study on the formation of thin liquid films (TLFs) of n-dodecane, as an intervening liquid phase in aqueous surfactant solution, was performed using a modified 3D-printed Scheludko-cell (MSC). The formation and stability of TLFs are electrically detected using the current density-voltage (J-Ψ) characteristics of the system, and it is confirmed by in-situ visualization of TLFs. The conductivity of the TLFs is measured using the J-Ψ curve and resistors in a series model of the system. The induced conductivity of the film is measured for different concentrations of potassium chloride (KCl) and sodium dodecyl sulfate (SDS) aqueous solutions. We monitored an increase in TLF conductivity due to the accumulation of inorganic hydrophilic ions like (K⁺ or Cl⁻) and adsorption of amphiphilic anion of dodecyl sulfate to the interface. The higher rate of increase in the TLF conductivity in the case of SDS is attributed to the ability of amphiphilic ions to pass through a so-called unscreened potential in the vicinity of oil-aqueous solution interface leading to an unscreenable potential at the boundary of the TLF. The predicted adsorption time-scale of surfactants using the MSC cell in ionic liquid (IL) phase, at O/W interface, is found to be in good agreement with the dynamic interfacial tension test results.