Adsorption Kinetics of C₁₂E₄ at the Air−Water Interface:  Adsorption onto a Fresh Interface

Abstract

The adsorption of C12E4 onto a fresh air-water interface was investigated by using video-enhanced pendant bubble tensiometry. From the comparison between the equilibrium surface tension data and the theoretical relaxation profiles predicted by the Frumkin adsorption isotherm, the adsorption process was found to be anticooperative. Dynamic surface tension data for C12E4 molecules absorbing onto a freshly created air-water interface for different bulk concentrations were used for the determination of the controlling mechanism and the evaluation of diffusivity. Comparison was made for the entire relaxation period of the surface tension data and the model predictions. It is concluded that the adsorption process is of diffusion control and the diffusion coefficient is 6.4 × 10 -6 cm 2 /s. The lower limit of the adsorption rate constant of C12E4 were obtained from the theoretical simulation. Besides, the pendant bubble, at which the interface had reached the equilibrium state, was expanded rapidly and a relationship between surface tension (γ) and surface area (A) was obtained. A curve relating γ and relative surface concentration Γ/Γref was obtained from the γ-A data and then used to examine the adsorption isotherm utilized in this study.

Surface Rheology Parameters of Source-Specific Surfactant Films as Indicators of Organic Matter Dynamics

“…Values of D for linear molecules are reported to be some 30% greater than that for substances of spherical molecules (Hsu et al, 2000). It should be pointed out that for salt-free ionic surfactant solutions electrostatic interactions are demonstrated to drastically affect the adsorption kinetics (Diamant & Andelman, 1996).…”

Adsorption Behavior of Oxyethylated Surfactants at the Air/Water Interface

“…activity at low concentrations and an unusual shape of the surface tension isotherms completely incompatible with the Langmuir model. Equilibrium surface and interfacial tension of oxyethylated alcohols (C n EO m ) was studied by different authors and were reported in many papers (13)(14)(15)(16)(17)(18)(19)(20)(21)(22).…”

Pattern search methods for pendant drops: Algorithms for rapid determination of surface tension and surfactant transport parameters

“…Then Eq. (8) must be iterated to find eq for that range [19]. The red + shows the equilibrium value found using the pattern search algorithm.…”

“…The sets include two pendant drops and one pendant bubble study: aqueous sodium oleate (SO) drops in mineral oil, aqueous sodium dodecyl sulfate (SDS) drops in mineral oil, and air bubbles in aqueous C 12 E 4 [19]. We also include two historical studies involving aqueous SDS in air [20,21] where equilibrium surface tension values are determined by foaming [22] and du Noüy ring [23] methods.…”

“…The constant m changes value depending on the surfactant where non-ionic surfactants have a value of m = 1 while 1:1 ionic surfactants require a value of m = 2 to account for the species generated by dissociation [16][17][18][19]. Using these two equations it is possible to predict how eq varies with C s for given K eq , ∞ and .…”