Effect of Nonionic Admixtures on the Adsorption of Ionic Surfactants at Fluid Interfaces. 2. Sodium Dodecylbenzene Sulfonate and Dodecylbenzene

Abstract

Equilibrium surface tension isotherms of sodium dodecylbenzene sulfonate (DDBS) are obtained at various fixed concentrations of NaCl. The contents of unsulfonated dodecylbenzene (DDB) in the used surfactant sample is determined by processing the surface-tension data. Having determined the parameters of the best fit, we computed the adsorption of surfactants (anionic DDBS and nonionic DDB), the binding of counterions in the Stern layer, the surface electric potential, the surface elasticity, etc., each of them for various surfactant and salt concentrations. The results show that for the solutions without added NaCl, the adsorption layer consists mostly of the nonionic DDB, irrespective of its small mole fraction in the surfactant blend. The admixture of DDB in the sample of DDBS leads to a significant increase of the surface elasticity. Moreover, even minimal added amounts of CrCl3 or Fe2(SO4)3 cause a considerable reduction in the surface tension, which is due to the greater binding energies of some of the counterions released by the latter electrolytes. The paper gives a quantitative analysis and description of the adsorption from aqueous solutions of a technical ionic surfactant. The followed strategy, which was to determine the contents of the admixtures and to account for their presence in the theoretical model, rather than to purify the surfactant, may find applications to other mixed surfactant systems.

Efficient Isolation and Solubilization of Pristine Single‐Walled Nanotubes in Bile Salt Micelles

“…As reported recently, DDBS is also very efficient in dispersing the nanotubes, but has considerable disadvantages: for example, DDBS is not available in pure form, and the impurities present are believed to be important to the detergent properties of DDBS [21] (similar effects have been observed for SDS [22] ). Also, the presence of an aromatic ring in this detergent limits its use in spectroscopic investigations.…”

On the mechanism of stomatocyte–echinocyte transformations of red blood cells: experiment and theoretical model

“…The influence of the H + and OH − ions on the membrane tension can be also described by means of equations similar to Eq. (5.10), however, a multicomponent ionic adsorption should be considered, as in [59].…”

“…For the system under consideration, we can expect that the negatively charged ionizable groups on the two membrane surfaces serve as adsorption sites for positively charged cations (K + , Na + , etc.). To describe the counterion adsorption, we will employ the Stern model [54][55][56], which has been found to compare very well with the experiment [57][58][59].…”

“…For the strong binding, the adsorption energy is µ (i) ≈ 9kT, see e.g. Table 4 in [59], which is close to the energy of formation of a weak hydrogen bond between water molecules, 20-25 kJ/mol, that is 8-10kT [60]. For example, such a bond might be -COO − · · · H-O-H, where the carboxilic group belongs to the head of phosphatidylserine, while the water molecule belongs to the hydration shell of a K + ion (or some other cation present in the cell).…”

Electrochemical mineralization of sodium dodecylbenzenesulfonate at boron doped diamond anodes

“…Danov et al [25] had observed that pH had no influence on the CMC value in electrolytic solutions of NaCl at pH 2.5 and 6. In fact, one can conclude also that pH has no influence if the concentrations of sulfuric acid and sodium sulfate are similar.…”