Reactivity and Models for Anion Distribution: Specific Iodide Binding to Sulfobetaine Micelles

Abstract

The reaction of I (-) with methyl naphthalene-2-sulfonate (MeONs) is accelerated by the micellized sulfobetaine surfactants N-decyl, N-dodecyl, N-tetradecyl, and N-hexadecyl- N, N-dimethylammonio-1-propanesulfonate. Concentrations of micellar-bound I (-) were determined by using ion-selective electrodes (ISE), and capillary electrophoresis. At low concentrations, I (-) incorporation fits Langmuir isotherms and is related to changes in micellar surface potentials. Rate effects of dilute KI are fitted quantitatively by a pseudophase model that describes I (-) binding in terms of a sorption isotherm, but at higher [KI], where the simple model predicts saturation, rates increase due to electrolyte invasion. This model considers transfer equilibria of both reactants between water and micelles and second-order rate constants in each pseudophase. Estimated second-order rate constants for reaction of MeONs with I (-) in the micellar pseudophase are 3.2- to 3.5-fold higher than the second-order rate constant, k 2w, in water, depending on surfactant structure and assumptions in the treatment.

Exploring the charged nature of supramolecular micelles based on p-sulfonatocalix[6]arene and dodecyltrimethylammonium bromide

“…33,34 Initially, the zeta potential of the C 12 TAB micelle was calculated above the CMC 2 of the free surfactant, where the behavior should be closely related to a solution of C 12 TAB without additives. 33,34 Initially, the zeta potential of the C 12 TAB micelle was calculated above the CMC 2 of the free surfactant, where the behavior should be closely related to a solution of C 12 TAB without additives.…”

“…where Z is the viscosity of the medium, f (kR m ) corresponds to Henry's function, k is the Debye-Hu ¨ckel shielding parameter (m À1 ), R m is the radius of C 12 TAB micelle, and e o and e correspond to the vacuum permittivity and the relative permittivity of the solvent. 33,34 Initially, the zeta potential of the C 12 TAB micelle was calculated above the CMC 2 of the free surfactant, where the behavior should be closely related to a solution of C 12 TAB without additives. In order to proceed with the calculation of zeta potential, we adopted the reported radius value (R m ) of the C 12 TAB micelle of 20 Å.…”

Reactivity in organised assemblies

“…Nome and coworkers 6 studied the S N 2 reaction of methyl napthalenesulfonate with iodide in zwitterionic sulfobetaine micelles at varying total iodide concentration. The authors demonstrated that the electrostatic and ion-specific interactions in sulfobetaine micelles become unimportant if the concentration of the reactive iodide ion is high.…”

Interaction between an organic dye in water and sand packs in a flume system

“…Understanding the properties of the interface is particularly important in organic materials and natural sand because of its abundance in the environment and its potential to bind inorganic and organic pollutants [9][10][11][12][13][14].…”