Kinetic investigation and numerical analysis of a “micelle-catalysed” metal complex formation

Abstract

The method for the computation of local ion concentrations in the vicinity of charged surfaces, presented in a preceding paper, is applied to an analysis of the complexation reaction between Ni²⁺(aq) and the bidentate ligand pyridine-2-azo-p-dimethylaniline (PADA) in micellar solutions of sodium-decylsulphate (NaDeS). The kinetics of the reaction are investigated by means of stopped flow and laser flash-photolysis techniques. The rate against surfactant concentration profile can be quantitatively explained in terms of the surface concentrations of the reactants for the entire range of surfactant concentrations. The calculations are performed with the cell-model of polyelectrolyte solutions using a modified non-linearized Poisson–Boltzmann, equation taking into account finite ion sizes and the dependence of the dielectric constant on the electric field strength. An attempt is made to extend this approach to micellar solutions of other surfactants.