Kinetic and mechanistic investigations of [Zn (II)‐Trp] + and ninhydrin in aqueous and cationic CTAB surfactant

Kinetic and mechanistic investigations of [Zn (II)‐Trp] + and ninhydrin in aqueous and cationic cetyltrimethylammonium bromide (CTAB) surfactant have been executed in CH 3 COOH‐CH 3 COONa buffers of pH 5.0. Spectrophotometric as well as conductometric techniques were employed to carry out the study at experimental temperature. The values of rate constant ( k obs in aqueous and k ψ in CTAB surfactant) and binding parameters ( K B for [Zn (II)‐Trp] + and K N for ninhydrin) have been determined by the means of a computer program referred to as linear least squares technique. Fractional‐ and first‐order kinetics were found in ninhydrin and [Zn (II)‐Trp] + , respectively, in aqueous and cationic CTAB. Study was catalyzed and accelerated by CTAB surfactant. An increase in CTAB surfactant concentration from 0 to 45 mmol kg −1 resulted to an increase in k ψ from 2.5 × 10 −5  s −1 to 22.7 × 10 −5  s −1 . Surfactant concentration beyond 45 mmol kg −1 had a slow decreasing effect in k ψ . In order to elucidate CTAB effect on k ψ , a pseudo‐phase model of micelles was applied.