Res. Chem. Intermed.
, Vol. 27, No. 4,5, pp. 415–423 (2001)
Effect of surfactant micelles on the redox reactions
of cresyl violet
V. B. GAWANDI, S. N. GUHA and H. MOHAN
Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay,
Mumbai 400 085, India
Abstract—Reaction of hydrated electron with cresyl violet (CV) has been studied in different
surfactant micelles using pulse radiolysis technique. This reaction, leading to the formation of
transient semi-reduced species, slows down and the decay of the transient is considerably arrested
in the micellar medium. Interactions of these surfactants have also been studied in both micellar and
pre-micellar regions following the changes in absorption and emission characteristics of cresyl violet.
Among the various surfactants investigated, anionic surfactants, particularly sodium lauryl sulphate
(SLS) and sodium dodecyl benzene sulfonate (SDDBS), show marked effect on these properties.
At surfactant concentrations below and above the CMC, formation of dye-surfactant complex and
micellization of CV are observed, respectively. The association constant, K
, for the formation of
the complex and the binding constant, K
, for the micellization of the dye are determined using
the method of iteration. The environment in terms of dielectric constant experienced by CV inside
the surfactant micelles has been estimated. Results of other surfactants, namely, bis (2-ethylhexyl)
sulfosuccinateNa salt (BSS), cetyl trimethyl ammonium bromide (CTAB) and Triton X-100 (TX-100)
have also been presented.
Cresyl violet, a phenoxazine dye, nds application as a sensitizer in photo-
electrochemical cells wherein its redox reactions play an important role [1, 2].
As a practical system, dye redox devices for harnessing solar energy suffer from
the drawback of very low power conversion ef ciency in homogeneous matrices
[3, 4]. Earlier studies have brought to light the possibilities of improving the cell
performance in a suitable micellar medium , which can have profound in uence
on reaction rates. Semi-reduced species involved as an intermediate in the dye
redox reactions are expected to play an important role in the performance of a
photogalvanic cell. Therefore, it is obvious that any system parameter that can
affect the kinetics of this radical species can have a considerable in uence on the