MIXED AGGREGATION PROCESSES AT THE ELECTRIFIED HG-ELECTROLYTE SOLUTION INTERFACE - THE CASE OF SODIUM DODECYL-SULFATE-TWEEN 80(R), SODIUM DODECYL-SULFATE-CETYLTRIMETHYLAMMONIUM BROMIDE AND TWEEN 80(R)-CETYLTRIMETHYLAMMONIUM BROMIDE COADSORPTION
S. Antoniou et P. Nikitas, MIXED AGGREGATION PROCESSES AT THE ELECTRIFIED HG-ELECTROLYTE SOLUTION INTERFACE - THE CASE OF SODIUM DODECYL-SULFATE-TWEEN 80(R), SODIUM DODECYL-SULFATE-CETYLTRIMETHYLAMMONIUM BROMIDE AND TWEEN 80(R)-CETYLTRIMETHYLAMMONIUM BROMIDE COADSORPTION, Electrochimica acta, 41(16), 1996, pp. 2613-2621
The formation and properties of mixed micellar-like films on the Hg el
ectrode in the presence of two surfactants in the electrolyte solution
is studied by means of differential capacity measurements. The experi
mental data are analysed on the basis of previous theoretical treatmen
ts. It is found that the system sodium dodecylsulphate-cetyltrimethyla
mmonium bromide exhibits two different behaviours: At bulk solutions r
ich in sodium dodecylsulphate a film of mixed aggregates covers the el
ectrode surface from positive polarizations up to -1.6V (see). In cont
rast, at bulk solutions rich in cetyltrimethylammonium bromide the ele
ctrode surface is covered with a bilayer of aggregates composed exclus
ively of cetyltrimethylammonium cations, which negative of -1.2 V (see
) collapses to a condensed layer due to its penetration from dodecylsu
lphate anions. When the electrolyte solution contains sodium dodecylsu
lphate and tween, then under favourable conditions the electrode is co
vered with aggregates of pure dodecylsulphate anions from positive pot
entials up to the first capacitance peak at negative potentials. Negat
ive of this peak and up to the second peak at far negative potentials
the electrode is covered with mixed aggregates rich in tween. Finally,
in the system of tween-cetyltrimethylammonium bromide the electrode i
s covered with a film of mixed aggregates, possibly of variable compos
ition, throughout the range of potentials we studied. Copyright (C) 19
96 Elsevier Science Ltd.