Cm. Chen et al., Comparisons of the effects of pH on the interfacial tension-lowering activity of surfactants Triton X-100 and Triton SP-190, COLL SURF A, 174(3), 2000, pp. 357-365
Citations number
35
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
A comparative study was conducted to investigate the effects of pH on the e
quilibrium and dynamic interfacial tension-lowering activity of a commercia
l splittable surfactant Triton SP-190 and a common surfactant Triton X-100
at the n-pentadecane/water interface. Equilibrium and dynamic interfacial t
ensions at the interface of n-pentadecane/aqueous phase containing surfacta
nts were measured by using a Wilhelmy plate tensiometer and a drop volume t
ensiometer, respectively. It was found that the addition of inorganic acids
did not have an effect on the equilibrium and dynamic interfacial tension-
lowering activity of Triton X-100 at the interface. However, though the equ
ilibrium interfacial tension-lowering activity of Triton SP-190 was not sig
nificantly affected by acids, the dynamic interfacial tension-lowering acti
vity of Triton SP-190 was strongly inhibited at lower pH, resulting in a sl
ower decreasing rate of dynamic interfacial tension. This phenomenon might
be explained by the presence of minor surface-active components in the comm
ercial Triton SP-190 surfactant, which dominate the equilibrium interfacial
tension behavior at the interface and are not affected by acids. Based on
the pH-dependent dynamic interfacial tension data, the percentages of the T
riton SP-190 surfactant split under acidic conditions were then estimated.
Moreover, the influence of pH was considerably enhanced at small adsorption
times and low Triton SP-190 concentrations. (C) 2000 Elsevier Science B.V.
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