An attenuated total internal reflectance spectroscopy study of ET(30) at the free oil-water interface

https://doi.org/10.1016/0927-7757(94)03018-UGet rights and content

Abstract

Visible attenuated total internal reflectance (ATR) spectroscopy has been used to measure the mean solvent microenvironment at free “oil”-water interfaces using the solvatochromic and acid-base properties of 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridino)phenoxide (ET(30)). From the wavelength maximum of the solvatochromic visible absorption band of ET(30), the effective interfacial dielectric constants of a range of oil-water interfaces have been determined to be ≈8. Titration of the interfacially located probe from high to low pH leads to the creation of a positive electrostatic surface potential which can be largely accounted for using simple Gouy-Chapman theory. Complete agreement, however, is not obtained due to the non-ideal behaviour of ET(30) at the interface as the pH of the bulk aqueous phase is lowered. The relevance of the results obtained to solvent extraction processes are discussed.

References (18)

  • M.B. Lay et al.

    J. Colloid Interface Sci.

    (1989)
  • D.S. Flett et al.

    J. Inorg. Nucl. Chem.

    (1975)
  • J.K. McCulloch et al.

    J. Colloid Interface Sci.

    (1993)
  • R.A. Hall et al.

    Colloids Surfaces

    (1991)
  • K.A. Zachariasse et al.

    J. Phys. Chem.

    (1981)
  • C.J. Drummond et al.

    Faraday Discuss. Chem. Soc.

    (1986)
  • G.G. Warr et al.

    Langmuir

    (1988)
  • J.M. Perera et al.

    Langmuir

    (1992)
There are more references available in the full text version of this article.

Cited by (43)

  • Synthesis of novel betaine dyes for multi chromic sensors

    2019, Journal of Molecular Structure
    Citation Excerpt :

    The solvatochromic phenomenon in hydrogen-bond donor (HBD) solvent depend on specific intermolecular hydrogen bond interactions with the phenolate oxygen atom, whereas in non-HBD solvents, it depends on London dispersion forces and induction forces (nonspecific intermolecular dye to solvent interactions) [47]. Finally, all the dyes showed distinct color changes visible to the naked eye in variable solvents, and therefore have potential in oil analysis, polymer characterization and biological probes [1,48–51]. A theoretical investigation has been performed in order to get further insight into the geometry of the structures, optical properties and electronic configurations of the betaine dyes.

  • Solvatochromic betaine dyes of different hydrophobicity in ionic surfactant micelles: Molecular dynamics modeling of location character

    2018, Colloids and Surfaces A: Physicochemical and Engineering Aspects
    Citation Excerpt :

    The abovementioned molecular probes of the first kind normally serve for determining of the surface electrical potential, Ψ, of micelles [1–7], lipoid monomolecular films [8], and surfactant monolayers on water–air interface [9]; for review of the problem, see ref. [10–12], whereas the second ones allow estimating the polarity of the pseudophase [13–18]. Pyridinium N-phenolate dyes are known as the most powerful solvatochromic indicators [19,20] often used for exploration of oil/water and air/water interfaces [21,22] and micellar solutions, microemulsions, etc. [4,11,12,15,20,23–33], and at the same time they act as acid-base indicators, which is also utilized in the same field of research [4,11,12,34–39]. The general formula and protolytic equilibrium of these dyes is shown in Scheme 1.

  • Extraction kinetics of Fe(III) by di-(2-ethylhexyl) phosphoric acid using a Y-Y shaped microfluidic device

    2014, Chemical Engineering Research and Design
    Citation Excerpt :

    Existence of the dimeric D2EHPA species at the interface should also be questioned. Note, for example, that interfacial dielectric properties differ from those of the bulk solutions (Perera et al., 1995) and so the extent of dimerisation is also expected to differ. Similarly, the presence of higher degrees of bulk extractant polymerisation must be confirmed (Buch et al., 2002).

View all citing articles on Scopus
View full text