Electrocapillary measurements at low concentrations of surfactants: Adsorption of tetrabutylammonium cation

1983 ◽  
Vol 48 (4) ◽  
pp. 964-975 ◽  
Author(s):  
Ladislav Novotný ◽  
Ivan Smoler ◽  
Jaroslav Kůta
Keyword(s):  
Surface Tension ◽  
Maximum Energy ◽  
Tetrabutylammonium Perchlorate ◽  
Adsorption Parameters ◽  
Surface Tension Data ◽  
Frumkin Isotherm ◽  
Low Concentrations ◽  
Drop Time

Using drop-time technique with long drop-times achieved by means of a spindle-type capillary with the combination of a interrupted convection the surface tension data of tetrabutylammonium perchlorate in 0.1 mol l-1 NaClO4 in the concentration range 3 . 10-3 mol l-1 down to 10-7 mol l-1 could be measured. The corresponding adsorption parameters have been evaluated both from Langmuir (for Θ ⪬ 0.8) and Frumkin isotherm. The maximum energy of adsorption amounts to -48.1 kJ . mol-1. The dependence of E vs log c (Yesin-Markov plot) carried out in the concentration range 10-7 to 10-3 mol l-1 showed a S-shaped curve.

Surface behaviour of tetrapropylammonium cation at the mercury/solution interface measured by use of controlled convective adsorptive accumulation

1985 ◽  
Vol 50 (11) ◽  
pp. 2525-2534 ◽  
Author(s):  
Ladislav Novotný ◽  
Ivan Smoler
Keyword(s):  
Surface Tension ◽  
Adsorption Isotherms ◽  
Adsorption Energy ◽  
Surface Coverage ◽  
Adsorption Parameters ◽  
Surface Tension Data ◽  
Solution Interface ◽  
Constant Potential ◽  
Drop Time ◽  
Constant Charge

Using drop time technique with long drop times and a controlled convection of the solution the surface tension data of Hg with tetrapropylammonium perchlorate in 0.1 mol l-1 NaClO4 in the concentration range 4 . 10-6 - 3 . 10-3 mol l-1 have been obtained. The corresponding adsorption parameters have been evaluated from the Frumkin isotherm both at constant potential E and at constant charge q. Both E and q could be chosen as an independent electrical variable. The maximum free adsorption energy amounts to approx. -36.5 kJ mol-1. The congruence of adsorption isotherms with respect to E and with respect to q was very well fulfilled for the surface coverage Θ ⪬ 0.6-0.7.

Studies of a Mixed Adsorption Layer of Butan-1-ol and o-Toluidine on Mercury Electrode

2002 ◽  
Vol 67 (11) ◽  
pp. 1579-1588 ◽  
Author(s):  
Dorota Sieńko ◽  
Dorota Gugała ◽  
Jolanta Nieszporek ◽  
Joanna Jankowska ◽  
Jadwiga Saba
Keyword(s):  
Thermodynamic Analysis ◽  
Adsorption Layer ◽  
Supporting Electrolyte ◽  
Mercury Electrode ◽  
Interaction Constant ◽  
Repulsive Interaction ◽  
Surface Excess ◽  
Adsorption Parameters ◽  
Frumkin Isotherm ◽  
Adsorption Layers

The results of thermodynamic analysis of o-toluidine adsorption on a mercury electrode in the presence of various butan-1-ol amounts complete our previous studies on properties of mixed adsorption layers of toluidine isomers-butan-1-ol. The values of the relative surface excess Γ'°T obtained for o-toluidine show that adsorption of this compound decreases with increasing of butan-1-ol concentration. Analysis of adsorption parameters derived from the Frumkin isotherm indicates that in the presence of 0.33 M BuOH in 1 M NaClO4 with adjusted pH 3 as supporting electrolyte, ∆G0 values for o-toluidine are the highest and, at the same time, the strongest repulsive interaction occurs. In the presence of 0.11 M butan-1-ol, smaller values of ∆G0 for o-toluidine correspond to weaker repulsive interaction. Therefore the change of the Γ'°T value for o-toluidine as a function of butan-1-ol concentration is the result of mutual changes of ∆G0 and interaction constant A between adsorbate molecules.

Probing Inclusion Complexes of Pentoxifylline and Pralidoxim inside Cyclic Oligosaccharides by Physicochemical Methodologies

2019 ◽  
Vol 233 (8) ◽  
pp. 1109-1127
Author(s):  
Biraj Kumar Barman ◽  
Kanak Roy ◽  
Mahendra Nath Roy
Keyword(s):  
Surface Tension ◽  
Free Energy ◽  
Inclusion Complexes ◽  
Apparent Molar Volume ◽  
Nmr Spectra ◽  
Drug Delivery Systems ◽  
Surface Tension Data ◽  
H Nmr ◽  
Ft Ir ◽  
Inclusion Phenomena

Abstract Structurally different Molecules namely Pentoxifylline and Pralidoxim were chosen along with α-cyclodextrin and β-cyclodextrin to study host-guest inclusion phenomena. The formations of host guest inclusion complexes were confirmed by studying 1H-NMR spectra, FT-IR spectra, apparent molar volume and viscosity co-efficient. The stabilities of inclusion complexes were compared calculating the binding constant from UV-VIS spectroscopic study. The 1:1 stoichiometry of the inclusion complexes were also determined by analysing the Jobs plot and surface tension data. The values for Gibbs’ free energy were found negative for both the processes. Based on all the above experiments the inclusion processes were found feasible for both the compounds. These types of inclusion complexes are of high interest in the field of research and industry as these are used as drug delivery systems.

scholarly journals Influence of Magnetic Field on Evaporation Rate and Surface Tension of Water

2018 ◽  
Vol 2 (4) ◽  
pp. 68 ◽  
Author(s):  
Emil Chibowski ◽  
Aleksandra Szcześ ◽  
Lucyna Hołysz
Keyword(s):  
Magnetic Field ◽  
Surface Tension ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Evaporation Rate ◽  
Water Evaporation ◽  
Water Molecules ◽  
Surface Tension Data ◽  
Ring Magnet ◽  
The Magnetic Field

Using neodymium ring magnets (0.5–0.65 T), the experiments on the magnetic field (MF) effects on water evaporation rate and surface tension were performed at room temperature (22–24 °C). In accordance with the literature data, the enhanced evaporation rates were observed in the experiments conducted in a period of several days or weeks. However, the evaporated amounts of water (up to 440 mg over 150 min) in particular experiments differed. The evaporated amounts depended partially on which pole of the ring magnet was directed up. The relatively strong MF (0.65 T) caused a slight decrease in surface tension (−2.11 mN/m) which lasted longer than 60 min and the memory effect vanished slowly. The surface tension data reduced by the MF action are reported in the literature, although contrary results can be also found. The observed effects can be explained based on literature data of molecular simulations and the suggestion that MF affects the hydrogen bonds of intra- and inter-clusters of water molecules, possibly even causing breakage some of them. The Lorentz force influence is also considered. These mechanisms are discussed in the paper.

scholarly journals Adsorption Parameters and Surface Species in the Nickel—Molybdenum Alumina System

1989 ◽  
Vol 6 (4) ◽  
pp. 192-211 ◽  
Author(s):  
R.A.E. Rodriguez ◽  
G.J. Siri ◽  
C.V. Cáceres ◽  
H.J. Thomas
Keyword(s):  
Nickel Content ◽  
Catalyst System ◽  
Atomic Ratio ◽  
Convincing Evidence ◽  
Intrinsic Activity ◽  
Adsorption Parameters ◽  
Low Concentrations ◽  
Thiophene Conversion ◽  
High Concentrations ◽  
Molybdenum Concentration

Isotherms corresponding to the adsorption of ammonium heptamolybdate solutions on nickel–alumina supports have been studied. Such isotherms exhibit two distinct adsorption regions, with both the support and the adsorbed species contributing to their formation. Two types of site are available for adsorption on the support and, depending on the molybdenum concentration present in solution, either monomeric (at low concentrations) or polymeric molybdenum species (at high concentrations) are formed and adsorbed. Monomer adsorption occurs at low concentrations, whereas polyanion adsorption predominates at high concentrations; the latter is reflected in an abrupt increase in molybdenum concentration adsorbed on the support. The adsorption isotherms measured at 20°C and 50°C, and TPR and XPS studies indicate that the samples prepared at 50°C contain a lower quantity of octahedral molybdenum, although dispersion of the molybdenum on the surface is higher. In addition, a direct relationship exists between the dispersion of the active component and the hydrodesulphurization activity of the sample. The presence of nickel on the support does not affect the total number of sites occupied by molybdenum. However, when the nickel content on the solid is increased, the molybdenum species occupy a higher proportion of octahedral sites. XPS studies have shown that samples with a higher nickel content possess a better dispersion of molybdenum species and exhibit a higher intrinsic activity. Enhanced molybdenum dispersion and thiophene conversion was associated with samples in which molybdenum adsorption occurred before nickel impregnation. For all the series studies, the maximum value in the intrinsic acitivity occurred at the same value of the Ni/Mo atomic ratio. This provides convincing evidence that the precursor ratio is important in this catalyst system.

scholarly journals Modeling the surface tension of complex, reactive organic–inorganic mixtures

2013 ◽  
Vol 13 (21) ◽  
pp. 10721-10732 ◽  
Author(s):  
A. N. Schwier ◽  
G. A. Viglione ◽  
Z. Li ◽  
V. Faye McNeill
Keyword(s):  
Surface Tension ◽  
Organic Compounds ◽  
Atmospheric Aerosols ◽  
Goodness Of Fit ◽  
Cloud Droplet ◽  
Aqueous Mixtures ◽  
Surface Tension Data ◽  
Inorganic Systems ◽  
Experimental Surface ◽  
Using Data

Abstract. Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as heterogeneous reactivity, ice nucleation, and cloud droplet formation. We present new experimental data for the surface tension of complex, reactive organic–inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2–6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two semi-empirical surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well described by a weighted Szyszkowski–Langmuir (S-L) model which was first presented by Henning et al. (2005). Two approaches for modeling the effects of salt were tested: (1) the Tuckermann approach (an extension of the Henning model with an additional explicit salt term), and (2) a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2) for surface tension modeling of aerosol systems because the Henning model (using data obtained from organic–inorganic systems) and Tuckermann approach provide similar modeling results and goodness-of-fit (χ2) values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

Quantitative Prediction of the Suppression of Drug-Induced Hemolysis by Cyclodextrins from Surface Tension Data

Langmuir ◽  
1999 ◽  
Vol 15 (2) ◽  
pp. 594-599 ◽  
Author(s):  
Noriaki Funasaki ◽  
Mariko Ohigashi ◽  
Sakae Hada ◽  
Saburo Neya
Keyword(s):  
Surface Tension ◽  
Quantitative Prediction ◽  
Drug Induced ◽  
Surface Tension Data

scholarly journals Theoretical Study of a Thermophysical Property of Molten Semiconductors

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Fathi Aqra ◽  
Ahmed Ayyad
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
High Temperature ◽  
Theoretical Calculation ◽  
Theoretical Approach ◽  
Theoretical Study ◽  
Molten Silicon ◽  
Surface Tension Data ◽  
Silicon And Germanium ◽  
Calculated Temperature Dependence

This paper deals with theoretical approach to surface tension of molten silicon and germanium, and contributes to this field, which is very important. A theoretical calculation for determining the surface tension of high-temperature semiconductor melts, such as molten silicon and germanium, in the temperature range 1687–1825 K and 1211–1400 K, respectively, is described. The calculated temperature-dependence surface tension data for both Si and Ge are expressed as and (mJ m−2), respectively. These values are in consistence with the reported experimental data (720–875 for Si and 560–632 mJ m−2 for Ge). The calculated surface tension for both elements decreases linearly with temperature.

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