Tsunetaka Sasaki

Corrections for surface tension measured by Wilhelmy method

In the Wilhelmy method of surface tension measurement it is necessary to correct for (1) the lowering of liquid level caused by the meniscus formation when the liquid touches the hanging plate (meniscus correction) and (2) for the difference between the effective and geometrical peripheral length of the plate (peripheral correction). The application of these two corrections is studied for both water and toluene using a number of hanging glass plates and rods and platinum plates differing in the size and shape of their horizontal cross sections. The following empirical equation was obtained: σPM=σ[1−(sS)][1+(l0L)], where πP M denotes the surface tension corrected for the peripheral and meniscus errors, π is the observed surface tension, S is the surface area of a liquid in a vessel, s and L are the cross-sectional area and peripheral length of the hanging plate and rod, and l0 is the constant for the peripheral correction. The values of l0 are from −0.008 to −0.010 cm for plates, −0.005 cm for triangular rods, and zero for cylindrical rods. These values are independent of the peripheral length and material of the plates or rods.

Solid-Counting of Octadecane-1-H3.

A solid sample of octadecane-1-H3 was found to show a fairly good proportionality of the counting rate to the amount of the sample. Taking account of the synthetic process, nonvolatility, and spreadability of octadecane, this compound offers a possibility of being used as a standard sample for counting the radioactivity of tritium.

The effect of monolayers on surface concentration of solutions under evaporation

Abstract The effect of monolayers on the surface evaporation and the subsequent surface concentration increase of the aqueous solutions was measured by the radiotracer technique. The presence of various kinds of monolayers on water not only retards the evaporation but also affects the concentration especially near the surface of the solution by interfering with the convection current of the underlying water; this produces a decrease in the concentration difference between the surface and bulk of the solution. The effect of monolayers on the surface concentration increase of the solution was correlated with the flow resistance of the monolayer, which was measured by its action against the rotation of a needle floating on the surface. A monolayer of stearic acid of varying flow resistance, controlled by adding aluminum salt to the substrate solution, showed an increase in surface concentration with increase of the flow resistance. The result with a monolayer of cetyl alcohol was similar. This relation is worth noting since in the case of the retardation of evaporation, such a simple relation has been reported not to hold.

Counting of tritium with a thin windowed Geiger-Müller counter tube

A thin film (10-40 μg cm-2) of polycarbonate treated with polyvinyl alcohol was prepared and used as a Geiger-Muller tube window. The counting efficiency of this tube for a tritium sample was 6 to 15% of that for the same source obtained by using the windowless 2π counter. A Geiger-Muller tube of 17 μg cm-2 window thickness proved satisfactory for tritium counting.

Some remarks on the accurate and absolute measurement of surface tension by a vertical plate method

A method for measuring an accurate and absolute surface tension using the so-called vertical plate technique was devised. The apparatus consists of a torsion balance and a glass plate; care was taken to avoid creep of the torsion wire and variation of a torsion constant in order to maintain a sufficient sensitivity. The equation for calculating an absolute surface tension was derived. The method is suited especially for the measurement of the surface tension and its changes over a long period, as shown by the aqueous surfactant solutions.

Some remarks on foaming and defoaming

Zusammenfassung1.Es sind zwei Schaumsysteme von wässerigen Lösungen des Saponins und Butylalkohols photographisch gezeigt. Beim Saponin ist die Schaumhöhe geringer, die Schaumdauer aber beträchtlich länger. Man erkennt daran, daß es zwei Faktoren gibt, die die Schaumbildung beherrschen, nämlich die Schaumfähigkeit und die Schaumbeständigkeit.2.Es sind weiter zwei schaumzerstörende Systeme gezeigt. Der in wässeriger Saponinlösung hergestellte Schaum ist bei Zusatz von einem Tropfen Butylalkohol leicht zu zerstören, während die ganze Lösung, wenn sie wieder geschüttelt wird, stärker schäumt. Die Wirkung des Silikoneschaumzerstörers auf die Saponinlösung ist ganz entgegengesetzt. Man kann daher sagen, daß auch in diesem Falle zwei Faktoren betrachtet werden müssen, um die Wirkung des Antischäumers zu charakterisieren: die schaumzerstörende und die schanmverhindernde Wirkung.3.Ferner wird ein „Schaum-Nichtschaumsystem“ beschrieben, das aus Benzol, Essigsäure und Wasser besteht und in zwei flüssige Phasen getrennt ist. Von zwei verschiedenen Arten des Schüttelns wirkt die eine schaumbildend und die andere -verhindernd. Die im Emulsionstropfen eingeschlossenen Blasen sind photographisch festgehalten.4.Eine fast 100 cm lange Blasenkette läßt sich mit einer besonderen einfachen Glasrohrvorrichtung erzeugen.

Wetting and Solute Adsorption for Paraffin-Aqueous Sodium Stearate System

The wettability of a paraffin surface by an aqueous solution of sodium stearate has been related to the adsorption of sodium stearate onto the solid surface. The contact angle (θ) and the amount of solute adsorption (Γ) at the solid/liquid interface were measured as a function of time for the compact paraffin surface together with the surface tensions of the wetting solutions (σl) and water (σw). A linear relationship was confirmed to hold between σl (1 + cos θ/(θl + σw) and Γi calculated from equilibrium data. The corresponding plots for nonequilibrium data fall near this straight line. The linear relationship is explained by generalizing the Doss and Bartell theories of wetting and by taking into account the fact that the work of adhesion of a solute against a solid surface is affected by the solute retention ΔS on the solid surface.

The electrodialysis of the aqueous solution of surface active agent

SummaryA new electrodialysis method for the study of micelle formation on aqueous solution of surface active substance is proposed. This method has advantages among other procedures using semipermeable membrane, in that (1) the time required for the measurement is far less than that of any other methods, thus the membrane can be practically rendered to be semipermeable for micelles, and (2) it is not essentially required to add an inorganic salt to inhibit the micelle permeation, so we are able to know, without extrapolation, the behavior of surface active substance free from the salt influence. We observed a sharp break point on the dialysis curve, and found that the point corresponded with the accepted CMC value of 7.4 × 10−3 mol/l for sodium dodecyl sulfate.ZusammenfassungEine neue Methode der Elektrodialyse, die für die Erforschung der Mizellbildung in wäßrigen Lösungen grenzflächenaktiver Stoffe geeignet ist, wird vorgeschlagen.Diese Methode hat gegenüber der üblichen mit halbdurchlässiger Membran erstens den Vorteil, daß die erforderliche Meßzeit wesentlich kürzer wird, weil die Bedingung der Semipermeabilität von Membranen praktisch zu verwirklichen ist, zweitens der Zusatz von anorganischen Salzen zu den Lösungen entfällt, wodurch das Verhalten grenzflächenaktiver Stoffe in Lösung ohne Beeinflussung durch ein Salz verfolgt werden kann. Ferner ist am Beispiel von Natriumdodecylsulfat der Knick der Dialysenkurve deutlich erkennbar in Übereinstimmung mit der kritischen Mizellenkonzentration dieser Substanz.

Strong adsorption from highly dilute solution: adsorption of sodium dodecyl sulfate from saturated ammonium sulfate solution

SummaryA method was devised to obtain a correct surface tension vs. equilibrium concentration curve for a very dilute solution of surface active substance, such as sodium dodecyl sulfate dissolved in an aqueous solution of saturated ammonium sulfate, where the decrease of the bulk concentration due to the adsorption is not negligible. Adsorption isotherm was obtained by applyingGibbs adsorption equation to the curve, and the pressure vs. area curve was plotted. The latter plot is in agreement with that directly measured for the spread film on saturated ammonium sulfate solution, the surface pressure of which was obtained by the extrapolation to time zero of the plot of log surface pressure vs. square root of time. The amount of calculated saturation value is in agreement with that directly measured by the radiotracer method. These agreements show the validity of the present method of obtaining surface tension and adsorption isotherms, together with the method of extrapolation to obtain the surface pressure vs. area curve for soluble film.ZusammenfassungEs wurde eine Methode entwickelt, die adsorbierte Menge aus hochverdünnten Lösungen von oberflächen-aktiven Substanzen — Natriumdodecylsulfat in gesättigter Ammoniumsulfatlösung-aus Oberflächenspannungs-Konzentrationskurven zu berechnen. Ferner wurde aus diesen Daten die Oberflfichendruck(F)-Fläche pro Molekül(A)-Kurve konstruiert. Sie stimmt mit derjenigen über-ein, die unmittelbar an Natriumdodecylsulfatfilmen auf der Oberflache gesattigter Ammoniumsulfatlösungen gemessen wurde. Die berechnete Menge im Sattigungswert stimmt gut mit derjenigen dberein, die nach radioaktiver Methode gemessen wurde.

Nonequilibrium electrodialysis of aqueous solution of sodium dodecyl sulfate

SummarySpecial dialysis apparatus was constructed which enabled to trace a short time nonequilibrium dialysis by the continuous measurement of electric resistance of dialyzing solution. The apparatus is particularly suited for the study of the formation of micelles in surfactant solution. The dialysis curves were constructed by plotting the change of electric resistance against dialysis time. The diagrams consisted of a nearly straight line at low concentration and two nearly straight lines above a certain concentration, from which CMC was sharply determined and the constancy of a single ion concentration above CMC was also demonstrated.ZusammenfassungEs wurde ein neuartiger Dialyseapparat entwickelt, der es ermöglicht, die Nichtgleichgewichtsdialyse über kurze Zeiten auszuführen und den Lösungszustand der grenzflächenaktiven Substanzen, die die Mizellen enthalten, genauer zu bestimmen. Die gemessenen Dialysekurven, die die Abhängigkeit des elektrischen Widerstands von der Zeit geben, stellen unterhalb der CMC eine fast gerade Linie dar, während oberhalb der CMC jede Kurve aus zwei geraden Stücken mit einem Knick im Schnittpunkt besteht. Hieraus konnten wir die CMC genau bestimmen und die Konstanz der Zwischenmizellkonzentration feststellen.