A rapid method for determining the lowering of tension of exposed water surfaces, with some observations on the surface tension of the sea and of Inland waters

Ordinary methods of determining surface tension require a certain amount of apparatus and time, and often disturb the surface, thereby altering the tension of a water surface covered by a film of oil. As it was desired to make a number of observations on the amount of invisible contamination on the sea, a method depending on the spreading power of drops of mixtures of different fatty substances has been worked out. An oil will just spread against an amount of contamination which lowers the tension by an amount equal to the spreading force, or “spreading coefficient”, of the oil. Pure long chain hydrocarbon oils do not spread on clean water; if small amounts of substances containing water-attracting groups in the molecule are dissolved in the hydrocarbon, spreading occurs, the spreading force depending on the amount of the second substance with the water-attracting group, in the solution. The theory has been treated particularly thoroughly by Langmuir (1933); this paper is, however, concerned only with the application of solutions of different concentrations of a substance such as dodecyl alcohol, in a pure, rather heavy, hydrocarbon oil, to the determination of the surface tension of either fresh or salt water. It is found that the behaviour of a single drop of each of three or four such solutions, observed for half a minute or so, indicates the value of the surface tension within an accuracy of 1 dyne/cm. Calibration against water surfaces with oily contamination depressing the tension by known amounts is of course required; this is however quickly done, once for all, and it is possible to find substances for the spreading solutions which behave similarly on waters differing widely in acidity and in salt content.

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Investigational Studies on Quantity of Salinity in Netravati River Estuary Sand-Coastal Karnataka

International Journal of Emerging Research in Management and Technology ◽

10.23956/ijermt.v6i6.243 ◽

2018 ◽

Vol 6 (6) ◽

pp. 46

Author(s):

Raveesha P ◽

K. E. Prakash ◽

B. T. Suresh Babu

Keyword(s):

Brackish Water ◽

Sea Water ◽

Salt Water ◽

Construction Material ◽

Salt Content ◽

River Estuary ◽

Sand Sample ◽

River Sand ◽

Natural Aggregates

The salt water mixes with fresh water and forms brackish water. The brackish water contains some quantity of salt, but not equal to sea water. Salinity determines the geographic distribution of the number of marshes found in estuary. Hence salinity is a very important environmental factor in estuary system. Sand is one major natural aggregate, required in construction industry mainly for the manufacture of concrete. The availability of good river sand is reduced due to salinity. The quality of sand available from estuarine regions is adversely affected due to this reason. It is the responsibility of engineers to check the quality of sand and its strength parameters before using it for any construction purpose. Presence of salt content in natural aggregates or manufactured aggregates is the cause for corrosion in steel. In this study the amount of salinity present in estuary sand was determined. Three different methods were used to determine the salinity in different seasonal variations. The sand sample collected nearer to the sea was found to be high in salinity in all methods. It can be concluded that care should be taken before we use estuary sand as a construction material due to the presence of salinity.

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Automation of selected brazes' dynamic properties in high-temperatures' measurement process

Image Processing & Communications ◽

10.2478/v10248-012-0077-0 ◽

2013 ◽

Vol 18 (2-3) ◽

pp. 33-41

Author(s):

Dominik Sankowski ◽

Marcin Bakala ◽

Rafał Wojciechowski

Keyword(s):

Surface Tension ◽

High Temperatures ◽

Dynamic Properties ◽

Automatic Measurement ◽

Measurement Methodology ◽

Joining Process ◽

Wetting Force ◽

Research Grant

Abstract The good quality of several manufactured components frequently depends on solidliquid interactions existing during processing. Nowadays, the research in material engineering focuses also on modern, automatic measurement methods of joining process properties, i.a. wetting force and surface tension, which allows for quantitative determination of above mentioned parameters. In the paper, the brazes’ dynamic properties in high-temperatures’ measurement methodology and the stand for automatic determination of braze’s properties, constructed and implmented within the research grant nr KBN N N519 441 839 - An integrated platform for automatic measurement of wettability and surface tension of solders at high temperatures, are widely described

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Surfactant Impurities Can Explain the Jones-Ray Effect

10.26434/chemrxiv.5732976 ◽

2018 ◽

Author(s):

Timothy Duignan ◽

Marcel Baer ◽

Christopher Mundy

Keyword(s):

Surface Tension ◽

Electrostatic Potential ◽

Driving Forces ◽

Salt Water ◽

Fundamental Property ◽

Apparent Contradiction ◽

Low Salt ◽

Air Water Interface ◽

Added Salt ◽

Effect Of Surface

<div> <p> </p><div> <div> <div> <p>The surface tension of dilute salt water is a fundamental property that is crucial to understanding the complexity of many aqueous phase processes. Small ions are known to be repelled from the air-water surface leading to an increase in the surface tension in accordance with the Gibbs adsorption isotherm. The Jones-Ray effect refers to the observation that at extremely low salt concentration the surface tension decreases in apparent contradiction with thermodynamics. Determining the mechanism that is responsible for this Jones-Ray effect is important for theoretically predicting the distribution of ions near surfaces. Here we show that this surface tension decrease can be explained by surfactant impurities in water that create a substantial negative electrostatic potential at the air-water interface. This potential strongly attracts positive cations in water to the interface lowering the surface tension and thus explaining the signature of the Jones-Ray effect. At higher salt concentrations, this electrostatic potential is screened by the added salt reducing the magnitude of this effect. The effect of surface curvature on this behavior is also examined and the implications for unexplained bubble phenomena is discussed. This work suggests that the purity standards for water may be inadequate and that the interactions between ions with background impurities are important to incorporate into our understanding of the driving forces that give rise to the speciation of ions at interfaces. </p> </div> </div> </div> </div>

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