Tensiometry

Tensiometry involves the measurement of Surface or Interfacial tension at the boundary between a liquid and another phase which may be gas, solid or another liquid. Force or Optical Tensiometers are used to perform Tensiometric measurements.

Tensiometry

Tensiometry refers to the measurement of Surface or Interfacial tension at the boundary between a liquid and another phase which may be gas, solid or another liquid (Note: The term Tensiometry is also used for a distinctly different application, in the study of soil water potential).

Tensiometry measurements are done using either Force or Optical Tensiometers. In Force Tensiometry, the equilibrium force exerted on a probe positioned at the free-liquid or liquid-liquid interface, is precisely measured and used to compute the surface tension. The measured force is a function of probe geometry, contact and the surface tension of the liquid. The du Noüy tensiometer is a common force measurement technique that is applied to surface tension interfacial tension measurements. A platinum ring suspended from a very sensitive measuring balance is immersed through the surface (or interface) and pulled out in a prescribed manner. The maximum measured force at pull-out is related to the interfacial tension. The Wilhelmy plate is another force-based technique that uses a rough platinum plate as the probe. The technique involves dipping the plate below the surface (or interface) and then moving it back in a prescribed manner and calculating surface tension from the measured force. In Optical Tensiometry, Surface and Interfacial tension measurements can be performed optically using the shape of a drop hanging from a needle. The Optical Tensiometer (also called Goniometer) records drop images and analyzes the shape of the drop using software. The shape of the drop is related to the surface tension of the liquid as well as other fluid and solid surface properties. There are other Surface tension measurement techniques which are not considered significant, such as the Du Noüy-Padday Force Tensiometry method which uses a rod instead of a ring or Bubble pressure Tensiometry.

Tensiometers are used in research and development laboratories as well as quality control related to surfactants, paints, coatings, lacquers. Tensiometers are also used monitoring detergent activity in industrial components cleaning or electroplating.

Common Uses of Tensiometry

• Research, development and quality control of products that need to spread on solid surfaces, such as coatings, paints, lacquers, adhesives.
• Development and quality control of anti-foam products
• Characterizing wettability of solids
• Development and quality control of detergents
• Measuring surface tension for process equipment design
• Oilfield chemistry analysis

Advantages of Tensiometry

• Simple and rapid
• Small sample sizes

Limitations of Tensiometry

• Corrosive and hazardous fluids need special care

Industrial Applications of Tensiometry

• Paint and coatings
• Adhesives
• Antifoams
• Process plant equipment design
• Secondary and tertiary Crude Oil recovery

• What is Optical Tensiometry? – Definition from Trenchlesspedia
• Tensiometer (surface tension) – Wikipedia