Determining liquid–liquid interfacial tension from a submerged meniscus

• Liquid–liquid interfacial tension was determined from submerged holm meridian.
• The interfacial tension was obtained successfully for four oil-water interfaces
• The method is applicable for a density difference as low as 10 kg/m3.

Liquid–liquid interfacial tension plays a crucial role in multiphase systems in the chemical industry. The available measurement methods for liquid–liquid interfacial tension are poorly suited to low bond number systems, which are often found in industrial processes. This study developed and verified a new method of calculating the interfacial tension of liquid–liquid systems by using the “submerged holm” meniscus. The holm meridian was experimentally formed around a solid object submerged at the interface. A program was developed in MATLAB to calculate the interfacial tension from the submerged holm meridian. The interfacial tension calculated by the new method was found to be consistent with available data for multiple oil–water systems. This is the first time the submerged holm meniscus has been used successfully for determining interfacial tension. More importantly, the method is applicable to liquid–liquid systems with a small density difference between the two phases. As a demonstration, the interfacial tension of silicone oil (1000 cP) – water was measured, where the difference in density was less than  30 kg/m3 (3%). The method is potentially suitable for processes involving hazardous or unstable chemicals, elevated pressure or temperature.

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