Dynamic Surface Tension Measurement with a Dynamic Wilhelmy Plate Technique

Area of Science:

• Colloid and Surface Science
• Physical Chemistry

Background:

• Dynamic surface tension is crucial for understanding surfactant behavior in various applications.
• Existing methods for measuring dynamic surface tension have limitations in accuracy and scope.

Purpose of the Study:

• To develop and validate a novel experimental method, the dynamic Wilhelmy plate technique (DWPT), for studying dynamic surface tension.
• To propose and apply diffusion-controlled models to analyze DWPT data and determine surfactant diffusion coefficients and interfacial energy barriers.

Main Methods:

• Development of the dynamic Wilhelmy plate technique (DWPT).
• Proposal of diffusion-controlled models for analyzing DWPT data.
• Measurement and analysis of dynamic surface tension for Triton X-100 and SDS solutions.
• Comparison with the drop mass technique for validation.

Main Results:

• DWPT successfully measured dynamic surface tension for Triton X-100 and SDS.
• Calculated diffusion coefficients for Triton X-100: 3.7 x 10⁻⁶ (short-time) and 0.97 x 10⁻⁶ cm²/s (long-time).
• Calculated diffusion coefficients for SDS: 4.6 x 10⁻⁶ (short-time) and 0.79 x 10⁻⁶ cm²/s (long-time).
• Predicted dynamic surface tension showed good agreement with the drop mass technique.
• Calculated energy barriers: 4.1–5.7 RT for Triton X-100 and 6.5–8.0 RT for SDS.

Conclusions:

• The dynamic Wilhelmy plate technique (DWPT) is a reliable method for studying dynamic surface tension.
• The proposed diffusion models accurately describe the experimental data and allow for the determination of key interfacial parameters.
• The study provides valuable insights into the dynamic behavior of surfactants at interfaces.