Dynamic Surface Tension Measurement with a Dynamic WilhelmyPlate Technique

      Ning Wu^a, Jialin Dai^b, Fortunato J Micale^c a

• Sun Chemical Corporation, 631 Central Avenue, Carlstadt, New Jersey, 07072

• ^b Department of Chemical Engineering, Southwest Petroleum Institute, Nanchong, Sichun, 637001, People's Republic of China
• ^c Zettlemoyer Center for Surface Studies, Lehigh University, Sinclair Lab 7, Bethlehem, Pennsylvania, 18015

Received 28 July 1998

Accepted 14 April 1999

Available online 1 April 2002

http://dx.doi.org/10.1006/jcis.1999.6270, How to Cite or Link Using DOI

Abstract

An experimental method called dynamic Wilhelmyplate technique (DWPT) for studying dynamic surfacetension was designed in this study. A diffusion-controlled model corresponding to the initial and boundary conditions of this method was proposed. Dynamic surfacetension of Triton X-100 and SDS was measured with this technique and analyzed with the proposed model. The calculated diffusion coefficients for the short- and long-time approximations are 3.7 × 10⁻⁶ and 0.97 × 10⁻⁶ cm²/s for Triton X-100 and 4.6 × 10⁻⁶ and 0.79 × 10⁻⁶ cm²/s for SDS, respectively. The predicted dynamic surfacetension with these diffusion coefficients for the simultaneously generated aqueous/air interfaces is in good agreement with the drop mass technique. Another diffusion controlled model that considers the energy barrier at the aqueous/air interface was also proposed in this study. The calculated energy barriers are in the range of 4.1–5.7 RT for Triton X-100 and 6.5–8.0 RT for SDS.

 

Keywords

• dynamic surfacetension;
• dynamic Wilhelmyplate technique;
• short-time approximation;
• long-time approximation;
• diffusion coefficient