New sensitive micro-measurements of dynamic surface tension and diffusion coefficients: Validated and tested for the adsorption of 1-Octanol at a microscopic air-water interface and its dissolution into water

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:488

Article

Kinoshita, Koji¹  Parra, Elisa¹  Needham, David^1,2 

[1] Univ Southern Denmark, Dept Phys Chem & Pharm, Ctr Single Particle Sci & Engn SPSE, Campusvej 55, DK-5230 Odense, Denmark

[2] Duke Univ, Dept Mech Engn & Mat Sci, Durham, NC 27708 USA

关键词: Micropipette interfacial area-expansion method;    Single microdroplet catching method;    Dynamic surface tension;    1-Octanol;    Diffusion coefficient;    Frumkin isotherm;    Ward-Tordai model;   

DOI  :  10.1016/j.jcis.2016.10.052

来源: Elsevier

【 摘 要 】

Currently available dynamic surface tension (DST) measurement methods, such as Wilhelmy plate, droplet- or bubble-based methods, still have various experimental limitations such as the large size of the interface, convection in the solution, or a certain dead time at initial measurement. These limitations create inconsistencies for the kinetic analysis of surfactant adsorption/desorption, especially significant for ionic surfactants. Here, the micropipette interfacial area-expansion method was introduced and validated as a new DST measurement having a high enough sensitivity to detect diffusion controlled molecular adsorption at the air-water interfaces. To validate the new technique, the diffusion coefficient of 1-Octanol in water was investigated with existing models: the Ward Tordai model for the long time adsorption regime (1-100 s), and the Langmuir and Frumkin adsorption isotherm models for surface excess concentration. We found that the measured diffusion coefficient of 1-Octanol, 7.2 +/- 0.8 x 10(-6) cm(2)/s, showed excellent agreement with the result from an alternative method, single microdroplet catching method, to measure the diffusion coefficient from diffusion-controlled micro droplet dissolution, 7.3 +/- 0.1 x 10(-6) cm(2)/s. These new techniques for determining adsorption and diffusion coefficients can apply for a range of surface active molecules, especially the less-characterized ionic surfactants, and biological compounds such as lipids, peptides, and proteins. (C) 2016 Elsevier Inc. All rights reserved.

【 授权许可】

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