Electrocapillary measurements by drop-time technique: Comparison of calibration methods. (August 2016)

• Record Type: Journal Article
• Authors: Kadis, Rouvim; Chunovkina, Anna
• Is Part Of: Measurement. Volume 90(2016)
• Page Start: 110
• Page End: 117
• Publication Date: 2016-08
• Subjects: Electrocapillary measurement -- Drop-time technique -- Calibration -- Measurement uncertainty; Weights and measures -- Periodicals; Measurement -- Periodicals; Measurement; Weights and measures; Periodicals; 530.8
• DOI: 10.1016/j.measurement.2016.04.012
• Languages: English
• ISSNs: 0263-2241

Abstract

Graphical abstract: Highlights: Drop-time electrocapillary measurement made under carefully controlled conditions. Examination of six calibration methods identified from an exhaustive literature review. Evaluation of the bias and uncertainty of the interfacial tension measurement. Ranging calibration methods according to their associated bias and uncertainty. Abstract: This paper considers the drop-time technique in electrocapillary measurements and focuses on calibration methods required to convert the drop-time t of a mercury electrode into the value of the interfacial tension γ . The relationships between t and γ, described in the literature, are reviewed and six calibration methods identified. On the basis of high-precision drop-time electrocapillary measurements carried out in 0.1 mol l −1 KCl aqueous solution, with γ values known from the absolute measurement method, the performance of the calibration methods, expressed in terms of measurement bias and uncertainty, is evaluated and compared. Better performance is observed for the methods that involve a nonlinear model such as γ = α t β fitted to calibration data, instead of a single-point linear calibration commonly used. The measurement uncertainty U ⩽ 0.12 mN m −1 evaluated with these advanced calibration approaches corresponds to the level of accuracy achieved with the classical capillary electrometer.