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Calculation of contact angles from surfactant adsorption isotherms.

Journal of colloid and interface science·2009

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Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices

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Published on: March 27, 2019

Calculation of contact angle on charged surface.

Stephen Chwastiak¹

¹steve.chwastiak@alum.mit.edu

Journal of Colloid and Interface Science

|September 20, 2011

Summary

Contact angle measurements correlate well with surfactant adsorption on neutral surfaces. For charged hematite surfaces, an electrostatic term is needed to accurately predict contact angles from adsorption data.

Area of Science:

Surface Chemistry
Colloid Science
Electrochemistry

Background:

Contact angle measurements predict surface wettability.
Surfactant adsorption influences surface properties.
Previous work established correlation for neutral hematite surfaces.

Purpose of the Study:

To develop a method for calculating contact angles on charged hematite surfaces.
To account for electrostatic contributions to contact angle in surfactant-adsorbed systems.
To improve the correlation between measured and calculated contact angles.

Main Methods:

Acid-base titration to determine hematite surface charge properties (pH-dependent).
Measurement of surfactant adsorption isotherms at various pH values.

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Development of an electrostatic term to incorporate into contact angle calculations.

Main Results:

The established correlation between contact angle and surfactant adsorption fails for charged hematite surfaces.
An electrostatic term was successfully developed and integrated into the calculation.
The modified calculation method showed good agreement with measured contact angles on charged surfaces.

Conclusions:

Electrostatic interactions are critical for accurate contact angle prediction on charged surfaces.
The developed electrostatic term enhances the predictive power of surfactant adsorption models.
This work provides a more robust method for analyzing hematite-aqueous-surfactant systems.