A double layer model of the gas bubble/water interface
Philippe Leroy1, Damien Jougnot, André Revil
1BRGM, UMR BRGM/CNRS/ISTO 7327, Orléans, France. p.leroy@brgm.fr
Journal of Colloid and Interface Science
|September 19, 2012
Summary
This study presents a new surface complexation model to accurately predict the zeta potential of gas bubbles. The model explains gas bubble surface conductivity and predicts surface tension, aligning with experimental data across various conditions.
Area of Science:
- Physical Chemistry
- Surface Science
- Colloid Science
Background:
- Zeta potential is crucial for understanding contaminant sorption on gas bubbles.
- Interpreting gas bubble electrophoretic mobility is complex due to interfacial behavior and surface conductivity.
- Existing models struggle to fully explain the electrical phenomena at gas-liquid interfaces.
Purpose of the Study:
- To develop a robust surface complexation model for predicting gas bubble zeta potential.
- To elucidate the mechanisms behind surface conductivity at the gas-water interface.
- To validate the model's predictions against experimental data for hydrogen and air bubbles.
Main Methods:
- Developed a surface complexation model assuming negative surface sites due to disrupted hydrogen bonding at the interface.
- Incorporated proton adsorption and a diffuse layer to calculate the electrical potential at the diffuse layer's edge, equating it to zeta potential.
- Compared model predictions with experimental zeta potential data for H(2) bubbles across varying pH and NaCl concentrations.
- Validated the model's ability to predict air bubble surface tension in KCl solutions.
Main Results:
- The model accurately predicts zeta potential for H(2) bubbles over a wide range of pH and NaCl concentrations.
- Results indicate the shear plane is located at the diffuse layer's edge, challenging the stagnant layer assumption.
- The model successfully predicts the surface tension of air bubbles in KCl solutions.
Conclusions:
- The developed surface complexation model provides a reliable method for determining gas bubble zeta potential.
- The findings offer new insights into the electrical double layer structure and shear plane location at gas-water interfaces.
- This model advances the understanding of interfacial phenomena relevant to contaminant sorption and bubble behavior.
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