Zeta potential is a physico-chemical parameter of particular importance
to describe sorption of contaminants at the surface of gas bubbles.
Nevertheless, the interpretation of electrophoretic mobilities of
gas bubbles is complex. This is due to the specific behavior of the
gas at interface and to the excess of electrical charge at interface,
which is responsible for surface conductivity. We developed a surface
complexation model based on the presence of negative surface sites
because the balance of accepting and donating hydrogen bonds is broken
at interface. By considering protons adsorbed on these sites followed
by a diffuse layer, the electrical potential at the head-end of the
diffuse layer is computed and considered to be equal to the zeta
potential. The predicted zeta potential values are in very good agreement
with the experimental data of H-2 bubbles for a broad range of pH
and NaCl concentrations. This implies that the shear plane is located
at the head-end of the diffuse layer, contradicting the assumption
of the presence of a stagnant diffuse layer at the gas/water interface.
Our model also successfully predicts the surface tension of air bubbles
in a KCl solution. (c) 2012 Elsevier Inc. All rights reserved.