Currently, I'm making co2-nanobubbles in water and characterizing them using Malvern Zetasizer instrument. Every time when I make zeta-potential measurements it gives me values close to 0. However, I'm looking for some negative values (-10 to -20), even I used some anionic surfactants but still the values are close to 0. what can be the problem, how can I improve my results?
Nayyar Iqbal
At the interface between the CO2 bubble/water phases, carbonic acid dissociates and equilibrium occurs
CO2 + H2O = HCO3- + H+
So your zeta potential is zero. Zeta potential occurs at the liquid/liquid, solid/liquid interface. A double electric layer is formed on such a surface. It cannot form on a gas/liquid surface, since gas has no surface.
"There is no adsorption on the gas."
Hello Nayyar Iqbal
some Zetasizer data were published that indicated a correlation between size and zeta potential, using pH as a variable. However those were oxygen nanobubbles. Nevertheless you might find this interesting:
https://www.materials-talks.com/nanobubbles-are-they-real/
and the reference Article Stability of Nanobubbles
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