Adsorption of carbonate and bicarbonate salts at the air-brine interface

Orhan Ozdemir, Stoyan I. Karakashev, Anh V. Nguyen, Jan D. Miller*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Previous research has shown that the flotation of soluble salt is determined by interfacial water structure, thermal stability, and viscosity. These salts include alkali halide and alkali oxyanion salts. Of particular interest are the carbonate salts such as those associated with the great trona deposit of the Green River basin in Wyoming. In this study, we investigated the adsorption of carbonate and bicarbonate salts at the air-brine interface and correlated the adsorption behavior with water structure. Specifically, the equilibrium and dynamic surface tensions of sodium carbonate and sodium bicarbonate salts have been measured as a function of the salt concentration up to saturation and compared with the model prediction using the Gibbs-Langmuir adsorption theory. The results show that the negative adsorption of sodium carbonate leads to a significant increase in surface tension of the brine solution. For sodium bicarbonate, both the negative adsorption and the increase in surface tension are significantly lower when compared with the sodium carbonate case. The negative adsorption is correlated with the water structure making/breaking character of carbonate and bicarbonate solutions. In particular, sodium ions are significantly more hydrated than carbonate and bicarbonate ions, and, therefore, tend to be excluded from the air-brine interface. On the other hand, carbonate and bicarbonate ions are accommodated at the air-brine interface. In any event, the balance between sodium exclusion and carbonate/bicarbonate accommodation results in an increase in the surface tension of these solutions with an increase in salt concentration.

Original languageEnglish
Pages (from-to)149-158
Number of pages10
JournalInternational Journal of Mineral Processing
Issue number3
Publication statusPublished - Dec 2006
Externally publishedYes


The authors gratefully acknowledge the Australian Research Council. In addition, this collaborative research was supported by NSF under Grant No. INT-0207583.

FundersFunder number
National Science Foundation
Australian Research Council


    • Adsorption
    • Sodium bicarbonate
    • Sodium carbonate
    • Surface tension
    • Trona
    • Water structure maker and breaker


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