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

The flotation of soluble salt is discussed, with particular reference to carbonate salts such as those associated with the trona deposit of the Green River basin, Wyoming. The equilibrium and dynamic surface tensions of sodium carbonate and sodium bicarbonate salts were measured as a function of the salt concentration up to saturation and compared with model predictions using the Gibbs-Langmuir adsorption theory. The results showed that negative adsorption of sodium carbonate leads to a significant increase in surface tension of the brine solution. The negative adsorption and the increase in surface tension are significantly lower for sodium bicarbonate compared with sodium carbonate. Sodium ions are significantly more hydrated than carbonate and bicarbonate ions, and tend to be excluded from the air-brine interface while carbonate and bicarbonate ions are accommodated at the interface. 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.
The flotation of soluble salt is discussed, with particular reference to carbonate salts such as those associated with the trona deposit of the Green River basin, Wyoming. The equilibrium and dynamic surface tensions of sodium carbonate and sodium bicarbonate salts were measured as a function of the salt concentration up to saturation and compared with model predictions using the Gibbs-Langmuir adsorption theory. The results showed that negative adsorption of sodium carbonate leads to a significant increase in surface tension of the brine solution. The negative adsorption and the increase in surface tension are significantly lower for sodium bicarbonate compared with sodium carbonate. Sodium ions are significantly more hydrated than carbonate and bicarbonate ions, and tend to be excluded from the air-brine interface while carbonate and bicarbonate ions are accommodated at the interface. 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.