Thermodynamics of multi-solute adsorption from dilute liquid solutions



The thermodynamics of ideal dilute solutions is applied toward establishing a method for predicting multi-solute adsorption using only data for single-solute adsorption from dilute liquid solution. The method is similar to that proposed by Myers and Prausnitz for adsorption of gas mixtures.

Experimental adsorption data for activated carbon at 25°C are reported for dilute aqueous solutions containing acetone and propionitrile, and p-chlorophenol and p-cresol. Calculated and experimental results are in excellent agreement for the first system and in fair agreement for the second system. It appears that the ideal dilute-solution theory for predicting multisolute adsorption is most reliable for those systems where solute adsorption loading is moderate. When solute adsorption loading is large, the simplifying assumptions in the theory must be relaxed to allow for solute-solute interactions on the surface. The method presented here is simple to use and provides good approximations for engineering design.