Thermodynamics of multi‐solute adsorption from dilute liquid solutions

TLDR

The approach parallels the Myers and Prausnitz method for gas‑mixture adsorption. The study develops a method to predict multi‑solute adsorption from single‑solute data using ideal dilute‑solution thermodynamics. Experimental adsorption data on activated carbon at 25 °C were collected for dilute aqueous solutions of acetone/propionitrile and p‑chlorophenol/p‑cresol. Calculated and experimental results agree well for the acetone–propionitrile system and reasonably for the p‑chlorophenol–p‑cresol system, indicating that the ideal dilute‑solution theory works best at moderate adsorption loadings but requires relaxation of assumptions at high loadings, and the method is simple and useful for engineering design.

Abstract

Abstract 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.