Relation between interfacial energy and adsorption of organic micropollutants onto activated carbon

Abstract

The adsorption efficacy of 16 pharmaceuticals on six different activated carbons is correlated to the thermodynamic work of adhesion, which was derived following the surface tension component approach. Immersion calorimetry was used to determine the surface tension components of activated carbon, while contact angle measurements on compressed plates were used to determine these for solutes. We found that the acid–base surface tension components of activated carbon correlated to the activated carbon oxygen content. Solute-water interaction correlated well to their solubility, although four solutes deviated from the trend. In the interaction between solute and activated carbon, van der Waals interactions were dominant and explained 65–94% of the total interaction energy, depending on the hydrophobicity of the activated carbon and solute. A reasonable relationship (r2>70) was found between the calculated work of adhesion and the experimentally determined activated carbon loading.