Surface properties of activated carbons in relation to their ability to adsorb nonylphenol aqueous contaminant

Nonylphenol is a compound with estrogenic activity that is found in aquatic environments as a consequence of the biodegradation of nonylphenyl polyeth oxylates discharged by many industries. The adsorption capacity for nonylph enol from aqueous solutions has been studied for four commercial microporou s carbons. The texture and properties of the activated carbons were studied by means of N-2 adsorption at 77 K and CO2 adsorption at 273 K, X-ray diff raction, immersion calorimetry and chemical analyses. Two-step isotherms ha ve been determined for all carbons. The first isotherm plateau of the adsor bed nonylphenol is related to the mean pore width of the activated carbons. The second plateau seems to be related to the presence of inorganic impuri ties (carbonates and SiO2). Depending on the type of inorganic carbonate im purity, different behaviour was found for the nonylphenol adsorption. These differences are attributed to the type of inorganic components present in the carbon, as well as their particle sizes and locations in the porous fra mework. Finally, the introduction of acidic oxygen surface groups on the ac tivated carbon surface enhances nonylphenol adsorption.