The adsorptive properties of oxidized activated carbons and their applications as carbon paste electrode modifiers

The adsorptive properties of the Organosorb-10 activated carbons treated with different ozone doses (15 and 45 min) and their applications as carbon paste electrode (CPE) modifiers have been studied. As a target organic contaminant the 4-chlorophenol (4-CP) has been selected. Both the physical and chemical properties of the activated carbon surface were characterized and the results show only low changes in porous structure of the oxidized activated carbons but significant changes in their surface chemistry. The adsorption isotherms of 4-CP on the activated carbons were analyzed using the Langmuir, Freundlich and Sips isotherm models. The equilibrium data followed the Langmuir isotherm. The activated carbons prepared by ozonation presented lower 4-CP adsorption than the unmodified adsorbent. Introduction of oxygen functional groups decreased their adsorption properties. The modified CPEs were prepared by mixing graphite powder with the unmodified and oxidized activated carbons (2.5%, 5% and 10% wt. content) and used for cyclic voltammetry measurements in 4-CP solutions of different concentrations. The measured peak currents were strongly dependent on oxidation of activated carbons and correlated with the 4-CP adsorption efficiency.