The effects of the thermal treatment of activated carbon on the phenols adsorption

The adsorptive properties of thermally treated activated carbon at 1,500 and 1,800 A degrees C were investigated. The adsorption kinetics and adsorption efficiency of phenol, 4-chlorophenol and 2,4-dichlorophenol from aqueous solutions were examined. The adsorption kinetic data were analyzed using the pseudo-first and pseudo-second order models, while the equilibrium adsorption data were described by the Langmuir and Freundlich isotherms. The adsorption rate and efficiency increased in the order: phenol < 4-chlorophenol < 2,4-dichlorophenol. The activated carbons were also used for the modification of the carbon paste electrodes for the detection of the phenols based on the differential pulse voltammetry. Compared to the non-modified electrode, all the new paste electrodes showed a significantly greater sensitivity for the detection of the phenols. The signal response was closely related to the porosity of the materials used, and increased with an increase in the adsorption ability and the specific surface area of the modifiers.