Effect of Different Treatment on the Adsorption

of p-Cresol by Activated Carbon

Sirous Nouri

Chemistry Department, College of Science,Urmia University, Urmia 57135-165, Iran

Abstract

Adsorption of p-Cresol by three activated carbons (one untreated and two treated) was carried out at 301 K and at controlled pH conditions. By treating the activated carbon the PZC and adsorption capacity (Qmax) of carbon change. The adsorption capacity of each carbon, by using the homogenous Langmuir-Freundlich model, was found to comparing the effect of different treatment. At pH lower than pKa of p-cresol (molecular form), it was observed that the electron density of aromatic ring and also those of the carbon surface, are the main forces involved in the adsorption process, by affecting the extent of London dispersion forces. Treating by H2 increase the PZC and treating by H2SO4 decrease this factor. At higher pH (in ionic form), it was found that the electrostatic forces played a significant role on the extent of adsorption. In this condition the adsorption of the solute dependent on the concentration of anionic form of the solute. The effect of pH must be considered from its combined effects on the carbon surface and on the solute molecules. It was found that the uptake of the molecular form of the aromatic solute was dependent on the PZC of the carbon.