ADSORPTION OF ACID DYE ERIOCHROME BLACK T FROM AQUEOUS SOLUTIONS ONTO ACTIVATED CARBON. KINETIC AND EQUILIBRIUM STUDIES

In the present paper is described the study of an am dye adsorption on a Romanian commercial activated carbon. Batch kinetics and isotherm studies were conducted to evaluate the adsorption behaviour of each activated carbon studied. Batch experiments were conducted to study the effects of temperature (25-55 degrees C) and initial concentration of adsorbate (5-15 mg.1(-1)) on dye adsorption. Equilibrium adsorption isotherms and kinetics were investigated. The adsorption capacity was found to increase with increase in the parameters studied. Equilibrium data were fitted to Langmuir, Freundlich, Temkin, Sips, Toth, Redlich-Peterson, Dubinin-Radushkevich, Radke-Prausnitz, Fritz-Schluender, Koble-Corrigan and Khan isotherms. The kinetic data were analysed using the Lagergren, Elovich, Ho, Weber and Bangham equations. The best results were achieved with the Langmuir isotherm equilibrium model and with the pseudo-second order kinetic model. Various thermodynamic parameters such as standard enthalpy (Delta H), standard entropy (Delta S) and standard free energy (Delta G) were evaluated.