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Thermodynamics of Adsorption of Eriochrome Black-T Dye from Aqueous Media on each Modified Kaolin Clay and Talc

Hayfaa J. Sonba and Sajida H. Ridha

Modified kaolin clay and talc have been employed as adsorbents for the removal of industrially important dye namely erichrame black-T from aqueous solution. The effect of solution pH, initial dye concentration, temperature and adsorption time on dye removal were studied using UV-visible spectroscopy technique at λmax = 541 mm. The equilibrium time was found to be 30 minutes on each surface. The best results were achieved at pH = 9 and T = 318 K on modified kaolin clay surface and at pH = 7 and T = 288 K on talc surface. It was noted that adsorption of the dye on modified kaolin clay increases with an increase in temperature while its adsorption on talc decrease with an increase in temperature. The result showed that the equilibrium datas were fitted by both of the Freundlich and Langmuir isotherm. Values of parameters for these isotherm equations were calculated. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption. The adsorption of EBT (Eriochrome Black-T) is endothermic on modified kaolin clay and exothermic on talc