EVALUATION OF THERMODYNAMIC PARAMETERS FOR SEPARATION OF HEXAVALENT CHROMIUM BY FLY-ASH

Kinetics and thermodynamic parameters of Cr6+ Separation by fly ash fr om aqueous solution has been evaluated. It was found that the separati on process is partly diffusion controlled and endothermic in nature. T he mass transfer coefficient increases with an increase in temperature , The activation energy and change of enthalpy were also evaluated and found to be 17.5 kJ/mol and 14.47 kcal/mol, respectively. The free en ergy of the process was small but positive, and it decreases with an i ncrease of temperature. The change of entropy was found to be small an d remains unchanged over the 30 to 50 degrees C temperature range. Thi s process follows the Langmuir isotherm model where Q(0) and b were al so determined at different temperatures.