Lee JJ

Vol. 18,  No. 1, pp. 76-82, Mar.  2012

Malachite green Zeolite Adsorption Adsorption kinetics Adsorption equilibrium

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The paper includes utlization of zeolite as potential adsorbent to remove a hazardous malachite green from waste water. The adsorption studies were carried out at 298, 308 and 318 K and effects of temperature, contact time, initial concentration on the adsorption were measured. On the basis of adsorption data Langmuir and Freundlich adsorption isotherm model were also confirmed. The equilibrium process was described well by Freundlich isotherm model, showing a selective adsorption by irregular energy of zeolite surface. From determined isotherm constants, zeolite could be employed as effective treatment for removal of malachite green. From kinetic experiments, the adsorption process followed the pseudo second order model, and the adsorption rate constant (k2) decreased with increasing initial concentration of malachite green. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption. The activation energy calculated from Arrhenius equation indicated that the adsorption of malachite green on the zeolite was physical process. The negative free energy change (ΔG° =-6.47~-9.07 kJ/mol) and the positive enthalpy change (ΔH° = +32.414 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption in the temperature range 298~318 K.