ADSORPTION CHARACTERISTICS OF HEAVY METALS ON MIXURE OF ANDISOL AND WASTE IRON POWDER AS COVER SOIL BARRIER

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This study is an attempt at development of low-cost and effective technologies for leachate treatment using cover soil. A mixture of Andisol and waste iron powder was selected as cover soil for adsorption of heavy metals in landfill leachate. Batch adsorption experiments were performed to assess the performance of Andisol and waste iron powder for heavy metal adsorption under various conditions (pH, temperature, etc.). The adsorption of heavy metals on both adsorbents was well described using the Freundlich isotherm equation model. Andisol and waste iron powder have high adsorption capability. For pH 4-6, the Freundlich constant K_F of both adsorbents remained almost constant. The Freundlich constant K_F, which reflects the adsorption capacity, increased with increasing temperature to 35, 3 K. Thermodynamic parameters were calculated. The thermodynamic parameters of both adsorbents showed the endothermic and spontaneous nature of the process. Using these results, it was concluded that the mixture is useful as cover soil for removal of heavy metals from leachate under oxidative condition. Column adsorption experiments were performed using the mixture for determination of kinetic parameters under a dynamic adsorption process. The Bohart and Adams model showed a better fit for Cu, Pb, and Zn. In the bed depth service time (BDST) model, the adsorption capacity N₀ and rate constant k are obtainable.