Browsing by Author "Mihretabe, Negash"

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    Removal Efficiency of Chromium Using Coffee Husk Activated Carbon in Hawassa Industrial Park Waste Water Treatment
    (Addis Ababa University, 2021-02) Mihretabe, Negash; Alemtsehay, Gebremeskel (PhD)
    In this study, the potential of activated carbon coffee husk for removal of chromium were examined. The influence of contact time, PH, adsorbent dosage, initial concentration and adsorption equilibrium were studied at batch experiments at room temperature. The modification process was done by treating the coffee husk with different chemicals and activation. Maximum sorption was found to be at pH 2. The biosorption was rapid for the first 45 minutes of contact, removing more than 75% and equilibrium has attained in 120 minutes. Kinetic studies demonstrate good correlation coefficient (R2) for a pseudo second order kinetic model. The biosorption capacity was found to increase with higher initial Cr( VI) concentration and lower solution pH. Langmuir model fitted the equilibrium data better. The calculated biosorption free energies from the D-R isotherm model indicated that the biosorption process proceeds via chemisorptions. Optimization using response surface methodology (RSM) indicated an initial metal ion concentration, solution pH; biosorbent dose and contact time played an important role for the biosorption of Cr (VI). The study concluded that coffee husk activated carbon could be applied as a low cost alternative biosorbent to remove Cr (VI) from aqueous solution.