Clean Technology 2010

Removal of Chromium Ions From Industrial Effluents by Adsorption Technique (Batch and Column) Studies

M.M. Aboabboud, H.G. Ibrahim and A.Y. Okasha
Al-Mergheb university, LY

Keywords: adsorption, tannery effluent, chromium, BCKD, fixed bed


Chromium(III) salts are the most widely used chemicals for tanning processes, but70% of total chromium salts react with the hides. In other word, about 30% of the chromium amount remains in the solids and liquid wastes (especially spent tanning solutions). Therefore, the removal and recovery of the chromium content of these wastewaters is necessary for environmental protection and economic reasons. The possibility of using bypass cement kiln dust (BCKD) as a low cost and natural adsorbent is investigated in this study for the removal of Cr(III) from synthetic and real wastewater. The parameters studied include contact time, adsorbent dose, initial chromium ion concentration, ph and temperature. The adsorption followed pseudo second order reaction rate and the rate is mainly controlled by intra-particle diffusion. Freundlich and Langmuir isotherm models were applied to the equilibrium data. The adsorption capacity obtained from the Langmuir isotherm plots were 142.7, 142.97, 142.323, 142.85 and 166.69 mg/g respectively at an initial ph 2.5 at 25, 30, 50, 70 and 90oC. The temperature variation study showed that the chromium ion adsorption is endothermic and spontaneous with increased randomness at the solid solution interface. Significant effect on adsorption was observed on varying the ph of the chromium ion solution. The percentage adsorption increased with decrease in ph and showed maximum removal of Cr(III) at initial ph value 2.5. Desorption of Cr(III) from the spent BCKD has also been investigated. Desorption process suggest that the adsorption of Cr(III) ions on BCKD involves physisorption mechanism. Column studies have been carried out to compare these with batch capacities. Removal of Cr(III) from tannery wastewater by BCKD was testified.
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