Journal
CHEMOSPHERE
Volume 184, Issue -, Pages 1168-1174Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.chemosphere.2017.06.094
Keywords
Adsorption capacity; Adsorption isotherm; Carbon nano-onions; Hexavalent chromium; Adsorption kinetics; Metal adsorption
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Funding
- Kasetsart University, Bangkok, Thailand
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The capacity of carbon nano-onions (CNOs) to remove hexavalent chromium (Cr(VI)) from aqueous solution was investigated. Batch experiments were performed to quantify the effects of the dosage rate, pH, counter ions, and temperature. The adsorption of Cr(VI) onto CNOs was best described by a pseudo second order rate expression. The adsorption efficiency increased with increasing adsorbent dosage and contact time and reached equilibrium in 24 h. The equilibrium data showed better compliance with a Langmuir isotherm than a Freundlich isotherm. Effective removal of Cr(VI) was demonstrated at pH values ranging from 2 to 10. The adsorption capacity of Cr(VI) was found to be highest (82%) at pH 3.4 and greatly depended on the solution pH. We found that Cr(VI) adsorption decreased with increasing pH over the pH range of 3.4-10. The adsorption capacity increased dramatically when the temperature increased from 10 degrees C to 50 degrees C regardless of the amount of CNOs used. Cr(VI) removal decreased by 13% when Zn(II), Cu(II), and Pb(II) were present, while there were no significant changes observed when NO3- or SO was present. The overall results support that CNOs can be used as an alternative adsorbent material to remove Cr(VI) in the water treatment industry. (C) 2017 Elsevier Ltd. All rights reserved.
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