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Kinetics and mechanism of Cr(VI) adsorption onto tea‐leaves waste
Author(s) -
Mozumder Md. Salatul Islam,
Khan Md. Maksudur Rahman,
Islam Md. Akhtarul
Publication year - 2008
Publication title -
asia‐pacific journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.348
H-Index - 35
eISSN - 1932-2143
pISSN - 1932-2135
DOI - 10.1002/apj.166
Subject(s) - adsorption , chemistry , desorption , fourier transform infrared spectroscopy , langmuir adsorption model , kinetic energy , kinetics , metal ions in aqueous solution , amine gas treating , langmuir , equilibrium constant , chemical engineering , metal , inorganic chemistry , organic chemistry , physics , quantum mechanics , engineering
Adsorption equilibrium and kinetic experiments have been conducted in batch mode to evaluate Cr(VI)‐tea‐leaves waste system. The equilibrium data followed the Langmuir adsorption isotherm and the adsorption was viewed as a physicochemical reversible process. A unified approach model was used to describe the adsorption system from both equilibrium and kinetic viewpoints. The model satisfactorily described both kinetic and equilibrium data. The adsorption and desorption rate constants were evaluated from the model fittings and were not dependent on initial concentration and adsorbent doses. pH zpc of the adsorbent was evaluated as 4.2 ± 0.1, and below that pH the adsorbent surface is positively charged. Adsorption of Cr(VI) was found highly pH‐dependent, and the removal efficiency dropped sharply from 95 to 10% when pH of the system changed from 2 to 5. The surface functional groups of tea‐leaves waste (before and after adsorption) were analyzed by Fourier transform infrared (FTIR) and the amine groups were found to take part in the adsorption of Cr(VI). The experimental result inferred that electrostatic attraction between the surface and the species is one of the major adsorption mechanisms for binding metal ions to the tea‐leaves waste. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.