Original scientific paper
Published in: Holistic Approach Environ. 2(2012) 4, pp. 143 – 156
Paper reference number: HAE-34
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AMMONIUM ADSORPTION ON NATURAL ZEOLITE (CLINOPTILOLITE): ADSORPTION ISOTHERMS AND KINETICS MODELING

Dajana Kučić^*, Marinko Markić^*, Felicita Briški^*

^* Faculty of Chemical Engineering and Technology, University of Zagreb, Croatia

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ABSTRACT

A batch sorption process for removal of ammonium ions from aqueous solution using natural zeolite was studied. Tree different particle sizes of zeolite (1 – 2 mm, 2 – 4 mm and 4 – 10 mm) were used in the experiments. Sorption of ammonium ions on natural zeolite were carried out at 298 K with the initial concentrations of ammonium in the range of 1000 – 7000 mg NH₄⁺-N/dm³. Equilibrium data were fitted by Freundlich and Langmuir isotherm and sorption kinetic data by pseudo-first and second order. The parameters were estimated by linear and non-linear method. Results show that non-linear method may be superior way to compute the parameters. The Langmuir isotherm model fitted better the experimental data with a maximum monolayer adsorption capacity of 58.36 mg NH₄⁺-N/g (1 – 2 mm), 49.02 mg NH₄⁺-N/g (2 – 4 mm) and 46.46 mg NH₄⁺-N/g (4 – 10 mm), respectively. Also, the pseudo-second-order kinetic model was the best applicable model to describe the sorption kinetics. The obtained results suggest that the natural zeolite is a good adsorbent for removal of ammonium ions from aqueous solution and that ion exchange increased with decreasing of particle sizes of natural zeolite.

Keywords: ammonium ions, natural zeolite, sorption isotherms, linear and non-linear regression
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