Investigating Regenerative Characteristics and Equilibrium Studies of Clinoptilolite, A Natural Zeolite Used in Ammonia Removal from Wastewater
Volume Title: 1
Authors
1Biotechnology and Environmental Engineering Laboratory, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran
2School of Chemical Engineering, University of Tehran, Tehran, Iran
3Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran
Abstract
Wastewater treatment for water reuse is one of the main concerns in oil refineries since it can lead to high economic and environmental benefits. This paper deals with treatment of Ammonia effluent through ion exchange method, which Clinoptilolite was selected as a natural adsorbent. The effect of Zeolite’s preconditioning on adsorption capacity as well as Zeolite’s regeneration efficiency and the best isotherm models fitted to the isothermal equilibrium data were examined for two particle size ranges 1-3 mm and 3-10 mm. In the case of this project the exchanger zeolite is initially in the Na+ form, and the influent contains NH4+ ions. During a cycle, the NH4+ ions will displace the sodium ions and after some time, breakthrough will begin to occur. Then adsorption process stopped and regeneration begins. The results after 9 consecutive regeneration stages were a decrease of 2.41% for 1-3 mm and 2.9% for 3-10 mm in Ammonium uptake capacity. In addition, preconditioning with an alkaline mixture of NaCl and NaOH results in a better affinity for Ammonium uptake and there was an increase in maximum capacity by 6.75%-8.07%. Finally, an adsorption isotherm, which is a relation curve between adsorption equilibrium capacity and equilibrium concentration, is illustrated. Results of all equilibria were modelled by fitting the Langmuir isotherm and the Freundlich isotherm alike to the experimental data. It was observed that Langmuir isotherm was the best fit to the experimental data due to assumptions made in deriving this isotherm model.
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