Removal of nickel, cobalt and chromium ions from aqueous solutions using natural zeolite

Jakupi, Shaban (2016) Removal of nickel, cobalt and chromium ions from aqueous solutions using natural zeolite. PhD thesis, Goce Delcev University, Stip.

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The modern trends of the water resources management, lately, are more oriented for development of the methods for waters treatment using low cost natural materials. Regarding to this, natural nanoporous materials are suitable raw materials as adsorbents for removal of the toxic pollutants from the wastewaters.
In the frame of this work, the possibility of the removal of Ni(II), Co(II) and Cr(VI) ions from water resources using natural zeolite (clinoptilolite) at different working conditions, was investigated. The applied raw material - natural zeolite (clinoptilolite) was characterized using the following analytical methods and techniques: chemical analysis, thermogravimetric analysis DTA and TG, XRD, XRF, FTIR, SEM and BET method. For the realization of the targets during the experimental research, the impact of the following operating parameters on the percentage of removal of heavy metals and the adsorption capacity of natural zeolite (clinoptilolite), was examined: initial concentration of adsorbate (350 - 650μg/l), time of adsorption (1 - 300min), initial pH of the solution (4 - 8) and amount of adsorbent (0.2 - 2.0 g/l). The experiments were performed in laboratory glass reactor (V = 2dm3), using the batch adsorption technique at room temperature (22oC) and a continuous stirring mode. Based on the obtained experimental results, the equilibrium of the investigated systems, heavy metals Ni(II), Co(II) and Cr(VI) - natural zeolite, was analyzed using the adsorption isotherms: Langmuir, Freundlich, Langmuir - Freundlich and Redlich - Peterson. The equilibrium parameters of the applied adsorption isotherms were determined by using the MATLAB/Curve Fitting Toolbox. Modeling the kinetics of the process of removal of metal ions Ni(II), Co(II) and Cr(VI) by natural zeolite, was carried out using the kinetic models: first and second order, pseudo-first and pseudo-second order models and Elovic model. The best results to define the kinetics of the studied systems, Ni(II), Co(II) and Cr(VI) - natural zeolite, were obtained by pseudo-second order model and Elovic model. NaCl and KCl with different concentrations were applied to perform the recovery of the employed adsorbent. In order to monitor the dynamic of the process of the Ni(II), Co(II) and Cr(VI) ions removal by natural zeolite, based on the obtained experimental data for equilibrium and kinetics, a continuous flow system of three serial columns in the process simulator SuperPro Designer,was designed. Based on the numerous simulations in SuperPro Designer, the optimal working mode in flow conditions for the removal of Ni(II), Co(II) and Cr(VI) ions from wastewaters using the natural zeolite, was defined.
Keywords: clinoptilolite, equilibrium, kinetics, heavy metals, adsorption

Item Type: Thesis (PhD)
Subjects: Engineering and Technology > Environmental engineering
Divisions: Faculty of Natural and Technical Sciences
Depositing User: Sladzana Mitrovska
Date Deposited: 10 Feb 2017 12:19
Last Modified: 10 Feb 2017 12:19

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