Kinetics and thermodynamic studies of Cr(VI) adsorption using environmental friendly multifunctional zeolites synthesized from coal fly ash under mild conditions |
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Authors: | Zahra Ghasemi Iman Sourinejad Hossein Kazemian Mojtaba Hadavifar Sohrab Rohani Habibollah Younesi |
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Affiliation: | 1. Department of Fisheries, Faculty of Marine Science and Technology, University of Hormozgan, Bandar Abbas, Iran;2. z.ghasemi@hormozgan.ac.ir zghasemi446@yahoo.com;4. Department of Chemical and Biochemical Engineering, University of Western Ontario (UWO), London, Ontario, Canada;5. College of Science and Management, University of Northern British Columbia (UNBC), Prince George, British Columbia, Canada;6. Department of Environmental Sciences, Hakim Sabzevari University, Sabzevar, Iran;7. Department of Environmental Science, Faculty of Natural Resources, Tarbiat Modares University (TMU), Noor, Iran |
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Abstract: | AbstractThe Na-P1 zeolite was produced from coal fly ash and modified with different environmental friendly surfactants. The potential of these green modified zeolites was investigated as adsorbents for Cr(VI) ions in a batch system. XRD, SEM, XRF, and ICP-AES analyses were used for the characterization of raw materials and zeolite samples. The environmental friendly modified zeolites successfully immobilized different toxic elements in their framework inhibiting the transfer of these toxic elements to the surrounding liquid phase. The effects of various operational parameters on Cr(VI) removal were studied. The Hexamethylenediamine (HDTMA) and Ammonyx KP (KP) modified zeolites had larger chromium removal potential than the other samples at all temperatures. The effectiveness of Cr(VI) ions elimination became greater as the pH decreased and the adsorbent dose increased. The Freundlich, Langmuir, and Dubinin–Radushkevich isotherms were fitted to the equilibrium data. The Dubinin–Radushkevich and Langmuir models gave a better fitness to equilibrium data of HDTMA-Na-P1 and KP-Na-P1, respectively. The positive and high ΔH° values showed the endothermic nature of the total Cr(VI) sorption procedure and indicated that Cr(VI) adsorption onto HDTMA-Na-P1 and KP-Na-P1 is a chemisorption. The negative ΔS° values also showed that chromium ions were stable on the surface of adsorbents. The adsorption potential of the developed eco-friendly KP-Na-P1 was higher than those of other adsorbents reported in the literature. |
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Keywords: | Cationic surfactants Coal fly ash Cr(VI) Eco-friendly modified zeolite Equilibrium adsorption isotherms Gibbs free energy |
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