Document Type : Original Article
Authors
1
MSc Student of Environmental Health Engineering, Students Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran
2
Associate Professor, Department of Environmental Health Engineering, School of Health, Iran University of Medical Sciences,Tehran, Iran
3
Assistants Professor, Department of Environmental Health Engineering, School of Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
4
PhD Candidate, Environmental Technologies Research Center, Department of Enviornmental Health, School of Health, Jundishapur University of Medical Sciences, Ahvaz, Iran
5
MSc Student, Department of Environmental Health Engineering, School of Health, Tehran University of Medical Sciences, Tehran, Iran
6
BSc, Department of Environmental Health Engineering, School of Health, Yazd University of Medical Sciences, Yazd, Iran
Abstract
Background: Chromium is one of the most common pollutants that has been noticed in recent years due to its accumulation in human tissues and health risks. The aim of this study is to magnetize powdered activated carbonby Nano zero-valent iron (NZVI) particles and use it as the adsorbent for removal of Cr (VI) from aquatic solutions. Methods: In this study, reduction and co-precipitation methods were used for converting divalent iron into zero-valent iron and depositing zero-valent iron particles on powdered activated carbon in order to induct magnetic effect, respectively. Adsorbent characteristics were analyzed using SEM and XRD techniques. The pH, contact time, stirring rounds, adsorbent dose and the concentration of chromium was determined in optimal condition by Regression coefficient (R2 ). Then the isotherm, kinetic and thermodynamic equations of adsorption were investigated based on optimum conditions. Statical analysis was done by Design Expert software. Results: The highest removal efficiency was observed in pH=3, 60 minutes contact time and 0.5 g/L of adsorbent dose in the initial concentration of 4 mg/l chromium. Isotherm and kinetic studies also showed that adsorption process of chromium follows the Freundlich model (R2>0.991) and pseudo-second order model kinetics (R2>0.982) respectively. In evaluating the reaction thermodynamic, values of ∆Ho and ∆So was equal to 146.99 and -0.452 respectively, which illustrates reactions are endothermic and spontaneous. Conclusion: Powdered activated carbon modified by zero-valent iron has the ability to remove chromium effectively and could be separated from the sample by magnet simply due to its magnetic property.
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