Application of magnetic-clay nanocomposite for removal of Cr(VI) from aqueous solutions
کد مقاله : 1033-INZC6
نویسندگان:
اسما اسماعیل زاده *1، مریم فیاضی2
1گروه شیمی- دانشکده شیمی و مهندسی شیمی- داشگاه تحصیلات تکمیلی صنعتی و فناوری پیشرفته- کرمان- ایران
2گروه محیط زیست، پژوهشکده علوم محیطی، دانشگاه تحصیلات تکمیلی صنعتی و فناوری پیشرفته، کرمان، ایران
چکیده مقاله:
Industrial activities including metallurgical, leather tanning, mining and textile dyeing constantly release chromium ions into the environment [1]. Hexavalent chromium (Cr(VI)) and trivalent chromium (Cr(III)) are the common and toxic heavy metal ions from these industrial waste waters, where Cr(VI) is hazardous to public health due to its high water solubility and carcinogenic properties [2]. The US Environmental Protection Agency allows a maximum permissible limit of 0.05 mg L−1 for Cr(VI) in domestic water [3]. In this work, the polyethylenimine functionalized magnetic montmorillonite clay (MMT-Fe3O4-PEI) was synthesized and applied as a novel sorbent for removal of Cr(VI). The prepared sorbent was characterized by using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer(VSM) analysis. The impact of several influential parameters including initial adsorbate concentration, pH, adsorbent mass and temperature were investigated to optimize the conditions for maximum Cr(VI) adsorption. Batch mode adsorption studies were performed to evaluate the adsorption kinetics, adsorption isotherms, and selective recognition of MMT-Fe3O4-PEI. The Langmuir, Freundlich, and Temkin models were employed to describe isotherm constants. The adsorption process was well interpreted with the Langmuir adsorption isotherm and the maximum adsorption capacity of Cr(VI) was achieved as 62.89 mg g−1.The pseudo-second-order kinetic model was fitted well suggested that the rate-controlling step of the adsorption could be controlled by chemical reactions. The main Cr(VI) uptake mechanism was confirmed to be electrostatic attractions between protonated amino groups with Cr(VI) anions, and followed by partial reduction of Cr(VI) to Cr(III).
کلیدواژه ها:
Hexavalent chromium; Montmorillonite; Magnetic sorbent; Adsorption; Nanocomposite.
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