期刊
CHEMICAL ENGINEERING JOURNAL
卷 244, 期 -, 页码 569-575出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2014.01.093
关键词
Hexavalent chromium; Nanoscale zerovalent iron; XPS analysis; Raman spectroscopy
资金
- Agencia Nacional de Promocion Cientifica y Tecnologica (ANPCyT, Argentina) [512-2006, 0463-2011]
Nanoscale zerovalent iron (nZVI) particles were successfully employed for Cr(VI) removal from aqueous solutions at pH 3. It was found that the capacity of the system increases with increasing nZVI dosage. Starting at 300 mu M, a complete Cr(VI) conversion was achieved in 30 min with a Fe:Cr(VI) molar ratio (MR) of 3, and 45% conversion with MR = 1 over the same period of time. The material exhibited an enhanced reactivity in comparison with other previously tested similar materials. The proposed mechanism involves an initial reduction of Cr(VI) to Cr(III) by reaction with Fe-0 or Fe(II) on the particle surface or in solution (secondary pathway), followed by an arrest on Cr(VI) removal attributed to the passivation of the surface of the nanoparticles. Passivation was confirmed by Raman and Xray photoelectron spectroscopies (XPS). Furthermore, XPS analysis demonstrated that Cr(III) is the only Cr species present in the external layer of the nanoparticles after the reaction. Raman analysis and XPS measurements performed after mild sputtering showed that nZVI exposed to Cr(VI) presented a structure, from outside to inside, of hydroxychromites -> magnetite -> Fe-0 (C) 2014 Elsevier B.V. All rights reserved.
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