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Indexed by:期刊论文

Date of Publication:2011-02-15

Journal:JOURNAL OF HAZARDOUS MATERIALS

Included Journals:Scopus、SCIE、EI、PubMed

Volume:186

Issue:1

Page Number:690-698

ISSN No.:0304-3894

Key Words:Ferric iron; Structure memory; Calcined hydrotalcite; Chromium (VI); Adsorption

Abstract:The influence of ferric iron in calcined nano-Mg/Al hydrotalcite on removal of Cr (VI) from aqueous solution was studied from aspects of structure characteristics, adsorption properties and mechanism discussions. The calcined hydrotalcites (CH-Mg/Al and CH-Mg/Al/Fe) were obtained by thermal decomposition of their corresponding precursors and characterized by XRD, TEM, pH(PZC) and FTIR. The adsorption properties were studied as a function of pH, initial Cr (VI) concentration and contact time. The results showed that the nature of adsorption is endothermic and spontaneous for both CH-Mg/Al and CH-Mg/Al/Fe, but the thermodynamic parameter value changes revealed the addition of Fe(3+) is disadvantage to adsorption process and the theoretical saturated adsorption capacity decreased by approximately 10.2 mg/g at tested temperatures. The removal mechanism involved not only intercalation but adsorption on external surface of the layers and interlayer anion exchange for both CH-Mg/Al and CH-Mg/Al/Fe. Furthermore, the results also indicated that intercalation accounts for a large proportion during removal process whatever for CH-Mg/Al, or for CH-Mg/Al/Fe. Additionally, the replacement of Al(3+) by Fe(3+) in CH-Mg/Al led to the interlayer anion exchange more difficult. On the basis of the results, it is concluded that the existence of ferric iron in calcined Mg/Al hydrotalcite is unfavorable to removal of Cr (VI) from aqueous solution. (C) 2010 Elsevier B.V. All rights reserved.