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One-pot synthesis and characterization of Fe super(II)-Fe super(III) hydroxide (green rust) intercalated with C9-C14 linear alkyl carboxylates
Layered Fe super(II)-Fe super(III) hydroxides (green rusts, GR) intercalated with monovalent aliphatic carboxylate anions, called GR-carboxylates, possess hydrophobic interlayer regions which can adsorb non-polar organic compounds. GRs are well known reductants and hence GR-carboxylates may have the...
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Published in: | Applied clay science 2010-12, Vol.50 (4), p.512-519 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | Layered Fe super(II)-Fe super(III) hydroxides (green rusts, GR) intercalated with monovalent aliphatic carboxylate anions, called GR-carboxylates, possess hydrophobic interlayer regions which can adsorb non-polar organic compounds. GRs are well known reductants and hence GR-carboxylates may have the potential to detoxify adsorbed compounds, such as chlorinated solvents. GR-carboxylates, GR sub(CX), for the first time, were precipitated directly by aerial oxidation of an ethanolic solution containing FeSO sub(4) and linear alkyl carboxylate ions synthesis condition using monovalent carboxylic acids with X, the total number of carbon atoms in the acid, varying from 5 (pentanoic acid) to 14 (tetradecanoic acid), synthesis conditions were tested. GR sub(CX) formed for X >= 9. The syntheses were carried out at constant pH of 8 using 1 M NaOH as neutralizing agent, and with a maximum duration of 3.5 h. The basal spacings of GR sub(CX) increased with X and they were 2.68 nm (GR sub(C9)), 2.94 nm (GR sub(C10)), 3.59 nm (GR sub(C12)) and 4.16 nm (GR sub(C14)). The Moessbauer spectra measured at 80 K of different GR sub(C12) synthesized under identical chemical conditions resulted in hyperfine parameters close to those of other GRs. The Fe super(II)/Fe super(III) ratios of the final products (R) ranged between 1.4 and 2.8 demonstrating that Fe super(II) in GR sub(CX) can be partly oxidized without degradation of the structure. R at various stages of the synthesis decreased from 5.2 at the start of the reaction to 2.8 at the end of synthesis. In the specific case of GR sub(C12), the optimum initial solution concentrations were [C12] sub(0) = 25 mM, [Fe super(II)] sub(0) = 30 mM and 40% (v/v) EtOH/H sub(2)O. |
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ISSN: | 0169-1317 |
DOI: | 10.1016/j.clay.2010.10.002 |