Main binding sites involved in Fe(III) and Cu(II) complexation in humic-based structures

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• 作者：Marta Fuentes^a ; ^{mfuentes@timacagro.es} ; Maite Olaetxea^a ; Roberto Baigorri^a ; Angel M. Zamarreñ ; o^a ; Philippe Etienne^b ; Philippe Laî ; né ; ^b ; Alain Ourry^b ; Jean-Claude Yvin^c ; Jose M. Garcia-Mina^a ; ^d
• 关键词：Humic substances ; Iron complexation ; Copper complexation ; Stability complexation constants ; Phenol groups ; Carboxylic groups
• 刊名：Journal of Geochemical Exploration
• 出版年：2013
• 出版时间：June, 2013
• 年：2013
• 卷：129
• 期：Complete
• 页码：14-17
• 全文大小：213 K

文摘

The main objective of this study is to investigate the more relevant binding sites (functional groups) involved in the complexation of Fe(III) and Cu(II) by humic-based structures. To this aim we have generated a set of seven humic-based samples (MHA) by the application of a hemi-synthetic process consisting in the oxidative polymerization of different combinations of three sources of natural organic molecules: two humic acids obtained from peat and leonardite, and natural tannin extracted from the quebracho tree (Schinopsis sp.) bark. These MHA were extensively characterized by using complementary analytical techniques (¹³C NMR, size-exclusion chromatography, electron paramagnetic resonance, and total phenol-reductant content), and their ability to complex Fe(III) and Cu(II) was also calculated by fluorescence quenching method. The data were studied by using general correlation matrix and principal component analysis.

The results obtained, taken together, indicated that in a set of humic-based structures presenting carboxylic, phenol and O-alkyl groups, and diverse aliphatic/aromatic character, the complexation of Fe(III) mainly involved specific structural arrangements including carboxylic groups distributed in aliphatic domains. However, Cu(II) complexation involved singular structural arrangements including phenols (and probably substituted phenols) and O-alkyl groups in side chains of aromatic domains.