This study investigates the complexes formed between amino acids, which are the natural degradation products of organic matter, and smectites. Thus, the adsorption and desorption behavior of cysteine and Na-, Ca-, Cu-homoionic smectites with different layer-charge location, a montmorillonite, and a beidellite, were studied. The clay samples were treated with Na, Ca, and Cu 1 N solutions and then with a 0.2 M cysteine solution. To test smectite-cysteine stability at acidic pH, the solids obtained were repeatedly treated with distilled water acidified to pH = 5. All treated samples were characterized by thermal, X-ray diffraction, chemical, and infrared analyses. The results showed that: 1) Na- and Ca rich smectites adsorbed and retained small amounts of cysteine, and did not show interlayer cation cysteine complexes, whereas the amino acid was strongly retained in the interlayer by Cu-rich smectites; 2) d(001)-values for Na- and Ca-rich smectites showed little or no expansion, whereas for the Cu-rich smectites the intercalation of the organic molecule produced a swelling of the structure; 3) the interaction mechanism of homoionic smectites with cysteine in an aqueous medium occurs by weak interactions, (e.g., van der Waals interactions, hydrogen bonding, dipole-dipole interactions, and other electrostatic forces such as entropy-driven hydrophobic bonding), and/or by complexes involving interlayer cations and organic ligands. The formation of a stable chelate complex with the saturating ion permits cysteine to be adsorbed by Cu(II)-rich smectites and to be resistant to migration in soils and groundwaters.
Attenzione! Scheda prodotto non ancora validata dall'Ateneo
Dati e metadati della pubblicazione sono in fase di verifica da parte dell'Ateneo. In caso di errori o violazione dei diritti d'autore, contattare: email@example.com
|Anno di pubblicazione:||1999|
|Titolo:||Effect of exchange cations and layer charge location on the sorption and retention of cysteine by smectites|
|Autori:||Brigatti M.F.; Lugli C.; Montorsi S.; Poppi L.|
|Digital Object Identifier (DOI):||10.1346/CCMN.1999.0470513|
|Appare nelle tipologie:||Articolo su rivista|
File in questo prodotto:
I documenti presenti in Iris Unimore sono rilasciati con licenza Creative Commons Attribuzione - Non commerciale - Non opere derivate 3.0 Italia, salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris