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27Al NMR Study of Al-Speciation in Aqueous Alumina-Sols

  • A new method of preparing concentrated alumo-sols, the hydrolysis of Al-tri-sec-butylate in acidic aqueous media at 85°C, was studied in detail by varying the H2O/Al- and NO3 -/Al-ratios in wide ranges. The components of the sols were characterized by 27Al NMR spectroscopy. The pH-value depends on both the chosen H2O/Al- and NO3 -/Al-ratio and on the aging time of the sols and reflects the composition of the sols. Al13 polycations were detected in sols with a pH-value between 3.0 and 3.7. As a new result its presence was shown by NMR below 3.4. The Al13 content of the sols increased with pH and the maximum fraction of Al13 polycations was detected in the sol with the highest pH (3.7). Nearly 65% of the entire aluminium content of this solution is bound in the Al13 polycations. Hence, a new synthetic method for the preparation of Al13 ions containing sols was developed. Aging studies of the sols showed, that the Al13 polycations were more stable in solutions with higher pH-value. Al13A new method of preparing concentrated alumo-sols, the hydrolysis of Al-tri-sec-butylate in acidic aqueous media at 85°C, was studied in detail by varying the H2O/Al- and NO3 -/Al-ratios in wide ranges. The components of the sols were characterized by 27Al NMR spectroscopy. The pH-value depends on both the chosen H2O/Al- and NO3 -/Al-ratio and on the aging time of the sols and reflects the composition of the sols. Al13 polycations were detected in sols with a pH-value between 3.0 and 3.7. As a new result its presence was shown by NMR below 3.4. The Al13 content of the sols increased with pH and the maximum fraction of Al13 polycations was detected in the sol with the highest pH (3.7). Nearly 65% of the entire aluminium content of this solution is bound in the Al13 polycations. Hence, a new synthetic method for the preparation of Al13 ions containing sols was developed. Aging studies of the sols showed, that the Al13 polycations were more stable in solutions with higher pH-value. Al13 polycations were detected after an aging time of four months only in sols with a pH-value of 3.7. Tempering the aged sols at 40° to 80°C caused formation of Al13 and also of Al30 polycations.zeige mehrzeige weniger

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Metadaten
Autor*innen:Marianne NofzORCiD, Jutta Pauli, Martin Dreßler, Christian Jäger, Wolfgang Altenburg
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Journal of sol gel science and technology
Jahr der Erstveröffentlichung:2006
Verlag:Kluwer Academic Publ.
Verlagsort:Dordrecht
Jahrgang/Band:38
Ausgabe/Heft:1
Erste Seite:25
Letzte Seite:35
Freie Schlagwörter:Al-27 NMR spectroscopy; Al13 polycations; Alumo-sol
ISSN:0928-0707
ISSN:1573-4846
Verfügbarkeit des Dokuments:Physisches Exemplar in der Bibliothek der BAM vorhanden ("Hardcopy Access")
Bibliotheksstandort:Sonderstandort: Publica-Schrank
Datum der Freischaltung:19.02.2016
Referierte Publikation:Ja
Datum der Eintragung als referierte Publikation:15.05.2006
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