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Early stage in situ detection of polynuclear aluminum phases in aqueous solution

  • Polynuclear cationic aluminum hydroxide phases are known intermediates in the formation of aluminum oxides or (oxide) ydroxides upon hydrolysis of aluminum salt solutions. In the presence of sulfate anions, these aluminum polyoxocations (Al13) can form crystalline Al13 sulfates with varying chemical composition. The formation of these Al13 sulfates in aqueous solution has been poorly understood. Here, we investigate the early stage crystallization of Al13 clusters in a sulfate-containing solution, in situ and in real time. Dynamics associated with Al13 sulfate formation have been obtained for the first time, using Synchrotron X-ray diffraction (XRD) of solutions suspended by acoustic levitation. Time-resolved in situ data show that the cubic phase, Na [(AlO4)Al12(OH)24(H2O)12](SO4)4*10H2O, forms after only minutes. The Formation mechanism of Al13 sulfates was found to depend on the sulfate:aluminum (SO4:Al) ratio. Ex situ XRD of the product Al13 sulfates in solution shows that forPolynuclear cationic aluminum hydroxide phases are known intermediates in the formation of aluminum oxides or (oxide) ydroxides upon hydrolysis of aluminum salt solutions. In the presence of sulfate anions, these aluminum polyoxocations (Al13) can form crystalline Al13 sulfates with varying chemical composition. The formation of these Al13 sulfates in aqueous solution has been poorly understood. Here, we investigate the early stage crystallization of Al13 clusters in a sulfate-containing solution, in situ and in real time. Dynamics associated with Al13 sulfate formation have been obtained for the first time, using Synchrotron X-ray diffraction (XRD) of solutions suspended by acoustic levitation. Time-resolved in situ data show that the cubic phase, Na [(AlO4)Al12(OH)24(H2O)12](SO4)4*10H2O, forms after only minutes. The Formation mechanism of Al13 sulfates was found to depend on the sulfate:aluminum (SO4:Al) ratio. Ex situ XRD of the product Al13 sulfates in solution shows that for SO4:Al ratio ≤ 1.5 two other crystalline phases form, and convert to the cubic phase upon washing and drying. In situ XRD for the same ratio shows transient formation of an intermediate during the crystallization process.zeige mehrzeige weniger

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Metadaten
Autor*innen:Anke Kabelitz, H. A. Dinh, Franziska EmmerlingORCiD
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Polyhedron
Jahr der Erstveröffentlichung:2019
Organisationseinheit der BAM:6 Materialchemie
6 Materialchemie / 6.3 Strukturanalytik
Verlag:Elsevier Ltd.
Jahrgang/Band:170
Erste Seite:639
Letzte Seite:648
Freie Schlagwörter:Acoustic levitation; Crystallization; In situ; Polyoxocation; Synchroton x-ray diffraction
Themenfelder/Aktivitätsfelder der BAM:Chemie und Prozesstechnik
Material
DOI:10.1016/j.poly.2019.05.049
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:29.07.2019
Referierte Publikation:Ja
Datum der Eintragung als referierte Publikation:24.10.2019
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