Hydrothermal transformation of mixed metal oxides and silicate anions to phyllosilicate under highly alkaline conditions

Qi Tao, Manyou Chen, Hongping He, Sridhar Komarneni

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Mixed metal oxides (MMO) were transformed to phyllosilicate in the presence of silicate anions under hydrothermal conditions. The product was shown to be saponite with a trioctahedral layer structure by characterization with XRD, FTIR, 27Al and 29Si MAS NMR, HRTEM and TG-DTG. The formation of saponite was through a rehydration-dissolution-precipitation pathway, involving the critical steps such as the reconstruction of MMO to hydrotalcite (Ht), exsolution of Al3+ from Ht, condensation of metasilicate anions with Ht, and finally crystallization of saponite. Isomorphous substitution of Al3+ for Si4+ in silicate oligomers is the key for the above conversion, which generated the negative charge necessary for the condensation between the silicate oligomers and Ht surface and the formation of 2:1 saponite TOT layers. High pH value (over 14.0) favored the condensation of silicate oligomers and led to crystallization of saponite. Thus, we report a novel method for the crystallization of saponite.

Original languageEnglish (US)
Pages (from-to)224-230
Number of pages7
JournalApplied Clay Science
Volume156
DOIs
StatePublished - May 1 2018

Fingerprint

hydrotalcite
saponite
Silicates
phyllosilicate
Oxides
Anions
anion
silicate
Metals
Crystallization
Oligomers
condensation
Condensation
crystallization
rehydration
MAS
exsolution
nuclear magnetic resonance
metal oxide
Dissolution

All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

Cite this

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title = "Hydrothermal transformation of mixed metal oxides and silicate anions to phyllosilicate under highly alkaline conditions",
abstract = "Mixed metal oxides (MMO) were transformed to phyllosilicate in the presence of silicate anions under hydrothermal conditions. The product was shown to be saponite with a trioctahedral layer structure by characterization with XRD, FTIR, 27Al and 29Si MAS NMR, HRTEM and TG-DTG. The formation of saponite was through a rehydration-dissolution-precipitation pathway, involving the critical steps such as the reconstruction of MMO to hydrotalcite (Ht), exsolution of Al3+ from Ht, condensation of metasilicate anions with Ht, and finally crystallization of saponite. Isomorphous substitution of Al3+ for Si4+ in silicate oligomers is the key for the above conversion, which generated the negative charge necessary for the condensation between the silicate oligomers and Ht surface and the formation of 2:1 saponite TOT layers. High pH value (over 14.0) favored the condensation of silicate oligomers and led to crystallization of saponite. Thus, we report a novel method for the crystallization of saponite.",
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Hydrothermal transformation of mixed metal oxides and silicate anions to phyllosilicate under highly alkaline conditions. / Tao, Qi; Chen, Manyou; He, Hongping; Komarneni, Sridhar.

In: Applied Clay Science, Vol. 156, 01.05.2018, p. 224-230.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Tao, Qi

AU - Chen, Manyou

AU - He, Hongping

AU - Komarneni, Sridhar

PY - 2018/5/1

Y1 - 2018/5/1

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AB - Mixed metal oxides (MMO) were transformed to phyllosilicate in the presence of silicate anions under hydrothermal conditions. The product was shown to be saponite with a trioctahedral layer structure by characterization with XRD, FTIR, 27Al and 29Si MAS NMR, HRTEM and TG-DTG. The formation of saponite was through a rehydration-dissolution-precipitation pathway, involving the critical steps such as the reconstruction of MMO to hydrotalcite (Ht), exsolution of Al3+ from Ht, condensation of metasilicate anions with Ht, and finally crystallization of saponite. Isomorphous substitution of Al3+ for Si4+ in silicate oligomers is the key for the above conversion, which generated the negative charge necessary for the condensation between the silicate oligomers and Ht surface and the formation of 2:1 saponite TOT layers. High pH value (over 14.0) favored the condensation of silicate oligomers and led to crystallization of saponite. Thus, we report a novel method for the crystallization of saponite.

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