TY - JOUR
T1 - Hydrothermal transformation of mixed metal oxides and silicate anions to phyllosilicate under highly alkaline conditions
AU - Tao, Qi
AU - Chen, Manyou
AU - He, Hongping
AU - Komarneni, Sridhar
N1 - Funding Information:
This work was financially supported by National Natural Science Foundation of China (grant numbers 41372048 , 41772039 , and 41530313 ), CAS Key Research Program of Frontier Sciences (grant number QYZDJSSW-DQC023-1 ), and Guangdong Provincial Youth Top-notch Talent Support Program (grant number 2015TQ01Z797 ), GIGCAS ( IS-2510 ).
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/5
Y1 - 2018/5
N2 - 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.
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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U2 - 10.1016/j.clay.2018.02.013
DO - 10.1016/j.clay.2018.02.013
M3 - Article
AN - SCOPUS:85042013150
SN - 0169-1317
VL - 156
SP - 224
EP - 230
JO - Applied Clay Science
JF - Applied Clay Science
ER -