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Metal occupancy and its influence on thermal stability of synthetic saponites
https://orcid.org/0000-0002-9002-4457
AbstractDue to high surface acidity and thermal stability, saponite has important applications in various fields. In this study, saponites with different Mg/Zn ratios (0–6) and a fixed Si/Al ratio of 5.43 were synthesized under hydrothermal condition. The resultant synthetic saponites were characterized by using XRD, FTIR, TG, SEM and MAS NMR. The characterization results demonstrated that, with a decrease of Mg/Zn ratio, both the crystallinity and layer stacking order of saponite were increased, and rose-like morphology was observed in Zn-saponite. Al3+ preferentially occupied tetrahedral sites in Si-O tetrahedral sheet in all synthetic saponites. A decrease of Mg/Zn ratio in octahedral sheet could improve the substitution extent of Al3+ for Si4+ and resulted in an increase of Al(IV)/Al(VI) ratio in the resultant saponite, which might be a crucial factor to control the crystal growth of saponite. The dehydroxylation temperature of saponite depended strongly on the Mg/Zn ratio and the replacement of Al3+ for Mg2+ and Zn2+ in octahedral sheets, due to their different bond strength. A ‘one-to-one’ mode was proposed for the substitution of Al3+ for Mg2+ and Zn2+ in octahedral sheets of the synthetic saponites.
HighlightsAl(IV)/Al(VI) ratio increases with a decrease of Mg/Zn ratio.Al(IV)/Al(VI) ratio is crucial for growth of saponite crystal.Saponite crystallinity increases with a decrease of Mg/Zn ratio.Dehydroxylation temperature depends on Mg/Zn ratio in saponite.Substitution of Al3+ for Mg2+ and Zn2+ follows ‘one to one’ mode.
Metal occupancy and its influence on thermal stability of synthetic saponites
https://orcid.org/0000-0002-9002-4457
AbstractDue to high surface acidity and thermal stability, saponite has important applications in various fields. In this study, saponites with different Mg/Zn ratios (0–6) and a fixed Si/Al ratio of 5.43 were synthesized under hydrothermal condition. The resultant synthetic saponites were characterized by using XRD, FTIR, TG, SEM and MAS NMR. The characterization results demonstrated that, with a decrease of Mg/Zn ratio, both the crystallinity and layer stacking order of saponite were increased, and rose-like morphology was observed in Zn-saponite. Al3+ preferentially occupied tetrahedral sites in Si-O tetrahedral sheet in all synthetic saponites. A decrease of Mg/Zn ratio in octahedral sheet could improve the substitution extent of Al3+ for Si4+ and resulted in an increase of Al(IV)/Al(VI) ratio in the resultant saponite, which might be a crucial factor to control the crystal growth of saponite. The dehydroxylation temperature of saponite depended strongly on the Mg/Zn ratio and the replacement of Al3+ for Mg2+ and Zn2+ in octahedral sheets, due to their different bond strength. A ‘one-to-one’ mode was proposed for the substitution of Al3+ for Mg2+ and Zn2+ in octahedral sheets of the synthetic saponites.
HighlightsAl(IV)/Al(VI) ratio increases with a decrease of Mg/Zn ratio.Al(IV)/Al(VI) ratio is crucial for growth of saponite crystal.Saponite crystallinity increases with a decrease of Mg/Zn ratio.Dehydroxylation temperature depends on Mg/Zn ratio in saponite.Substitution of Al3+ for Mg2+ and Zn2+ follows ‘one to one’ mode.
Metal occupancy and its influence on thermal stability of synthetic saponites
https://orcid.org/0000-0002-9002-4457
AbstractDue to high surface acidity and thermal stability, saponite has important applications in various fields. In this study, saponites with different Mg/Zn ratios (0–6) and a fixed Si/Al ratio of 5.43 were synthesized under hydrothermal condition. The resultant synthetic saponites were characterized by using XRD, FTIR, TG, SEM and MAS NMR. The characterization results demonstrated that, with a decrease of Mg/Zn ratio, both the crystallinity and layer stacking order of saponite were increased, and rose-like morphology was observed in Zn-saponite. Al3+ preferentially occupied tetrahedral sites in Si-O tetrahedral sheet in all synthetic saponites. A decrease of Mg/Zn ratio in octahedral sheet could improve the substitution extent of Al3+ for Si4+ and resulted in an increase of Al(IV)/Al(VI) ratio in the resultant saponite, which might be a crucial factor to control the crystal growth of saponite. The dehydroxylation temperature of saponite depended strongly on the Mg/Zn ratio and the replacement of Al3+ for Mg2+ and Zn2+ in octahedral sheets, due to their different bond strength. A ‘one-to-one’ mode was proposed for the substitution of Al3+ for Mg2+ and Zn2+ in octahedral sheets of the synthetic saponites.
HighlightsAl(IV)/Al(VI) ratio increases with a decrease of Mg/Zn ratio.Al(IV)/Al(VI) ratio is crucial for growth of saponite crystal.Saponite crystallinity increases with a decrease of Mg/Zn ratio.Dehydroxylation temperature depends on Mg/Zn ratio in saponite.Substitution of Al3+ for Mg2+ and Zn2+ follows ‘one to one’ mode.
Metal occupancy and its influence on thermal stability of synthetic saponites
Zhang, Chaoqun (author) / He, Hongping (author) / Tao, Qi (author) / Ji, Shichao (author) / Li, Shangying (author) / Ma, Lingya (author) / Su, Xiaoli (author) / Zhu, Jianxi (author)
Applied Clay Science ; 135 ; 282-288
2016-10-04
7 pages
Article (Journal)
Electronic Resource
English
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