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Saponites containing divalent transition metal cations in octahedral positions — Exploration of synthesis possibilities using microwave radiation and NMR characterization
Abstract The synthesis using microwave radiation of saponites containing Co2+, Zn2+ or Cu2+ in octahedral positions has been explored (in the case of Cu2+, together with Mg2+ or Ni2+). Pure saponite phases were formed under some synthesis conditions, although in other cases some impurities were also formed. Microwave treatment at 180°C favored the formation of ordered solids, but induced the crystallization of other phases in some cases. Cu2+-containing saponites were formed only if Mg2+ or Ni2+ were used as octahedral sheet co-cations. The solids were characterized by different techniques, including MAS-NMR spectroscopy, which gave very precise information in the case of Zn-saponite, allowing us to estimate the content of tetrahedral Al, but much more undefined information for samples with paramagnetic cations. Nevertheless, the presence of tetrahedral Fe3+ and octahedral Fe2+ species was evidenced. Cu2+ slightly perturbed the NMR signals, while Co2+ strongly perturbed 27Al, 23Na and especially 29Si NMR spectral signals.
Graphical abstract Display Omitted
Highlights Saponites containing Co2+, Zn2+ or Cu2+ in octahedral positions have been prepared. Microwave treatment favored the formation of ordered saponites. Cu2+-saponites were formed only if Mg2+ or Ni2+ were octahedral sheet co-cations. MAS-NMR spectroscopy gave very precise information for Zn-saponite.
Saponites containing divalent transition metal cations in octahedral positions — Exploration of synthesis possibilities using microwave radiation and NMR characterization
Abstract The synthesis using microwave radiation of saponites containing Co2+, Zn2+ or Cu2+ in octahedral positions has been explored (in the case of Cu2+, together with Mg2+ or Ni2+). Pure saponite phases were formed under some synthesis conditions, although in other cases some impurities were also formed. Microwave treatment at 180°C favored the formation of ordered solids, but induced the crystallization of other phases in some cases. Cu2+-containing saponites were formed only if Mg2+ or Ni2+ were used as octahedral sheet co-cations. The solids were characterized by different techniques, including MAS-NMR spectroscopy, which gave very precise information in the case of Zn-saponite, allowing us to estimate the content of tetrahedral Al, but much more undefined information for samples with paramagnetic cations. Nevertheless, the presence of tetrahedral Fe3+ and octahedral Fe2+ species was evidenced. Cu2+ slightly perturbed the NMR signals, while Co2+ strongly perturbed 27Al, 23Na and especially 29Si NMR spectral signals.
Graphical abstract Display Omitted
Highlights Saponites containing Co2+, Zn2+ or Cu2+ in octahedral positions have been prepared. Microwave treatment favored the formation of ordered saponites. Cu2+-saponites were formed only if Mg2+ or Ni2+ were octahedral sheet co-cations. MAS-NMR spectroscopy gave very precise information for Zn-saponite.
Saponites containing divalent transition metal cations in octahedral positions — Exploration of synthesis possibilities using microwave radiation and NMR characterization
Trujillano, R. (author) / Rico, E. (author) / Vicente, M.A. (author) / Rives, V. (author) / Sobrados, I. (author) / Sanz, J. (author)
Applied Clay Science ; 115 ; 24-29
2015-07-11
6 pages
Article (Journal)
Electronic Resource
English
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