Novel route to synthesize CaAl- and MgAl-layered double hydroxides with highly regular morphology
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A facile, sol–gel method was developed to obtain Al-containing layered double hydroxides (LDHs) with Ca or Mg divalent cations. Ca- and Al-alkoxide were added to aqueous NaNO3 solution, and, after rapid gelation, a solid product, phase-pure, highly crystalline CaAl–LDH was formed with exceptionally regular morphology without impurities for the first time with sol–gel method. The lack of salt in the solution used for the hydrolysis resulted in a non-desirable by-product (katoite). For the sol–gel synthesis of MgAl–LDH, it was found that its formation was less sensitive to the presence of nitrate ions, and pure water or aqueous NaOH worked equally well. The product was also a highly crystalline material with thin, plate-like morphology as revealed by X-ray diffractometry and scanning electron microscopy. IR measurements indicate the lack of organic substance in the interlamellar space for both materials.
A novel version of sol–gel synthesis was utilized to prepare two types of layered double hydroxides.
The platelets have well-defined hexagonal morphology.
The products have thin crystals with high aspect ratio.
KeywordsCaAl- and MgAl-layered double hydroxides Sol–gel process X-ray diffractometry and microscopic analysis Metal alkoxides Crystals with regular morphology
This work was supported by the European Union and the Hungarian Government through Grant GINOP-2.3.2-15-2016-00013. The financial help is highly appreciated.
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Conflict of interest
The authors declare that they have no conflict of interest.
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