Mechano-hydrothermal preparation of Li-Al-OH layered double hydroxides

A mechano-hydrothermal (MHT) method was used to synthesize Li-Al-OH layered double hydroxides (LDHs) from LiOH center dot H2O, Al(OH)(3) and H2O as starting materials. A two-step synthesis was conducted, that is, Al(OH)(3) was milled for 1 h, followed by hydrothermal treatment with LiOH center dot H2O solution. Effects of the LiOH/Al(OH)(3) molar ratio (R-Li/Al) and hydrothermal temperature (T-ht) on the crystallinity, morphology, and composition of the product were examined. The resulting LDHs were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared, and elemental analyses. The results showed that pre-milling plays a key role in the LDH formation during subsequent hydrothermal treatment. The Li/Al molar ratio of the obtained LDHs keeps constant at 0.5, independent from the R-Li/Al (0.5-5.0) in the starting materials. An increase in the T-ht (20-80 degrees C) can enhance the crystallinity and morphology regularity of the products. The so-obtained Li-Al-OH LDHs exhibit high crystallinity and well-dispersity, which may have wider applications than the aggregate ones obtained using conventional mechanochemical and Lithorn-imbibition methods. (C) 2018 Elsevier Masson SAS. All rights reserved.