Structural characterization and delamination of lactate-intercalated Zn,Al-layered double hydroxides

Organic-inorganic hybrid hydrotalcite-like compounds containing Zn2+ and Al3+ in the brucite-like layers (nominal Zn:Al molar ratios of 2:1, 3:1, and 4:1) and lactate (Lc) as counteranion were synthesized by coprecipitation using 0: 1 and 3: 1 lactic acid: Al molar ratios to prepare the starting solutions. Their physicochemical properties were studied by element chemical analysis, powder X-ray diffraction, infrared spectroscopy, and thermal analyses. Powder X-ray diffraction showed a pattern characteristic of a hydrotalcite-like structure. FT-IR spectroscopy confirmed the retention of the lactate anions in the interlayer without further contamination. Thermal analyses showed four stages of weight loss and five of heat change when recorded under oxidizing conditions. Dispersion of the dried samples in decarbonated water by ultrasound-assisted treatment at room temperature led to delamination of all wet fractions. Upon solvent evaporation, dried fractions restacked with a higher crystallinity and an increase in basal spacing.