Insight into the Essence of Solubility and Agglomeration of Chloride-Layered Double Hydroxides

This work explored the essence of LDH aggregation and studied the change of the solubility product (Ksp) of LDHs under different temperatures. It was found that with the metal molar ratio increasing, Ksp decreased, indicating that the dissolution–precipitation equilibrium reaction of surface ions was slower. Also, the dissolution activation energy decreases with the increasing temperature based on dissolution kinetics. Both of them were not conducive to the rearrangement of atoms during crystallization, leading to poor regularity of surface atom arrangement, and thus product agglomeration. Based on the low solubility and high activation energy, the prolonging crystallization time could be an effective route to promote atomic arrangement and reduce agglomeration. More importantly, the essence of preparing more uniform LDHs by a separate nucleation and aging strategy was presented relative to single- and double-drop methods due to the control of supersaturation during nucleation, promoting homogeneous atomic collision, and therefore improving the order degree of crystal nucleus atoms.