Kinetic analysis of secondary crystal growth for hydrotalcite film formation

Hydrotalcite films find application in many areas of current importance, including catalysis, membranes, anticorrosion coating materials and sensors, because of their flexibility of composition modification. Conventional methods of hydrotalcite film synthesis have their limitations. For instance, the physical deposition method can result in weak interaction between particles and the in situ synthesis method can only be applied in limited synthetic conditions. In this study, hydrotalcite film was synthesized by a novel secondary crystal growth method that involved two main stages. In the first stage, primarily synthesized hydrotalcite seeds were deposited on a support. Then, secondary crystal growth was carried out by hydrothermal treatment to obtain the hydrotalcite film. Various synthetic conditions and methods were investigated to optimize conditions for the formation of hydrotalcite seeds and films. The secondary crystal growth of hydrotalcite films was also monitored to understand the mechanism and kinetics of crystal growth. The results showed that hydrotalcite crystals grow well with vertically oriented morphology when a coprecipitation method is used at pH 10. Solid state kinetic analysis showed that the secondary crystal growth of hydrotalcite can be explained by the nucleation and nuclei growth mechanism.