Ab Initio Study of Layered Double Hydroxides Containing Iron and Its Potential Use as Fertilizer

Mg–Fe layered double hydroxides had their electronic structures calculated by ab initio density-functional theory with GGA, GGA spin polarized, and GGA+U with periodic boundary conditions in order to study some of their properties, such as the anion release to use these compounds as fertilizers. The proposed fertilizer anions were HPO 4 2– and NO 3 –, and the anion release was investigated from anionic exchange reactions with CO 3 2– . We performed thermodynamic analyses in which the Gibbs energy, the enthalpy, and the entropy of these exchange reactions were calculated at 298.15 K. Also, charge difference plots were computed to study the interactions between the anions, the water molecules, and the hydrotalcite layers, and the projected density of states (pDOS) was also computed to compare the acidity and alkalinity sites for each structure.