Study on the mechanism of controlling the morphology of basic magnesium carbonate prepared under different hydration conditions

Abstract

Basic magnesium carbonate is gaining prominence in flame retardant materials due to its excellent flame-retardant properties and clean decomposition products. This study investigates a hydration-carbonation method to address challenges related to the preparation, morphology control, and stability of magnesium basic carbonate. The impact of hydration conditions on the morphology of the carbonate was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicate that spherical magnesium basic carbonate with regular morphology and uniform particle size can be achieved at a hydration temperature of 50°C for 1.5 hours. However, extending the hydration time and increasing the temperature resulted in irregular morphologies. Molecular dynamics simulations using the CASTEP and Forcite modules of Materials Studio were employed to understand the influence of hydration-carbonation conditions on the carbonate's morphology. The simulations revealed that the (1 1 1) and (2 0 0) crystal faces of MgO, with higher surface energies, promote the formation of precursor magnesium hydroxide nuclei, leading to heterogeneous magnesium alkali carbonate at elevated temperatures. Prolonged hydration time resulted in fragmented carbonate structures. To control the morphology of magnesium alkali carbonate, it is essential to optimize hydration temperature and duration. The simulation results corroborate experimental findings, providing deeper insights into the liquid-gas-solid adsorption relationships during the carbonation process. This study offers valuable guidelines for the controlled synthesis of magnesium basic carbonate, enhancing its applicability in flame retardant materials.