LaCO3OH microstructures with tunable morphologies: EDTA-assisted hydrothermal synthesis, formation mechanism and adsorption properties

Spiky ball- and triangular heart-like LaCO3OH microstructures were successfully prepared via a facile and mild hydrothermal route with the assistance of EDTA. The effect of reaction parameters such as chelators, reaction temperature and time on the product morphology was systematically investigated. It was found that the morphological modulation of the as-obtained products could be realized simply by changing reaction time. The possible formation mechanism for the stepwise self-assembly of spiky balls and triangular hearts was proposed on the basis of a series of time-dependent experiments. The adsorption properties of LaCO3OH spiky balls and triangular hearts for the removal of Rhodamine B (RhB) were evaluated. Due to the high specific surface area and complicated internal microstructure, the spiky balls exhibited a much higher adsorption rate and mass-specific adsorption capacity than bulk-shaped triangular hearts. However, a relatively higher area-specific adsorption capacity was found with bulk-shaped triangular hearts with a higher crystallinity. In addition, the adsorption kinetics of RhB by spiky balls follows the first-order reaction while that by triangular hearts zeroth-order, demonstrating the different adsorption behaviors of different microstructures.