Hydrothermal synthesis and methylene blue adsorption performance of novel 3D hierarchical Li2Si2O5 hydrate particles

Abstract

Li2Si2O5 are generally obtained in form of granules with unavoidable impurities including Li2SiO3 and SiO2. Here, we demonstrated a facile hydrothermal route to synthesize novel 3D hierarchical Li2Si2O5 hydrate hollow flower-like microstructures assembled by rod subunits with high purity. The crystal growth was accomplished by complete transformation from poorly crystallized metastable phases formed in the initial stage including Li2SiO3, SiO2 and various Li2Si2O5 hydrate species to Li2Si2O5 hydrate rods. The transformation over many times gave a sustainable high chemical potential to direct the anisotropic growth of Li2Si2O5 hydrate rods with large aspect ratios. Besides, the variation of Li/Si molar ratios confirmed that Li2Si2O5 hydrate rods were obtained only at Li/Si = 1. The perfection and aspect ratio of the rods could be controlled very well by adjusting the hydrothermal temperatures and precursor concentrations. Some new points about obtaining pure phase and anisotropic morphology were discussed, including careful selection of precursors and synthetic method. The obtained novel 3D Li2Si2O5 hydrate structures exhibited a characteristic of mesoporous material and had an excellent adsorption capability of methylene blue with high adsorption amount of 49.42 mg·g−1 and color removal of 98.85%, indicating the potential use in wastewater treatment.