A novel Fe3O4/MgAl-LDH hollow microspheres for effective removal of dyes from wastewater

A novel Fe3O4/MgAl-TA LDH (FTLDH) nanocomposites with tartrate anion-intercalation is successfully synthesized by a one-step hydrothermal process. The synthesized FTLDH are flower-like hollow microspheres composed of nanosheets with an average thickness of 25 nm. The specific surface area of the calcined FTLDH (FTLDH-C) greatly increases to 120 m2/g, exposing more adsorption sites which can bind the target adsorbates. The adsorption capacities of obtained hollow microspheres towards Congo Red (CR), Malachite Green (MG) and Neutral Red (NR) can reach 1520, 819 and 929 mg/g at room temperature, 2590, 1041 and 1153 mg/g at 45 °C, receptively. The excellent dye adsorption performance can be attributed to the unique hollow and porous microstructure, trumpet-shaped through channels in shell layer and high specific surface area. The dye adsorption process on FTLDH-C hollow microsphere is in accordance with Langmuir isotherm and pseudo-second-order kinetic models. The adsorption is mainly driven by electrostatic attraction (CR) and the hydrogen bonds/π-π conjugation etc. chemical interaction (CR, MG, NR etc.) between dye molecules and LDH nanoflakes. Due to the presence of magnetic Fe3O4 nanoparticles in the nanocomposites, the used adsorbent can be easily recollected with magnetic field. This study puts forward a new way to develop high-performance adsorbent via microstrucure-design and magnetic functionalization.