Defluoridation behavior of layered Fe-Mg-Zr hydroxides and its continuous purification of groundwater

Abstract Microsized layered Fe-Mg-Zr tri-metal hydroxide particles were synthesized by co-precipitation method and used for defluoridation of the groundwater. The obtained powders were characterized by various instruments such as FTIR, BET, XRD, SEM, XPS. Batch adsorption experiment showed that the composite had good defluoridation efficiency, and the experimental data fit well with the Langmuir model and the pseudo second-order kinetic model. The composite has a maximum adsorption capacity of 88.55mg/g, which is much higher than the adsorbents already reported. The adsorbent still has 85% adsorption capacity even after 5 cycles of adsorption-desorption-adsorption, showing good regenerative capacity. HPO 4 2− and SO 4 2− take slight interference with fluorine removal efficiency, while Cl-, CO 3 2− and HCO 3 - have no effect on fluoride removal. A simultaneous feeding continuous defluoridation process was designed, and the experiments were carried out by using the actual fluorine-containing water collected from the rural areas of North China with the initial fluoride concentration of 2.71mg/L. It was found that above established setup has quite good defluoridation efficiency for real groundwater in a continuous way, providing an example for the water purification by microsized particles that are conventionally performed by using packed column with the problem of easy blocking due to the fine particle size. This work demonstrated a successful model with great potential in the defluoridation by using the fine materials on a large scale with the low cost and high efficiency.