Removal of As(V) and Sb(V) in water using magnetic nanoparticle-supported layered double hydroxide nanocomposites

To remove As(V) and Sb(V) in water, magnetic nanoparticles (MNPs) supported calcined layered double oxide (MLDO) was prepared in order to enhance the separability and removal capacity. MLDO was successfully prepared using a flocculation method and the MNPs stably attached onto the surface of LDH by both chemical bonding and physical attachment. MLDO rapidly separated As(V) and Sb(V) from water due to its external magnetic field, with the saturation magnetism of raw MNPs and MLDO being 63.2 emu/g and 14.3 emu/g, respectively. In addition, MLDO enhanced the removal capacity for As(V) and Sb(V) by reconstruction process. A kinetic study revealed that the removal of As(V) and Sb(V) rapidly reached equilibrium within 120 min for an initial concentration of 50 mg/L, and that the maximum removal capacities for As(V) and Sb(V) as calculated from the Langmuir isotherm are 83.01 mg/g and 180.96 mg/g, respectively. The regeneration rate of As(V) could be maintained at about 70% for five regeneration cycles for 0.5 M NaOH and 5 M NaCl solutions, whereas Sb(V) displayed a lower regenerability due to its higher irreversible fraction in MLDO. Nevertheless, the effective removal efficiency for As(V) and Sb(V), with its easy magnetic separation, implies that MLDO has a potential for use in field applications of wastewater treatment.