Synthesis of Zn/Al layered double hydroxides magnetic-nanoparticle for removal of humic acid

Abstract

A novel adsorbent of Zn/Al-LDH functionalized magnetic composite nanomaterial was successfully synthesis using a hydrothermal co-precipitation approach with NaOH as precipitating agent, and applied for the removal of humic acid (HA) from aqueous solution. The preparation, morphology, composition, and magnetic properties of Fe3O4 @SiO2-Zn/Al LDH were characterized by SEM, TEM, EDS, XRD, VSM, FT-IR and XPS. Batch experiments were carried out to investigate the influence of contact time, initial concentration, solution pH and conformed to the pseudo-second-order and Freundlich isotherm models. The adsorption test on HA demonstrated that Fe3O4 @SiO2-Zn/Al LDH exhibited optimal removal efficiency at pH 4.0, with an initial concentration of 100 mg/L and contact time of 10 min. At room temperature, 1 g Fe3O4 @SiO2-Zn/Al LDH demonstrated a removal capacity of 46.16 mg/g. These results indicated that lower pH were beneficial to the adsorption process. Fe3O4 coated with SiO2, which improves the stability and acid resistance of the overall material. Moreover, XRD, XPS and FT-IR analyzes proved that the electrostatic interactions and ion-exchange were responsible for removal of HA on Fe3O4 @SiO2-Zn/Al LDH.