Elaboration of a core@shell bimagnetic nanoadsorbent (CoFe2O4@gamma-Fe2O3) for the removal of As(V) from water

摘要

The present work addresses the synthesis and characterization of a novel adsorbent based on core@shell bimagnetic nanoparticles (CoFe2O4@gamma-Fe2O3), and its application for arsenate (As(V)) removal from water. The magnetic core allows efficient magnetic separation from aqueous medium, while the shell confers adsorption capacity and long-term chemical stability. The nanoadsorbent was characterized by XRD, TEM, EDS, BET, FTIR, potentiometric-conductometric titrations and SQUID magnetometry. The influence of major factors governing the efficiency of the adsorption process such as the initial concentration of As(V), pH, ionic strength and the equilibration time on the removal was investigated from batch studies using 0.67 g L-1 of nanoadsorbent. The equilibrium adsorption data were well described by the Freundlich model while the kinetic data followed the Elovich model. The adsorption was highly pH dependent and increased with decreasing pH. The maximum adsorption capacity obtained was 46.9 mg g(-1) at final pH 6.4. The adsorption rate was fast in the first seven hours and reached 85% of the value at equilibrium after 24 h. The influence of competitive interferents shows that phosphate significantly reduced the adsorption of As(V). Increasing ionic strength showed a positive effect on the removal of As(V). Desorption and readsorption studies showed that the nanoadsorbent can be effectively reused.