Influence of heavy metals on the adsorption of arsenate by magnetite nanoparticles: Kinetics and thermodynamic

Abstract Magnetite nanoparticles were produced from iron ore tailings and used to remove arsenate ions from water. The produced spherical nanoparticles were 25 ± 3 nm in diameter and had ferromagnetic properties as discovered by XRD, FTIR, TEM, and VSM analyses. The kinetic and equilibrium of the arsenate (As 5+ ) adsorption by the magnetite nanoparticles was investigated in the presence of Cu 2+ , Zn 2+ and Mn 2+ at pH = 5.5 (>pH PZC  = 3.8). Due to the high stability of CuH 2 AsO 4 + , the adsorption of arsenate was more noticeably affected by the copper ions compared to the rest of the metal ions. Biphasic first-order, pseudo-second-order, and Langmuir kinetic models were applied to simulate the arsenate adsorption. The maximum adsorption (9.72 mg/g) occurred at pH = 5.5 with the initial 13 mg/l concentration of arsenic while the adsorption reactions were endothermic and elevated as a function of temperature increase. However, the presence of Fe 3+ and Al 3+ cations at pH = 2.5  PZC reduced the As(V) adsorption by the formation of FeH 2 AsO 4 2+ and AlH 2 AsO 4 2+ complexes. The synthesized nanoparticles could also be readily regenerated by NaOH solution and reused that indicates a promising adsorbent for As(V) removal.