Adsorption kinetics and isotherms of arsenic(V) from aqueous solution onto Ni0.5Zn0.5Fe2O4 nanoparticles.

Magnetic Ni0.5Zn0.5Fe2O4 nanoparticles were synthesized by the facile citrate-gel process. Their morphology, chemical composition, microstructure, and magnetic properties were investigated by XRD, TEM, EDX, BET, and VSM. The as-prepared magnetic Ni0.5Zn0.5Fe2O4 nanoparticles consisting of grains about 20 nm were characterized with specific surface area of 49.0 m2/g and magnetization of 46.1 A m2/kg. The arsenic(V) adsorption onto these magnetic Ni0.5Zn0.5Fe2O4 nanoparticles at room temperature was determined by the ICP-AES measurement of arsenic(V) in aqueous solution. The results show that the pseudo-second-order kinetic model is fitted well to describe the arsenic(V) adsorption process with a determination coefficient (R2 = 0.9862). By comparing with the two- and three-parameter models for adsorption isotherms of arsenic(V) onto the magnetic Ni0.5Zn0.5Fe2O4 nanoparticles at room temperature, the Temkin and Redlich-Peterson model can be used to evaluate the arsenic(V) adsorption isotherm at room temperature. The arsenic(V) equilibrium adsorption quantity is up to 7.2 mg/g for these magnetic Ni0.5Zn0.5Fe2O4 nanoparticles when the initial arsenic(V) concentration is 3 mg/L in aqueous solution.