Enhanced Arsenate Removal from Water by Novel Magnetic Fe-Mn-Y Tri-Metal Composite

Abstract

A magnetic Fe-Mn-Y tri-metal composite served as an adsorbent for the arsenate [As(V)] removal, and it was synthesized by hydro-thermal synthesis for the first time. The adsorbent was further characterized by field emission scanning electron microscopy with an energy-dispersive X-ray spectrometer, vibrating sample magnetometer, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The effect of solution chemistry, including different pH, different initial As(V) concentrations, as well as different coexisting ions on As(V) removal, was investigated. The maximum adsorption capacity of As(V) (135 mg/g) was obtained at pH 4.00. The adsorption isotherm was better fitted by Langmuir model, and the adsorption kinetics was well described by the pseudo-second-order model. Presence of NO₃⁻, SO₄²⁻, or CO₃²⁻ exerted a weak effect on the As(V) uptake, but PO₄³⁻ greatly inhibited the As(V) removal. Combining the results of FTIR and XPS, it was concluded that the abundant hydroxyl groups existed on the surface of the Fe-Mn-Y tri-metal composite and they played a key role in the high uptake of As(V). In addition, the adsorbent was easily separated from the solution with a magnet and regenerated with 0.1 M NaOH. Removal efficiency of As(V) by the adsorbent for five times cycle-uses maintained >98.0%. Therefore, it is expected that the magnetic Fe-Mn-Y tri-metal composite is a promising novel adsorbent for As(V) removal.