Adsorption of arsenic (V) on magnetite-enriched particles separated from the mill scale

The magnetite-enriched particles (MEP) were separated from the mill scale on low magnetic intensity ranging from 300 to 500 gauss. The characterization of the MEP was done with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The adsorption efficiency of MEP was investigated with batch tests and column operation. The maximum adsorption capacity was observed about 12.69 mg of arsenate on 1 g of adsorbent. Langmuir and Freundlich isotherm models were used to explain the experimental data and it was found that adsorption followed the Langmuir model more closely. Four columns were operated based on empty bed contact time (0.5 h and 1 h) and particle size (75–150 µm and 150–300 µm). The operated columns successfully removed arsenate from influent (0.5 mg/L concentration) during continuous operation for 6 weeks. This study introduces a cost effective and ecofriendly process for arsenate removal with MEP separated at low intensity of magnetic field.