The removal of heavy metal such as lead (Pb), cadmium (Cd), and copper (Cu) was assessed using magnesium oxide cores with silica coated nano-magnetite (MTM) prepared by a simple method using chemicals such as iron(II) sulfate heptahydrate (FeSO4·7H2O), magnesium (II) nitrate hexahydrate [Mg(NO3)2·6H2O], tetraethyl orthosilicate (TEOS), and urea. The MTM was characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and alternating gradient magnetometer (AGM) analyses. The isotherm, kinetic, and intra-particle diffusion studies indicated that the MTM had excellent removal capacities towards heavy metals (Pb, Cd, Cu) and the adsorption capacities were as high as 238 mg g−1 (1.15 mmol g−1) for Pb, 85.1 mg g−1 (0.75 mmol g−1) for Cd, and 33.5 mg g−1 (0.5 mmol g−1) for Cu. The intra-particle diffusion, FE-SEM, XPS, and XRD results indicated that the mechanism of heavy metal removal was mainly substitution, followed by precipitation. A leaching test revealed that MTM showed no leaching of Fe ions at pH > 2. This material is cheap, simple, and can be produced in massive amounts. MTM can be used for the large-scale remediation of waste water containing heavy metals via applying a simple and fast magnetic separation.
- Heavy metals
- Magnesium oxide