Treatment of Pb (II) and Cu (II) using Na-bentonite-supported nanoscale zero-valent iron

Nanoscale zero-valent iron (Fe) modified by sodium (Na) bentonite (B-nZVI) was prepared to remove copper (II) (Cu2+) and lead (II) (Pb2+) from an aqueous solution. B-nZVI and sodium bentonite were characterised by X-ray diffraction, Lorentz transmission electron microscopy and X-ray photoelectron spectroscopy (XPS). From the XPS spectra, lead (II) was detected on the surface of B-nZVI, indicating that lead (II) was removed by adsorption to B-nZVI. The copper (II) in the solution obtained electrons from B-nZVI and was reduced to copper (0). Sodium bentonite (B-nZVI) showed higher removal efficiencies for lead (II) than copper (II) under various conditions. As the concentration of copper (II) increased from 75 to 200 mg/l at a constant lead (II) concentration of 100 mg/l, the removal efficiency of lead (II) decreased considerably, from 81 to 49%. The removal efficiencies of copper (II) and lead (II) by B-nZVI were close to 100% at pH = 6. The temperature of best removal efficiency for copper (II) and lead (II) was 50°C when the adsorbent dose was 1 g/l, the pH was 5, the concentration of lead (II) was 200 mg/l, the concentration of copper (II) was 100 mg/l and the adsorption time was 4 h. In general, the synthesised B-nZVI exhibits great potential as an excellent material for use in the treatment of waste water that simultaneously contains copper (II) and lead (II).