Synthesis of Multicomponent Nanoparticles for Immobilization of Heavy Metals in Aqueous Phase

This study is focused on the preparation of multicomponent nanoparticles (MCNPs) used to remediate artificial and real mine tailings. The nanoparticles were synthesized with 0.035 M or 0.007 M of sodium sulfate, 0.5 M of iron chloride and 0.8 M of sodium borohydride. Characterization of nanoparticles performed with a Transmission Electron Microscope (TEM), X-ray diffractometer (XRD), Fourier Transform Infrared Spectrometer (FTIR), and X-ray Photoelectron Spectrometer (XPS) demonstrated, these materials are in the nanoscale range, contain zero valent iron Fe(0) and iron sulfide (FeS) and are structurally modified after treatment. Simultaneous removal of heavy metals was carried out under oxidizing and reducing conditions using MCNPs reaching an efficiency of more than 98% for all of them. Kinetics conducted under oxidizing condition, pH 3 and 0.035 M sodium sulfate shows that the highest removal of heavy metals from artificial mine tailings was achieved after 160 min of treatment although steady state was reached in 240 mins. Results of kinetic tests fit very well to a pseudo-second-order model, while the isothermal equilibrium adsorption tests were adjusted to a Freundlich isotherm. Also, nanoparticles showed a high adsorption capacity (~140 mg/g) when they were in contact with 200 mg Cu 2+ /L. Finally, multicomponent nanoparticles tested with real mine tailings in the presence of other competing chemicals results in heavy metals removal over 90%.