Synthesis and characterization of magnetite nanoparticles using waste iron ore tailings for adsorptive removal of dyes from aqueous solution

The ferric iron recovered from waste iron ore tailings (IOTs) via acid leaching and precipitation to iron (hydr)oxide was used to synthesize magnetite nanoparticles (MNPs) by coprecipitation of its aqueous acidic solution along with ferrous iron under inert atmosphere. The electrostatically stabilized MNPs showed super paramagnetic behavior and good dispersibility in aqueous medium with high stability. Powder XRD, UV-Vis and FT-IR spectra confirmed the formation of single phase magnetite. The scanning and transmission electron micrographs revealed that the MNPs were spheroidal or cubic in shape with size ranging from 8.3 to 23.0 nm. The MNPs were found effective for fast adsorptive removal of both cationic (methylene blue) and anionic (Congo red) dyes from their aqueous solutions. Under optimized condition, the maximum monolayer adsorption capacities were found to be 70.4 mg g(-1) and 172.4 mg g(-1) for methylene blue and Congo red, respectively. Moreover, the present study addressed a feasible alternative use of waste IOT to synthesize a value added product for its possible large scale application in treatment of wastewaters. (C) 2011 Elsevier B.V. All rights reserved.