M. Essandoh and R. Garcia
United States Department of Agriculture,
Keywords: Iron oxide composite (Fe3O4), chemical coprecipitation, adsorption, dyes, adsorbent reusability
Summary:Magnetic particles entrapped in different matrices that display high thermal stability, low toxicity, interactive functions at the surface, and high saturation magnetization are of great interest. The objective of this work was to synthesize a novel hemoglobin/iron oxide composite (Hb/Fe3O4) for the removal of six different dyes (indigo carmine, naphthol blue black, tartrazine, erythrosine, eriochrome black T and bromophenol blue) from aqueous solutions. Hb/Fe3O4 composite was prepared by using alkaline solution to induce iron oxide particle formation on hemoglobin from an aqueous Fe3+ and Fe2+ salts. The Hb/Fe3O4 composite was characterized using scanning electron microscopy (SEM), laser diffraction particle size analysis, FT-IR spectroscopy, isoelectric point determination and thermogravimetric analysis (TGA). The techniques employed revealed alteration of Hb after magnetization. The Hb/Fe3O4 composite showed high removal efficiency toward all the different classes of dyes studied. Adsorption was found to follow pseudo-second order kinetic model and Langmuir isotherm. The Langmuir monolayer adsorption capacities for all the six dyes range from 80 to 178 mg/g. The Hb/Fe3O4 composite possesses extra advantage of being easily isolated from aqueous suspension using an external magnet. The reusability of the prepared Hb/Fe3O4 composite was also demonstrated by recycling at least four times with 98% of the initial adsorption capacity remaining. The prepared Hb/Fe3O4 composite are useful for subsequent functionalization reactions and have potential for various applications.