Preparation Of Fe₃O₄-based Magnetic Nanocomposites And Their Applications In Separation Of Metal Ions

Magnetic nanocomposites have been well recognized as a promising candidate for enzyme immobilization, DNA extraction, targeted drug delivery, and removal of various metal ions. In this paper, dedoped Fe3O4/PPy nanocomposite has been obtained by simple ammonia-washing of the newly-formed Fe3O4 ferrofluid/PPy derived from in situ polymerization approach. The magnetic nanocomposite is characterized with XRD, FT-IR, TEM, BET, zeta potential, and magnetometry techniques, and further tested in the role of separating Ag(â… ) from mixed metal-ion solutions containing Ag(â… ), Mg(â…¡), Cu(â…¡), Zn(â…¡), As(â…¢), and Pb(â…¡).The adsorption of Ag(â… ) upon dedoped Fe3O4/PPy is an endothermic and spontaneous chemisorption process, ensuring rapid separation of Ag(â… ) from aqueous solution. The maximum adsorption capacity of Ag(â… ) upon dedoped Fe3O4/PPy is 143.3 mg/g. The total adsorption process preferably follows the Langmuir model and the pseudo-second order kinetics. Mg(â…¡), Cu(â…¡), Zn(â…¡), and As(â…¢) have minor effects whereas Pb(â…¡) has a relatively remarkable effect on selective separation of Ag(â… ) from solution. The magnetic nanocomposite is featured with superparamagnetism, multicore/shell structure, soft-base surface, excellent reusability, and high anti-interfering ability in the case of selectively separating Ag(â… ) from mixed metal-ion solutions, presenting a promising candidate for practical application in selective separation of Ag(â… ) from silver-containing emission.Thiol-functionalized Fe3O4/SiO2 microspheres (Fe3O4/SiO2-SH) with high saturation magnetization (69.3 emu/g), superparamagnetism, and good dispersibility have been prepared through an ethylene glycol reduction method in combination with a modified Stober method. The as-prepared composite magnetic spheres are characterized with fourier transform infrared spectroscopy (FT-IR), zeta potential, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference magnetometer, and tested in the role of separating Au(III) ions from aqueous solutions. The adsorption data of Au(III) upon Fe3O4/SiO2-SH are analyzed with the Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich isotherm models, and the pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics models.The adsorption behaviors of Au(â…¢) upon Fe3O4/SiO2-SH follow the Langmuir isotherm model, and the adsorption process conforms to the pseudo-second-order kinetic model. The maximum adsorption capacity of Au(â…¢) upon Fe3O4/SiO2-SH is 43.7 mg/g. Acetate anions play an important role yet Cu(II) ions have little interference in the adsorption of Au(â…¢) upon the adsorbent. A satisfactory recovery percentage of 89.5% is acquired by using an eluent with 1 M thiourea and 5% HCl, although thiols have a high affinity to Au(â…¢) ions based on the hard-soft acid-base (HSAB) theory by Pearson.