Synthesis of CoFe₂O₄–Zeolite Materials and Application to the Adsorption of Gallium and Indium

Abstract

Magnetic cobalt ferrite (CoFe2O4)-coated zeolite was prepared with a hydrothermal method and used for the adsorption of gallium and indium. The magnetic zeolite was characterized with X-ray diffraction, X-ray photoelectric spectroscopy, Fourier-transformed infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy to determine its crystal structure, element valence, chemical bond, morphology, and grain size, respectively. Gallium and indium were determined with graphite furnace atomic absorption spectrometry. Effects of experimental parameters, including solution pH and adsorption time, were discussed. The experimental data were studied by employing various isotherm and kinetic models, such as Langmuir/Freundlich and pseudo-first-order/pseudo-second-order models. Furthermore, thermodynamic functions, such as changes of enthalpy (ΔHo), entropy (ΔSo), and Gibbs energy (ΔGo), were obtained.