RESUMEN
This study focuses on the development of new amino-functionalized magnetic Fe2O3/SiO2 nanocomposites with varying silicate shell ratios (1:0.5, 1:1, and 1:2) for the efficient elimination of Hg2+ ions found in solutions. The Fe2O3/SiO2-NH2 adsorbents were characterized for their structural, surface, and magnetic properties using various techniques, including Fourier transform infrared spectrum (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Braunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), zeta-potential, and particle size measurement. We investigated the adsorption circumstances, such as pH, dosage of the adsorbent, and duration of adsorption. The pH value that yielded the best results was determined to be 5.0. The Fe2O3/SiO2-NH2 adsorbent with a silicate ratio of (1:2) exhibited the largest amount of adsorption capacity of 152.03 mg g-1. This can be attributed to its significantly large specific surface area of 100.1 m2 g-1, which surpasses that of other adsorbents. The adsorbent with amino functionalization demonstrated a strong affinity for Hg2+ ions due to the chemical interactions between the metal ions and the amino groups on the surface. The analysis of adsorption kinetics demonstrated that the adsorption outcomes adhere to the pseudo-second-order kinetic model. The study of adsorption isotherms revealed that the adsorption followed the Langmuir model, indicating that the adsorption of Hg2+ ions with the adsorbent occurred as a monomolecular layer adsorption process. Furthermore, the thermodynamic analyses revealed that the adsorption of Hg2+ ions using the adsorbent was characterized by a spontaneous and endothermic process. Additionally, the adsorbent has the ability to selectively extract mercury ions from a complex mixture of ions. The Fe2O3/SiO2-NH2 nanocomposite, which is loaded with metal, can be easily recovered from a water solution due to its magnetic properties. Moreover, it can be regenerated effortlessly through acid treatment. This study highlights the potential use of amino-functionalized Fe2O3/SiO2 magnetic nanoparticles as a highly efficient, reusable adsorbent for the removal of mercury ions from contaminated wastewater.
RESUMEN
Platinum/silver (Pt@Ag) and palladium/silver (Pd@Ag) core/shell NPs have been synthesized in two steps reaction using the citrate method. The progress of nanoparticle formation was followed by the UV/Vis spectroscopy. Transmission electron microscopy revealed spherical shaped core/shell nanoparticles with average particle diameter 32.17nm for Pt@Ag and 8.8nm for Pd@Ag. The core/shell NPs were further characterized by FT-IR and XRD. Reductive degradation of the Congo red dye was chosen to demonstrate the excellent catalytic activity of these core/shell nanostructures. The nanocatalysts act as electron mediators for the transfer of electrons from the reducing agent (NaBH4) to the dye molecules. Effect of reaction parameters such as nanocatalyst dose, dye and NaBH4 concentrations on the dye degradation was investigated. A comparison between the catalytic activities of both nanocatalysts was made to realize which of them the best in catalytic performance. Pd@Ag was the higher in catalytic activity over Pt@Ag. Such greater activity is originated from the smaller particle size and larger surface area. Pd@Ag nanocatalyst was catalytically stable through four subsequent reaction runs under the utilized reaction conditions. These findings can thus be considered as possible economical alternative for environmental safety against water pollution by dyes.