Synthesis of Fe2SiO4-Fe7Co3 Nanocomposite Dispersed in the Mesoporous SBA-15: Application as Magnetically Separable Adsorbent

Abstract

The mixture containing alloy and oxide with iron-based phases has shown interesting properties compared to the isolated species and the synergy between the phases has shown positive effect on dye adsorption. This paper describes the synthesis of Fe2SiO4-Fe7Co3-based nanocomposite dispersed in Santa Barbara Amorphous (SBA)-15 and its application in dye adsorption followed by magnetic separation. Thus, it was studied the variation of reduction temperature and amount of hydrogen used in synthesis and the effect of these parameters on the physicochemical properties of the iron and cobalt based oxide/alloy mixture, as well as the methylene blue adsorption capacity. The XRD and Mössbauer results, along with the temperature-programmed reduction (TPR) profiles, confirmed the formation of Fe2SiO4-Fe7Co3-based nanocomposites. Low-angle XRD, N2 isotherms, and TEM images show the formation of the SBA-15 based mesoporous support with a high surface area (640 m2/g). Adsorption tests confirmed that the material reduced at 700 °C using 2% of H2 presented the highest adsorption capacity (49 mg/g). The nanocomposites can be easily separated from the dispersion by applying an external magnetic field. The interaction between the dye and the nanocomposite occurs mainly by π-π interactions and the mixture of the Fe2SiO4 and Fe7Co3 leads to a synergistic effect, which favor the adsorption.

Synthesis, Characterization and Photocatalytic Activity of CoFe2O4/Fe2O3 Dispersed in Mesoporous KIT-6

“…However, for the CoFe 2 O 4 /Fe 2 O 3 -KIT-6 catalyst, the lower magnetization of hematite and the presence of non-magnetic KIT-6 support justify the lower saturation magnetization found in the hysteresis curve. Additionally, the low magnetization is also related to the low concentration of ferrite present in the catalyst, which corresponds to less than 20% of the total mass [ 10 , 18 ]. Despite this reduction, the catalyst still showed strong interactions with magnets, enabling its magnetic separation from the reaction medium.…”

“…Among them, AOPs stand out for using oxidizing agents, such as hydroxyl radicals (HO•), peroxyl radicals (•O 2 -), and hydroperoxide radicals (HOO•), to degrade and mineralize organic materials into carbon dioxide and water [ 9 ]. These processes can be divided into two groups: firstly, degradation occurs in the presence of irradiation (photocatalytic processes); secondly, oxidation occurs by electrochemical processes [ 10 ]. Photocatalytic processes are the solution with the highest potential for total mineralization of organic compounds in wastewater; they use several materials such as TiO 2 , CeO 2 , and iron-based solids.…”

25th Anniversary of Molecules—Recent Advances in Inorganic Chemistry

“…Similarly, iron-based ferrocenylsubphthalocyanines have been recently used to design dyads due to their tunable redox behaviour [ 7 ], while magnetite nanoparticles, when surface-functionalised with organophosphonates, allow the reversible formation and cleavage of organic bonds with high potential in switchable applications such as self-healing materials [ 8 ]. Hierarchical structures composed of materials, also called hybrid materials, may address specific environmental issue such as wastewater treatment; da Silva et al report the development of Fe alloys and Fe-oxides dispersed in mesoporous matrixes that provide new nanodispersed materials able to adsorb organic molecules (mainly dyes) present in wastewater followed by magnetic separation [ 9 ]. Most catalysts are based on inorganic compounds, and among them, d -block metals have shown important applications in heterogeneous catalysis throughout the last decades.…”