Fe3O4 nanocubes assembled on RGO nanosheets: Ultrasound induced in-situ and eco-friendly synthesis, characterization and their excellent catalytic performance for the production of liquid fuel in Fischer-tropsch synthesis

Polycarboxylate functionalized magnetic nanoparticles Fe3O4@SiO2@CS-COOH: Preparation, characterization, and immobilization of bovine serum albumin

Magnetic nanoparticles with increasing superparamagnetism and magnetic targeting have found widespread application in fields such as food and medicine. In this study, polycarboxylated magnetic nanoparticles (Fe3O4@SiO2@CS-COOH) were prepared by surface functionalizing iron tetraoxide (Fe3O4) nanoparticles with ethylenediaminetetraacetic acid (EDTA) as a modifier. The appropriate degree of functionalization modification was obtained by adjusting the EDTA concentration and the ratio of cross-linking agents. The prepared magnetic nanoparticles were analyzed with structural and property characterization. The results showed that the Fe3O4@SiO2@CS-COOH magnetic nanoparticles prepared with 4 % EDTA and cross-linking agents at a molar ratio of 3:4 were uniform in particle size, with an average size of roughly 7 nm, and possessed an abundant carboxylate content (310.8064 μmol/g) and a high magnetization intensity (35.05 emu/g). As a model protein, bovine serum albumin (BSA) was immobilized on the surface of magnetic particles. The largest amount of immobilized protein was 500.4376 mg BSA/g at pH 4.0 and no extra salt ions. According to molecular docking simulations, its immobilization was due to the interaction of amino and carboxyl groups at the Fe3O4@SiO2@CS-COOH/BSA interface. Fe3O4@SiO2@CS-COOH possesses a large number of carboxyl groups, strong protein immobilization, and magnetic responsiveness, which may have potential applications in biomedical and food fields.

Adsorption of Cr(Ⅵ) polluted water by Fe3O4@SiO2-APTMS nanocomposites prepared in the presence of ultrasonic irradiation for sustainable water resources utilization

The research on developing a purification technology for Cr(Ⅵ) polluted water with high efficiency and the low energy consumption is crucial for achieving several Sustainable Development Goals (SDGs). In order to achieve these goals, Fe₃O₄@SiO₂-APTMS nanocomposites were prepared by Fe₃O₄ nanoparticles modified with silica and 3-aminopropyltrimethoxysilane in the presence of ultrasonic irradiation. The nanocomposites were characterized by TEM, FT-IR, VSM, TGA, BET, XRD, XPS and these analytic results proved that the nanocomposites were successfully prepared. The influential factors of Fe₃O₄@SiO₂-APTMS on Cr(Ⅵ) adsorption have been explored and better experimental conditions have been obtained. The adsorption isotherm conformed to the Freundlich model. Pseudo-second-order kinetic model provided a better correlation for the experimental data compared to other kinetic models. Thermodynamic parameters for adsorption indicated that the adsorption of Cr(Ⅵ) was a spontaneous process. It was speculated that the adsorption mechanism of this adsorbent includes redox, electrostatic adsorption and physical adsorption. In summary, the Fe₃O₄@SiO₂-APTMS nanocomposites were of great significance to human health and the remediation of heavy ion pollution, contributing to achievement of the Sustainable Development Goals (SDGs), including SDG-3, SDG-6.

The role of Ca2+ in the improvement of phosphate adsorption in natural waters: Establishing an environmentally friendly La/Ca bimetallic organic framework

Modified metal-organic framework (MOF) materials are promising adsorbents for phosphate removal in aquatic environment. Herein, a high-efficiency and eco-friendly La/Ca composite (La/Ca-BTC) was designed by calcining La/Ca MOFs for phosphate adsorption. Batch adsorption experiments showed that La/Ca-BTC-3/1 (La: Ca molar ratio of 3: 1) had an excellent phosphate sorption capacity of 101.01 mg P/g, and could also maintain relatively high adsorption in the range of pH 4-8. Anion coexistence experiments showed that, except for carbonate ions, common anions have little effect on adsorption. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) analysis indicated that oxygen vacancies formed in the La/Ca-BTC, probably by metal doping. The density functional theory (DFT) calculation showed that oxygen vacancies could affect the orbital hybridization energy during phosphate adsorption by changing the state density, reducing the bond energy barrier for phosphate adsorption, thereby enhancing the adsorption effect of La/Ca-BTC. Phosphate adsorbents generally incur severe environmental risk by their gradual release of metal ions due to changes in water quality, especially where there is high natural organic matter (NOM). The DFT calculation further demonstrated that Ca²⁺ in the La/Ca-BTC was more inclined to combine with humic acid (HA) than La³⁺. Therefore, due to the introduction of Ca²⁺, La/Ca-BTC exhibited lower La-release in the presence of HA than La-BTC, which could be reduced by about 52.04%. Furthermore, La/Ca-BTC had the potential to simultaneously remove NOM which has important implication for aquatic remediation. These results are of great significance for the development of environmentally friendly phosphate adsorbents.

Highly robust and efficient MnZnFe2O4 decorated fibrous KCC-SiO2 catalyst for the synthesis of light olefins from syngas

In this study, high light olefin (C2–C4) selectivity is obtained through FTS reaction and using a novel and robust catalyst of KCC-SiO2 fibrous nanospheres decorated with MnZnFe2O4 NPs.

From methylarenes to Esters: Efficient oxidative Csp3-H activation promoted by CuO decorated magnetic reduced graphene oxide

Magnetic reduced graphene oxide supported CuO (rGO/Fe3O4-CuO) as the heterogeneous catalyst in cross dehydrogenative coupling (CDC) reactions has been demonstrated for the synthesis of esters using methyl aromatics, aldehydes/benzyl alcohols...

Sonochemical synthesis of Co3O4 nanoparticles deposited on GO sheets and their potential application as a nanofiller in MMMs for O2/N2 separation

In this study we report an environmentally friendly, facile and straightforward sonochemical synthetic strategy for a Co3O4/GO nanocomposite using N,N'-bis(salicylidene)ethylenediaminocobalt(ii) as a precursor and graphene oxide sheets as an immobilization support for Co3O4 nanoparticles. The synthesis was facilitated by physical and chemical effects of cavitation bubbles. The synthesized nanocomposite was thoroughly characterized for its composition and morphology using Fourier transform infrared spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDS), Scanning electron microscopy (SEM), UV-visible, Raman and X-ray diffraction spectroscopy (XRD), etc. The results show Co3O4 nanoparticles of 10 nm (SD 3 nm) were prepared on well exfoliated sheets of GO. The applicability of the synthesized Co3O4/GO nanocomposite was optimized as a nanofiller for mixed matrix membranes (MMMs) comprised of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) and polyvinyl chloride. The affinity of the prepared MMMs was evaluated for the separation of O2/N2 gases by varying the concentration of nanofiller, i.e. 0.03%, 0.04%, 0.05% and 0.075% (w/v). The results display high separation performance for O2/N2 gases with excellent permeance (N2 167 GPU and O2 432 GPU at 1 bar) and O2/N2 selectivity of 2.58, when the MMMs were loaded with 0.05% (w/v) of Co3O4/GO nanocomposite.

Sonochemical engineering of highly efficient and robust Au nanoparticle-wrapped on Fe/ZrO2 nanorods and their controllable product selectivity in dimethyl oxalate hydrogenation

A facile sonochemical approach is adopted for the synthesis of Fe/ZrO₂ and Au decorated Fe/ZrO₂ NRs catalysts and their outstanding stability and catalytic performance for the synthesis of EtOH and MG from DMO hydrogenation were reported.

Sonochemical synthesis of Fe3O4/carbon nanotubes using low frequency ultrasonic devices and their performance for heterogeneous sono-persulfate process on inactivation of Microcystis aeruginosa

Iron oxide nanoparticles decorated on multi-wall nanotube (MWCNTs) were successfully fabricated through a facile and rapid sonochemical method without any pre-treatment on MWCNTs. Fe₃O₄/MWCNTs-20 showed a uniform and fine distribution of nanoparticles in the MWCNTs. The obtained Fe₃O₄/MWCNTs were analysed using TEM and XPS. Notably, Fe₃O₄/MWCNTs were used for persulfate activation on cyanobacterial cell removal. With 20 mg/L persulfate, Fe₃O₄/MWCNTs showed an efficient catalytic performance after 1 h treatment. In the Fe₃O₄/MWCNTs hybrid catalyst, Fe₃O₄ helps to produce sulfate radicals and hydroxyl radicals whereas the size of the Fe₃O₄ clusters could affect the electron transfer for radical generation. Moreover, using high frequency low intensity ultrasound, the combination of persulfate and Fe₃O₄/MWCNTs-20 reduced the remaining cell number to 9.4% within 30 min treatment. In conclusion, our work demonstrated that low frequency ultrasonic devices are capable of fabricating Fe₃O₄/MWCNTs via a simple and time-saving route, and the obtained catalysts showed superior catalytic performance on persulfate for harmful cyanobacteria control.

Microwave-Assisted Synthesis of SPION-Reduced Graphene Oxide Hybrids for Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging (MRI) is a useful tool for disease diagnosis and treatment monitoring. Superparamagnetic iron oxide nanoparticles (SPION) show good performance as transverse relaxation (T2) contrast agents, thus facilitating the interpretation of the acquired images. Attachment of SPION onto nanocarriers prevents their agglomeration, improving the circulation time and efficiency. Graphene derivatives, such as graphene oxide (GO) and reduced graphene oxide (RGO), are appealing nanocarriers since they have both high surface area and functional moieties that make them ideal substrates for the attachment of nanoparticles. We have employed a fast, simple and environmentally friendly microwave-assisted approach for the synthesis of SPION-RGO hybrids. Different iron precursor/GO ratios were used leading to SPION, with a median diameter of 7.1 nm, homogeneously distributed along the RGO surface. Good relaxivity (r2*) values were obtained in MRI studies and no significant toxicity was detected within in vitro tests following GL261 glioma and J774 macrophage-like cells for 24 h with SPION-RGO, demonstrating the applicability of the hybrids as T2-weighted MRI contrast agents.

In Situ Synthesis of a Stable Fe₃O₄@Cellulose Nanocomposite for Efficient Catalytic Degradation of Methylene Blue

To rapidly obtain a stable Fe₃O₄@cellulose heterogeneous Fenton catalyst, a novel in situ chemical co-precipitation method was developed. Compared with mechanical activation (MA)-pretreated cellulose (MAC), MA + FeCl₃ (MAFC)-pretreated cellulose (MAFCC) was more easily dissolved and uniformly distributed in NaOH/urea solvent. MAFCC and MAC solutions were used as precipitators to prepare Fe₃O₄@MAFCC and Fe₃O₄@MAC nanocomposites, respectively. MAFCC showed stronger interaction and more uniform combination with Fe₃O₄ nanoparticles than MAC, implying that MAFC pretreatment enhanced the accessibility, reactivity, and dissolving capacity of cellulose thus, provided reactive sites for the in situ growth of Fe₃O₄ nanoparticles on the regenerated cellulose. Additionally, the catalytic performance of Fe₃O₄@MAFCC nanocomposite was evaluated by using for catalytic degradation of methylene blue (MB), and Fe₃O₄@MAC nanocomposite and Fe₃O₄ nanoparticles were used for comparative studies. Fe₃O₄@MAFCC nanocomposite exhibited superior catalytic activity for the degradation and mineralization of MB in practical applications. After ten cycles, the structure of Fe₃O₄@MAFCC nanocomposite was not significantly changed owing to the strong interaction between MAFCC and Fe₃O₄ nanoparticles. This study provides a green pathway to the fabrication of a stable nanocomposite catalyst with high catalytic performance and reusability for the degradation of organic pollutants.

Fe3O4@C Core-Shell Carbon Hybrid Materials as Magnetically Separable Adsorbents for the Removal of Dibenzothiophene in Fuels

Herein, we demonstrate a new class of core-shell magnetic carbon hybrid materials (Fe₃O₄@C) for remarkable adsorptive desulfurization of dibenzothiophene (DBT), which have been successfully prepared through hydrocarbonization of glucose on the surface of Fe₃O₄ and the subsequent pyrolyzation process. The as-obtained Fe₃O₄@C retains amorphous nature of carbon shells with a large surface area and displays an increase of iron atoms as active sites under elevated pyrolyzation temperature which is favorable in the adsorption of sulfur-containing species through physical and chemical adsorption, respectively. We investigate the adsorption capacity and efficiency of Fe₃O₄@C as a magnetically adsorbent for the removal of DBT in model oils under various experimental conditions including the adsorbent obtained at different temperatures, the amount of adsorbents, the DBT initial concentration, the regeneration approach, as well as the interference species. Our results demonstrated that the as-obtained Fe₃O₄@C at 650 °C (Fe₃O₄@C-650) displays a remarkable estimated adsorption performance (57.5 mg DBT/g for 200 ppmw), extraordinary high desulfurization efficiency (99% for 200 ppmw), and a high selectivity for DBT compared with its derivatives. Moreover, Fe₃O₄@C can be recovered in a quite easy, economical, and eco-friendly manner by an external magnet after five cycles without significant weight loss, which significantly simplifies the operation procedure and favors the recycle of Fe₃O₄@C. Combined with the economic and eco-friendly merits, Fe₃O₄@C offers a new avenue to employ the magnetic carbon materials for industrial applications and provides a promising substitute for adsorptive desulfurization in view of academic, industrial, and environmental aspects.

Magnetic Fe₂O₃⁻SiO₂⁻MeO₂⁻Pt (Me = Ti, Sn, Ce) as Catalysts for the Selective Hydrogenation of Cinnamaldehyde. Effect of the Nature of the Metal Oxide

The type of metal oxide affects the activity and selectivity of Fe₂O₃–SiO₂–MeO₂–Pt (Me = Ti, Sn, Ce) catalysts on the hydrogenation of cinnamaldehyde. The double shell structure design is thought to protect the magnetic Fe₂O₃ cores, and also act as a platform for depositing a second shell of TiO₂, SnO₂ or CeO₂ metal oxide. To obtain a homogeneous metallic dispersion, the incorporation of 5 wt % of Pt was carried out over Fe₂O₃–SiO₂–MeO₂ (Me = Ti, Sn, Ce) structures modified with (3-aminopropyl)triethoxysilane by successive impregnation-reduction cycles. The full characterization by HR-TEM, STEM-EDX, XRD, N₂ adsorption isotherm at −196 °C, TPR-H₂ and VSM of the catalysts indicates that homogeneous core-shell structures with controlled nano-sized magnetic cores, multi-shells and metallic Pt were obtained. The nature of the metal oxide affects the Pt nanoparticle sizes where the mean Pt diameter is in the order: –TiO₂–Pt > –SnO₂–Pt > –CeO₂–Pt. Among the catalysts studied, –CeO₂–Pt had the best catalytic performance, reaching the maximum of conversion at 240 min. of reaction without producing hydrocinnamaldehyde (HCAL). It also showed a plot volcano type for the production of cinnamic alcohol (COL), with 3-phenyl-1-propanol (HCOL) as a main product. The –SnO₂–Pt catalyst showed a poor catalytic performance attributable to the Pt clusters’ occlusion in the irregular surface of the –SnO₂. Finally, the –TiO₂–Pt catalyst showed a continuous production of COL with a 100% conversion and 65% selectivity at 600 min of reaction.

Directly Converting Syngas to Linear α-Olefins over Core-Shell Fe3O4@MnO2 Catalysts

Converting syngas to value-added chemicals via Fischer-Tropsch synthesis has attracted much attention, whereas the direct hydrogenation of CO to heavy olefins, especially linear α-olefins (LAOs), remains a challenge. In this study, we designed a core-shell Fe₃O₄@MnO₂ catalyst to realize the direct conversion of syngas to LAOs with high efficiency. This catalyst exhibited a high selectivity of 79.60% for total alkenes and 64.95% for C₄⁺ alkenes, 91% of which are LAOs, at a CO conversion of approximately 75%. Promotion of the electron transfer from MnO₂ to Fe₃O₄ inside the core-shell Fe₃O₄@MnO₂ catalyst facilitated the dissociative adsorption of CO molecules on Fe₃O₄ and the spillover of H atoms onto the MnO₂, which enhanced C-C coupling, weakened the hydrogenation activity of the catalyst, and improved the production of LAOs. A superior stability over 100 h was observed, demonstrating the promising potential of this catalyst for industrial applications.