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•Segregated Fe3O4@rGO/natural rubber composites (NRMG) were firstly prepared.•Fe3O4 nanoparticles were uniformly decorated on the rGO sheets.•Enhancing the electrical conductivity of ...NRMG composites by thermal treatment.•EMI SE of NRMG is 1.4 times higher than that of NR/rGO with the same rGO content.•The EMI SE of NRMG composites exhibited excellent stability under bending cycle.
Flexible natural rubber/magnetic iron oxide (Fe3O4)@reduced graphene oxide (NRMG) composites with segregated structure were prepared by a self-assembly method in latex. Various characterization techniques were employed to verify the successful preparation of Fe3O4@rGO and the formation of segregated structure within the bulk composites. Compared with natural rubber/reduced graphene oxide (NRG) composites, the presence of Fe3O4 enhances the electromagnetic interference shielding effectiveness (EMI SE) of NRMG composites. The EMI SE value of NRMG composite with 10 phr (part per hundred parts of rubber) rGO is 1.4 times higher than that of NRG composite with the same rGO content in the frequency range of 8.2–12.4 GHz. The specific EMI SE of NRMG composite reaches 26.4 dB mm−1, outperforming the ever-reported polymer/Fe3O4@rGO composites with low rGO content. Excitingly, the EMI SE of NRMG composite decreases only 3.5% even after 2000 bending-release cycles, demonstrating potential applications in flexible shielding materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Iron oxide nanoparticles (IONPs) have emerging anticancer applications via polarizing tumor-associated macrophages from tumor-promoting phenotype (M2) to tumor-suppressing phenotype (M1). However, ...the underlying mechanism and structure–function relationship remain unclear. We report magnetite IONPs are more effective compared to hematite in M1 polarization and tumor suppression. Moreover, magnetite IONPs specifically rely on interferon regulatory factor 5 signaling pathway for M1 polarization and down-regulate M2-assoicated arginase-1. This study provides new understandings and paves the way for designing advanced iron-based anticancer technologies.
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IJS, KILJ, NUK, PNG, UL, UM
The mechanisms involved in the activation of persulfate by nanosized zero-valent iron (NZVI) were elucidated and the NZVI transformation products identified. Two distinct reaction stages, in terms of ...the kinetics and radical formation mechanism, were found when phenol was oxidized by the persulfate/NZVI system. In the initial stage, lasting 10 min, Fe0 (s) was consumed rapidly and sulfate radicals were produced through activation by aqueous Fe2+. The second stage was governed by Fe catalyzed activation in the presence of aqueous Fe3+ and iron (oxyhydr)oxides in the NZVI shells. The second stage was 3 orders of magnitude slower than the initial stage. An electron balance showed that the sulfate radical yield per mole of persulfate was more than two times higher in the persulfate/NZVI system than in the persulfate/Fe2+ system. Radicals were believed to be produced more efficiently in the persulfate/NZVI system because aqueous Fe2+ was supplied slowly, preventing sulfate radicals being scavenged by excess aqueous Fe2+. In the second stage, the multilayered shell conducted electrons, and magnetite in the shell provided electrons for the activation of persulfate. Iron speciation analysis (including X-ray absorption spectroscopy) results indicated that a shrinking core/growing shell model explained NZVI transformation during the persulfate/NZVI process.
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IJS, KILJ, NUK, PNG, UL, UM
Abstract
This work reports the fabrication of magnetite (Fe
3
O
4
) nanoparticles (NPs) coated with various biocompatible surfactants such as glutamic acid (GA), citric acid (CA), polyethylene glycol ...(PEG), polyvinylpyrrolidine (PVP), ethylene diamine (EDA) and cetyl-trimethyl ammonium bromide (CTAB) via co-precipitation method and their comparative inductive heating ability for hyperthermia (HT) applications. X-ray and electron diffraction analyses validated the formation of well crystallined inverse spinel structured Fe
3
O
4
NPs (crystallite size of ~ 8–10 nm). Magnetic studies confirmed the superparamagnetic (SPM) behaviour for all the NPs with substantial magnetisation (63–68 emu/g) and enhanced magnetic susceptibility is attributed to the greater number of occupations of Fe
2+
ions in the lattice as revealed by X-ray photoelectron spectroscopy (XPS). Moreover, distinctive heating response (specific absorption rate, SAR from 130 to 44 W/g) of NPs with similar size and magnetisation is observed. The present study was successful in establishing a direct correlation between relaxation time (~ 9.42–15.92 ns) and heating efficiency of each surface functionalised NPs. Moreover, heat dissipated in different surface grafted NPs is found to be dependent on magnetic susceptibility, magnetic anisotropy and magnetic relaxation time. These results open very promising avenues to design surface functionalised magnetite NPs for effective HT applications.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Organizing inorganic nanocrystals into complex architectures is challenging and typically relies on preexisting templates, such as properly folded DNA or polypeptide chains. We found that under ...carefully controlled conditions, cubic nanocrystals of magnetite self-assemble into arrays of helical superstructures in a template-free manner with >99% yield. Computer simulations revealed that the formation of helices is determined by the interplay of van der Waals and magnetic dipole-dipole interactions, Zeeman coupling, and entropic forces and can be attributed to spontaneous formation of chiral nanocube clusters. Neighboring helices within their densely packed ensembles tended to adopt the same handedness in order to maximize packing, thus revealing a novel mechanism of symmetry breaking and chirality amplification.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
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•Magnetite was promoted by Ce and CeO2, and anchored onto graphene oxide sheets.•The prepared nanocomposites were evaluated for photocatalytic degradation of OTC.•Fe2.8Ce0.2O4/GO ...nanocomposite displayed great photo-activity in the visible region.•Degradation byproducts of OTC were identified, and a pathway was proposed.•The mechanism of the OTC photodegradation over Fe2.8Ce0.2O4/GO is described.
The main prerequisite of an active visible-light-driven photocatalyst is to effectively utilize the visible light to induce electron-hole (e−/h+) pairs of expanded lifetime. To this end, for the first time, the ternary heterojunctions of CeO2/Fe3O4 /Graphene oxide and Ce3+/ Fe3O4 /Graphene oxide (CeO2/Fe3O4/GO and Fe2.8Ce0.2O4/GO) were prepared via facile ultrasonic-assisted procedures and employed for destruction of oxytetracycline (OTC) under visible light irradiation. The changes in the relative crystal structure, morphology, atomic and surface functional group composition, magnetic, and optic properties of magnetite were uncovered by various techniques. The substantial degradation and mineralization of OTC via visible light/Fe2.8Ce0.2O4/GO system were thoroughly discussed in terms of narrowed band gap energy, the principal function of Ce3+/Ce4+ and Fe2+/Fe3+ redox pairs and GO platelets, enhanced charge separation and transfer, and enlarged active surface area. Furthermore, the performance of visible light/Fe2.8Ce0.2O4/GO system was evaluated for treating real wastewater and its efficiency was investigated using a number of enhancers and scavengers. Finally, the generated byproducts in the course of photodegradation were determined and the oxidation pathway, photocatalytic kinetics, and plausible mechanism were proposed. The results confirmed that the introduced Ce ions and graphene oxide sheets boost the photo-catalytic efficiency of magnetite for photodegradation of OTC.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A highly active graphdiyne heterojunction with highly efficient photocatalysis is designed and fabricated. This catalyst demonstrates transformative properties on photocatalysis for ammonia ...synthesis. Such excellent properties are reigned from graphdiyne incorporating Fe site‐specific magnetite resulting in a valence state transition within the catalyst. Our results show the strong advantages of graphdiyne in effectively regulating magnetite activity and coordination environments and also indicate that magnetite can selectively form two different valence tetrahedral coordination Fe and octahedral coordination Fe. The catalysts show remarkable catalytic performance for ammonia synthesis by photocatalysis, indicating transformative photocatalytic activity with an ammonia yield (YNH3
) of unprecedented level of 1762.35±153.71 μmol h−1 gcat.−1 (the highest YNH3
could reach up to 1916.06 μmol h−1 gcat.−1). This work makes full use of the structural and property features of graphdiyne and opens up a new direction for photocatalysis in the field of catalysis.
A graphdiyne heterojunction photocatalyst for ammonia synthesis reaches reaction rates of 1762.35±153.71 μmol h−1 gcat.−1 (the highest YNH3
could reach up to 1916.06 μmol h−1 gcat.−1). Our results demonstrated that the excellent properties originated from graphdiyne incorporating Fe site‐specific magnetite, resulting in a valence state transition in the catalytic process.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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•A Fe3O4/ZnO/graphene composites was synthesized through hydrothermal method as Fenton catalyst.•The methylene blue and congo red degradation occurred at different pH condition.•The ...introduction of ultrasound and light irradiation could improve the Fenton reaction of Fe3O4/ZnO/graphene.•The incorporation of graphene could prevent the leaching of Iron.
In a quest to develop effective methods for the elimination of organic pollutants and water remediation, a series of Fe3O4/ZnO/graphene composites are prepared and characterized. These composites are utilized as heterogeneous catalysts during the Fenton oxidation reaction for the degradation of the dyes, Congo red (CR) and methylene blue (MB), in aqueous solutions in the dark or under light and ultrasound, separately or simultaneously. The effects of various parameters, such as initial pH, H2O2 concentration, and graphene content, on the activity of the catalysts and, the iron leaching from the heterogeneous catalyst are investigated. The results demonstrate that all the catalysts exhibit excellent activities during the Fenton reaction under light and ultrasonic irradiation and that the incorporation of graphene significantly accelerates the MB and CR degradation. Complete elimination of CR and MB can be achieved in less than 1 h by simultaneous light and ultrasonic irradiation although CR was more effectively degraded as compared to MB. Moreover, the incorporation of graphene could reduce the leaching of iron ions from Fe3O4 to the solution. Thus, the Fe3O4/ZnO/graphene composite exhibits good stability after 4 repetitions of the cycling process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Fe3O4 was synthesized by coprecipitation using TMAOH and thoroughly characterized.•Magnetite nanoparticles successfully remediated aqueous Cr6+ and Pb2+.•Magnetite Langmuir ...adsorption capacities of ∼35 (Cr6+) and ∼53 (Pb2+)mg/g were obtained.•Likely Cr6+ and Pb2+ sorption mechanisms versus pH were described.•Kinetics were pseudo-second order, rate dependent on the number of surface sites.
Magnetic magnetite (Fe3O4) nanoparticles synthesized by chemical co-precipitation were characterized using XRD, TEM, SEM-EDX, FT-IR, ED-XRF, PPMS, point of zero charge (pHpzc) and surface area measurements. As-prepared Fe3O4 nanoparticles were successful for aqueous Cr6+ and Pb2+ removal. Batch adsorption experiments systematically investigated the influence of pH, temperature, contact time and adsorbate/adsorbent concentration on Cr6+ and Pb2+ adsorption. Maximum Cr6+ and Pb2+ removal occurred at pH 2.0 and 5.0, respectively. Sorption data fit pseudo-second order kinetics, indicating a chemical adsorption. The Freundlich, Langmuir, Redlich–Peterson, Toth, Radke and Sips adsorption isotherm models were applied to describe equilibrium data. The Sips and Langmuir models best described Cr6+ and Pb2+ adsorption on magnetite nanoparticles, respectively. The maximum Langmuir adsorption capacities were 34.87 (Cr6+) and 53.11 (Pb2+)mg/g at 45°C, respectively. Fe3O4 nanoparticles are promising potential adsorbents and exhibited remarkable reusability for metal ions removal in water and wastewater treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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