As-prepared Fe3O4 Research Articles

Photocatalytic Degradation of Organic Dyes by Magnetite Nanoparticles Prepared by Co-Precipitation.

Iron oxide nanoparticles were synthesized by co-precipitation using three different iron salt stoichiometric mole ratios. Powder X-ray diffraction patterns revealed the inverse cubic spinel structure of magnetite iron oxide. Transmission electron microscopic images showed Fe3O4 nanoparticles with different shapes and average particle sizes of 5.48 nm for Fe3O4-1:2, 6.02 nm for Fe3O4-1.5:2, and 6.98 nm for Fe3O4-2:3 with an energy bandgap of 3.27 to 3.53 eV. The as-prepared Fe3O4 nanoparticles were used as photocatalysts to degrade brilliant green (BG), rhodamine B (RhB), indigo carmine (IC), and methyl red (MR) under visible light irradiation. The photocatalytic degradation efficiency of 80.4% was obtained from Fe3O4-1:2 for brilliant green, 61.5% from Fe3O4-1.5:2 for rhodamine B, and 77.9% and 73.9% from Fe3O4-2:3 for both indigo carmine and methyl red. This indicates that Fe3O4-2:3 is more efficient in the degradation of more than one dye. This study shows that brilliant green degrades most effectively at pH 9, rhodamine B degrades best at pH 6.5, and indigo carmine and methyl red degrade most efficiently at pH 3. Recyclability experiments showed that the Fe3O4 photocatalysts can be recycled four times and are photostable.

Hydrothermal synthesis of carbon dots incorporated in magnetite iron oxide nanoparticles for potential targeted brain cancer therapy: In-Vitro study

Surface modification of magnetite (Fe3O4) nanoparticles (NPs) using carbon dots (CDs) is a promising approach in biomedical applications due to excellent biocompatibility. Herein, the CDs were incorporated in the Fe3O4 NPs to observe the performance of CDs-Fe3O4 NPs for targeted brain cancer therapy. Scanning electron microscopy (SEM) images revealed the morphology of Fe3O4 NPs is rough and agglomerated. X-ray diffraction (XRD) diffraction pattern exhibits that the CDs are successfully incorporated in Fe3O4 NPs. Furthermore, magnetic properties evaluated using vibrating sample magnetometer (VSM) exhibited significant magnetization (51.362 emu/g) attributed to the greater occupancy of Fe+2 ions in the crystal lattice. XRD pattern confirmed the formation of NPs. Furthermore, functional groups of the NPs were validated through Fourier-transform infrared spectroscopy (FT-IR). The measurement of zeta potential affirmed the stability of the as-prepared Fe3O4 NPs, CDs, and CDs-Fe3O4 NPs, indicating a value of −7.64 mV, −0.5754 mV and −3.881 mV, respectively. Fe3O4 NPs exhibited a surface area of 58.6 m2/g as determined by Brunauer-Emmett-Teller (BET) analysis. The anticancer activity of the synthesized CDs-Fe3O4 NPs demonstrated inhibition against MG-U87 cells. Therefore, the synthesized CDs-Fe3O4 NPs hold potential for application in brain cancer therapy. In addition, CDs-Fe3O4 NPs exhibited exceptional biocompatibility and low cytotoxicity against osteoblast cells, establishing them as a safe biomaterial for biomedical applications.

Fabrication of porous X-shaped Fe3O4@C core-shell structures for tunable microwave absorption

Designing porous materials with low density and high specific surface area is one of the strategies to obtain excellent wave absorbing properties. In this study, the carbon-coated porous X-shaped Fe3O4 composites used as microwave absorption materials were prepared by heat treatment of FeOOH@Polydopamine (PDA) core-shell precursors. It revealed that the X-shaped Fe3O4 core showed improved magnetic loss in GHz band due to its special shape anisotropy and large specific surface area. In addition, the modification of carbon enabled the Fe3O4 absorbers to have stronger polarization and higher electrical conductivity. The composites exhibited great freedom in performance tunability, allowing for strong absorption (RL<−40 dB) at different frequencies. For composites with thick carbon shell, the reflection loss reached the optimal value of − 64.92 dB at 15.04 GHz at the thickness of 1.75 mm, and the effective bandwidth was up to 4.64 GHz (13.04–17.68 GHz). The impressive performance of the as-prepared Fe3O4 @C core-shell composites was mainly attributed to the complementary behaviors of strong dielectric loss and magnetic loss.

Efficient photocatalysis-Fenton for degradation of rhodamine B and inhibition of bacteria by core-shell Fe3O4 @UiO-66-NH2 nanospheres

Core-shell Fe3O4 @UiO-66-NH2 nanospheres with superior photocatalytic activity and photo-Fenton performance were synthesized using a layer-by-layer growth strategy. The synthesis involved the use of FeCl3, trisodium citrate, sodium acetate, ZrCl4, and 2-aminoterephthalic acid as raw materials, with mercaptoacetic acid serving as a modifier. Fe3O4 @UiO-66-NH2 demonstrated improved visible-light-driven photocatalytic performance in the oxidation degradation of Rhodamine B (RhB) in the presence of trace amounts of H2O2 under visible light irradiation. The Fe(II)/Fe(III) cycle was accelerated by the transfer of the photogenerated electrons (e-) from UiO-66-NH2 to Fe3O4, which in turn encouraged the Fenton reaction to produce hydroxyl radicals (•OH). With only 10 mmol/L H2O2, the removal rate of RhB approached 94% in 120 min. Furthermore, when exposed to visible light, Fe3O4 @UiO-66-NH2 exhibited 99% efficacious antibacterial activity against Escherichia coli and Staphylococcus aureus. Overall, the as-prepared Fe3O4 @UiO-66-NH2 core-shell nanospheres show promise for practical applications as photocatalysts for the degradation of organic pollutants and the inactivation of bacteria in wastewater.

Magnetic properties of Al3+ doped Fe3O4 by solid-solid reaction and biological applications of GQDs grafted MNPs

2.79 % Al3+ doped Fe3O4 magnetic nanoparticles (Al-Fe3O4 MNPs) was prepared by a solid–solid reaction between aluminum formic acid hydrazide and as-prepared Fe3O4 magnetic nanoparticles. The obtained Al-Fe3O4 MNPs were strongly ferromagnetic, and their greatest saturation magnetization value was 82.3 electromagnetic units per gram (emu/g). The Al-Fe3O4 MNPs were subsequently coated with SiO2. High-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), Mössbauer spectroscopy, and vibrating-sample magnetometry (VSM) were used to characterize the morphology, structure, magnetic properties, and doping mechanism of the doped magnetic particles, respectively. Then graphene quantum dot (GQD) is loaded on the surface of aminated Al-Fe3O4@SiO2 (AFS) MNPs by a covalent connection, and Al-Fe3O4@SiO2-GQDs (AFSG) MNPs. Furthermore, AFSG MNPs were labeled with the metastable nuclear isomer of technetium-99 (99mTc) and their in vivo targeting performance was investigated. The AFSG-99mTc MNPs demonstrated a relatively strong magnetic response in a pulsed magnetic gradient field. The data obtained from the control and experimental groups indicated that the ability to uptake radioactivity of the livers of New Zealand rabbits via the magnetic targeted intervention was 3.69 times higher than that without the magnetic targeted intervention.

Waste Camellia oleifera shell-derived hierarchically porous carbon modified by Fe3O4 nanoparticles for capacitive removal of heavy metal ions

Capacitive deionization is an efficient technology for water purification and treatment. The electrode material is crucial to improving the performance of capacitive deionization. Herein, Fe3O4 nanoparticles-modified hierarchically porous carbon (Fe3O4 NPs/HPC) was successfully synthesized by the pyrolysis of waste Camellia oleifera shell coupling with the post-modification. Owing to its unique structure and composition, the as-prepared Fe3O4 NPs/HPC delivered great potential in capacitive deionization and heavy metal removal. Under the current density of 0.5 A g-1, the Fe3O4 NPs/HPC electrode showed a high specific capacitance of 134.5 F g−1 in 1 M NaCl solution, much more than the bare HPC electrode of 99.9 F g−1. In addition, the Fe3O4 NPs/HPC electrode exhibited excellent cycle stability with negligible loss of capacitance after 1000 cycles at 2 A g-1. At an operating voltage of 1.2 V, the Fe3O4 NPs/HPC electrode released high uptake capacity of 34.22 and 39.52 mg g−1 for Cd(II) and Pb(II) ions, respectively. XPS spectra and competitive adsorption demonstrated that Cd(II) was mainly removed by the oxygen-containing groups of HPC through an electrosorption coupling with an electrodeposition multilayer process, but Pb(II) was uniformly adsorbed on the active sites including the oxygen-containing groups of HPC and the modified Fe3O4 NPs by a monolayer electrosorption process. The impressive results indicate that the as-prepared Fe3O4 NPs/HPC composites possess potential for the selective removal of heavy metal ions from saline wastewater.

Uniform Fe2 O3 Nanospheres Anchored on Multilayer Graphene as Anode Materials for High-Rate Ni-Fe Batteries.

Ni-Fe battery is one of prospective aqueous alkaline batteries due to its high safety, eco-friendliness and cost-effectiveness. However, the electrochemical performance of Fe-based anodes is limited due to the particle aggregation and low electric conductivity. In this work, iron powder is used as a precursor in a chemical bath deposition method. By optimizing the concentration of HNO3 , a balanced dissolution-crystallization process is achieved to obtain uniform Fe2 O3 nanospheres in size between 60 and 90 nm, which are separately anchored on ultrasonically prepared multilayer graphene (MLG). This composite delivers specific discharge capacities of 191.1 and 160.8 mAh g-1 at the current densities of 2 and 10 A g-1 , respectively. A Ni-Fe battery with the as-prepared Fe2 O3 /MLG as anode and Ni(OH)2 /MLG as cathode exhibits an energy density of 69.5 Wh kg-1 at a high power density of 3931.6 W kg-1 .

Magnetic covalent organic framework nanospheres with enhanced peroxidase-like activity for colorimetric detection of H2O2 and glucose

The nanomaterials-based artificial enzymes have attracted great attention because of their high stability, good biocompatibility, high catalytic efficiency, and low cost in recent years. Herein, we synthesized a new covalent organic framework (COFs) through the dehydration reaction of 2,5-dihydroxyterephthalaldehyde and tetra-(4-aminophenyl) porphyrin, which was then used to fabricate the core-shell structured nanospheres (Fe3O4 @COFs) by decorating on magnetic Fe3O4. In the presence of hydrogen peroxide (H2O2), the Fe3O4 @COFs nanospheres were able to catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue product (ox-TMB), indicating their high peroxidase-like activity. Based on this phenomenon, the Fe3O4 @COFs was used as a colorimetric probe for sensitive and selective detection of H2O2 and glucose. The detection limit (LOD) of H2O2 was calculated to be 2.6 μM in a linear range from 0.1 to 4 mM, while the LOD of glucose was valued as 6 μM ranging from 0.05 to 0.9 mM. Finally, this method was applied in the determination of the glucose concentration in human serum with high accuracy. Thus, the as-prepared Fe3O4 @COFs could be used as a highly sensitive and selective peroxidase mimic to detect hydrogen peroxide-related molecules, suggesting their great potential in biomedical application.

Coal gasification fine slag residual carbon decorated with hollow-spherical Fe3O4 nanoparticles for microwave absorption

Reasonable design and optimization of the dielectric and magnetic properties of materials are important to achieve excellent electromagnetic wave (EMW) absorption capacities. Residual carbon (RC) derived from coal gasification fine slag-loaded hollow-spherical Fe3O4 nanoparticles (Fe3O4 NPs@RC) was synthesized via hydrothermal strategy. The chemical compositions, morphologies, structures, and electromagnetic parameters of the as-prepared RC and Fe3O4 NPs@RC revealed that the phase components (RC and Fe3O4 phases) and microstructure (hollow spherical and micro/nano blocks) were well modified by modulating the content of Fe3O4. Such modifications result in variations in the hierarchical structure, defects, electromagnetic parameters, and EMW absorption performance. The Fe3O4 NPs@RC composites (S1 and S2) exhibited superior EMW absorption capacity. The binary composite with an additive amount of FeCl3·6H2O of 2.66 g (S2) exhibited the minimum reflection loss (RLmin) of −32.6 dB at 2.0 mm and a broad absorption bandwidth (fe, RL less than −10 dB) of 4.64 GHz at a lower thickness value of 1.65 mm under a filler content of 40%. In addition, the ultra-broad fe reached 14.35 GHz, which contained the entire Ku, X, and C bands by easily regulating the thicknesses from 1.5 mm to 5 mm. A possible EMW absorption mechanism was proposed. This study offers an effective strategy for designing novel coal gasification solid waste-based materials for high-performance absorbers.

Fe3O4@SiO2 Core–Shell Nanoparticles: Synthesis, Characterization Prepared by Green Method for Iraqi Aloe Vera Extract

In this work, a green approach was used to create Fe3O4 nanoparticles. After that, ferrous chloride tetrahydrate and ferric chloride hexahydrate solutions were mixed with various quantities of Iraqi Aloe Vera gel and sodium hydroxide solution to achieve pH(8). Then, in the scale synthesis of silica-coated iron oxide NPs utilizing nontoxic and low-cost materials, tetraethyl orthosilicate (TEOS) was employed as a precursor to silica. (UV–Vis), FT-IR, XRD, AFM, EDS, TEM, Zeta Potential, VSM, FESEM and VSM were used to characterize the as-prepared silica-coated (Fe3O4@SiO2 CSNPs) and Fe3O4 NPs. UV–Vis exhibits an absorption band in the ultraviolet region at approximately 300 nm in Fe3O4NPs and 310[Formula: see text]nm in Fe3O4@SiO2 CSNPs, this means red shift occurs successively. Results of (XRD) and (EDS) analyses demonstrate that magnetite nanoparticles were effectively coated using this easy process. FESEM and TEM measurements demonstrate that the particle size of iron oxide nanoparticles and iron oxide NPs CSNPs increases before and after coating with spherical particles in form. AFM evaluates surface tension and surface energy. It is found that the surface roughness of magnetite nanoparticles NPs is 49.31[Formula: see text]nm and root mean square (RMS) is 319.8[Formula: see text]nm, whereas in core–shell it is 25.45[Formula: see text]nm and 166.7[Formula: see text]nm, respectively, it was raised in the case of the core–shell. This means decrease in particle size. Magnetic properties from (VSM) test demonstrate that the magnetization of the as-synthesized TEOS-coated magnetite NPs is lower than that of freshly created bare magnetite NPs, demonstrating the formation of Fe3O4@SiO2 CSNPs. The stability was around [Formula: see text][Formula: see text]mV, and the addition of magnetic and optical features improved their biocompatibility. The antibacterial activity of Fe3O4 NPs and Fe3O4@SiO2 CSNPs was investigated using the agar well diffusion method agains t Staphylococcus aureus Gram-positive and Escherichia coli Gram-negative bacteria, which exhibited a wide spectrum of antibacterial potency inhibiting the growth of both Gram-negative (8[Formula: see text]mm, 10[Formula: see text]mm) and Gram-positive (7[Formula: see text]mm, 12[Formula: see text]mm), respectively.

Assessing the Heat Generation and Self-Heating Mechanism of Superparamagnetic Fe3O4 Nanoparticles for Magnetic Hyperthermia Application: The Effects of Concentration, Frequency, and Magnetic Field.

Magnetite nanoparticles (MNPs) exhibit favorable heating responses under magnetic excitation, which makes them particularly suited for various hyperthermia applications. Herein, we report the detailed self-heating mechanisms of MNPs prepared via the Ko-precipitation Hydrolytic Basic (KHB) methodology. The as-prepared MNPs were fully characterized using various spectroscopic techniques including transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). MNPs exhibited stable 15 nm quasi-spherical small-sized particles, pure crystalline cubic Fe3O4 phases, high saturation magnetizations (Ms = ~40 emu·g-1), and superparamagnetic behavior. In response to alternating magnetic fields (AMFs), these MNPs displayed excellent self-heating efficiencies with distinctive heating responses, even when minimal doses of MNPs were used. Heating efficacies and specific absorption rate (SAR) values as functions of concentration, frequency, and amplitude were systematically investigated. Remarkably, within only a few minutes, MNPs (2.5 mg/mL) showed a rapid dissipation of heat energy, giving a maximum intrinsic loss power (ILP) of 4.29 nHm2/kg and a SAR of 261 W/g. Hyperthermia temperatures were rapidly reached in as early as 3 min and could rise up to 80 °C. In addition, Rietveld refinement, Langevin, and linear response theory (LRT) models were studied to further assess the magnetic and heating mechanisms. The LRT model was used to determine the Néel relaxation time (τR = 5.41 × 10-7 s), which was compared to the Brownian relation time value (τB = 11 × 10-7 s), showing that both mechanisms are responsible for heat dissipated by the MNPs. Finally, the cytotoxicity assay was conducted on aqueous dispersions of MNPs, indicating their biocompatibility and low toxicity. Our results strongly suggest that the as-prepared Fe3O4 MNPs are promising vehicles for potential magnetically triggered biomedical hyperthermia applications.

Integration strategy for facile fabrication of porous carbon coated Fe3O4 nanospindles with enhanced lithium storage

Despite high capacities, the practical use of the Fe3O4-based anodes is still impeded because of poor cyclic performance caused by their large volumetric variation and pulverization during cycle. Aimed at the aforementioned problems, a composite of conformal porous carbon coated Fe3O4 nanospindles (Fe3O4 @PC) has been prepared by a well-designed integration strategy which not only simplifies the experimental steps but also restrains the severe aggregation of nano-sized Fe3O4 during carbon coating process. In particular, the superficially conformal porous carbon is demonstrated to not only accommodate the volumetric variation of the Fe3O4 nanospindles better with its flexible spongy structure but also provide fast and stable diffusion pathways for ions through its defect-enriched pores. With a combination of superficially conformal porous carbon coating, nano-sized one-dimensional structure and Fe–O–C chemical bonding, therefore, the as-prepared Fe3O4 @PC shows outstanding electrochemical behaviors in terms of high capacity, long lifespan and good rate performance, demonstrating 896.3 and 592.9 mA h g−1 after 400 cycles at 200 and 1000 mA g−1, respectively. Moreover, this work is expected to open up new avenues for designing and preparing other conformal porous carbon coated metal oxides for advanced LIB anodes or other applications.

Oxygen vacancy-rich Fe3O4 nanoparticle synthesized via facile electrochemical method as anode material for high-performance lithium-ion batteries

Oxygen vacancies (Ov), which are internal defects of metal oxides, can effectively alter intrinsic properties of materials. Developing an anode material containing Ovs applied in lithium-ion batteries (LIBs) was hypothesized to enhance their electrochemical performance, which has currently attracted extensive attention. Herein, we successfully synthesized three groups of Fe3O4 nanoparticles with different Ov concentrations by a facile and controllable electrochemical oxidation corrosion method. First, density functional theory was applied to predict the Li-ion storage performance and electronic properties of pristine Fe3O4 and the synthesized different Ov-content Fe3O4 materials. When used as an anode material in LIBs, all the three as-prepared Ov-rich Fe3O4 electrodes possessed excellent cycling performance and high reversibility. After 330 cycles, the reversible capacity achieved 745 mAh g−1, 921 mAh g−1, and 850 mAh g−1, respectively. Ovs in the Fe3O4 not only promote high electronic conductivity in the materials, but also afford additional active sites for lithiation and delithiation, further enhancing the electrochemical performance. However, excessive Ovs are not conducive to the improvement of lithium storage capacity. Theoretical predictions and experimental results are consistent with each other. This work has great importance in the direction of oxygen defect applications in the field of LIBs.

Ultrafast self-assembly Fe2O3 nanoparticles confined in carbon layers toward robust heterogeneous electro-Fenton reaction

Heterogeneous electro-Fenton (EF) is a promising advanced oxidation process for refractory wastewater treatment. However, typical calcination or hydrothermal method for heterogeneous EF cathode fabrication is time-consuming, energy-consuming, or harmful to the environment. High-temperature shock (HTS) technique is a novel and rapid material synthesis method with the advantages of low-cost, eco-friendly. In this study, the electrodes named Fe2O3@C/carbon cloth (Fe2O3@C/CC), were synthesized by HTS for the first time within an extremely short time (∼5 s). The Fe2O3 nanoparticles with an average diameter of 61.90 ± 15.09 nm are uniformly dispersed on carbon cloth (CC) with the confinement and protection of the carbon layers. The as-prepared Fe2O3@C/CC cathode exhibited excellent electrocatalytic properties in the EF system. The removal efficiency of methylisothiazolinone (MIT) could reach 90.60 ± 1.70% in 40 min at a low current density of 1.11 mA cm−2 under the oxidation of the hydroxyl radical. In addition, the degradation pathways of MIT were further studied. According to the results of theoretical calculation, the –S–N– bond is the primary active site attacked during MIT degradation process. Therefore, heterocyclic loop opening is the main pathway of MIT degradation. HTS is an ultrafast and convenient potential technique compared with other cathode synthesis methods.

Facile synthesis of hyperbranched magnetic nanomaterials for selective adsorption of proteins

The separation and purification of proteins is an essential precondition for proteomics research because of the intricate matrix environment. Hence, a facile method has been developed to synthesize hyperbranched polyethyleneimine modified magnetic nanomaterials (Fe3O4–NH2-BPEI) with dendritic structure, unique electrostatic effect, and abundant functional groups for the selective adsorption of proteins which greatly avoids the drawbacks of time consumption and leakage of metal ions in traditional pre-treatment. The preparation conditions, physical and chemical properties, and adsorption performance of Fe3O4–NH2-BPEI have been fully studied. The obtained materials have stable crystal shape, adequate superparamagnetism, fast adsorption kinetics, high adsorption amount, and admirable reusability. In addition, the as-prepared Fe3O4–NH2-BPEI exhibits good selective adsorption ability for electronegative proteins in the neutral solution, exhibiting a potential value for special adsorption for proteins with different pI.

Highly significant fluorescence enhancement effect of silver-deposited Fe3O4@C core/shell nanoparticles for detection of dyes and fluorescein

Developing multifunctional composite materials has always drawn the researchers particularly. In this work, silver-deposited Fe3O4@C core/shell nanoparticles were fabricated via a facile two-step method. As-prepared Fe3O4@C@Ag as substrates displayed significant fluorescent enhancement and stability by controlling amount of Ag nanoparticles, as well as great reproducibility due to magnetic nature. It was indicated that the highest enhancement factors reached 33.1-fold for detecting RB and 108.3-fold for detecting FITC, respectively. The amount of Ag nanoparticles was of great importance for fluorescence enhancement and Fe3O4@C@Ag nanocomposites with fewer Ag nanoparticles deposited showed better stability. The research findings brought insight into widespread application in fluorescence detection, such as chemical analysis, material identification, medical diagnosis and environmental monitoring.

A 3D printed synergistic aerogel microreactor toward stable and high-efficiency photocatalytic degradation

Photocatalysis offers a credible and prompt approach to solving the growing problems of environmental pollution and energy shortages. However, the practical application of photocatalytic materials still faces the challenge of the efficient catalytic system without secondary recovery. Herein, hollow Fe2O3 microspheres with uniform size (polydispersity index = 0.067) were synthesized using an innovative microgel template–assisted solvothermal method with high yield. Via direct writing three-dimensional printing, the as-prepared Fe2O3 microspheres and graphene oxide were fabricated into an ultralight, stable, and high-performance aerogel microreactor, achieving wastewater treatment without catalyst recovery. Photocatalytic degradation efficiency of rhodamine B achieved 97.8% by the microreactor under simulated sunlight irradiation for 120 min. The rich porous structures and highly interconnected networks of the microreactor provide high specific surface area and increased numbers of multidimensional mass transfer channels, further enabling the catalytic performance and reusability for photocatalytic degradation.

Adsorption mechanism for tetracycline onto magnetic Fe3O4 nanoparticles: Adsorption isotherm and dynamic behavior, location of adsorption sites and interaction bonds

Fe3O4 nanoparticles as a magnetic adsorbent were prepared and used to effectively remove tetracycline (TC) from neutral aqueous solution. Several characterizations show that the as-prepared Fe3O4 nanoparticles possess a saturation magnetization of 79.4 emu/g, a specific surface area of 58.8 m2/g and an average particle size of 25 nm. Batch experiments were carried out to investigate the adsorption behavior and mechanisms. For a 100 mL TC solution with an initial concentration of 10 mg/L, the TC absorption reached adsorption-desorption equilibrium with a removal efficiency of 97.2% in 90 min. Adsorption kinetic and isotherm studies demonstrated that the adsorption process fits well with pseudo-second-order kinetics models. The Langmuir isotherm model was found to be more suitable than the Freundlich isotherm model for describing the adsorption equilibrium data. Adsorption between Fe3O4 and TC is achieved by the formation of hydrogen bonds between the H atoms of the C–O(H) bonds located at the B or D ring of TC and the O atoms of Fe3O4. Furthermore, the hydrogen bonds formed at the octahedral site are stronger than those formed at the tetrahedral site. This new understanding provides an important reference and guidance for the design and modification of Fe3O4-based nanomaterials for TC removal.

Influence of the Hollowness and Size Distribution on the Magnetic Properties of Fe3O4 Nanospheres.

In this study, Fe3O4 nanospheres with different levels of hollowness were successfully prepared by the solvent thermal method. The synthesized Fe3O4 nanospheres were characterized by transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometry, and Image-Pro software was used to analyze the hollowness of the Fe3O4 nanospheres for the first time. It was found that excess reactants could lead to the disappearance of the hollow structure of the Fe3O4 nanospheres, and the reason for this phenomenon was discussed as due to entropy increase theory. Furthermore, the influence of the hollowness and size distribution on the magnetic properties of the Fe3O4 nanospheres was evaluated. The magnetic properties of a Fe3O4 nanosphere with a hollowness of 10.48% showed a relatively high saturation magnetization of 103 emu/g and a rather low coercivity (54 Oe). The as-prepared Fe3O4 nanospheres are expected to be useful in a wide range of fields such as drug-delivery and energy applications.

Biogenic synthesis of husked rice-shaped iron oxide nanoparticles using coconut pulp (Cocos nucifera L.) extract for photocatalytic degradation of Rhodamine B dye and their in vitro antibacterial and anticancer activity

In this present study, photocatalytic and in-vitro biological properties of biogenic preparation of husked rice-shaped iron oxide nanoparticles (Fe2O3 NPs) are investigated. Fe2O3 NPs have been prepared by the reduction of iron chloride (FeCl3) using coconut pulp (Cocos nucifera L.) extract. The Fe2O3 NPs were characterized by various analytical techniques such as FE-SEM, TEM, XRD, FT-IR, TGA, VSM, PL, and UV-DRS. Based on the characterization results, the as-prepared Fe2O3 NPs are in husked rice shape and exhibit rhombohedral crystal phase and also show an excellent stability. The prepared Fe2O3 NPs was investigated as a catalyst for the photocatalytic degradation of Rhodamine B solution. The photocatalytic results indicated that the Fe2O3 NPs catalyst possesses good activity with efficiency of 92% after 50 min under visible-light irradiation. In addition, the Fe2O3 NPs showed good antibacterial and anticancer properties against Gram-negative Escherichia coli and Gram-positive, Staphylococcus aureus and HepG2 cell lines, resulting in effective antibacterial and anticancer activity. The prepared Fe2O3 NPs, thus, proved to be a potential material for environmental remediation and biological applications.