Efficiency and mechanisms of rhodamine B degradation in Fenton-like systems based on zero-valent iron

Based on the Fe⁰/H₂O₂ heterogeneous Fenton system, the degradation of rhodamine B (RhB, an organic dye pollutant) was researched in this paper. The effects of initial pH value, concentration of H₂O₂, dosage of zero-valent iron (ZVI), and initial RhB concentration on RhB degradation by Fe⁰/H₂O₂ were studied. The results showed that when the initial pH = 4, dosage of ZVI was 9 mM, and concentrations of H₂O₂ and RhB were 8 mM and 0.1 mM, respectively, the color of RhB could be completely faded within 30 min, and the total organic carbon (TOC) removal percentage was about 63% after 120 min. The dissolved oxygen (DO) content and oxidation–reduction potential (ORP) were monitored during the reaction. Quenching experiments with methanol confirmed that the degradation of the dye was mainly due to oxidation by the ˙OH radical. Besides, the results from UV-Vis spectroscopy showed that the degradation of RhB was mainly due to the destruction of the conjugated oxygen hetero-anthracene in the RhB molecule. The solid-phase characterization of the ZVI samples after reaction confirmed that the original regular and slippery ZVI samples finally were corroded into rough and irregular lepidocrocite and magnetite. Two possible competitive reaction pathways for the degradation of RhB by Fe⁰/H₂O₂ were proposed by GC-MS analysis, which were attributed to the dissociation of ethyl radicals and the degradation of chromophore radicals.

Based on the Fe⁰/H₂O₂ heterogeneous Fenton system, the degradation of rhodamine B (RhB, an organic dye pollutant) was researched in this paper.     

Removal of fluoride ions using a polypyrrole magnetic nanocomposite influenced by a rotating magnetic field

The impact of a varying rotating magnetic field in stimulating adsorption of fluoride ions onto a polypyrrole magnetic nanocomposite synthesized via in situ a polymerization process was evaluated. Under the effect of a rotating magnetic field, improved removal of adsorbate (10 mg L⁻¹) from aqueous solution using the polypyrrole magnetic nanocomposite was observed, with a maximum removal of 78.2% observed at a magnetic field intensity of 0.019 T. Particle aggregation resulting from the force owing to the gradient on the particles as the magnetic field was increased resulted in improved fluoride removal. This aggregation of particles leads to an improved chain collision and expanse of particle interaction with the fluoride solution. The process of adsorption of fluoride by the PPy/Fe₃O₄ nanocomposite followed both the Freudlich isotherm and the Temkin isotherm. Interestingly, under the effect of the rotating magnetic field, the adsorption process was best described by the Freundlich isotherm.

The impact of a varying rotating magnetic field in stimulating adsorption of fluoride ions onto a polypyrrole magnetic nanocomposite synthesized via in situ a polymerization process was evaluated.     

Correction: Removal of fluoride ions using a polypyrrole magnetic nanocomposite influenced by a rotating magnetic field

Correction for ‘Removal of fluoride ions using a polypyrrole magnetic nanocomposite influenced by a rotating magnetic field’ by Uyiosa Osagie Aigbe et al., RSC Adv., 2020, 10, 595–609.

The authors regret that

Detection of weak D with a fully automated solid-phase red cell adherence system

BACKGROUND: Microplate agglutination methods (MAMs) and column agglutination technology are widely employed for red cell typing and can be automated. Some tests, however, such as detection of weak D, require manual testing. The possibility of detecting weak D by a solid-phase RBC adherence (SPRCA) test was studied in a fully automated system. STUDY DESIGN AND METHODS: The results of 2609 blood samples, characterized as being D- or with a incomplete agglutination reaction, were analyzed for the presence of the weak D phenotype. The 2609 samples were tested by a weak D tube test (antiglobulin method) and a weak D-test with the new SPRCA method. When weak D was detected, which D epitope was involved and whether it was associated with a partial D phenotype were determined. RESULTS: Weak D was detected in 60 (2.3%) of the 2609 samples. The 60 samples that were weak D by the tube test were also weak D+ with the new automated SPRCA test. The sensitivity and specificity for the new weak D typing method were 100 percent, when compared with the standard weak D manual test. CONCLUSIONS: These results support the possibility of performing weak D detection with a SPRCA fully automated system. These preliminary results are encouraging, showing good sensitivity and specificity of the test. Detection of weak D will permit full automation of blood typing.     

Facile assembly of novel g-C3N4@expanded graphite and surface loading of nano zero-valent iron for enhanced synergistic degradation of tetracycline

The two-stage removal process of tetracycline (TC) in aqueous solutions using a novel photocatalyst based on nano-zero-valent iron (NZVI), g-C₃N₄ and expanded graphite by carbon layer (EGC) is reported for the first time. The composite (NZVI/g-C₃N₄@EGC) exhibits remarkable adsorption, reduction ability and visible light activity over the reaction course. Compared with pristine g-C₃N₄ (25.9%) and pure NZVI (45.9%), NZVI/g-C₃N₄@EGC achieves high degradation efficiency of TC (98.5%) due to the formation of a heterogeneous photo-Fenton system. This study shows that synergistic effects are achieved in the reaction system, including maintaining the reduction ability of NZVI and enhancing the photocatalytic activity of g-C₃N₄ by facilitating the separation of photogenerated electrons (e⁻) and holes (h⁺). TC removal involved a two-stage process of adsorption–reduction and photo-degradation. The quencher experiments determined that holes (h⁺) and superoxide radicals (˙O₂⁻) are the major reactive species in the degradation of TC. The degradation pathways of TC were proposed based on the analysis of the intermediates. In addition, NZVI/g-C₃N₄@EGC revealed a high stability in a five-cycle test and good magnetic properties for facile separation from aqueous solutions. From an application viewpoint, NZVI/g-C₃N₄@EGC has favorable prospects in the direction of the photocatalytic degradation of antibiotic wastewater.

The two-stage removal process of tetracycline (TC) in aqueous solutions using a novel photocatalyst based on nano-zero-valent iron (NZVI), g-C₃N₄ and expanded graphite by carbon layer (EGC) is reported for the first time.     

Fabrication of a low-cost adsorbent supported zero-valent iron by using red mud for removing Pb(ii) and Cr(vi) from aqueous solutions

In this study, a granular red mud supported zero-valent iron (ZVI@GRM) was successfully prepared and was used to remove Pb(ii) and Cr(vi) from aqueous solution. Zero-valent iron (ZVI) was synthesized by direct reduction of iron oxide in red mud by maize straw as a reductant at 900 °C in an anoxic atmosphere. The technical characterization (SEM, EDS, XRD, FTIR and BET) revealed that ZVI@GRM was loaded with zero-valent iron and contained different size pores. The factors of adsorption experiments include initial concentration, contact time, pH and temperature. The Pb(ii) and Cr(vi) removal by ZVI@GRM well fitted the pseudo-second-order kinetics model and the removal of heavy metals was an endothermic process. Essentially, Pb(ii) was transformed to precipitate forms (Pb⁰, Pb (OH)₂, or 2PbCO₃·Pb (OH)₂) and Cr(vi) was converted to Cr (OH)₃ or Cr³⁺/Fe³⁺ hydroxides. The maximum removal capacity for Pb(ii) and Cr(vi) by ZVI@GRM was 149.42 and 37.14 mg g⁻¹. ZVI@GRM was a low-cost material and had outstanding performance and great potential in wastewater treatment.

In this study, a granular red mud supported zero-valent iron (ZVI@GRM) was successfully prepared and was used to remove Pb(ii) and Cr(vi) from aqueous solution.     

极低频磁场增敏X线诱导的肝癌细胞凋亡的研究

目的探讨极低频磁场(ELF-EMF)能否增敏X线的肝癌细胞凋亡诱导作用。方法 BEL-7402肝癌细胞培养在37℃CO2培养箱内的25cm2培养瓶内,采用充电螺线管建立ELF-EMF,磁场磁力线垂直照射细胞培养瓶以诱导细胞凋亡。采用医用直线加速器6MVX线源皮距法照射细胞培养瓶以诱导细胞凋亡。肝癌细胞BEL-7402的凋亡率采用Annexin V-Fit凋亡检测试剂盒和流式细胞仪来检测。细胞DNA倍体图通过流式细胞仪来检测。比较ELF-EMF联合X线照射组和单纯X线照射组的肝癌细胞凋亡率。比较ELF-EMF照射后肝癌细胞异倍体百分率的变化。结果 ELF-EMF联合低剂量X线照射细胞组诱导的BEL-7402细胞的凋亡率显著高于单纯低剂量X线照射组。但是对于高剂量X线照射组,加用ELF-EMF并未增加其凋亡率。而且,在低剂量X线照射的基础上,ELF-EMF照射次数越多,诱导的肝癌细胞凋亡率越高。肝癌细胞异倍体的百分占比随着ELF-EMF照射的次数增加而上升。结论 ELF-EMF在增敏低剂量X线诱导肝癌细胞的凋亡作用中具有协同作用和累积效应,且该效应可能与ELF-EMF诱导肝癌细胞DNA异倍体的产生有关。     

The enhanced reduction of bromate by highly reactive and dispersive green nano-zerovalent iron (G-NZVI) synthesized with onion peel extract

In this study, novel green nano-zerovalent iron (G-NZVI) is synthesized for the first time using onion peel extract for the prevention of rapid surface oxidation and the enhancement of particle dispersibility with a high reductive capacity. The results from various surface analyses revealed that the spherical shape of G-NZVI was fully covered by the onion peel extract composed of polyphenolic compounds with C C–C C unsaturated carbon, C C, C–O, and O–H bonds, resulting in high mobility during column chromatography. Furthermore, the obtained G-NZVI showed the complete removal of 50 mg L⁻¹ of bromate (BrO₃⁻) in 2 min under both aerobic (k = 4.42 min⁻¹) and anaerobic conditions (k = 4.50 min⁻¹), showing that G-NZVI had outstanding oxidation resistance compared to that of bare NZVI. Moreover, the observed performance of G-NZVI showed that it was much more reactive than other well-known reductants (e.g., Fe and Co metal organic frameworks), regardless of whether aerobic or anaerobic conditions were used. The effects of G-NZVI loading, the BrO₃⁻ concentration, and pH on the BrO₃⁻ removal kinetics using G-NZVI were also investigated in this study. The results provide the novel insight that organic onion peel waste can be reused to synthesize highly reactive anti-oxidative nanoparticles for the treatment of inorganic chemical species and heavy metals in water and wastewater.

In this study, novel green nano-zerovalent iron (G-NZVI) is synthesized for the first time using onion peel extract for the prevention of rapid surface oxidation and the enhancement of particle dispersibility with a high reductive capacity.     

Removal of white cells from red cells by transfusion through a new filter

The effectiveness of a new filter (RC100) for the preparation of white cell-depleted red cells (RBCs) at the bedside was evaluated in vitro and in vivo using three RBC products: standard RBC concentrate (CPDA units), RBCs suspended in saline-adenine-glucose-mannitol additive solution after the removal of plasma (SAGM units), and RBCs suspended in SAGM after the removal of plasma and buffy coat (SAGM-BC units). Median RBC recovery was at least 92 percent when 2 units were administered through one filter; median values for residual white cells and platelets were less than or equal to 20 × 10(6) and less than or equal to 2.5 × 10(9) per 2 units, respectively. The in vivo study was carried out in 80 multiply transfused patients with thalassemia, 35 of whom had experienced frequent nonhemolytic transfusion reactions when given standard or buffy coat-free RBCs. During the 6-month study, each patient was given two transfusions of each type of RBC product One febrile nonhemolytic transfusion reaction occurred in each of two patients receiving SAGM-BC units, but in no other case. If the flow rate is not reduced, the median transfusion time is 35 minutes per CPDA unit and 15 minutes per SAGM and SAGM-BC unit. It is concluded that the transfusion of RBCs through the RC100 is a simple and effective procedure to administer white cell-depleted RBCs prepared at the bedside.     

Roles of hydroxyl and carbonate radicals in bisphenol a degradation via a nanoscale zero-valent iron/percarbonate system: influencing factors and mechanisms

In this work, nanoscale-zero-valent iron (nZVI) was applied to activate sodium percarbonate (SPC) to eliminate bisphenol A (BPA), which poses a risk to ecological and human health as a typical endocrine disruptor. The influence of nZVI loading, SPC dosing, initial pH, and the presence of inorganic anions (including Cl⁻, HPO₄²⁻, NO₃⁻ and NO₂⁻) and humic acid on BPA removal by the nZVI/SPC system were investigated. Based on the scavenger test results, ˙OH and CO₃˙⁻ participated in the degradation of BPA, and ˙OH was illustrated to be the dominant radical. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis suggested that surface iron oxide generation, electron transfer and Fe²⁺ release were the main processes of the SPC activation by nZVI. Moreover, BPA transformation products were detected by LC-MS allowing the proposal of a possible degradation pathway of BPA. Along with the degradation of the parent compound BPA, the total organic carbon (TOC) gradually decreased, while the bio-toxicity increased at the initial stage of the reaction (0–3 min) and then decreased to a lower level rapidly at 20 min. Overall, this study evidenced the feasibility of the nZVI/SPC system to efficiently degrade BPA, broadening the applications of nZVI in wastewater treatment.

Both ˙OH and CO₃˙⁻ participated in the degradation of BPA in the nZVI/SPC system, and ˙OH was the main radical.     

主动脉夹层的低场MRI诊断

目的评价低场磁共振成像(MRI)对主动脉夹层(AD)的诊断价值。方法分析14例AD的低场MRI表现,所有病例采用自旋回波(SE)序列轴位T1WI、T2WI和冠、矢状位T1WI扫描,部分病例加做梯度回波(GR)序列轴位扫描。结果14例主动脉夹层中,DeBakey A型2例,DeBakey B型12例。10例B型夹层,在轴位SE序列T1WI结合T2WI,可清晰显示真腔和假腔;2例B型夹层胸主动脉迂曲在冠状位和矢状位T1WI显示清晰。对于SE序列不能区别真假腔的2例A型夹层,轴位T1WI可显示剥离的内膜片。2例主动脉迂曲形成涡流的B型夹层,T1WI和T2WI不能区别真假腔,也不能显示内膜片,加行GR序列轴位扫描,可清晰显示等信号的内膜片。所有序列对内膜破口和再破口的显示效果不佳,对主动脉主要分支受累情况显示也不满意。结论低场MRI的SE序列可显示主动脉扩张和迂曲,也可准确识别主动脉夹层的真假腔和内膜片,但对内膜破口和再破口的显示不满意。     

Evaluation of a Subject specific dual-transmit approach for improving B1 field homogeneity in cardiovascular magnetic resonance at 3T

Background

Radiofrequency (RF) shading artifacts degrade image quality while performing cardiovascular magnetic resonance (CMR) at higher field strengths. In this article, we sought to evaluate the effect of local RF (B₁ field) shimming by using a dual-source–transmit RF system for cardiac cine imaging and to systematically evaluate the effect of subject body type on the B₁ field with and without local RF shimming.

Methods

We obtained cardiac images from 37 subjects (including 11 patients) by using dual-transmit 3T CMR. B₁ maps with and without subject-specific local RF shimming (exploiting the independent control of transmit amplitude and phase of the 2 RF transmitters) were obtained. Metrics quantifying B₁ field homogeneity were calculated and compared with subject body habitus.

Results

Local RF shimming across the region encompassed by the heart increased the mean flip angle (μ) in that area (88.5 ± 15.2% vs. 81.2 ± 13.3%; P = 0.0014), reduced the B₁ field variation by 42.2 ± 13%, and significantly improved the percentage of voxels closer to μ (39% and 82% more voxels were closer to ± 10% and ± 5% of μ, respectively) when compared with no RF shimming. B₁ homogeneity was independent of subject body type (body surface area [BSA], body mass index [BMI] or anterior-posterior/right-left patient width ratio [AP/RL]). Subject specific RF (B₁) shimming with a dual-transmit system improved local RF homogeneity across all body types.

Conclusion

With or without RF shimming, cardiac B1 field homogeneity does not depend on body type, as characterized by BMI, BSA, and AP/RL. For all body types studied, cardiac B₁ field homogeneity was significantly improved by performing local RF shimming with 2 independent RF-transmit channels. This finding indicates the need for subject-specific RF shimming.     

Weak magnetic field enhances the activation of peroxymonosulfate by ZnO@Fe3O4

The effect of weak magnetic field (WMF) on Acid Orange 7 (AO7) removal by ZnO@Fe₃O₄/peroxymonosulphate (PMS) was investigated. The results showed that the AO7 sequestration rate enhanced progressively to 0.14183 min⁻¹ in the presence of WMF, approximately 3 times the 0.04966 min⁻¹ in the absence of WMF. SO₄˙⁻/SO₅˙⁻ and O₂˙⁻ radicals were generated from the decomposition of PMS catalyzed by ZnO@Fe₃O₄ causing the degradation of AO7. In addition, a weak magnetic field promoted the production of O₂˙⁻ radicals and transition of Fe³⁺ to Fe²⁺. Radical-pair theory was used in this study to describe the role of WMF and a possible reaction mechanism was derived. Based on that, the influence of magnetic field flux intensity, pH and the reusability of ZnO@Fe₃O₄ were investigated in this paper.

The effect of weak magnetic field (WFM) on Acid Orange 7 (AO7) removal by ZnO@Fe₃O₄/peroxymonosulphate (PMS) was investigated. And a possible reaction mechanism was derived.     

Adsorption of arsenic from aqueous solution using a zero-valent iron material modified by the ionic liquid [Hmim]SbF6

The environmental and health impacts caused by arsenic (As) in wastewater make it necessary to carefully manage As wastes. In the present work, a composite of the ionic liquid [Hmim]SbF₆ and nano-iron (H/Fe) was used as an adsorbent to remove As(v) from aqueous solution. To better understand the removal effect of H/Fe on As(v) in aqueous solution, the reaction parameters of pH, reaction temperature, time and H/Fe dosage were systematically analyzed in detail. The results show that H/Fe has significant removal efficiency toward As(v), and that the adsorption of As(v) by 0.5 g H/Fe reaches its maximum adsorption capacity within 2 h. The adsorption of As(v) on H/Fe is a non-linear, time-varying process. The initial adsorption reaction is fast; however, unlike at the beginning, the later reaction involves sustained slow absorption, resulting in a distinct two-phase adsorption characteristic. Redox reaction may be one of the mechanisms responsible for the slow adsorption of As(v) on H/Fe. At the same time, the As(v) removal effect of H/Fe is greatly restricted by the pH. Electrostatic adsorption, adsorption co-precipitation and redox reactions act together on H/Fe in the As(v) removal process. This study provides a basis for further clarifying the adsorption, adsorption rules and mechanism of As(v) on H/Fe and a feasible method for the improvement of As(v) removal efficiency of zero-valent iron materials.

The environmental and health impacts caused by arsenic (As) in wastewater make it necessary to carefully manage As wastes.     

Strongly enhanced luminescence of Sr4Al14O25:Mn4+ phosphor by co-doping B3+ and Na+ ions with red emission for plant growth LEDs

Development of a more cost-effective radiation source for use in plant-growing facilities would be of significant benefit for commercial crop production applications. A series of co-doped B³⁺ and Na⁺ ions Sr₄Al₁₄O₂₅:Mn⁴⁺ inorganic luminescence materials which can be used for plant growth were successfully synthesized through a conventional high-temperature solid-state reaction. Powder X-ray diffraction was used to confirm the crystal structure and phase purity of the obtained samples. Then scanning electron microscopy elemental mapping was undertaken to characterize the distribution of the doped ions. Detail investigations on the photoluminescence emission and excitation spectra revealed that emission intensity of tetravalent manganese ions can be well enhanced by monovalent sodium ions and trivalent boron ions under near-ultraviolet and blue excitation. Additionally, crystal field parameters and energies of states are calculated and discussed in detail. Particularly we achieve a photoluminescence internal quantum yield as high as 60.8% under 450 nm blue light excitation for Sr₄Al₁₄O₂₅:Mn⁴⁺, Na⁺, B³⁺. Therefore, satisfactory luminescence properties make these phosphors available to LEDs for plant growth.

(a) Emission spectrum of LEDs fabricated with 445 nm blue chip and Sr₂Si₅N₈:Eu²⁺ red phosphor. (b) Emission spectrum of LEDs fabricated with 445 nm blue chip and Sr₄Al₁₄O₂₅:Mn⁴⁺ phosphor. (c and d) Absorption spectrum of chlorophyll-b and chlorophyll-a.     

Removal of Au3+ and Ag+ from aqueous media with magnetic nanoparticles functionalized with squaramide derivatives

New magnetic hybrid nanoparticles of Fe₃O₄ coated with organosulfur-squaramide compounds are prepared. The modified-nanoparticles show a good coordination for Ag⁺ and Hg²⁺ cations in water, and present a high affinity for Au³⁺ ions. The behaviour of the squaramide-coated nanoparticles differs significantly from that previously reported for nanoparticles used as Au³⁺ scavengers. In the presence of organosulfur-squaramide, the Au³⁺ salt is reduced to gold nanoparticles that are deposited upon Fe₃O₄ nanoparticles. For the first time, the coordination capacity of the carbonyl squaramide groups with the gold cation, based on purely electrostatic cation–dipole interactions, is proved.

An efficient methodology, based on squaramide-coated magnetite nanoparticles, for the removal of Au³⁺ and Ag⁺ by magneto filtration from water.     

Improving the properties of Fe2O3 by a sparking method under a uniform magnetic field for a high-performance humidity sensor

Iron oxide (Fe₂O₃) thin films are promising semiconductors for electronic applications because Fe₂O₃ is an earth-abundant semiconductor with an appropriate band gap. However, many methods for the synthesis of Fe₂O₃ thin films require a corrosive source, complex procedures, and many types of equipment. Here, we report, for the first time, a simple method for Fe₂O₃ deposition using sparking under a uniform magnetic field. The morphology of Fe₂O₃ displayed an agglomeration of particles with a network-like structure. The crystallite size, % Fe content, and optical bandgap of Fe₂O₃ were influenced by changes in the magnitude of the magnetic field. For application in humidity sensors, Fe₂O₃ at a magnetic field of 200 mT demonstrated a sensitivity of 99.81%, response time of 0.33 s, and recovery time of 2.57 s. These results can provide references for new research studies.

Fe₂O₃ deposition by a sparking method under a uniform magnetic field.     

High field magnetic resonance microscopy of the human hippocampus in Alzheimer's disease: quantitative imaging and correlation with iron

We report R₂ and R₂* in human hippocampus from five unfixed post-mortem Alzheimer's disease (AD) and three age-matched control cases. Formalin-fixed tissues from opposing hemispheres in a matched AD and control were included for comparison. Imaging was performed in a 600 MHz (14 T) vertical bore magnet at MR microscopy resolution to obtain R₂ and R₂* (62 μm × 62 μm in-plane, 80 μm slice thickness), and R₁ at 250 μm isotropic resolution. R₁, R₂ and R₂* maps were computed for individual slices in each case, and used to compare subfields between AD and controls. The magnitudes of R₂ and R₂* changed very little between AD and control, but their variances in the Cornu Ammonis and dentate gyrus were significantly higher in AD compared for controls (p < 0.001). To investigate the relationship between tissue iron and MRI parameters, each tissue block was cryosectioned at 30 μm in the imaging plane, and iron distribution was mapped using synchrotron microfocus X-ray fluorescence spectroscopy. A positive correlation of R₂ and R₂* with iron was demonstrated. While studies with fixed tissues are more straightforward to conduct, fixation can alter iron status in tissues, making measurement of unfixed tissue relevant. To our knowledge, these data represent an advance in quantitative imaging of hippocampal subfields in unfixed tissue, and the methods facilitate direct analysis of the relationship between MRI parameters and iron. The significantly increased variance in AD compared for controls warrants investigation at lower fields and in-vivo, to determine if this parameter is clinically relevant.     

Shape-controlled synthesis of magnetic Fe3O4 nanoparticles with different iron precursors and capping agents

This paper describes a modified method to prepare monodisperse Fe₃O₄ magnetic nanoparticles with different shapes (cube, octahedron, and sphere). The shape of the magnetic nanoparticles could be conveniently controlled by changing the types of precursor/capping agent and concentration of capping agent. The prepared samples were characterized using scanning electron microscopy, X-ray diffraction and vibrating sample magnetometry. Cubes and octahedra were formed using ferrous sulfate heptahydrate as an iron source, ethylene glycol as a solvent and potassium hydroxide (KOH) as a capping agent while spheres were formed by using ferric chloride hexahydrate as an iron source, ethylene glycol as a solvent and ammonium acetate as a capping agent. By varying KOH concentration (0.5 M, 1 M, 1.5 M, and 5 M), the shape was transformed from cubes to octahedra because octahedra are developed dominantly at higher concentration of KOH within the reaction mixture. The magnetic studies show superparamagnetic behavior for all samples at room temperature. The Fe₃O₄ nanoparticles show the magnetic saturation values of 87 emu g⁻¹, 85 emu g⁻¹, and 82 emu g⁻¹ for spheres, cubes, and octahedrons, respectively.

This paper describes a modified method to prepare monodisperse Fe₃O₄ magnetic nanoparticles with different shapes (cube, octahedron, and sphere).