Magnetochemistry

20 pages, 5439 KiB

Open AccessArticle

The Efficient Degradation of Oxytetracycline in Wastewater Using Fe/Mn-Modified Magnetic Oak Biochar: Pathways and Mechanistic Investigation

by Yujie Zhou, Yuzhe Fu, Xiaoxue Niu, Bohan Wu, Xinghan Liu, Fu Hao, Zichuan Ma, Hao Cai and Yuheng Liu

Magnetochemistry 2025, 11(6), 49; https://doi.org/10.3390/magnetochemistry11060049 - 6 Jun 2025

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Abstract

Antibiotic resistance has been recognized as a global threat to human health. Therefore, it is urgent to develop effective strategies to address the contamination of water environments caused by antibiotics. In this study, Fe/Mn bimetallic-modified biochar (FMBC) was synthesized through a one-pot oxidation/reduction-hydrothermal co-precipitation method, demonstrating an exceptional photocatalytic-Fenton degradation performance for oxytetracycline (OTC). Characterization techniques including FTIR, SEM, XRD, VSM, and N₂ adsorption–desorption analysis confirmed that the Fe/Mn bimetals were successfully loaded onto the surface of biochar in the form of Fe₃O₄ and MnFe₂O₄ mixed crystals and exhibited favorable paramagnetic properties that facilitate magnetic recovery. A key innovation is the utilization of biochar’s inherent phenol/quinone structures as reactive sites and electron transfer mediators, which synergistically interact with the loaded bimetallic oxides to significantly enhance the generation of highly reactive ·OH radicals, thereby boosting catalytic activity. Even after five recycling cycles, the material exhibited minimal changes in degradation efficiency and bimetallic crystal structure, indicating its notable stability and reusability. The photocatalytic degradation experiment conducted in a Fenton-like reaction system demonstrates that, under the conditions of pH 4.0, a H₂O₂ concentration of 5.16 mmol/L, a catalyst dosage of 0.20 g/L, and an OTC concentration of 100 mg/L, the optimal degradation efficiency of 98.3% can be achieved. Additionally, the pseudo-first-order kinetic rate constant was determined to be 4.88 min⁻¹. Furthermore, this study elucidated the detailed degradation mechanisms, pathways, and the influence of various ions, providing valuable theoretical insights and technical support for the degradation of antibiotics in real wastewater. Full article

(This article belongs to the Special Issue Applications of Magnetic Materials in Water Treatment)

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13 pages, 1841 KiB

Open AccessArticle

A Heptacobalt(II/III) Dicubane Cluster with Polyoxometalate and Acetato Ligands: Synthesis, Crystal Structure, and Magnetic Properties

by Gonzalo Abellán-Dumont, Juan Modesto Clemente-Juan and Carlos Giménez-Saiz

Magnetochemistry 2025, 11(6), 48; https://doi.org/10.3390/magnetochemistry11060048 - 3 Jun 2025

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Abstract

The new polyoxometalate [Co₇(OH)₆(H₂O)₂(CH₃COO)₄(PW₉O₃₄)₂]¹³⁻ (1) has been synthesized and characterized by IR, UV-Vis-NIR, TGA-TDA, X-ray single crystal analysis, and magnetic studies; 1 consists of two trilacunary heptadentate B-α-[PW₉O₃₄]⁹⁻ ligands encapsulating a heptacobalt dicubane-like {Co^II₆Co^IIIO₈} core, in which the Co²⁺ ions are further coordinated by two water molecules and four acetate anions acting as monodentate ligands. The magnetic properties of 1 have been fitted according to an anisotropic exchange model in the low-temperature regime and discussed on the basis of ferromagnetic interactions between Co²⁺ ions with angles Co–L–Co (L = O, OH) close to orthogonality and weakly antiferromagnetic interactions between Co²⁺ ions connected through a central diamagnetic Co³⁺ ion. Full article

(This article belongs to the Special Issue Magnetic Coordination Compounds and More... a Long and Successful Story: A Tribute to M. Julve and F. Lloret)

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18 pages, 2149 KiB

Open AccessReview

Nuclear Magnetic Resonance-Based Approaches for the Structural and Quantitative Analysis of Mycotoxins

by Yun Hwan Kim, Seon Yeong Lee, Jin Young Kim, Hyojin Cho, Hyang Sook Chun and Sangdoo Ahn

Magnetochemistry 2025, 11(6), 47; https://doi.org/10.3390/magnetochemistry11060047 - 3 Jun 2025

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Abstract

Mycotoxins are toxic secondary metabolites produced by various fungal species, posing significant food safety concerns due to their health impacts and economic burden. Accurate structural elucidation and quantitative analysis are essential for effective risk assessment and regulatory control. This review highlights recent advances in the application of nuclear magnetic resonance (NMR) spectroscopy for the structural and quantitative analysis of major mycotoxins, including aflatoxins, ochratoxins, fumonisins, trichothecenes, and zearalenone. One- and two-dimensional NMR techniques enable precise molecular characterization, positional isomer identification, including modified forms such as masked or conjugated mycotoxins, and toxicity-related molecular interaction investigation. NMR spectroscopy offers superior structural resolution, high reproducibility, and nondestructive analysis, making it invaluable in mycotoxin research. Quantitative NMR spectroscopy has emerged as a robust and accurate method for determining the absolute concentration and purity of mycotoxins, without requiring analyte-specific reference standards, an advantage particularly important for modified toxins lacking commercially available standards. The integration of NMR-based approaches strengthens analytical reliability, supports reference material development, and contributes to enhanced food safety assessment. This review also discusses ongoing analytical challenges and future directions, including the application of artificial intelligence to improve the automation and interpretation of NMR data in mycotoxin research. Full article

(This article belongs to the Section Magnetic Resonances)

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18 pages, 5082 KiB

Open AccessArticle

Research on 3D Magnetic Memory Signals Induced by Circular Hole Defects

by Bin Yang, Zhifeng Liu and Yang Gao

Magnetochemistry 2025, 11(6), 46; https://doi.org/10.3390/magnetochemistry11060046 - 25 May 2025

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Abstract

Metal magnetic memory testing technology can not only detect macroscopic defects in ferromagnetic materials but also rapidly and conveniently detect early damage and stress concentration areas of components. Therefore, it is widely used in the nondestructive testing of ferromagnetic materials. However, the mechanism of magnetic memory detection is not yet clarified, and experimental research is unsystematic. Previous studies mainly focus on the normal and tangential components of magnetic memory signals (MMSs), and the third directional component is rarely considered, resulting in problems such as missed detection and misjudgement in practical applications. In this research, specimens without and with a circular hole defect were designed, and the correlation between the 3D MMS and the defect size, as well as the applied load, were investigated using tensile tests. Magnetic parameters were defined to characterize the stress and defect-induced abnormal magnetic change. The effects of applied load and defect size on magnetic parameters were discussed. The experimental results showed that the peak–valley difference in the 3D MMS increases with increasing load and defect size, and the peak–valley spacing in the 3D MMS is not influenced by applied load but increases with increasing defect size. The 3D MMS gradient exhibits a good correlation with the equivalent stress along the loading direction. Additionally, the applied load and defect size were quantitatively evaluated by utilizing the Lissajous figure area generated from the X and Z components of the 3D MMS. Finally, a nonlinear fitting equation for defect size evaluation was presented. This study can provide a theoretical basis for the quantitative detection and evaluation of defect size and stress in engineering applications. Full article

(This article belongs to the Special Issue Latest Updates in Soft Magnetic Materials)

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Magnetochemistry, Volume 11, Issue 6 (June 2025) – 4 articles

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