JOURNAL OF RARE EARTHS
·
2021
·
IF 3.712
He Sun,Tuoyao Wang,Chengxiang Li,Yusheng Yang
Ultrafine NdFeB waste is a relatively clean waste produced during NdFeB magnet processing. Fluorine-containing wastewater is a common type of industrial wastewater, such as stainless steel pickling wastewater. In this work, rare earth element neodynium was recycled from ultrafine NdFeB waste by capturing fluorine ions in the fluorine-containing wastewater and prepared into neodynium oxyfluoride. The reaction process was investigated through UV-Vis-NIR, thermogravimetry/differential thermogravimetry (TG/DTG), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The neodymium hydroxide in the ultrafine NdFeB waste reacted with fluorine ions to form Nd(OH) 2 F, and Nd(OH) 2 F was then transformed into neodymium oxyfluoride after decomposition. The formed neodymium oxyfluoride is found to be particles with rhombohedral structure and a particle size of around 50 nm. The reaction kinetics of forming Nd(OH) 2 F was investigated. The reaction kinetic equation was established and the reaction activation energy was calculated. The effect of fluorine ion concentration on the reaction rate and products was evaluated. The results show that the reaction rate increases with the increase of fluorine ion concentration in the range of 0.01 – 1.5 mol/L, but it has little effect. In addition, the fluorine ion concentration affects the crystallinity of formed neodymium oxyfluoride. The recycling process not only realizes the sustainable utilization of rare earths, but also reduces the concentration of fluorine ions in the fluorine-containing wastewater, achieving two goals with one stone.
研究领域:
材料科学
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环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Pengjie Zhang,Hongyi Yang,Wei Sun,Pengfei Zhang,Guangqing Xu
Epoxy resin coatings incorporating tannic acid-modified carbon nanotubes (TCNTs) and cerium nitrate were deposited onto NdFeB magnets via air spraying to enhance corrosion resistance through synergistic filler/inhibitor effects. The composition and dispersion stability of the fillers were characterized using thermogravimetric analysis and zeta potential measurements. The morphology and microstructure of the composite coatings were analyzed by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Corrosion behavior was evaluated through full immersion tests (55 days), accelerated aging tests, and electrochemical measurements (potentiodynamic polarization, electrochemical impedance spectroscopy). The coating containing TCNTs exhibited superior corrosion resistance, achieving the highest low-frequency impedance modulus (| Z | 0.01 Hz = 4.01 × 10 9 Ω·cm²) and the lowest corrosion current density ( J corr = 8.930 × 10 −12 A·cm −2 ) after immersion. Incorporation of cerium nitrate endowed the coatings with self-repairing functionality during corrosion. The enhanced corrosion resistance of the EP(TCNTsCe ₓ )/NdFeB specimens is attributed to the combined barrier effect of uniformly dispersed TCNTs and the self-healing effect of insoluble cerium-containing corrosion products formed within the coating.
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Kun Zhao,Zhenhua Song,Zongqiang Gao,Wei Gao,Ming-Jin Liu,Bingni Gu,Junhong Guo,Yu-Lun Chueh
Triboelectric-electromagnetic hybrid nanogenerator (HNG) with high output performance provides a very promising solution for realizing self-powered microelectronic devices. However, the complex structures and large mass of traditional HNGs make them difficult to prepare and carry. In this study, a rotating HNG based on flexible neodymium iron boron/ethyl cellulose (NdFeB/EC) composite films was designed for wind energy scavenging. A lightweight composite film with triboelectric and ferromagnetic properties, which can significantly reduce the weight of the rotor, was prepared to replace the magnet. Operated at a wind speed of 15.5 m/s, the triboelectric nanogenerator (TENG) unit of the optimized HNG with an interdigitated electrode gap of 2 mm can generate an open-circuit voltage (V oc ) and a short-circuit current (I sc ) of 55 V and 5.4 μA, respectively. The maximum power of TENG is 99.2 μW under the condition of an external load resistance of 10 MΩ. The corresponding electromagnetic generator (EMG) unit can produce V oc and I sc of approximately 0.16 V and 59.3 μA, delivering an output power of 2.5 μW at a matched loading resistance of 2.3 kΩ. Compared to the individual TENG or EMG units, the HNG exhibited better charging performance. A 470 μF capacitor can charge to 3.4 V within 600 s, and the stored energy can successfully power a commercial soil temperature–humidity meter to work continuously for 75 s and light 30 blue LEDs in parallel. This research is of great scientific significance for developing triboelectric–ferromagnetic dual-functional materials and designing highly integrated and lightweight HNGs.
研究领域:
材料科学
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能源技术
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纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry B
·
2021
·Vol. 9
·期 44
·9183-9190
·
IF 6.331
Jingda Tang,Bonan Sun,Qianfeng Yin,Meng Yang,Jian Hu,Tiejun Wang
Magnetic hydrogels have demonstrated great potential in soft robots, drug delivery, and bioengineering, and their functions are usually determined by the deforming capability. However, most magnetic hydrogels are embedded with soft magnetic particles (e.g. Fe3O4), where the magnetic domains cannot be programmed and retained under external magnetic fields. Here, we present a strategy to prepare a microgel-reinforced magnetic hydrogel, embedded with hard magnetic NdFeB particles. These magnetic hydrogels show outstanding mechanical properties (ultimate stretching ratio >15 and fracture toughness >15 000 J m−2) and fast actuation speed under external magnetic fields. We use direct ink writing to fabricate magnetic hydrogels with sophisticated geometry and program their magnetization to achieve complex deformations. Fast, reversible, shape-changing structures have been demonstrated with printed magnetic hydrogels. It is hoped that this material system of hard magnetic hydrogels can open opportunities for wide applications.
研究领域:
材料科学
·
机器人技术
·
生物医学工程
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Yusheng Yang,Ying Qin,Tuoyao Wang,Yazhu Zhang,Tianyi Shi,Jiayi Li,Haoran Xu,Zhengxiang Xia,He Sun,Zengwu Zhao
Neodymium-iron-boron (NdFeB) magnets are the rare earth products with the largest output, and their recycling is of significance for the sustainable development of rare earth resources. Currently, the recycling technology of NdFeB wastes is more concerned with the recovery of rare-earth elements, while iron is regarded as a low-value by-product. In this work, chemical dealloying method in molten chlorides was proposed to separate neodymium from FeNd alloy and simultaneously to prepare porous iron alloy. The effects of the molar ratio of reactants, dealloying temperature and time on the separation efficiency of neodymium were investigated. The maximum separation efficiency of neodymium from FeNd alloy can reach 96 %. The separation process of neodymium and the formation process of porous iron alloy were estimated based on the ICP, XRD, XPS, SEM-EDS analyses of recycled products. Neodymium was separated from FeNd alloy by the reaction with Nd(III) ions to form Nd(II) ions in molten chlorides, while the porous iron alloy was formed. The formed Nd(II) ions can be transformed into Nd(III) ions and metallic neodymium particles by the disproportionation reaction. In the process, Nd(III) ions can act as a complement to react with FeNd alloy. And neodymium was recovered in the form of metallic neodymium and NdOCl from the chloride melt and the rinsing solution of porous iron alloy, respectively. The formed porous iron alloy had the surface area of unit volume in the range of (2 ∼ 20) × 10 4 cm 2 cm −3 , the pore width around 10 nm and good hardness. The porous iron alloy is a high value-added product.
研究领域:
材料科学
·
资源回收
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2018
·
IF 3.141
Pan Sun,Kun Huang,Weiyuan Song,Zhen Gao,Huizhou Liu
An ionic-liquid-based aqueous two-phase system (iL-ATPS) consisting of an ionic liquid, tributylmethylammonium nitrate (N4441NO3), and NaNO3 aqueous solutions was developed for the extraction and separation of rare-earth ions, for example Nd(III), from transition-metal ions. The excellent selectivity of a green nonfluorinated ionic liquid and the low-viscosity feature of an aqueous two-phase system were combined in our suggested iL-ATPS. The results indicated that efficient separation of Nd(III) from transition-metal ions, Fe(III), Ni(II), and Co(II), could be obtained in our suggested iL-ATPS. Furthermore, different parameters of the separation process, including the concentrations of HNO3 and NaNO3 and the added amount of N4441NO3, were optimized. Notably, the extraction kinetics of Nd(III) could be improved significantly in the present iL-ATPS compared with the conventional organic-solvent-based ionic-liquid extraction systems. The similar environment across the liquid–liquid interface was revealed by the ultralow viscosity and interfacial tension of the ionic-liquid-rich phase in the iL-ATPS. This feature was responsible for the enhanced extraction kinetics of Nd(III). In addition, the structures of the extraction complexes were elucidated by using NMR spectroscopy and molecular simulations. It was demonstrated that NO3– ions were in the inner coordination shell of Nd(III) ions to interact with Nd(III) ions, while N4441+ surrounded Nd(III) ions at the outer coordination shell of Nd(III) ions. Moreover, 2 mol/L HNO3 aqueous solutions could be used to effectively strip Nd(III) from the loaded ionic-liquid-rich phase. After 5 cycles, the extraction performance of the ionic liquid remained nearly unchanged. The present work highlights an environmental method to selectively separate rare-earth ions from the complicated solutions coexisting with other transition-metal impurity ions. It provides a basis for the future application in recycling of rare-earth elements from the spent NdFeB magnets.
研究领域:
环境化学
·
湿法冶金
·
可持续回收
·
分离科学
·
稀土元素
✓ 已验证
DOI
高影响因子
Advanced Intelligent Systems
·
2024
·
IF 6.8
Xingcheng Ou,Yu Sheng,Jiaqi Huang,Dantong Huang,Xiaohong Li,Ran Bi,Guoliang Chen,Weijie Hu,Shuang-Zhuang Guo
Inspired by the efficient swimming capabilities of swordfish, a novel wireless soft swordfish-like robot with programmable magnetization has been developed, integrating direct-ink-writing (DIW) 3D printing and assembly technology. This 20 mm long robot features a streamlined form and magnetically programmable movements, enabling biomimetic locomotion patterns such as straight-line swimming and turning swimming. The robot includes a silicone-based torso (body, abdomen, and pectoral fin) and a crescent-shaped tail fin made from a magnetically programmable polymer embedded with neodymium-iron-boron (NdFeB) particles. The tail fin, fabricated by multi-material alternating printing to achieve a gradient magnetism distribution, is controlled by an external magnetic field to mimic the rapid oscillation of a swordfish's tail, achieving a swimming speed of 0.51 BL/ s. The tail fin's asymmetric oscillation amplitudes, adjusted by magnetic field control, allow the robot to transition seamlessly from high-speed straight swimming to agile turning. The robot can perform tracking swimming along specific planned paths, such as “C” and “Z” shaped trajectories. Potential applications include environmental monitoring and targeted drug release. The multi-material 3D printing technology enhances the robot's efficiency and sensitivity in simulating natural biological movements, extending to the design and development of various flexible devices and soft robots.
研究领域:
机器人技术
·
生物医学工程
·
材料科学
·
仿生学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）