烧结NdFeB磁体表面Zn-Al/T8超疏水复合涂层的显微组织及耐蚀性

为提升烧结NdFeB磁体的耐蚀性,采用旋涂法和等离子体增强化学气相沉积技术在其表面制备Zn-Al/T8(2-全氟辛基乙基丙烯酸酯)超疏水复合涂层。结果表明,Zn-Al涂层主要由片层状的Zn和Al相组成,厚度大约为28μm。Zn-Al/T8复合涂层的接触角达到151.78°,而滚动角仅为5.13°,说明Zn-Al/T8复合涂层可提供一个超疏水表面。Zn-Al涂层和Zn-Al/T8复合涂层对烧结NdFeB的磁性能均无显著影响。Zn-Al涂层通过牺牲阳极来提高NdFeB磁体的耐蚀性,而Zn-Al/T8复合涂层通过超疏水表面进一步提升耐蚀性。Zn-Al/T8复合涂层较Zn-Al涂层具有更好的耐盐雾性能。Zn-Al/T8超疏水复合涂层是一种非常有前途的烧结NdFeB磁体保护涂层。

高性能烧结NdFeB永磁材料市场发展与低成本技术途径

烧结NdFeB永磁材料以其优异的磁性能在各领域获得了广泛应用。首先概括了烧结NdFeB永磁材料的应用领域,然后简要介绍了材料的生产工艺流程。在此基础上,重点阐述了烧结NdFeB永磁材料高性能化和低成本化的重要技术途径——重稀土晶界扩散工艺,详细介绍了各类晶界扩散方法及其优缺点。最后展望了高性能烧结NdFeB永磁市场发展趋势。

晶界添加Pr-Cu合金纳米粉对烧结NdFeB磁性能及耐腐蚀性能的影响

为了提升Nd FeB磁体的磁性能及耐腐蚀性能,首先用等离子体直流电弧法得到Pr-Cu合金纳米粉,再用双元合金法即晶界添加Pr-Cu合金纳米粉得到高性能烧结NdFeB磁体。借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)、振动样品磁强计(VSM)和电化学工作站、恒温恒湿箱表征了磁体微观结构、磁性能及耐腐蚀性能。结果表明,添加质量分数0.6%Pr-Cu合金纳米粉时,磁体的矫顽力由959.1 kA/m增加到1 080.5 kA/m,提高了12.6%;剩磁则由1.24 T下降至1.13 T,下降了9.1%。此外,磁体的耐腐蚀性能明显提高,磁体的腐蚀电流密度由62.0m A/cm^(2)下降至22.0m A/cm^(2);在0.2MPa、120℃、100%相对湿度下进行失重腐蚀实验96h后磁体的质量损失为4.5mg/cm^(2),仅为未添加时的26.5%。适量添加Pr-Cu合金纳米粉改善烧结NdFeB磁体的性能是可行的。

Particle agglomeration and inhibition method in the fluidized pyrolysis reaction of waste resin

This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.

Sn-8.8Zn-x Bi合金在烧结NdFeB上的润湿过程及界面反应行为

采用座滴法研究了在Ar-5%H_(2)气氛中Sn-8.8Zn-x Bi合金在NdFeB基体上的润湿性和润湿界面形貌。结果表明,Sn-8.8Zn-x Bi合金在NdFeB基板上润湿过程分为两个阶段:以范德华力和扩散力为驱动力的非反应性润湿阶段及由界面反应产物和反应产物的吸附作用影响的反应性润湿阶段。Sn-8.8Zn-x Bi合金中随着Bi含量提高,合金的润湿性得到改善,相同加热条件下润湿时间缩短,其中Sn-8.8Zn-7Bi在NdFeB基板表面接触角为120.11°。Sn-8.8Zn-x Bi合金在NdFeB基板上的润湿类型为反应性润湿,反应产物为ζ-FeZn_(13)相。ζ-FeZn_(13)相提高了Sn-8.8Zn-x Bi合金在NdFeB表面的黏结强度,证明Sn-8.8Zn-x Bi合金可作为NdFeB表面焊料。

DyF_(3)对三明治结构热变形NdFeB磁体温度稳定性和耐腐蚀性能的影响

为了提高热变形NdFeB磁体的热稳定性和耐腐蚀性能,设计了一种添加DyF_(3)的三明治结构热变形磁体。通过对磁体上下端添加不同含量DyF_(3)粉末,调控磁体上下端晶界相的相组成、结构及成分,提高磁体的耐腐蚀性能,另一方面Dy元素部分扩散进入主相,形成了(Nd,Dy)_(2)Fe_(14)B相提高磁体磁晶各向异性场,优化热变形磁体的温度稳定性。利用脉冲磁场磁强计测试三明治结构热变形磁体的磁性能,得到高达2.16 T的矫顽力。利用电化学工作站测试三明治结构热变形磁体的极化曲线,其腐蚀电流速率较基体降低一个数量极。失重实验测试168 h后,近表面添加5%(质量分数)DyF_(3)的三明治结构热变形磁体单位表面积失重(0.061 mg·cm^(-2))远低于基体单位表面积失重(1.172 mg·cm^(-2))。微观结构分析表明,富Nd相和F元素、O元素和Dy元素分别生成NdF_(3)和Dy_(2)O_(3)化合物。XRD分析表明三明治结构热变形磁体上下端添加DyF3后织构会变差。该研究为提高热变形NdFeB磁体的温度稳定性和耐腐蚀性提供了一个新思路。

Optimizing Household Wastes (Rice, Vegetables, and Fruit) as an Environmentally Friendly Electricity Generator

The high consumption of electricity and issues related to fossil energy have triggered an increase in energy prices and the scarcity of fossil resources.Consequently,many researchers are seeking alternative energy sources.One potential technology,the Microbial Fuel Cell(MFC)based on rice,vegetable,and fruit wastes,can convert chemical energy into electrical energy.This study aims to determine the potency of rice,vegetable,and fruit waste assisted by Cu/Mg electrodes as a generator of electricity.The method used was a laboratory experiment,including the following steps:electrode preparation,waste sample preparation,incubation of the waste samples,construction of a reactor using rice,vegetable,and fruit waste as a source of electricity,and testing.The tests included measuring electrical conductivity,electric current,voltage,current density,and power density.Based on the test results,the maximum current and voltage values for the fruit waste samples were 5.53 V and 11.5 mA,respectively,with a current density of 2.300 mA/cm^(2) and a power density of 12.719 mW/cm^(2).The results indicate the potential for a future development.The next step in development involves determining the optimum conditions for utilizing of rice,vegetable,and fruit waste.The results of the electrical conductivity test on rice,vegetable,and fruit waste samples were 1.51,2.88,and 3.98 mS,respectively,with the highest electrical conductivity value found in the fruit waste sample.

Bearing capacity of circular footings on multi-layered sand-waste tire shreds reinforced with geogrids

The presence of waste tires poses an environmental challenge as they occupy a significant amount of land and are expensive to dispose in landfills.However,reusing waste tires can address this issue when waste tires are used in geotechnical applications.To determine the viability of this approach,laboratoryscale tests were conducted to investigate load-bearing capacity of circular footings on sand-tire shred(STS)mixtures with shredded waste tire contents of 5%e15%by weight and three different widths of shreds.The investigation focused on analyzing the thickness of layers composed of STS mixtures,the soil cap,and the impact of geogrids on bearing capacity.The results indicate that a specific mixture of sand and tire shreds provides the highest footing-bearing capacity.In addition,the optimal shred content and size were found to be 10%by weight and 2 cm×10 cm,respectively.Furthermore,for a given tire shred width,a particular length provides the largest bearing capacity.The results agree well with that of previous research conducted by the first author and his colleagues in direct shear and California bearing ratio(CBR)tests.The primary finding of this research is that the use of two-layered STS mixtures reinforced by geogrids significantly enhances the bearing capacity.

A functionalized activated carbon adsorbent prepared from waste amidoxime resin by modifying with H_(3)PO_(4) and ZnCl_(2) and its excellent Cr(Ⅵ)adsorption

With the application of resins in various fields, numerous waste resins that are difficult to treat have been produced. The industrial wastewater containing Cr(Ⅵ) has severely polluted soil and groundwater environments, thereby endangering human health. Therefore, in this paper, a novel functionalized mesoporous adsorbent PPR-Z was synthesized from waste amidoxime resin for adsorbing Cr(Ⅵ). The waste amidoxime resin was first modified with H3PO4 and ZnCl_(2), and subsequently, it was carbonized through slow thermal decomposition. The static adsorption of PPR-Z conforms to the pseudo-second-order kinetic model and Langmuir isotherm, indicating that the Cr(Ⅵ) adsorption by PPR-Z is mostly chemical adsorption and exhibits single-layer adsorption. The saturated adsorption capacity of the adsorbent for Cr(Ⅵ) could reach 255.86 mg/g. The adsorbent could effectively reduce Cr(Ⅵ) to Cr(Ⅲ) and decrease the toxicity of Cr(Ⅵ) during adsorption. PPR-Z exhibited Cr(Ⅵ) selectivity in electroplating wastewater. The main mechanisms involved in the Cr(Ⅵ) adsorption are the chemical reduction of Cr(Ⅵ) into Cr(Ⅲ) and electrostatic and coordination interactions. Preparation of PPR-Z not only solves the problem of waste resin treatment but also effectively controls Cr(Ⅵ) pollution and realizes the concept of “treating waste with waste”.

Effect of In doping on the evolution of microstructure,magnetic properties and corrosion resistance of NdFeB magnets

The grain boundary phase affects the magnetic properties and corrosion resistance of sintered NdFeB magnets.In this work,a small amount of In was added to NdFeB magnets by induction melting to systematically investigate its effect on the evolution of the microstructure,magnetic properties and corrosion resistance of NdFeB magnets.Microstructural analysis illustrated that minor In addition generated more grain boundary phases and an abundant amorphous phase at the triple-junction grain boundary.While the addition of In failed to enhance the magnetic isolation effect between adjacent matrix grains,its incorporation fortuitously elevated the electrochemical potential of the In-containing magnets.Besides,during corrosion,an In-rich precipitate phase formed,hindering the ingress of the corrosive medium into the magnet.Consequently,this significantly bolstered the corrosion resistance of the sintered NdFeB magnets.The phase formation,magnetic properties and corrosion resistance of In-doped NdFeB magnets are detailed in this work,which provides new prospects for the preparation of high-performance sintered NdFeB magnets.

NdFeB/316L不锈钢双极板对PEMFC性能的影响

在质子交换膜燃料电池(PEMFC)中,双极板起到分配隔离氢气和氧气、支撑膜电极组件(MEA)、收集电子和传递热量的作用。把316L不锈钢粉末与钕铁硼(NdFeB)磁粉均匀掺杂,通过三维(3D)打印制成燃料电池复合金属双极板,钕铁硼磁粉掺杂的质量分数分别为0、20%、35%和50%。通过设置不同励磁强度和温度条件,研究在磁场作用与无磁场作用下PEMFC的工作性能差异。磁场可以优化PEMFC的工作性能。钕铁硼质量分数为50%的316L不锈钢极板燃料电池,工作性能表现较好,相比于未掺杂钕铁硼的316L不锈钢极板燃料电池,最高输出功率密度提高14.03%,极限电流密度提高12.54%。在相同的磁场强度下,钕铁硼质量分数为50%的316L不锈钢极板燃料电池在60℃下的工作性能提升最明显,70℃下的工作性能最高。

Photocatalytic Degradation of Plastic Waste: Recent Progress and Future Perspectives

Microplastics are persistent anthropogenic pollutants that have become a global concern due to their widespread distribution and unfamiliar threat to the environment and living organisms. Conventional technologies are unable to fully decompose and mineralize plastic waste. Therefore, there is a need to develop an environmentally friendly, innovative and sustainable photocatalytic process that can destroy these wastes with much less energy and chemical consumption. In photocatalysis, various nanomaterials based on wide energy band gap semiconductors such as TiO2 and ZnO are used for the conversion of plastic contaminants into environmentally friendly compounds. In this work, the removal of plastic fragments by photocatalytic reactions using newly developed photocatalytic composites and the mechanism of photocatalytic degradation of microplastics are systematically investigated. In these degradation processes, sunlight or an artificial light source is used to activate the photocatalyst in the presence of oxygen.

Impact of Plastic Waste on the Human Health in Low-Income Countries: A Systematic Review

Background: Plastic pollution is the accumulation of waste composed of plastic and its derivatives all over the environment. Whether in the form of visible garbage or microparticles, as it slowly degrades, plastic pollution poses significant threats to terrestrial and aquatic habitats and the wildlife that call them home, whether through ingestion, entanglement or exposure to the chemicals contained in the material. Unfortunately, there is a lack of documentation on the impact of plastic waste on human health in low- and middle-income countries (LMICs). Methods: We searched five electronic databases (PubMed, Embase, Global Health, CINAHL and Web of Science) and gray literature, following the preferred reporting elements for systematic reviews and meta-analyses (PRISMA), for the impact of plastic waste on human health in developing countries. We included quantitative and qualitative studies written in English and French. We assessed the quality of the included articles using the Mixed Methods Appraisal tool (MMAT). Results: A total of 3779 articles were initially identified by searching electronic databases. After eliminating duplicates, 3167 articles were reviewed based on title and abstract, and 26 were selected for full-text review. Only three articles were retained. The three articles dealt with practices likely to lead to oral exposure to plastic chemicals in human health, as well as the level of awareness of participants concerning the possible impact of plastic on human health, namely, the use of plastic baby bottles, the use of microwaves to cook food and reheat precooked food, the use of plastic bottles to store water in the refrigerator, water purifier containers with plastic bodies and plastic lunch boxes, the reuse of plastic bags and the inadequacy of treatment facilities. Conclusion: Plastic waste poses different risks to human health at every stage of its life cycle. Hence, strategies must be adopted to raise public awareness of the dangers of plastic waste to their health. Trial registration: The review protocol is registered in the PROSPERO international prospective register of systematic reviews (ID = CRD42023409087).

Household Solid Waste Awareness and Practices among Residents of Windhoek, Namibia

This study explores household solid waste management (HSWM) practices and awareness among residents of Windhoek West, a rapidly urbanizing constituency in the Khomas Region of Namibia. Employing a descriptive methodology, the research investigates the interplay between public awareness, regulatory frameworks, and the availability of waste management facilities to assess their impact on waste management behaviors. Our findings indicate significant gaps in both knowledge and infrastructure that hinder effective waste management. The study reveals that while there is a high willingness among residents to engage in recycling and waste reduction, actual practices are limited due to inadequate facilities and lack of stringent enforcement of waste policies. This research identifies key factors that influence waste management practices, including demographic characteristics and access to waste management facilities. It also proposes actionable strategies such as expanding recycling and sorting facilities, enhancing educational campaigns tailored to local needs, and implementing regular enforcement mechanisms. These strategies are aimed at improving compliance with waste management protocols and fostering a culture of environmental responsibility. The results of this investigation show the critical role of ongoing education and infrastructural improvement in bridging existing knowledge gaps and facilitating effective waste management practices. This research lays a foundational step toward enhancing sustainable urban development and effective waste management in Windhoek, providing valuable insights for policymakers, community leaders, and stakeholders engaged in urban environmental management.

Fabrication and anti-corrosion performance of superhydrophobic silane film on sintered NdFeB

An eco-friendly superhydrophobic protective film(DTMS/TEOS silane film)was fabricated on sintered NdFeB substrate through the utilization of electrochemically assisted deposition technology.The structure,properties,and film-forming mechanism of dodecyltrime-thoxysilane(DTMS)/tetraethoxysilane(TEOS)silane films were comprehensively analyzed using Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS).Based on the test results,it can be determined that this film has a superhydrophobic property with a hydrophobicity angle of 152°.This special property can be attributed to the long alkyl chains in the DTMS molecule,the rough morphology,and the low surface energy of the DTMS/TEOS silane film.The surface of sintered NdFeB is coated with a layered three-dimensional network silane film that forms through the condensation of silanol substances.This film provides excellent corrosion resistance to the sintered NdFeB substrate,reducing its corrosion current density to 2.02×10~(-6)A/cm~2.Moreover,the impact of film on the magnetic characteristics of sintered NdFeB was assessed and found to be minimal.

Study on synergistic leaching of potassium and phosphorus from potassium feldspar and solid waste phosphogypsum via coupling reactions

To achieve the resource utilization of solid waste phosphogypsum(PG)and tackle the problem of utilizing potassium feldspar(PF),a coupled synergistic process between PG and PF is proposed in this paper.The study investigates the features of P and F in PG,and explores the decomposition of PF using hydrofluoric acid(HF)in the sulfuric acid system for K leaching and leaching of P and F in PG.The impact factors such as sulfuric acid concentration,reaction temperature,reaction time,material ratio(PG/PF),liquid–solid ratio,PF particle size,and PF calcination temperature on the leaching of P and K is systematically investigated in this paper.The results show that under optimal conditions,the leaching rate of K and P reach more than 93%and 96%,respectively.Kinetics study using shrinking core model(SCM)indicates two significant stages with internal diffusion predominantly controlling the leaching of K.The apparent activation energies of these two stages are 11.92 kJ·mol^(-1)and 11.55 kJ·mol^(-1),respectively.

Efficient and rapid capture of uranium(Ⅵ) in wastewater via multiamine modified β-cyclodextrin porous polymer

It is quite important to ensure the safety and sustainable development of nuclear energy for the treatment of radioactive wastewater. To treat radioactive wastewater efficiently and rapidly, two multi-amine β-cyclodextrin polymers(diethylenetriamine β-cyclodextrin polymer(DETA-TFCDP) and triethylenetetramine β-cyclodextrin polymer(TETA-TFCDP)) were prepared and applied to capture uranium. Results exhibited that DETA-TFCDP and TETA-TFCDP displayed the advantages of high adsorption amounts(612.2and 628.2 mg·g-1, respectively) and rapid adsorption rates, which can reach(88 ± 1)% of their equilibrium adsorption amounts in 10 min. Moreover, the adsorbent processes of DETA-TFCDP and TETATFCDP on uranium(Ⅵ) followed the Langmuir model and pseudo-second-order model, stating they were mainly chemisorption and self-endothermic. Besides, TETA-TFCDP also showed excellent selectivity in the presence of seven competing cations and could be effectively reused five times via Na2CO3as the desorption reagent. Meanwhile, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy illustrated that the enriched multi-amine groups and oxygen-containing functional groups on the surface of TETA-TFCDP were the main active sites for capturing uranium(Ⅵ). Hence, multi-amine β-cyclodextrin polymers are a highly efficient, rapid, and promising adsorbent for capturing uranium(Ⅵ)from radioactive wastewater.

Synergetic Bioproduction of Short-Chain Fatty Acids from Waste Activated Sludge Intensified by the Combined Use of Potassium Ferrate and Biosurfactants

The synergetic effect and underlying mechanism of potassium ferrate(PF)with tea saponin(TS,a biosurfactant)in producing short chain fatty acids(SCFAs)from anaerobic fermentation of waste activated sludge(WAS)were explored in this work.Experimental results showed that 0.2 g PF(g TSS)^(-1)(total suspended solid)combined with 0.02 g TS(g TSS)^(-1) could further improve SCFAs’production,and the maximum SCFAs content reached 2008.7 mg COD L^(-1),which is 1.2 and 4.5 times higher than those with PF and TS individually added,respectively,and 5.3 times higher than that of blank WAS on Day 12.In the model substrates experiments,the degradation rates of bovine serum albumin and dextran with combination of PF and TS were 41.3%±0.1% and 48.5%±0.06%,respectively,on Day 3,which are lower than those in blank WAS(with degradation rates of 72.3%±0.5%and 90.3%±0.3%).It was revealed that the oxidative effect of PF and the solubilization of TS caused more organic matters to be dissolved out from WAS,providing a large number of biodegradable substances for subsequent SCFAs production.While WAS pretreated with the combination of PF and TS,the relative abundances of Firmicutes increased from 6.4%(blank)to 38.6%,and that of Proteobacteria decreased from 41.8%(blank)to 21.8%.The combination of PF and TS promoted the hydrolysis process of WAS by enriching Firmicutes,and then increased acetic acid production by inhibiting Proteobacteria that consumed SCFAs.Meanwhile,at the genus level,acidogenesis bacteria(e.g.,Proteiniclasticum and Petrimonas)were enriched whereas SCFAs consuming bacteria(e.g.,Dokdonella)were inhibited.

Performance and Emission Characteristics of a CRDI Diesel Engine Fuelled by SiO_(2) Nanoparticle-Waste Fat Biodiesel Blends

This study investigates the use of waste fat biodiesel(WFB)from the leather industry as a substitute for diesel fuel.Specifically,it examines the diesel engine performance of WFB,a blend of WFB and diesel(B50),and different blends of WFB and silicon dioxide(SiO_(2))nanoparticles(B50SiO_(2)40,B50SiO_(2)80,and B50SiO_(2)120μg/g).The results indicate that the B50SiO_(2)120 blend increases brake thermal efficiency by 10.03%compared to pure biodiesel but falls 1.93%short of neat diesel.Furthermore,the B50SiO_(2)120 mixture reduces smoke,hydrocarbon,and carbon monoxide emissions by 31.87%,34.14%,and 43.97%respectively,compared to diesel.However,the B50SiO_(2)120 blend shows a 4.91%increase in nitrogen oxide emissions compared to diesel.

Utilization of recycled solid waste as ecological reclamation materials based on plant growth experiments and soil quality analysis

During the highway construction,a large number of spoil areas will be generated while a large amount of waste slag and soil could not be rationally utilized.Besides,the vegetation recovery is slow in the spoil areas due to the soil depletion.Aiming at recycling the solid waste,the sieved engineering waste slag with local red clay and corn straw biochar was supplied to solve the problem of insufficient nutrients in engineering waste slag and soil.In addition,planting experiments of alfalfa(Medicago sativa L.)and Amorpha fruticosa L.combined with physical and chemical experiments were carried out to prove the feasibility of the novel improved substrate for the reclamation of spoil areas.The results show that the substrate's improvement effect is mainly affected by the soil to slag ratio and the biochar content.The improvement effect of soil matrix in highway spoil area decreases with the increase of the waste slag content,especially when the soil-slag ratio is less than 3,and the promotion of plants is limited.On the contrary,the improvement effect is proportional to the biochar content(3%-8%).But it is noted that the Cu and Pb in the soil will exceed the clean limit corresponding to the Nemero soil pollution index level when the biochar content is 8%.Therefore,it is recommended that the soil-slag ratio should be≥3,and the biochar content should reach 3%-5%.This research provides experimental basis and technical support for utilizing solid waste resources in the reclamation of highway spoil areas.