Optimizing the stability and electrical transport properties of CeNbO4+δ-based oxide ceramics by regulating oxygen ion content

CeNbO_4+δ ceramics have attracted extensive research interest because of their unique mixed ion-electron transport characteristics and interesting structure-functional characteristics caused by the difference in oxygen ion content. Although the change of oxygen ion content brings rich redox properties, it also causes serious crystal transformation and abnormal electrical transport properties. In order to obtain stable structure and excellent electrical transport properties, the directional regulation of the oxygen ion content has been realized through introducing Al₂O₃ and high temperature aging. After 600 h of aging at 1073 K, the prepared composite ceramics not only obtain a stable structure without crystal transformation, but also show good negative temperature coefficient (NTC) thermistor characteristics in the temperature range of 473 K–1273 K, in which the linear fitting maximum Pearson's r of the relationship between lnρ and 1000/T can reach 99.97%. The proposed method provides a new thought for the design and application of high-temperature electronic ceramics.     

大洋多金属结核低温氢还原-湿法冶金联用回收有价金属

以大洋多金属结核为原料, 采用低温氢还原-湿法冶金联用工艺回收有价金属, 湿法冶金过程包括硫酸浸出、M5640萃取铜、针铁矿法除铁、P204萃取除锌、HBL110萃取回收镍。在HBL110萃取回收镍过程中, 考察了平衡pH值、相比O/A等因素对萃取镍的影响, 并绘制了镍萃取与反萃平衡等温线。结果表明, 采用50%HBL110+50%磺化煤油组成的有机相, 经过6级逆流萃取-4级逆流洗涤, 镍萃取率达99.85%, 除钴外, 杂质金属Mn、Ca、Mg、Al基本不被萃取。负载有机相经5级逆流反萃, 镍反萃率达98.53%。     

催化湿式氧化法处理制药污泥的实验研究

以硝酸铜作为催化剂,应用催化湿式氧化法处理制药污泥,研究该方法对COD和VS的去除效果.结果表明,添加催化剂能有效提高湿式氧化法的处理效果,且在反应温度为260℃,搅拌转数为300 r/min,起始氧气压力为1.0 MPa,催化剂添加量为0.5 g/L,反应时间为60 min的条件下,污泥VS和COD的去除率分别可达到...     

Ultralow-threshold wideband-tunable single-mode ultraviolet lasing from lanthanide-doped upconversion nanomaterials

Ultraviolet (UV) lasers with dynamic wavelength-tunability and high monochromaticity are crucial in a multitude of practical applications yet still remarkable challenges. Here, we show wide wavelength-tuning of single-mode UV lasing based on lanthanide-doped upconversion nanoparticles (UCNPs). The rationally designed Yb³⁺/Er³⁺/Tm³⁺/Gd³⁺/Ce³⁺ co-doped multilayer UCNPs, which exhibits a broad gain spectrum with the full width of half maximum of around 57 nm in the UV regime, are developed. More importantly, by taking advantages of a diffraction grating as the tuning component, stable single-mode emission can be achieved in the UCNPs-based external-cavity-extended Fabry–Pérot laser at room temperature. Specifically, the lasing threshold is around 137 µJ cm^–2, which is two orders of magnitude lower than that in the previously reported articles. Precise wavelength-tuning from 310 to 363 nm can be realized by adjusting the Littrow angle. This achievement highlights a portable alternative to continuously wideband-tunable UV lasers and opens up new opportunities for constructing compact solid-state UV photon sources.     

膜技术在回收电镀废水中金属离子的应用研究进展

近年来电镀行业蓬勃发展,每年平均废水总排放量占工业废水总排放量的20％左右,电镀废水中主要含有铬、镍、铜、锌等重金属污染物.膜分离技术具备分离精度高、出水水质好,无二次污染、工艺简单等特点,能够高效处理电镀废水并回收其中有价值的金属离子,实现废水资源化利用,因此在电镀废水处理中得到广泛应用.本文针对电镀废水中的铬、镍、...     

Synthesis of strontium (Sr) doped hydroxyapatite (HAp) nanorods for enhanced adsorption of Cr (VI) ions from wastewater

The development of high-efficiency adsorbents for heavy metal ion removal from wastewater is highly desirable and challenging due to their synthesis complexity and low adsorption capacities. Herein, we reported the synthesis of strontium (Sr) doped hydroxyapatite (HAp) for the increased Cr (VI) adsorption. The effects of pH, temperature, and time on adsorption performances were studied. As a result, the Sr-HAp nanorods can achieve a Cr (VI) adsorption capacity of 443 mg/g, which is significantly higher than that of HAp nanorods (318 mg/g). To better understand the adsorption mechanism, the Langmuir isotherm model was established. The modeling results indicated that Langmuir monolayer chemical adsorption contributed to the efficient Cr (VI) ion removal for Sr-HAp nanorods adsorbents. The surface area and surface functional groups (O–H) contributed to the different Cr (VI) adsorption capacities between HAp and Sr-HAp.     

Microstructural and electrical changes in Ca0.9R0.1CeNbMoO8 (R = Y,Sm, Nd,La) ceramics induced by rare-earth ion doping

Rare-earth ions doped Ca_0.9R_0.1CeNbMoO₈ (R = Y, Sm, Nd, La) ceramics have been successfully prepared by solid-state method, and their modifications to the microstructure and electrical properties are also investigated. The rare-earth ions doped ceramics exhibit the scheelite structure. With the increase in the radius of rare-earth ions, the lattice distortion and bond interaction will be enhanced, and the consistency of grain size will be reduced. The ceramics exhibit negative temperature coefficient (NTC) thermistor characteristics in the temperature range of 473 K-1273 K, and the activation energy decreases with the increase of the radius of rare-earth ions. Rare-earth ions doping can increase the content of Ce³⁺ ions and promote the conductivity of ceramics. Except for Sm³⁺-doped ceramics, the high-temperature aging rate of other ceramics is less than 2%. The existence of some metastable Sm²⁺ ions in Sm³⁺-doped ceramics not only increases the activation energy, but also reduces the high-temperature stability of the ceramics.     

Carbon nanotube filter for heavy metal ion adsorption

This study investigated carbon nanotube filtration technology using catalyst particles supported on silicalite-1–biomorphic carbon materials (BCMs). Aqueous solutions of Mn(II), Cu(II), Cr(III), Cd(II), and Pb(II) were used to test the efficiency of heavy metal ions removal. Carbon nanotubes (CNTs) were synthesized and grown on BCMs by the chemical vapor deposition method catalyzed with the catalyst (Co, Fe, and Ni). The synthesized CNTs with Co– and Fe– nanoparticles were typically multi-walled carbon nanotubes, and they showed good crystallinity (I_D/I_G = 1.05) and yield of (11.10 and 8.86) %. The removal efficiency of Mn(II), Cu(II), Cr(III), Cd(II), and Pb(II) ions using Co-catalyzed CNT filter was 97.57%, 98.01%, 97.89%, 97.42%, and 99.99%, respectively.     

Synthesis of SnO2@MnO2@graphite nanosheet with high reversibility and stable structure as a high-performance anode material for lithium-ion batteries

In this study, SnO₂@MnO₂@graphite (SMG) anode material is prepared via a facile ball-milling approach combined with hydrothermal treatment. SnO₂ and MnO₂ nanoparticles are evenly dispersed on numerous sheet-like graphite. MnO₂ can not only play a catalytic role for facilitating the conversion reaction of Sn/Li₂O to SnO₂, but also as a barrier to impede the coarsening of Sn in the composite. Meanwhile, graphite nanosheets could serve as an ideal volume expansion buffer and good electron conductor. Consequently, the SMG anode delivers superior reversible capacity of 1048.5 mAhg⁻¹, ideal rate capability of 522.2 mAhg⁻¹ at 5.0 A g^-1 and stable long-life cyclic performance of 814.8 mAhg⁻¹ at 1.0 A g^-1 after 1000 cycles. This result indicates that the incorporation of MnO₂, graphite nanosheet and SnO₂ have a great potential in enhancing the performance of SnO₂-based anode for battery applications.     

Effect of Fe2+ and Fe0 Applied Photo‐Fenton Processes on Sludge Disintegration

The disintegration of waste active sludge was investigated by photo‐Fenton processes. A batch study was conducted to evaluate parameters, such as Fe²⁺ and Fe⁰ ions and H₂O₂, governing the activated sludge integration by the photo‐Fenton process. Under optimum conditions, the concentration of soluble chemical oxygen demand (SCOD) with the classical Fenton process (CFP) increased very rapidly in the first five minutes due to the sufficient presence of reaction components in the medium, and then the rate of increase declined. In the modified Fenton process (FTP), the SCOD concentration increased more slowly as metallic iron powder must first be dissolved. The photo‐Fenton process proved to be a feasible and efficient process for the disintegration of waste sludge.