查找使用阿拉丁产品的科研文献

U(VI) sequestration by Al-rich minerals: Mechanism on phase dependence and the influence of natural organic matter

Zequan Liu,Tao Ou,Minhua Su,Hairong Peng,Gang Song,Lingjun Kong,Diyun Chen

Uranium and uranium-containing pollutants are excessively released into the environment, leading to serious water and soil contamination. Minerals such as alumina are naturally abundant and frequently affect the fate and migration behavior of uranium ions. A thorough understanding of the migration and immobilization behavior of uranium on Al-rich minerals (e.g., α-alumina [α-Al 2 O 3 ] and γ-alumina [γ-Al 2 O 3 )]) is essential for unraveling numerous environmental issues. We performed a systematic comparative analysis of U(VI) retention by α-/γ-alumina. The effects of coexisting ions and natural organic matter were explored. Solution pH contributed critically to the retention of U(VI) by α-/γ-alumina. The adsorption rate of γ-Al 2 O 3 for U(VI) removal was faster than that of α-Al 2 O 3 , reaching equilibrium within 15 min with a high removal efficiency of 94.43%. PO 4 3− ions significantly promoted U(VI) adsorption, especially for the case of α-Al 2 O 3 . The addition of phosphate resulted in a 15-fold enhancement in adsorption capacity. Humic acid promoted U(VI) removal by γ-Al 2 O 3 under acidic conditions while strong inhibition on both α-Al 2 O 3 and γ-Al 2 O 3 in basic conditions. The removal mechanism of U(VI) by alumina is mainly ascribable to electrostatic interaction and surface complexation from various oxygenated functional groups. The present findings are pivotal to the understanding of uranium migration and immobilization in the environment.

Dissimilar joining mechanism, microstructure and properties of Ni to 316 stainless steel via Ni-Al thermal explosion reaction

Xiaoping Cai,Xuanru Ren,Changcheng Sang,Lu Zhu,Zhoujun Li,Peizhong Feng

To meet the requirements of energy-efficiency and high quality joining in the emerging industries field, a novel thermal explosion (TE) joining method was developed. The dissimilar Ni/316SS joint was first obtained by the TE reaction technology. The Ni-Al mixed powder was selected as TE reaction system, and the reaction product was used as interlayer. The effect of temperature (800, 850 and 900 °C), hold time (5, 10, 15 and 20 min) and joining pressure (0, 10, 20 and 30 MPa) on interfacial microstructure, diffusion behavior and mechanical properties of Ni/316SS joint were investigated. The maximum combustion temperature of Ni-Al interlayer during heating process was 1655 °C and a significant exothermic phenomenon was lasted for 2 s. 316SS(Al), Fe 2 Al 5 (Ni, Cr) and serration-like Ni 5 Al 3 and Ni 3 Al were detected at the interface containing a reaction layer because of element diffusion. The maximum shear strength of the Ni/316SS joint was 65.2 MPa, and the failure is characterized by typical brittleness fracture. The fracture mode is the combination of partial spalling and fracture of the interlayer. The post heat-treatment assisted TE joining technique significantly shortened the bonding process of the dissimilar Ni/316SS joint at moderate temperatures, realizing the low energy and efficient joining between Ni and 316SS.

Dielectric strength of glass fibre fabric reinforced epoxy by nano-Al2O3

Shuang Wang,Yu Chen,Jiale Mao,Cong Liu,Lei Zhang,Yonghong Cheng,Chaoyun Du,Toshikatsu Tanaka

Sacrificial carbon nitride-templated hollow FeCo-NC material for highly efficient oxygen reduction reaction and Al-air battery

Yu Wang,Guoxin Zhang,Mang Ma,Yiyan Wang,Ying Zhang,Xiaoming Sun,Zifeng Yan

Solid-phase templates are commonly used for building hollow-structured carbon materials (CMs) but often demand post treatments to remove templates. Herein, we develop an efficient and general method to construct hollow carbonaceous structure via the templating of sacrificial carbon nitride (termed as f-NC) without post treatment. The f-NC template can be decomposed under high-temperature annealing, additionally, it can serve as N source to enrich the N content. Applying f-NC template, we manage the synthesis of hollow-structured highly dispersed binary FeCo-nitrogen-carbon material (termed as f-NC@FeCo-NC). Its hollow feature is confirmed by direct observation using HRTEM . Meanwhile, Fe/Co in oxidation states have been verified uniformly distributing in heavily N-doped CMs (N content ∼ 13.2 at.%). The resulted f-NC@FeCo-NC, as examined by electrochemical measurements, exhibits highly efficient performance toward oxygen reduction reaction (ORR) in alkaline medium. It respectively shows much enhanced onset and half-wave potentials of 1.01 and 0.89 V relative to the FeCo-NC that is obtained without f-NC, in contrast, 20 wt% Pt/C shows 0.95 V onset potential and 0.83 V half-wave potential. The f-NC@FeCo-NC catalyst also shows excellent Al-air battery performance when applied as cathode, which possesses a high open circuit voltage of 1.91 V and a high peak power density of 241 mW cm −2 . We believe this sacrificial f-NC can be applied as general template for the fabrication of other hollow-structured carbon-based materials for broad electrochemical applications.

In Situ Synthesized MEMS Compatible Energetic Arrays Based on Energetic Coordination Polymer and Nano-Al with Tunable Properties

Xiaoxia Ma,Ke Cao,Xiaona Huang,Shaoran Yang,Yinghua Ye,Ruiqi Shen,Guangcheng Yang,Kaili Zhang

Integrating energetic materials with a microelectromechanical system (MEMS) to achieve miniaturized integrated smart energetic microchips is promising. The potential applications include actuation in lab-on-a-chip devices, ignition in automobile airbags, propulsion and attitude control of micro-/nano-satellites, and miniaturized electro-explosive devices. In this work, a new type of MEMS-compatible energetic arrays was in situ realized on a copper substrate, which comprised a new energetic coordination polymer (ECP; Cu1.5C2N8O2·H2O) with tunable nanostructures and a nano-aluminum (nano-Al) covering layer. The composition, morphology, and energetic characteristics of the energetic arrays can be easily tuned by adjusting the reaction time. The maximum heat release of 1850.2 J/g in thermal analysis and the intense flame in open burning experiment proved its excellent exothermic and combustion performance. A closed-bomb experiment further revealed that the ECP@nano-Al energetic arrays supported on Cu(OH)2 nanorods had a peak pressure (5.5 MPa) and a pressure duration (0.5 s) more than twice those of nanoscale Al/CuO powder because of the introduction of gas elements (e.g., C, H, and N). A preliminary impulse experiment was also conducted through the torsion pendulum method. The displacement of the torsion pendulum in the micrometer scale proved the potential application of the energetic arrays in micropropulsion systems. Overall, this work can serve as a reference for the synthesis and applications of ECPs.

Influence of particulate B4C size on microstructural evolution and mechanical behavior in nanostructured Al matrix during heat treatment

Chuandong Wu,Yuehui Lu,Guoqiang Luo,Qiang Shen,Zhanghua Gan,Jing Liu

We reported the influence of particle size (micro-B 4 C and nano-B 4 C) on microstructural evolution and mechanical properties in nanostructured Al matrix during heat treatment. The results indicated the incorporation of nano-B 4 C could significantly inhibit the grain growth of Al during heat treatment. The segregation layer in Al/B 4 C interface increased after heat treatment for all the composites samples. High density of Guinier-Preston (GP) zones and platelet η' could be observed in grain interior of all samples, while some coarse η phases (MgZn 2 ) could be only detected in grain boundaries of AA7075 alloys and the composites with micro-B 4 C. The yield strength of the composites with the incorporation of nano-B 4 C could reach up to 958 ± 28 MPa after heat treatment, which could be ascribed to the Hall-Petch strengthening and dislocation strengthening.

Effect of Reduction Atmosphere on Structure and Catalytic Performance of PtIn/Mg(Al)O/ZnO for Propane Dehydrogenation

Ming Zhang,Zhen Song,Mengquan Guo,Xiangxiang Li,Yanjun Lin,Lihong Zhang

The effect of reduction atmospheres, H2/N2, C3H8/H2/N2, C3H8and CO, on the structure and propane direct dehydrogenation performance of PtIn/Mg(Al)O/ZnO catalyst derived from ZnO-supported PtIn-hydrotalcite was studied. The physicochemical properties of the as-prepared and used catalytic system were characterized by various characterization methods. The results show that the dehydrogenation performance, especially the stability of the PtIn/Mg(Al)O/ZnO catalyst, was significantly improved along with the change in reduction atmosphere. The highest catalytic activity (51% of propane conversion and 97% propylene selectivity), resistance toward coke deposition, and stability for more than 30 h were achieved with the H2/N2-reduced catalyst. The optimal dehydrogenation performance and coke resistance are mainly related to the high Pt dispersion and In0/In3+molar ratio, strong Pt–In interaction and small metal particle size, depending on the nature of the reduction atmospheres. The reconstruction of meixnerite favors the stability and coke resistance to some extent.Keywords:propane dehydrogenation;reduction atmosphere;coke deposition;meixnerite;PtIn/Mg(Al)O/ZnO

Electrical property of Al/La/Cu modified ZnO-based negative temperature coefficient (NTC) ceramics with high ageing stability

Li Pengfei,Zhang Hong,Gao Caiyun,Jiang Guoxiang,Li Zhicheng

N egative temperature coefficient (NTC) ceramics based on simple ZnO were prepared and investigated in present work, where slight amount of Al- and La- ions were added as semiconductor dopants, and Cu-ions were selected as the sintering agent and property modificator. All the prepared ZnO-based ceramics have a wurtzite structure and show typical NTC characteristic. For various contents of Al-, La- and Cu- ions in ZnO-based ceramics, ρ 25 can be adjusted from 0.65 kΩ cm to 3.28 MΩ cm, and B values were obtained in range of 2500 K to 5850 K. The ageing treatment at 125 °C for 600 h in air revealed that the ZnO-based ceramics have high thermal stability with the resistance shift < 2%. The complex impedance spectra were applied to analyze the electrical performance.

Effect of salinity on adsorption of sodium hexametaphosphate and hydrophobically-modified polyacrylamide flocculant on kaolinite Al-OH surface

Wenjie Zou,Zichuan Fang,Jun Huang,Zhijun Zhang

Solution salinity is critical for the inhibition effect of sodium hexametaphosphate on different mineral surfaces, further affecting the separation of minerals in aqueous solution. In this work, the effect of K + and Ca 2+ on adsorption of sodium hexametaphosphate (SHMP) and hydrophobically modified polyacrylamide , poly(AM-NaAA-C 16 DMAAC) (HMPAM), on alumina surface (i.e., kaolinite Al-OH surface) were investigated using quartz crystal microbalance with dissipation (QCM-D). The deposition layer on alumina surface with the effect of adding 1 mM SHMP in 10 mM of CaCl 2 solution were examined by glancing angle X-ray diffraction (GAXRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The 100 mM KCl solution promoted the adsorption of both HMPAM and SHMP on alumina surface, which would be mainly caused by the molecular configuration change. The more flexible and coiled configuration of HMPAM and SHMP in 100 mM KCl solution could be helpful for increasing the adsorption sites on alumina surface. Moreover, the intermolecular hydrophobic interaction between the alkane chains of HMPAM would lead to the multilayer adsorption of HMPAM instead of adsorbing directly onto alumina surface. Alternatively, 1 mM and 10 mM CaCl 2 solutions lead to a lower adsorption amount of HMPAM on alumina surface, which is most likely caused by the suppressed electrostatic attraction and condensed conformation of HMPAM. The adsorption layer of SHMP formed on alumina surface could prevent the adsorption of HMPAM through different mechanisms in KCl and CaCl 2 solutions at different concentrations. Interestingly, scattered micro-spheres were found to adsorb on alumina surface with 1 mM SHMP in 10 mM CaCl 2 solution, mainly in forms of calcium hydrogen phosphate hydrate. Our work provides fundamental insights into the effect of adding dispersant (e.g., SHMP) and polymer flocculant (e.g., HMPAM) during selective flocculation of kaolinite , with helpful guidance for clay-involved mineral processing.

Performance and influencing mechanisms of magnetically separable Ni-M layered double hydroxides (M = Fe, Al) for catalytic ozonation

Yougan Xiao,Jiahui Lu,Shunjian Cheng,Zilong Wang,Antong Shi,Jyunhong Shen,Zhuwu Jiang

From a preliminary performance comparison of several layered double hydroxides (LDHs), magnetically separable Ni-M LDHs (M = Fe, Al) were synthesized and applied as efficient ozonation catalysts for degrading dye Rhodamine B (RhB). As proved by various characterizations, the micromorphology, nanostructure size, and porous feature of the synthesized Ni-M LDHs significantly varied with different metal components. Among them, Ni 3 -Fe LDH and Ni 2 -Al LDH possessed a relatively larger specific surface area to react with O 3 interfacially, thereby exhibiting excellent catalytic ozonation performance. The RhB was almost completely degraded within 60 min, and the removal efficiencies of COD and TOC reached above 70% and 50%, respectively. The effects of catalyst dosage, initial dye concentration, solution pH, and coexisting inorganic anions on RhB degradation were studied systematically. ESR measurements and radical quenching experiments indicated that OH , O 2 − , and 1 O 2 are primary reactive oxygen species (ROS), while 1 O 2 induced the most dominant degradation contribution. According to the variations of ROS formation and material properties during the catalytic ozonation process, the possible reaction mechanisms were proposed. Moreover, the differences involved in the redox of multivalent metals and the transformation of surface hydroxyls over Ni-Fe and Ni-Al LDHs were further revealed.

A novel intelligent hybrid nano-sensor (IHNS) for detection and clearance of Al(Ⅲ) prepared via “click chemistry”

Gang Zhao,Peipei Xu,Gang Wei,Kezhen Zhang,Chunxue Yi,Shanyi Guang,Hongyao Xu

Intelligent materials are functional material systems with intelligent responses to external stimulation. With the continuous advances in science and technology, intelligent materials have surfaced as a research trend in material science and are providing a new direction for the systematic application of nanocomposite materials. In this study, an intelligent organic-inorganic nano-hybrid sensor or intelligent nanorobot, POSS-RHB-PEG, was developed by employing density functional theoretic calculations (DFT) under the Gaussian 03 program by a “Click Chemistry” based preparation strategy, in which RHB group can act as a recognizing ion in the cell under the action of intense coordination field and then as a function of coordinating ions. A low-chain PEG with good cell permeability functions as a machine wheel on account of the principle of osmotic pressure. The POSS-based nanorobotic molecular analytical device, with appropriate bio-compatibility, was designed and developed for the semiquantitative, intuitive, and sensitive detection and morphological analysis of Al 3+ ions in a real sample with a detection limit of 1.0×10 −8 M. Significant color evolutions from colorless to red were observed by the naked eye under the ultraviolet lamp, resulting in a semiquantitative visual detection. Compared to the organic sensing material RHB-Ac, the intelligent nanorobot POSS-RHB-PEG has high stability, selectivity (sulfhydryl group can self-screen Fe 3+ ions), and good biocompatibility. Furthermore, the nanohybrid nanorobot sensor successfully targeted HeLa cells, monitored cellular endogenous Al 3+ , and assessed cell stress in living cells. The nanohybrid nanorobot sensor POSS-RHB-PEG was also able to detect and image Al 3+ in living nude mice, indicating its exceptional detection potential in biological systems, it mainly involves the detection of metal ions in blood and the detection and treatment of heavy metal ions caused by clinical bone and joint replacement.

A fluorescence and SERS dual-mode sensing on tetracycline antibiotics based on Ag@NH2-MIL-101(Al) nanoprobe

Junjie Qi,Jingkun Li,Yuqi Wan,Yu Li,Fuwei Pi

Antibiotic residues are becoming more and more concern due to the increasingly serious resistance from bacteria to organism. On-site and accurate evaluation on antibiotics is necessary and urgent to effectively solve such public issue. To provide point-of-care-test (POCT) ideas for antibiotic accurate evaluation, a fluorescence (FL)-surface-enhanced Raman scattering (SERS) dual-mode detection of tetracycline antibiotic (TCs) was realized for the first time. Based on the inner filter effect in Ag@NH 2 -MIL-101(Al) nanoprobe, the fluorescence quenching was induced and the SERS signal was swiftly turn on through π-π interaction and hydrogen bonding in the presence of TCs. This FL-SERS dual mode sensor displayed excellent detection limits (FL in ∼10 −3 ppm, SERS in ∼10 −5 ppm), and achieved a reliable detection of TCs in honey with a recovery rate of 84.45%−112.08%. This method combines the advantages of FL and SERS detection, meanwhile, two techniques verified against each other to achieve highly sensitive and specific FL-SERS dual-mode sensor for TCs. We believe that such antibody-or aptamer-independent FL and SERS complementary nanoprobe can be applied to fast, direct and multiple sensing in environment and food hazards.