Rapid preparation of Palygorskite/Al2O3 composite aerogels with superhydrophobicity,high-temperature thermal insulation and improved mechanical properties

Al₂O₃ aerogels are widely employed in heat insulation and flame retardancy because of their unique combination of low thermal conductivity and exceptional high-temperature stability. However, the mechanical properties of Al₂O₃ aerogel are poor, and the preparation time is considerably long. In this study, we present a simple and scalable approach to construct monolithic Pal/Al₂O₃ composite aerogels using solvothermal treatment instead of traditional solvent replacement, which remarkably shortened the preparation time. Subsequently, to obtain stable superhydrophobicity (θ > 152°), the Pal/Al₂O₃ aerogel was modified by gas-phase modification method. The obtained Pal/Al₂O₃ composite aerogels demonstrate the integrated properties of low density (0.078–0.106 g/cm³), low thermal conductivity (1000 °C, 0.143 W/(m·K)), good mechanical properties (Young's modulus, 1.6 MPa), and good heat resistance. The monolithic Pal/Al₂O₃ composite aerogels with improved mechanical performance and improved thermal stability can show great potential in the field of thermal insulation.     

纳米零价铁材料对放射性核素的 去除及机理研究进展

随着人类社会的发展，放射性铀矿的开采和使用越来越多，环境面临着越来越严重的放射性污染问题。从生物和环境的角度来看，有效地清除环境中的放射性核素是核能利用过程中最重要的问题之一。纳米零价铁（nanoscale zero valent iron, nZVI）具有较大的比表面积和较高的活性位点，能显著提高放射性污染物的修复效率。本综述的目的是展示nZVI基材料对放射性核素的高效去除能力和环境修复作用。简介了常用的nZVI基材料（表面改性或多孔材料支撑的nZVI材料）及其对放射性核素的去除效果和相互作用机制（如吸附和氧化还原）。最后，对nZVI材料的应用和挑战给出个人见解。本综述有助于为高效去除放射性核素的nZVI材料的设计指明方向，为放射性核素的高效处理处置提供新材料。     

Novel nanorod Ti0·7Ir0·3O2 prepared by facile hydrothermal process: A promising non-carbon support for Pt in PEMFCs

Late transition metal doped TiO₂ has been exploited for generating efficient catalyst support by enhancing electrical conductivity and modifying properties of TiO₂. The Ti_0·7Ir_0·3O₂ nanorod (NRs), a novel catalyst support for Pt nanoparticles, was prepared for the first time via single-step hydrothermal process at low temperature using IrCl₃·3H₂O and TiCl₄ as starting materials. We found that the Ti_0·7Ir_0·3O₂ NRs with 70–80 nm in length and 25–30 nm in width is successful prepared at 210 °C for 12 h without utilizing surfactants or stabilizers. In addition, the Ti_0·7Ir_0·3O₂ NRs was presented principally as a single-phase solid with the TiO₂ is in the rutile form with high crystallinity without using further treatment after synthesis. More importantly, we found that the Ti_0·7Ir_0·3O₂ NRs possesses high electrical conductivity (0.028 S cm⁻¹) dealing the intrinsically non-conducted drawback of TiO₂. The Pt nanoparticles were then deposited on the support of Ti_0·7Ir_0·3O₂ NRs via chemical reduction method. The properties of 20 wt % Pt/Ti_0·7Ir_0·3O₂ NRs electrocatalyst were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), the cyclic voltammetry (CV). The uniformly distributed small Pt nanoparticles (3–4 nm diameter) were well adhered to the Ti_0·7Ir_0·3O₂ NRs. The electrochemically active surface area (ECSA) of 20 wt % Pt/Ti_0·7Ir_0·3O₂ NRs was higher than that of the commercial 20 wt % Pt/C (E-TEK) due to the small size and good dispersion of Pt nanoparticles on the surface of Ti_0·7Ir_0·3O₂ NRs. Moreover, the ECSA value of the Pt/Ti_0·7Ir_0·3O₂ NRs retained up to 88% after 2000 cycles of cyclic voltammetry, suggesting the high stability of catalyst resulted from strong metal support interaction (SMSI) of Titania-based materials with the noble metals. More importantly, the onset potential of Pt/Ti_0·7Ir_0·3O₂ NRs catalyst towards oxygen reduction reaction is more positive (∼80 mV) compared to commercial Pt/C, indicating the high catalytic activity of the Pt/Ti_0·7Ir_0·3O₂ NRs catalyst. The results of this research suggested that novel Ti_0·7Ir_0·3O₂ NRs could be applied as promising robust non-carbon support for Pt. This research also creates a preliminary step for investigating systematically promising Iridium doped Titania materials.     

Methane bi-reforming over boron-doped Ni/SBA-15 catalyst: Longevity evaluation

A highly active and stable boron-promoted catalyst was successfully prepared by using the sequential incipient wetness impregnation technique and examined for methane bi-reforming reaction. The initial investigation found that the NiO and B₂O₃ particles were dispersed on the outer surface of the high surface area SBA-15 support. In addition, the catalytic activity was increased linearly with the tested reaction temperature due to the endothermic nature of the reaction. In fact, the catalyst achieved the CH₄ conversion and H₂/CO molar ratio of approximately 67.3% and 2.7, respectively at 1073 K. The resulting product ratio is highly suitable for downstream Fischer-Tropsch (FT) synthesis. The B-promoted catalyst showed the lowest degree of catalyst deactivation (4%) at 1023 K. Additionally, the XPS measurements unveiled that the boron facilitates the adsorption of CO₂ by donating electrons to the neighbouring Ni cluster and thus improved its catalytic performance. Furthermore, Raman and XRD analysis revealed that the boron promotion on 10%Ni/SBA-15 could prevent the reoxidation and deposition of carbonaceous species.     

高温深井通风降温技术的适用条件研究

随着矿山开采深度的不断增加，“三高一扰动”恶劣开采环境问题日益突出，给矿井通风降温工作带来极大困难。对于深井矿山，仅采用通风降温难以满足深部开采的需要，系统研究高温深井矿山通风降温技术的适用性问题，对矿山深部开采具有重要的理论意义和工程适用价值。首先从热力学角度，揭示风流在通风线路中的热交换规律；其次利用差分法原理计算深井筒风流温度，并依此推导出巷道和回采工作面风流温度变化趋势；然后结合采场安全生产允许温度进行反推，最终获取通风降温条件下的可采极限深度计算公式，并选取广西铜坑矿锌多金属矿体作为工程应用试验区进行论证分析。结果表明：基于风流的热交换模型可以推导出风流在井筒、巷道及工作面的温度计算公式，该公式与低温梯度、风流流经路径长度有关；假定工作面温度达到安全开采允许最高温度，可反推出该条件下矿山可采极限深度和巷道通风极限长度（仅采用通风降温措施时）；基于铜坑矿区锌多金属矿的实际条件，代入相关数据，验证计算所得极限开采深度符合实际，即所推导公式是可行的。     

Ultrafast fabrication of nanostructure WO3 photoanodes by hybrid microwave annealing with enhanced photoelectrochemical and photoelectrocatalytic activities

Tungsten oxide (WO₃) nanoplate films with a relatively rough surface were successfully fabricated via a simple hydrothermal method, followed by the hybrid microwave annealing (HMA) treatment only a few minutes for the first time. The microscopic morphology and phase were characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Raman spectrum and X-ray diffraction (XRD). Photoelectrochemical measurements demonstrated that the obtained WO₃ film of microwave processing for 11 min exhibited the photocurrent density of 1.60 mA/cm² at 1.2 V (vs. Ag/AgCl) and the IPCE value of 55% at 355 nm under an applied voltage of 1.0 V (vs. Ag/AgCl), which were about 3 and 2.5 times compared with the WO₃ film prepared by the conventional annealing method, respectively. Moreover, the WO₃-HMA films were applied to the versatile photoanode-driven photoelectrochemical system for CO₂ reduction into formic acid. The maximum formic acid generation rate and faradaic efficiency of the WO₃-HMA films were 9.21 μmol h^?1 cm^?2 and 45.45%, respectively. This study provided a facial and rapid method to synthesize the high-performance WO₃ photoanodes with better photoelectrochemical and photoelectrocatalytic activities.     

锡石多金属硫化矿微波助磨试验研究

本文以广西某选矿厂锡石多金属硫化矿矿石为原料,研究了微波预处理对矿石磨矿产物粒度组成、磨矿动力学、破碎速率及磨机生产能力的影响。结果表明,微波预处理后,矿石在不同磨矿时间下的磨矿产物粒度均变细,-0.074mm粒级含量提高了4.41%~12.90%；微波预处理前后该矿石磨矿均符合一级磨矿动力学模型；微波预处理使矿石的破碎速率(S₁)值提高近57%,且磨机的生产能力得到了明显提升。因此,微波预处理可以降低矿石的强度,强化矿石的磨矿过程,是一种有效的降低磨矿能耗、提高磨矿效率的方法。     

Phase evolution and microstructure of new Sr0.5Zr2(PO4)3-NdPO4 composite ceramics prepared by one-step microwave sintering

Sodium Zirconium Phosphate (NaZr₂(PO₄)₃, hereinafter NZP) and monazite are both potential materials for immobilization of nuclear waste. In this work, novel (1-x)Sr_0.5Zr₂(PO₄)₃-xNdPO₄ composite ceramics (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) for simultaneously immobilizing the simulated fission product (FP) Sr and trivalent minor actinide (MA) Nd were prepared by one-step microwave sintering technique, in which Sr and Nd were immobilized into NZP and monazite type structures, respectively. The phase evolution and microstructure of the samples were investigated by X-ray diffraction (XRD), Raman, and backscattering scanning electron microscopy (BSE). The results showed that the expected composite ceramics were successfully obtained by one-step microwave sintering at 1050 °C for 2 h. The as-prepared samples consisted of Sr_0.5Zr₂(PO₄)₃ and NdPO₄ phases, and the content of the two phases varied regularly as x changed, generally conforming to the designed nominal chemical composition. Importantly, the composite ceramics presented the homogenous and dense microstructure. The relative density of the composite ceramics was more than 95%, meanwhile, the Vickers-hardness of the samples was higher than 600 MPa. It was indicated that NZP-monazite type composite ceramics could be a potential matrix for the simultaneous immobilization of actinide and fission product.     

Finite element optimization of sample geometry for measuring the torsional shear strength of glass/metal joints

Assessment of mechanical properties of glass/metal joints is a challenging process, especially when the application relevant conditions of the joints have to be considered in the test design. In this study, a finite element method (FEM) is implemented to analyze a torsional shear strength test designed for glass-ceramic/steel joints aiming towards solid oxide fuel/electrolysis cells application. Deviations from axial symmetry of the square flanges (ends) of respective hourglass-shaped specimens and also supporting and loading sockets of the test set-up are included in the model to simulate conditions close to reality. Undesirable tensile stress and also shear stress concentration appear at the outer edge of glass-ceramic layers, which are less for the hollow-full specimen. The simulation results show that for a specimen with either 9 mm thick square- or 6 mm thick triangular-flanges, locally enhanced tensile stresses almost disappear, resulting in a symmetric shear stress distribution. The difference between the analytically derived nominal shear strength and the real critical shear stress derived via simulation reduces with decreasing the fracture torque.