具有良好可再生性的新型二氧化硅磁性氧化石墨烯纳米复合材料

Graphene oxide (GO) wrapped Fe₃O₄ nanoparticles (NPs) were prepared by coating the Fe₃O₄ NPs with a SiO₂ layer, and then modifying by amino groups, which interact with the GO nanosheets to form covalent bonding. The SiO₂ coating layer plays a key role in integrating the magnetic nanoparticles with the GO nanosheets. The effect of the amount of SiO₂ on the morphology, structure, adsorption, and regenerability of the composites was studied in detail. An appropriate SiO₂ layer can effectively induce the GO nanosheets to completely wrap the Fe₃O₄ NPs, forming a core-shell Fe₃O₄@SiO₂@GO composite where Fe₃O₄@SiO₂ NPs are firmly encapsulated by GO nanosheets. The optimized Fe₃O₄@SiO₂@GO sample exhibits a high saturated adsorption capacity of 253 mg·g?1 Pb(II) cations from wastewater, and the adsorption process is well fitted by Langmuir adsorption model. Notably, the composite displays excellent regeneration, maintaining a ~90% adsorption capacity for five cycles, while other samples decrease their adsorption capacity rapidly. This work provides a theoretical guidance to improve the regeneration of the GO-based adsorbents.     

微波预处理对复杂铜矿磨矿及浮选动力学的影响

The effect of CaCO₃, Na₂CO₃, and CaF₂ on the reduction roasting and magnetic separation of high-phosphorus iron ore containing phosphorus in the form of Fe₃PO₇ and apatite was investigated. The results revealed that Na₂CO₃ had the most significant effect on iron recovery and dephosphorization, followed by CaCO₃, the effect of CaF₂ was negligible. The mechanisms of CaCO₃, Na₂CO₃, and CaF₂ were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS). Without additives, Fe₃PO₇ was reduced to elemental phosphorus and formed an iron–phosphorus alloy with metallic iron. The addition of CaCO₃ reacted with Fe₃PO₇ to generate an enormous amount of Ca₃(PO₄)₂ and promoted the reduction of iron oxides. However, the growth of iron particles was inhibited. With the addition of Na₂CO₃, the phosphorus in Fe₃PO₇ migrated to nepheline and Na₂CO₃ improved the reduction of iron oxides and growth of iron particles. Therefore, the recovery of iron and the separation of iron and phosphorus were the best. In contrast, CaF₂ reacted with Fe₃PO₇ to form fine Ca₃(PO₄)₂ particles scattered around the iron particles, making the separation of iron and phosphorus difficult.     

不同硅饱和系数水榴石的碳酸化分解动力学

Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method, which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method. In this study, the effect of the silica saturation coefficient (x) on the carbonation of hydrogarnet was investigated from the kinetic perspective. The results indicated that the carbonation of hydrogarnets with different x values (x = 0.27, 0.36, 0.70, and 0.73) underwent two stages with significantly different rates, and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3. The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol, respectively. Moreover, the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.     

一种超重力燃烧合成制备高性能高熵合金的新方法

A new method of high-gravity combustion synthesis (HGCS) followed by post-treatment (PT) is reported for preparing high-performance high-entropy alloys (HEAs), Cr_0.9FeNi_2.5V_0.2Al_0.5 alloy, whereby cheap thermite powder is used as the raw material. In this process, the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field. Then, the master alloy is obtained after cooling. Subsequently, the master alloy is sequentially subjected to conventional vacuum arc melting (VAM), homogenization treatment, cold rolling, and annealing treatment to realize a tensile strength, yield strength, and elongation of 1250 MPa, 1075 MPa, and 2.9%, respectively. The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating. Based on the calculation of phase separation kinetics in the high-temperature melt, it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients.     

窄板坯结晶器内连铸工艺参数对钢液流场的影响

Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting (CC) molds with narrow widths for the production of automobile exposed panels. Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process. The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold. Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone. The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min?1 and casting speed of 1.7 m·min?1. Under the present experimental conditions, the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm.     

电渣重熔脱硫技术研究进展

Electroslag remelting (ESR) gives a combination of liquid metal refining and solidification structure control. One of the typical aspects of liquid metal refining during ESR for the advanced steel and alloy production is desulfurization. It involves two patterns, i.e., slag–metal reaction and gas–slag reaction (gasifying desulfurization). In this paper, the advances in desulfurization practices of ESR are reviewed. The effects of processing parameters, including the initial sulfur level of consumable electrode, remelting atmosphere, deoxidation schemes of ESR, slag composition, melting rate, and electrical parameters on the desulfurization in ESR are assessed. The interrelation between desulfurization and sulfide inclusion evolution during ESR is discussed, and advancements in the production of sulfur-bearing steel at a high-sulfur level during ESR are described. The remaining challenges for future work are also proposed.     

利用皮秒激光烧蚀制备非球形铝纳米颗粒

We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid (chloroform, CHCl₃) with ~2 ps laser pulses at an input energy of ~350 μJ. The synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at ~340 nm. Scanning electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of (27 ± 3.6) nm. The formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al nanoparticles. In addition to spherical aluminum nanoparticles, triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal solution. Field emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures (LIPSSs), which were the high spatial frequency LIPSSs (HSF-LIPSSs) since their grating period was ~280 nm. Additionally, coarse structures with a period of ~700 nm were observed.     

Mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al2O3?Na2O system during high-temperature sintering

The mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al₂O₃?Na₂O system during the high-temperature sintering process were systematically investigated using DSC?TG, XRD, SEM?EDS, FTIR, and Raman spectra, and the crystal structure of Na₄Ca₃(AlO₂)₁₀ was also simulated by Material Studio software. The results indicated that the minerals formed during the sintering process included Na₄Ca₃(AlO₂)₁₀, CaO·Al₂O₃, and 12CaO·7Al₂O₃, and the content of Na₄Ca₃(AlO₂)₁₀ could reach 92wt% when sintered at 1200°C for 30 min. The main formation stage of Na₄Ca₃(AlO₂)₁₀ occurred at temperatures from 970 to 1100°C, and the content could reach 82wt% when the reaction temperature increased to 1100°C. The crystal system of Na₄Ca₃(AlO₂)₁₀ was tetragonal, and the cells preferred to grow along crystal planes (110) and (210). The formation of Na₄Ca₃(AlO₂)₁₀ was an exothermic reaction that followed a secondary reaction model, and its activation energy was 223.97 kJ/mol.     

含细夹层的分矿充填层中流动特性的可视化

Ore particles, especially fine interlayers, commonly segregate in heap stacking, leading to undesirable flow paths and changeable flow velocity fields of packed beds. Computed tomography (CT), COMSOL Multiphysics, and MATLAB were utilized to quantify pore structures and visualize flow behavior inside packed beds with segregated fine interlayers. The formation of fine interlayers was accompanied with the segregation of particles in packed beds. Fine particles reached the upper position of the packed beds during stacking. CT revealed that the average porosity of fine interlayers (24.21%) was significantly lower than that of the heap packed by coarse ores (37.42%), which directly affected the formation of flow paths. Specifically, the potential flow paths in the internal regions of fine interlayers were undeveloped. Fluid flowed and bypassed the fine interlayers and along the sides of the packed beds. Flow velocity also indicated that the flow paths easily gathered in the pore throat where flow velocity (1.8 × 10?5 m/s) suddenly increased. Fluid stagnant regions with a flow velocity lower than 0.2 × 10?5 m/s appeared in flow paths with a large diameter.     

反相高效液相色谱保留值方程的简化

系统地考察了31种有机化合物在反相高效液相色谱条件下和在较宽的流动相（甲醇—水体系）组成范围内溶质的保留值k′与有机改性剂甲醇浓度CB之间的关系,在大量数据基础上,回归得到了描述反相液相色谱溶质保留值与二元流动相中有机改性剂浓度CB的关系式：lnk′=b0＋b1CB.该关系式实际上是对反相液相色谱保留值方程的合理简化,最后对此关系式中的几个参数做了简要的讨论.     

残留量原理与更正压榨损失

本文首先陈述Deerr更正压榨收回率公式及其它修正公式,然后作者用残留量原理和更正压榨损失的概念加以解析评述,指出各式的理论依据、假设条件之异同和各式间的相互关系,并指出影响更正因数的因素和主要因素,根据我区实例进行计算及分析,提出对More公式(3)的修正式。     

对多氯代二苯并-对-二噁英的定量结构色谱保留时间的理论研究

采用密度泛函理论的B3LYP方法和分子连接性指数理论,计算了氯代二苯并-对-二噁英的结构参数,并用逐步回归分析建立了相应的QSRR模型.所建模型计算值和观察值的相关系数分别为0.944和0.936,标准偏差分别为0.299和0.464,模型具有良好的稳健性和预测能力,交互验证系数分别为0.818和0.79。比较得出量子化学方法所建模型的性能更好.     

两性离子聚丙烯酰胺在岩心中滞留量的测定

研究聚合物浓度、含盐量及岩心的渗透率对两性离子聚丙烯酰胺在岩心中滞留量的影响,结果表明:两性聚合物浓度增加,滞留量增加;在本实验研究的含盐量区间内,滞留量随含盐量的增加而下降;随岩心渗透率的增加,滞留量降低.     

酚类化合物色谱保留指数的估计与预测

用根据非氢原子类型分类、基于非氢原子相对电负性和非氢原子间距离等进行计算得到的分子电性距离矢量(MEDV)为描述子,对酚类化合物结构进行表征.用多元线性回归(MLR)方法,研究并建立了酚类化合物定量结构-色谱保留(QSRR)关系的10变量模型,其相关系数为0.9512;采用SPSS统计处理软件对变量进行逐步回归(SMR)筛选后,建立了8变量的QSRR模型,其相关系数为0.9508.上述模型对102种酚类化合物色谱保留的预测值与实验值能较好吻合,留一法交互检验的结果分别为Rcv=0.9269和Rcv=0.9377.结果表明所建模型具有良好的稳定性和预测能力.     

木质素磺酸钙改性聚羧酸的研制及其保水性能

为解决工程上聚羧酸高效减水剂(PCE)对掺量敏感和容易出现离析泌水的问题,采用水溶液聚合法和复配法,以甲氧基聚乙二醇甲基丙烯酸酯(MPEGMA)、丙烯酸(AA)、木质素磺酸钙(CL)为原料,制备共聚型木质素磺酸钙改性聚羧酸高效减水剂(GCL-PCE)和复配型木质素磺酸钙改性聚羧酸高效减水剂(FCLPCE),研究了木质素磺酸钙用量对两者保水性等性能的影响,并与改性前的聚羧酸高效减水剂进行对比.通过FT-IR证明,GCL-PCE与FCL-PCE被成功制备,随着CL用量的增加,掺FCL-PCE和GCL-PCE的砂浆泌水率比总体呈先上升后下降的趋势,掺FCL-PCE的砂浆泌水率比均小于100%,保水性好,符合高效减水剂泌水率比≤100%的要求.当CL用量达10%,GCL-PCE掺量达0.2%时的减水率为23.16%;当CL用量相同时,GCL-PCE的减水分散作用较FCL-PCE更佳.     

生物滞留设施基础研究和应用借鉴

城市的快速发展在改变社会生活的同时,对城市水环境构成威胁.作为新型雨洪管理措施之一的生物滞留设施,在有效解决城市雨洪问题中发挥着重要作用.对生物滞留设施进行了概念、构造、机理、植物和填料等基础研究,提出生物滞留设施规模确定的多种方法,各地可根据地域条件参考选定.总结生物滞留设施的研究进展,对美国波特兰市NE Siskiyou绿色街道和深圳市光明新区36号、38号道路建设案例进行分析,比较思考国内研究和建设现状的空缺与不足,总结先进的经验成果,提出我国生物滞留设施的思考借鉴.     

反相高效液相色谱中溶质的保留机理与能量守恒

由于在反相液相色谱（ＲＰＬＣ）中的分配保留机理忽略了在溶质进入固定相时溶剂分子必须要离开固定相的这一事实，所以，首次得出了ＲＰＬＣ中的分配机理是违背了物理学中的两个基本原理，一个空间不能同时被两个物体占据和能量守恒定律的结论。分配机理不考虑固定相对溶质保留的贡献和惯常置换（吸附）机理不考虑流动相对溶质保留的贡献是不合理的。溶质的计量置换保留模型（ＳＤＭ—Ｒ）不仅符合上述的两个物理学基本原理，而且考虑了ＲＰＬＣ体系中分子间的各种相互作用。用文献中发表的本是用来支持分配机理的原始ｋ’值，着重检验和比较该ＳＤＭ—Ｒ与分配机理的结果，发现这些数据更支持ＳＤＭ—Ｒ。还得出上述结论亦适用于生物大分子。首次证实ＳＤＭ—Ｒ可以用来统一迄今仍在争论的ＲＰＬＣ中的分配机理和置换机理。     

6种保水剂吸水保水性能的比较

比较分析了6种保水剂在0～0.5 mol/L的NaCl、KCl、CaCl2电解质溶液,以及pH为2～12的蒸馏水中的吸水倍数和保水剂对土壤水分蒸发的影响.结果表明:随着3种电解质盐溶液浓度升高,保水剂吸水倍数呈下降趋势;CaCl2对保水剂吸水倍数的影响明显大于KCl和NaCl.在pH为6～8的蒸馏水中保水剂能保持较好的吸水性能;当pH≤4或pH≥10时吸水倍数明显下降,保水剂对酸性水溶液更为敏感.保水剂能有效地降低土壤水分蒸发速率.几种保水剂呈相似的变化趋势,其中"高能抗旱保水剂(GN)"表现最佳.以GN进行的土壤质地对保水剂保水效果影响的试验表明,壤土中保水剂对抑制土壤水分蒸发速率的效果较明显.     

织物保水性研究

通过建立导湿干爽织物结构模型，研究织物内层液态水流量、外层液态水储水量，提出了汗水不倒流到织物里层的条件，为解决这一难题提供了理论依据，可用于指导织物设计，解决汗水在织物表面流淌和汗水从织物外层流回织物里层的难题。