多点进水倒置A2/O工艺处理某工业园污水

针对某大型工业园综合污水氮磷含量高的特点,应用多点进水倒置A/A/O工艺处理该工业园排放的综合污水,通过改变内回流的回流点及回流比例,使倒置A/A/O工艺可以根据进水水质,既可按缺氧-厌氧-好氧顺序运行,也可按照厌氧-缺氧-好氧顺序运行,而多点进水方式可以有效地解决反硝化菌和聚磷菌对有机底物的竞争.采用该工艺处理后出水...     

超临界流体技术在分离工程领域中的应用

文章阐述了超临界流体分离技术的原理、流程与特点.综述了该技术在分离工程领域的应用方向、存在的问题及未来的发展前景.指出了该技术兼具精馏和萃取两种分离作用效果,在天然资源成份的分离提取、脱除有害成份或杂质、清洗、色谱分析等诸多领域部有着其独特的开发应用优势.     

PAN/PPG纤维预氧化及碳纤维结构和性能研究

采用聚丙二醇(PPG)与聚丙烯腈(PAN)共混制备的PAN/PPG原丝进行预氧化和碳化,利用SEM、FTIR、元素分析仪、力学性能测试等仪器和手段,研究了PPG的加入对预氧丝和碳丝的结构和性能的影响.研究发现:PPG的加入使PAN预氧丝的表面结构更加均匀,减少了碳纤维中的孔洞;同时还促进了纤维在预氧化和碳化过程中的氧化...     

材料科学与工程专业无机与分析化学教学改革的探索

结合我院近四年来材料科学与工程专业无机与分析化学课程的教学实践,阐述了无机与分析化学课程整合之后在教学内容、教学方法和教学手段等环节上的具体改革措施.     

Porous graphitic carbons prepared by combining chemical activation with catalytic graphitization

Porous graphitic carbons were prepared by combining chemical activation (ZnCl₂) with catalytic graphitization (metal Fe and Ni). The activating agent ZnCl₂ increased the surface area of porous carbon, and the catalyst (Fe, Ni) accelerated the graphitization. With increasing heat treatment temperature (600–900 °C), metal Fe and Ni promoted the degree of graphitization which was characterized by powder X-ray diffraction, Raman spectroscopy and high-resolution transmission electron microscopy. The surface area of samples prepared using Fe and Ni catalysts varied from 275 to 787 m² g⁻¹ and from 83 to 121 m² g⁻¹, respectively.     

Particle motion and separation in a laminar tube flow with downstream enlargement

Particle classification becomes difficult when the difference in density between particle and fluid is low or negligible and the fluid is viscous. For such applications, a process capable of separating the particles according to their size is needed. Such applications are, e.g. found in biological systems for cell separation or in the removal of gel particles from polymer melts. Particle transport in laminar tube flows at low but non zero Reynolds numbers leads to accumulation of large particles near the tube center and forms a particle free zone near the wall. Small particles find their position on their equilibrium radius. Downstream widening of the flow enhances segregation between large and small particles. Large particles can be collected in a centered collector tube downstream, whereas small particles follow their streamlines around the collector tube and can be removed with the remaining flow. The said particle migration is observed when the ratio of particle to tube diameter is 0.2<d/D<0.51 and the tube Reynolds number is in between 0.2<Re<40. CFD simulations reveal the shape of the streamlines in the downstream enlargement with different tube Reynolds number. The efficiency of the classification process is characterized. Particles need a sufficient transportation length in the tube for proper demixing. This effect is analyzed by a laser sheet illuminated system within an acrylic glass tube.     

Effective monitoring of corrosion in reinforcing steel in concrete constructions by a multifunctional sensor

A novel multifunctional sensor is developed for in situ and non-destructive monitoring of the corrosion current and open circuit potential of reinforcing steel, as well as the pH and Cl⁻ concentration of concrete. The pH and Cl⁻ sensors show good responses to the pH and Cl⁻ concentration of concrete pore solutions, respectively, and are able to monitor both the carbonization process of concrete and the ingress of Cl⁻ in concrete. Combined with measurements of the corrosion potential and corrosion current density, as well as the EIS spectra of reinforcing steel in concrete, this study demonstrates that the pH and the Cl⁻ concentration of concrete are two of the most crucial factors that determine the corrosion of reinforcing steel in concrete. The corrosion tendency and corrosion rate of reinforcing steel largely depend on the chemical environment in the concrete. The multifunctional sensor is a powerful tool for in situ monitoring corrosion of steel in concrete, and provides accurate details of the chemical condition of the concrete pore solution and the corrosion status of the reinforcing steel in concrete. These are essential for corrosion predictions and service life evaluations of concrete constructions.     

Influence of 4-N,N-dimethylaminopyridine on the photovoltaic performance of dye-sensitized solar cells with poly(ethyleneoxide)/oligo(ethylene glycol) blend electrolytes

4-N,N-Dimethylaminopyridine (DMAP) was introduced into poly(ethyleneoxide)/oligo(ethylene glycol) (PEO/PEG) electrolytes for dye-sensitized solar cells (DSCs). The improved photovoltaic performance of DMAP-doped DSCs was attributed to the integrated effects of the upward displacement of the TiO₂ band edge and the decrease in the electron recombination rate. Remarkably, the presence of DMAP suppresses electron recombination via two combined pathways involving the dissociation of triiodide to iodide by a complexation reaction and a modification of the surface state distribution in the band gap of TiO₂. With the addition of DMAP, the open-circuit voltage enhances dramatically. The short-circuit photocurrent density has a small increase at low DMAP concentration and drops afterwards. The power conversion efficiency is 4.07%, which corresponds to a 63% increase over that of the DSC without DMAP.     

Preparation and characterization of thermosensitive organic-inorganic hybrid microgels with functional Fe3O4 nanoparticles as crosslinker

A methodology is described for the preparation of thermosensitive organic-inorganic hybrid microgels with functional Fe₃O₄ nanoparticles as the crosslinker and N-isopropylacrylamide (NIPAm) as the monomer. Magnetic Fe₃O₄ nanoparticles were first prepared via a redox reaction in aqueous solution and then modified with 3-(trimethoxysilyl)propylmethacrylate (TMSPMA) via the silanization. The bonding of multiple TMSPMA monomers on the surface of Fe₃O₄ nanoparticles renders them as crosslinker. Surfactant-free emulsion polymerization (SFEP) of NIPAm was then carried out with the presence of TMSPMA-modified Fe₃O₄ nanoparticles at 70 °C in aqueous solution, leading to the formation of thermosensitive PNIPAm-Fe₃O₄ hybrid microgels crosslinked with Fe₃O₄ nanoparticles. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), dynamic light scattering (DLS) and physical properties measurement system (PPMS) were then used to characterize the resultant hybrid microgels. The experimental results show that the PNIPAm-Fe₃O₄ hybrid microgels were spherical in shape with a large size distribution and the Fe₃O₄ nanoparticles were randomly distributed inside the microgels. The PNIPAm-Fe₃O₄ hybrid microgels were thermosensitive, exhibiting a reversible swelling and deswelling behavior as a function of temperature. The PNIPAm-Fe₃O₄ hybrid microgels also show superparamagnetic behavior at room temperature (300 K).     

制备重结晶碳化硅用α-SiC微粉的表面改性

将聚醚改性聚二甲基硅烷(PMPDMS)与α-SiC微粉按一定比例充分混合,于120℃烘干12 h后碾碎,放入刚玉坩埚内,在N2保护下以一定的加热制度进行热处理,然后分析其相组成、比表面积、烧结块密度及其显微结构的变化;同时以B4C微粉取代α-SiC微粉做同样处理后进行XRD和SEM分析,以确定包覆在B4C微粉表面的PMPDMS在热处理过程中是否生成了β-SiC.结果表明:1)包覆在B4C微粉表面的PMPDMS在试验确定的热处理条件下可以生成β-SiC;2)表面改性后α-SiC微粉相组成发生一定改变,比表面积增大,用其制成的烧结块的密度增大,显微结构更加致密,表明其烧结活性增强.