NaCl-MnO2联合改性沸石对水中Zn2+的动态吸附

研究了NaCl-MnO₂改性沸石填料柱对水中Zn²⁺的动态吸附性能。探讨了填料厚度、Zn²⁺的初始质量浓度和流速对穿透曲线的影响。结果表明,NaCl-MnO₂改性沸石能有效去除水中的Zn²,填料层增厚,穿透曲线上的穿透点向右移动,穿透时间延长;而流速、Zn²⁺的初始浓度增大,穿透曲线上的穿透点向左移动,穿透时间缩短;用Thomas模型描述Zn²⁺初始质量浓度为50mg/L、滤速为4mL/min时改性沸石对Zn²⁺的吸附动力学,相关系数为0.9994,平衡吸附容量为12.04mg/g。     

活性炭纤维对水中Cr(Ⅵ)的吸附研究

采用吸附实验,研究了活性炭纤维(ACF)对水中六价铬[Cr(Ⅵ)]的吸附行为,探讨了溶液pH值、吸附时间、ACF用量、表面改性以及电化学改性对Cr(Ⅵ)吸附效果的影响。研究结果表明:ACF在pH为1~3时吸附性能较好;而在吸附时间为1.5h时吸附接近平衡。施加恒电压-2.0mA时,吸附率由76.31%上升到83.03%,而在恒电流+2mA时,吸附率由83.03%下降到79.22%。利用ACF去除水中的Cr(Ⅵ),其适宜条件为pH=1~3,吸附时间为1.5h;通过电化学改性可以提高吸附率,并可实现ACF的现场再生。     

NaCl—MnO2联合改性沸石对水中Zn^2＋的动态吸附

研究了NaCl—MnO2改性沸石填料柱对水中Zn^2＋的动态吸附性能。探讨了填料厚度、Zn^2＋的初始质量浓度和流速对穿透曲线的影响。结果表明，NaCl-MnO2改性沸石能有效去除水中的zn^2＋，填料层增厚，穿透曲线上的穿透点向右移动，穿透时间延长；而流速、Zn^2＋的初始浓度增大，穿透曲线上的穿透点向左移动，穿透时...     

新型SiO_2基微/介孔材料的合成及其对集成电路生产中VOCs废气的吸附研究

采用新型SiO2基微/介孔材料为吸附剂,针对集成电路(Integrated Ciruit,IC)产业中废气排放的特点,以丙酮、苯、甲苯为挥发性有机化合物(VOCs)的典型,进行了一系列吸附实验.用气相色谱定时测取VOCs获得动态穿透曲线,就各VOCs分别在SiO2基微/介孔材料、疏水沸石、活性炭3种吸附荆上的吸附以及SiO2基微/介孔材料对3种不同VOCs的吸附进行了研究,同时考察了水蒸汽脱附对该材料吸附性能的影响.实验结果显示,该吸附剂在对VOCs的吸附中较疏水沸石FX-I和活性炭有着明显的优势,主要表现在透过时间的延迟和传质区长度的缩短.     

用活性碳纤维（ACF）回收1.2——二氯乙烷废气的研究

本文概述了使用气相色谱在线分析方法,连续测定了模拟工业排放尾气1.2—二氯乙烷,经活性碳纤维(ACF)吸附后,在不同时间点的浓度.评价了ACF填充量的改变,穿透点的时间也随着改变,而饱和吸附量(单位质量ACF的吸附量)基本不变.讨论了随着1.2—二氯乙烷流量的变小,饱和吸附量略有增大的原因.同时还评价了ACF经再生后使用,仍然保持着良好的吸附性能.     

用吸附处理工艺去除饮用水中阴离子表面活性物质的实验研究

采用活性炭、沸石和硅藻土三种常用吸附剂,通过静态实验和动态实验对饮用水中低浓度阴离子表面活性物质(LAS)的去除进行了考察.静态实验结果表明,用吸附法可有效地去除LAS,并且在通常条件下受温度、pH影响不显著,但在有机物如腐殖酸浓度较高的情况下LAS的吸附明显受到抑制.动态实验比较了不同LAS浓度、不同吸附剂对流出曲线的影响,并求出LAS的孔扩散系数和液膜扩散系数.考察LAS和腐殖酸双组分溶液穿透时间及饱和分数的结果表明,腐殖酸为控制化合物,因此实际应用中只需要考虑腐殖酸的去除即可满足LAS的去除要求.     

用改性沸石处理含铜废水的试验研究

通过电导法研究了改性沸石对Cu2 的吸附性能,考察了吸附时间、改性沸石的质量、溶液的pH值及溶液中其他离子对改性沸石吸附性能的影响.结果表明,当改性沸石的质量一定时,电导率连续降低,直至恒定不变.随着改性沸石投加量的增大,电导率减小,最佳投加量为2 g,最佳pH值为5,去除效率为65%.ZnSO4、NiSO4、CdCl2、CuCl2和Cu(NO3)2的存在不会影响改性沸石对Cu2 的吸附性能.     

ACFs对溶液中Cr(Ⅵ)的吸附性能研究

利用比表面分析仪、扫描电镜和红外光谱仪对活性炭纤维(ACFs)的性能进行表征。选择一定浓度的六价铬[Cr(Ⅵ)]溶液进行吸附研究,考察接触时间、溶液pH值以及溶液中Cr(Ⅵ)的初始质量浓度对吸附行为的影响。结果表明,最佳接触时间为125 min;Cr(Ⅵ)的去除率随着pH值的减小而增大,当pH=2.0时达到最大;Cr(Ⅵ)的吸附量随着Cr(Ⅵ)初始质量浓度的增加而增大,而去除率随着Cr(Ⅵ)初始质量浓度的增加而减小。此外,对材料的吸附机制进行了简要的分析。     

新型CO2-PSA吸附剂的性能研究

改性后的活性炭表面形成特殊的吸附中心，我们研究二氧化碳在其表面的吸附穿透曲线及压力和解吸时间对吸附性能的影响，经过对Ca^2 ,Mg^2 ,Cu^2 改性的活性炭吸附剂的研究，我们得出Cu^2 改性的果壳基活性炭具有很好的对二氧化碳的吸附可逆行，而且可逆吸附量受压力变化的影响在一定压力时十分明显，因此是一种优良的CO2－PSA吸附剂。     

聚吡咯/壳聚糖复合膜的制备及其对Cu(Ⅱ)和Cr(Ⅵ)吸附机制

以聚吡咯(PPy)和壳聚糖(CS)为原料,制备PPy/CS复合膜,通过红外、孔径分析、热分析和SEM等手段对其结构进行表征,并研究了PPy/CS复合膜对Cu(Ⅱ)和Cr(Ⅵ)吸附性能的影响及吸附机制,考察了pH值、吸附时间、溶液起始浓度等因素对吸附率的影响.结果表明,初始浓度对吸附率影响最大;在pH=3.5、温度为33...     

Hierarchical carbon nanostructure design: ultra-long carbon nanofibers decorated with carbon nanotubes

Hierarchical carbon nanostructures based on ultra-long carbon nanofibers (CNF) decorated with carbon nanotubes (CNT) have been prepared using plasma processes. The nickel/carbon composite nanofibers, used as a support for the growth of CNT, were deposited on nanopatterned silicon substrate by a hybrid plasma process, combining magnetron sputtering and plasma-enhanced chemical vapor deposition (PECVD). Transmission electron microscopy revealed the presence of spherical nanoparticles randomly dispersed within the carbon nanofibers. The nickel nanoparticles have been used as a catalyst to initiate the growth of CNT by PECVD at 600°C. After the growth of CNT onto the ultra-long CNF, SEM imaging revealed the formation of hierarchical carbon nanostructures which consist of CNF sheathed with CNTs. Furthermore, we demonstrate that reducing the growth temperature of CNT to less than 500°C leads to the formation of carbon nanowalls on the CNF instead of CNT. This simple fabrication method allows an easy preparation of hierarchical carbon nanostructures over a large surface area, as well as a simple manipulation of such material in order to integrate it into nanodevices.     

短切炭纤维增强沥青基C/C复合材料的组织特征

利用新型、高效的模压半炭化成型工艺，在大气环境下制备出了短切炭纤维增强沥青基C／C复合材料制品，并借助光学显做镜和扫描电镜对其微观组织和断口形貌进行了观察。通过分析，解释了短切炭纤维增强沥青基C／C复合材料中炭纤维损伤的形成机制，提出了作为增强体相的短切炭纤维和焦炭颗粒与基体炭之间独特的界而结构模型。研究还表明：复合材料中明显存在着基体相和颗粒相一基体相的显微结构不仅呈层片状，而且层片状的结构好像数层桔子皮，将颗粒相包裹起来，这种“桔皮包裹”式的结构与炭纤维表面的POG结构基本相似。     

短切炭纤维增强沥青基C/C复合材料的力学性能

利用模压半炭化成型工艺在大气环境下制备出了短切炭纤维增强沥青基C／C复合材料（简称SCFRC）。研究了短切炭纤维的体积分数对SCFRC材料的体积密度和力学性能的影响规律。借助光学显微镜和扫描电镜对其微观组织和断口形貌进行了观察，分析了短切炭纤维对SCFRC材料的增强机制。结果表明，当短切炭纤维的体积分数由0％增大到11．8％时，SCFRC材料的力学性能随之呈线性增加；短切炭纤维增强SCFRC材料的机制主要有裂纹偏转效应、桥联效应以及脱粘和拔出效应。     

Kinetics of chemical vapor infiltration of carbon nanofiber-reinforced carbon/carbon composites

Preforms containing 0, 5, 10, 15 and 20 wt.% carbon nanofibers (CNFs) were fabricated by spreading layers of carbon cloth, and infiltrated by using the technique of isothermal chemical vapor infiltration (ICVI) at the temperature of 1100 °C under the total pressure of 1 kPa and with the flow of the mixture of propane/nitrogen in a ratio of 13:1. The infiltration rates increased with the rising of CNF content, and after 580 h of infiltration, the achievable degree of pore filling was the highest when the CNF content was 5 wt.%, but the composite could not be densified efficiently as the CNF content ranged from 10 to 20 wt.%. An analysis of the results, based on the effective diffusion coefficient and on the in-pore deposition rates, shows that the CNFs, due to their higher aspect ratio, accelerate overgrowth at pore entrances and thus lead to incomplete pore filling.     

软硬混编预制体增强沥青基4D-C/C材料的拉伸破坏行为

以X-Y平面依次铺设炭纤维束、Z向穿插炭棒的4D软硬混编为预制体,采用沥青液相常压、高压浸渍/炭化-石墨化循环致密工艺制备4D-C/C复合材料。通过该材料Z向(炭棒方向)的拉伸实验,测定其拉伸性能和力学行为,并采用SEM分析试样表面及断口形貌。结果表明:宏观上拉伸试样以炭棒整体拔出的形式破坏;细观尺度上,试样表面形成了与载荷方向垂直的贯穿性裂纹,裂纹以2 mm左右的距离呈等间距分布;材料进一步的破坏过程中,基体裂纹在X-Y向纤维束中呈线性扩展,快速分割了基体材料,使4D-C/C复合材料的拉伸破坏演变为1D-C/C复合材料的破坏模式,由于炭棒与基体炭界面结合弱,炭棒以拔出方式失效和破坏。     

Diamond formation on carbon/carbon composite

A carbon/carbon composite was used as substrate for low-pressure diamond deposition. To enhanced diamond nucleation on carbon/carbon composites, a total of ten surface preparation methods have been investigated. These methods involved the use of atomic hydrogen etching, mechanical polishing, sonication, or coating. Diamond nucleation was found to occur on either the defects of the carbon/carbon composite substrates or diamond particulate left on the substrates. The defects were created primarily by atomic hydrogen etching during the coating process. Seeding with diamond powders was performed by dip coating, sonication, or spray-coating processes. It was found that these seeding processes resulted in excellent nucleation of diamond.     

Graphitization behaviour of carbon fibre-glassy carbon composites

Carbon fibre-carbon composites were fabricated by aligning PAN-based carbon fibre unidirectionally in furfuryl alcohol resin char. The graphitization behaviour was investigated by an X-ray diffraction technique and by the measurement of magnetoresistance. The time-temperature superimposition study for interlayer spacing resulted in an activation energy of 242±35 kcal mol⁻¹. The kinetic study on magnetoresistance agreed with the result of X-ray measurement. The activation energy is that for the graphitization of the layer structure formed in the glassy carbon matrix of the composites. The graphitization mechanism of the layer structure is the same as that of soft carbons.     

Mesoscale evolution of non-graphitizing pyrolytic carbon in aligned carbon nanotube carbon matrix nanocomposites

Polymer-derived pyrolytic carbons (PyCs) are highly desirable building blocks for high-strength low-density ceramic meta-materials, and reinforcement with nanofibers is of interest to address brittleness and tailor multi-functional properties. The properties of carbon nanotubes (CNTs) make them leading candidates for nanocomposite reinforcement, but how CNT confinement influences the structural evolution of the PyC matrix is unknown. Here, the influence of aligned CNT proximity interactions on nano- and mesoscale structural evolution of phenol-formaldehyde-derived PyCs is established as a function of pyrolysis temperature (\(T_{\mathrm {p}}\)) using X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy. Aligned CNT PyC matrix nanocomposites are found to evolve faster at the mesoscale by plateauing in crystallite size at \(T_{\mathrm {p}}\) \(\sim\)800 \(^{\circ }\hbox {C}\), which is more than \(200\,\,^{\circ }\hbox {C}\) below that of unconfined PyCs. Since the aligned CNTs used here exhibit \(\sim\)80 nm average separations and \(\sim\)8 nm diameters, confinement effects are surprisingly not found to influence PyC structure on the atomic-scale at \(T_{\mathrm {p}}\) \(\le \)1400 \(^{\circ }\hbox {C}\). Since CNT confinement could lead to anisotropic crystallite growth in PyCs synthesized below \(\sim\)1000 \(^{\circ }\hbox {C}\), and recent modeling indicates that more slender crystallites increase PyC hardness, these results inform fabrication of PyC-based meta-materials with unrivaled specific mechanical properties.     

Development of vapor grown carbon fibers (VGCF) reinforced carbon/carbon composites

C/C composites are developed using vapor grown carbon fibers (VGCF) with two types of pitches as matrix precursor. The composites are carbonized at 1000°C by applying the isostatic pressure throughout the carbonization process and further heat treated at different temperatures up to 2500°C in the inert atmosphere. By applying iso-static pressure one can able to developed VGCF based C/C composites possessing the very high bulk density (1.80 g/cm³) and apparent density (2.01 g/cm³) only by heat treatment up to 2500°C without any densification cycle. This high value of density is due to the extremely strong fiber-matrix interactions and self sintering between the VGCF fibers during carbonization process under iso-static pressure. From the SEM study it reveals that, fiber-matrix interactions are strong and fiber boundaries merges with each other, also there is not a evidence of matrix shrinkage cracks in case 1500°C heat treated composites. On the other hand, in 2500°C heat treated composites, there is evidence of uniform fiber-matrix interfacial cracks and porosity in nanometer dimensions. This is due to the change in fiber morphology above HTT 1500°C. But the formation of nano width cracks does not affect on the mechanical properties of composites. The compressive strength increases from 95MPa of 1500°C to 105 MPa of 2500°C heat treated composites. However, hardness decreases due to the increase in the degree of graphitization of composites on 2500°C. The study reveals that by controlling processing condition and the uniform dispersion of VGCF fibers in the matrix phase, it can be possible to developed nano porosity at fiber-matrix interface.