利用模板合成纳米材料研究的新进展

在当今纳米科学技术研究突飞猛进的年代，本文分别介绍了近几年来以无机材料、有机高分子及天然大分子为模板进行的纳米材料合成研究的新进展。     

三氯氢硅技改措施及效果

分析了三氯氢硅生产中存在的问题,提出技改措施,改造后氯化氢含水体积分数在1×10-4左右,产品中含硼质量分数低于4×10-8,硅粉单耗降低30 kg/t.     

Crystallization of calcium silicate hydrates on the surface of nanomaterials

The poorly crystalline calcium silicate hydrate (C‐S‐H) is the primary binding phase in portland cement concrete. In this paper, the influence of adding anatase phase nano‐TiO₂, nano‐SiO₂, graphene oxide (GO), and multiwalled carbon nanotubes (CNT) on the crystallization and morphology of C‐S‐H are systematically investigated through tests. C‐S‐H gels were prepared using the double decomposition method, and the nanomaterial additions of nano‐TiO₂, nano‐SiO₂, GO, and CNT were 2 wt%, 2 wt%, 0.5 wt%, and 0.5 wt%, respectively. X‐ray diffraction (XRD) results show that a more crystalline nanostructure of C‐S‐H is induced by the addition of nano‐TiO₂ or GO. This phenomenon is further confirmed by the transmission electron microscopy (TEM) observations. The TEM observations demonstrate that C‐S‐H would grow on the crystal face of TiO₂ to form nanocrystalline regions with a lattice fringe spacing of 3.0 Å. When incorporated with GO, it will form a square lattice structure with a lattice constant of 3.1 Å on the surface of GO and later change to the lattice fringe structure with a spacing of 3.1 Å on the region bit away the GO surface. However, when adding nano‐SiO₂ or CNT, these nanocrystalline regions are not observed. Further characterization through scanning electron microscopy (SEM) and atomic force microscopy (AFM) has been performed to investigate the effect of nanomaterials on C‐S‐H morphology. Different nanomaterials take a different morphology of C‐S‐H: sheet‐shape structures for pure C‐S‐H, rod‐shape with for C‐S‐H with nano‐TiO₂, and granular agglomeration for C‐S‐H with nano‐SiO₂. C‐S‐H with GO or CNT forms a structure of C‐S‐H growing on the templates.     

Effects of the electrical conductivity and orientation of silicon substrate on the synthesis of multi-walled carbon nanotubes by thermal chemical vapor deposition

We studied the effects of the electrical conductivity and orientation of silicon substrate on both catalytic Fe thin film and the structure and morphology of multi-walled carbon nanotube (MWNT) grown by low-pressure chemical vapor deposition. Both p-type Si(100) and Si(111) substrates with three different doping concentrations (high, low, undoped) were used to evaluate the formation of catalytic nanoparticles and the growth of MWNTs. The morphology of catalytic nanoparticles such as size and density was characterized by field-emission scanning electron microscopy, Cs-corrected energy-filtered transmission electron microscopy, and X-ray photoelectron spectroscopy. Structural characteristics of MWNTs grown on different combinations of silicon substrate orientation and electrical conductivities (σ) were also systematically analyzed. Based on the experimental results, growth modes of MWNTs could be controlled by choosing an appropriate combination of σ and orientation of Si substrates.     

Memory effect of locally ordered α-phase in the melting and phase transformation behavior of β-isotactic polypropylene

Structural changes in β-isotactic polypropylene (β-iPP) during the heating were studied by means of differential scanning calorimetry and real-time in situ X-ray diffraction using a synchrotron source. Crystalline phase transformation and the memory effect caused by residual nuclei of α-iPP were observed during the heating of β-iPP. The memory effect observed in β-iPP during heating and crystallization is believed to be due to the existence of locally ordered α-from in the melt. The effect of local α-form order was probed by studying the behavior under heating of samples with a range of thermal histories. Samples were heated above the equilibrium melting temperature of iPP to remove all residual local order and the memory effect associated with this local order. The samples crystallized isothermally at different temperatures exhibited a significantly different melting and phase transformation behavior during heating. β-iPP is found to be an excellent material for the study of polymorphism, phase transformations, and characteristic memory effects in semicrystalline polymers.     

海泡石吸附果糖的性能研究

研究海泡石对果糖的吸附性能,并与活性炭对其的吸附作对比。同室温条件下考察两种吸附剂的吸附时间、投加量对果糖去除率的影响。结果表明,海泡石的吸附效果明显优于活性炭,前者0．3g几乎就可将50rnL0．1mg／mL标准液中果糖去除干净,而等量此标液,后者2．4g才能达到最大吸附量,且果糖去除率只有前者的一半。综合考虑实际应用,获得了最佳吸附条件。     

基于相转化的金纳米棒表面修饰

利用种子生长法,以CTAB为表面活性剂制备的金纳米棒具有生物毒性.本研究利用相转化的方法修饰金纳米棒,修饰后金纳米棒的理化性质稳定,生物相容性更好,有更广的应用前景.     

富勒型篦冷机的性能特点和技术改造

富勒型篦冷机具有急冷熟料、热回收效率高和冷却效率高等性能。自1985年引进富勒篦冷机设计和制造技术以来，我国的篦冷机技术已完成了第一代、第二代、茅三代的技术更新和发展历程。针对第二篦冷机一些固有的缺陷，巢湖铁道水泥厂采用第三代篦冷机技术，对原609S-819S／809S-1025S型第二代篦冷机进行了改造并获成功。改造4年来，篦冷机运行稳定，维修较少，经济效益明显。     

Rapid determination of triazophos using acetylcholinesterase biosensor based on sol–gel interface assembling multiwall carbon nanotubes

A sensitive and stable amperometric sensor has been devised for rapid determination of triazophos based on efficient immobilization of acetylcholinesterase (AChE) on silica sol–gel (SiSG) film assembling multiwall carbon nanotubes (MWNTs). The sol–gel matrix provided a biocompatible microenvironment around the enzyme and efficiently prevented leakage of the enzyme from the film. In the presence of acetylthiocholine chloride (ATCl) as a substrate, MWNTs promoted electron transfer reactions at a lower potential and catalyzed electrochemical oxidation of enzymatically formed thiocholine, thus increasing detection sensitivity. Based on the inhibition of organophosphorous compound on the enzymatic activity of AChE, using triazophos as a model compound, the effects of pH, temperature, and MWNTs contents were explored. Under optimum conditions, the inhibition of triazophos was proportional to its concentration from 0.02 μM to 1 μM and from 5 μM to 30 μM, with a detection limit of 0.005 μM. The determination of triazophos in garlic samples showed acceptable accuracy. Fabrication reproducibility of the sensor was good and stability was acceptable. The sensor is a promising new tool for pesticide analysis.     

苏氨酸基于表面活性效应在碳糊电极上的伏安行为研究

研究了苏氨酸在表面活性剂存在下于碳糊电极上的电化学行为,发现表面活性剂能显著提高苏氨酸的氧化电流,在此基础上,建立了一种直接测定苏氨酸的电化学方法。优化了测定条件,即介质的pH、扫描速度、富集时间和表面活性剂的种类等。氧化峰电流与苏氨酸在2.0×10-7~3.0×10-5mol/L之间呈良好的线性关系,检出限为7.56×10-9mol/L。应用于实际样品分析,回收率为97%~105%。     

A pH sensor based on electric properties of nanotubes on a glass substrate

We fabricated a pH-sensitive device on a glass substrate based on properties of carbon nanotubes. Nanotubes were immobilized specifically on chemically modified areas on a substrate followed by deposition of metallic source and drain electrodes on the area. Some nanotubes connected the source and drain electrodes. A top gate electrode was fabricated on an insulating layer of silane coupling agent on the nanotube. The device showed properties of an n-type field effect transistor when a potential was applied to the nanotube from the top gate electrode. Before fabrication of the insulating layer, the device showed that the p-type field effect transistor and the current through the source and drain electrodes depend on the buffer pH. The current increases with decreasing pH of the CNT solution. This device, which can detect pH, is applicable for use as a biosensor through modification of the CNT surface.     

A disposable sensor based on immobilization of acetylcholinesterase to multiwall carbon nanotube modified screen-printed electrode for determination of carbaryl

A simple method has been devised for immobilization of acetylcholinesterase (AChE) covalent bonding to a multiwall carbon nanotube (MWNT)-cross-linked cellulose acetate composite on a screen-printed carbon electrode (SPCE) and a sensitive and disposable amperometric sensor for rapid determination of carbaryl pesticide is proposed. The immobilized enzyme was preserved on this film because of the excellent biocompatibility and non-toxicity of cellulose acetate. Based on the inherent conductive properties of the MWNT, the immobilized AChE had greater affinity for ATCl and excellent catalytic effect in the hydrolysis of ATCl. MWNT improved the interface enzymatic hydrolysis reaction and increased the amperometric response of the sensor. Under optimum conditions, the inhibition of carbaryl on AChE increased linearly with the increasing concentration of carbaryl in two ranges, from 0.01 to 0.5 μg mL⁻¹ and from 2 to 20 μg mL⁻¹, with the correlation coefficients of 0.9985 and 0.9977, respectively. The detection limit was 0.004 μg mL⁻¹ taken as the concentration equivalent to 10% decrease in signal. The sensor showed acceptable stability, accuracy and could be fabricated in batches, thus it is economic and portable. This type of disposable enzyme-based amperometric sensor has extensive application potential in environmental monitoring of pesticides.     

碳纳米管水泥基复合机敏材料的研究进展

具有机敏特性的功能性水泥材料能够用于监测水泥路面质量和通过车辆的载荷,有良好的应用前景。碳纳米管材料拥有优异的导电性能,作为水泥的添加剂提高其复合材料的机敏性能。对碳纳米管水泥基复合材料的机敏特性进行了系统考察,分析了CNT水泥复合材料机敏特性机理,对影响机敏性能的因素进行了分析。通过CNT水泥基复合材料在公路监测上的实际应用试验,展示了其作为一种新型智能道路监测技术所具有的良好应用前景。     

Real time in situ X-ray diffraction studies on the melting memory effect in the crystallization of β-isotactic polypropylene

The melting memory effect during the crystallization and heating of semi-crystalline polymers was clearly demonstrated using β-isotactic polypropylene (β-iPP). Differential scanning calorimetry and real-time in situ X-ray diffraction using a synchrotron radiation source were employed to investigate the role of the newly formed α-form crystals via phase transformation from the metastable β-form during the melting process, and to elucidate the memory effect of these new α-form crystals during the crystallization process. The evolution of the memory effect in β-iPP during the crystallization and melting processes is ideally based on the existence of locally ordered α-form in the melt. We monitored the role of this local order by preparing the melt state using a range of hold temperatures and hold times. It was found that the final melt temperature and hold time greatly affect the crystallization behavior during cooling and the phase transformation behavior during heating. Lower hold temperatures and shorter hold times lead to samples rich in α-modification, whereas longer hold times generate samples rich in β-modification during crystallization. At higher hold temperatures even a short hold time is sufficient to destroy the local order in the melt, and the resulting sample exhibits more β-modification. The results are explained on the basis of the existence of local order in the amorphous melt along with external nucleating agent during the crystallization process.     

配水管网中有机营养基质的变化规律及对细菌再生长的影响

试验研究了有机营养基质在配水管网中的变化规律及其对细菌再繁殖的影响.结果表明:配水管网中CODMn和不可吹除有机物(NPOC)含量基本没有变化,它们所代表的有机物对细菌生长不起关键作用;管网水中AOC在氯氧化作用和细菌利用的共同作用下,在管网中含量有升高也有降低,没有明显的规律性.AOC是控制细菌再生长的主要因素,管网水中最大AOC含量决定了管网水中细菌再生长能够达到的最大数量.     

Stabilizing effect of the carbon shell on phase transformation of the nanocrystalline alumina particles

Intensive phase transformations of alumina are known to occur at temperatures above 1000 °C. In the present work, high temperature behaviour of pure Al₂O₃ and the carbon coated Al₂O₃@C sample with core-shell structure was comparatively studied using low-temperature nitrogen adsorption, transmission electron microscopy, powder X-ray diffraction (XRD) analysis and solid-state nuclear magnetic resonance (NMR). The solid-state NMR ²⁷Al method has allowed us to identify and estimate the concentration of all phases appeared during the transformation of pseudoboehmite γ-Al₂O₃ into corundum α-Al₂O₃. The data obtained correlate well with the results of XRD analysis and low-temperature nitrogen adsorption. It is shown that the deposition of carbon coating with formation of core-shell Al₂O₃@C system stabilizes the size of oxide core and prevents the formation of corundum phase until the temperatures of 1350–1400 °C, which are close to the temperature of carbothermal reduction of alumina. The stabilization of the size of the oxide core nanoparticles was considered as a main factor preventing the formation of corundum phase at high temperatures. At the same time, the carbon coating does not affect the phase transformation of γ-Al₂O₃ to δ-Al₂O₃.     

A study on the effect of heat treatment on functional groups of pitch based activated carbon fiber using FTIR

Pitch based active carbon fibers (ACFs) were analyzed by a FTIR micro-ATR technique by introducing a very thin KBr layer on their surfaces. The ACFs were thermally treated at 600, 1100, and 1200 °C respectively, to investigate the change of their surface functionalities. As the heat treatment temperature increased, the amount of oxygen containing surface functional groups were reduced and the ACFs became more hydrophobic. When the ACFs were thermally treated, the decrease of carboxylic acid groups occurred first and ketone or quinone groups subsequently disappeared at higher heat treatment temperatures. The degree of graphitization of the ACF was increased significantly when it was treated at 1100 and 1200 °C and this was partially attributed to the release of the CO groups in the conjugated ketone or quinone structures.     

Chiral sensing system based on the formation of diastereomeric metal complex on a homocysteine monolayer using field effect transistor

A self-assembled monolayer (SAM) of l-homocysteine (l-Hcy) formed on the surface of a gold-deposited gate of a field effect transistor (FET) was used to differentiate between enantiomers of amino acids, for which the formation of diastereomeric metal complexes is fundamental for chiral discrimination. Here, we focus our attention on the dependence of the FET response on the analyte amino acids, the central metal ions involved in complex formation, and the solution pH. Using the l-Hcy SAM-modified gate with added Cu(II), notable negative FET responses were enantioselectively observed for the l-enantiomers of alanine (Ala), phenylalanine, and tryptophan, whereas differences in the FET responses between enantiomers were negligible for asparagine and aspartic acid. Regarding the enantioselectivity for Ala, the addition of Cu(II) was demonstrated to show higher selectivity as compared to other metal ions such as Co(II) and Ni(II). Moreover, for the addition of l-Ala and Cu(II), a particularly strong negative FET response was observed at pH 5.5.     

The effect of morphological modification on the thermoelectric properties of ZnO nanomaterials

At present, huge research efforts are dedicated to improve the efficiency of thermoelectric (TE) materials. Nanostructuring is one of the suggested methods to improve their TE performance. However, the morphology of a nanomaterial might play a significant role on its TE properties. In this work, we demonstrated this effect by producing zinc oxide (ZnO) in two different morphologies using the microwave assisted chemical route. Nanoparticles (NPs) and nanorods (NRs) were synthesised by changing the molar ratios of the starting precursors. The obtained results show that the NRs have improved TE properties compared to those of the NPs, particularly at high temperature. At 673 K the Seebeck coefficient, electrical conductivity and power factor values of the ZnO NRs reached ?1020 μV/K, 22 S/m and 23 μW/m.K², respectively. The NPs have only recorded ?850 μV/K, 3 S/m and 2.4 μW/m.K² of these factors. Moreover, the thermal conductivity of the NRs was found to be three times lower than that of the NPs. As a result of these differences the Figure of Merit (zT) value of the NRs is around 0.012, while that of the NPs is only 0.001. Power generation characteristics of single leg modules made of the ZnO NPs and NRs, measured under the conditions of actual applications in an air atmosphere were also investigated. The output power of the ZnO NRs is found to be several times higher than that of the NPs. These results have clearly demonstrated the effect of nanostructures morphology on the TE performance, which might be important for future TE generators.     

锌冶炼烟气制酸系统技术改造总结

总结200kt/a锌冶炼烟气酸装置投产5年来进行的扩产技术改造。改造后提高了技术经济指标,改善了产品酸质量。