煤焦油沥青基纤维状活性炭的吸附性能

煤焦油沥青基炭纤维（ＣＰＣＦ）价格低廉含炭量高、易于活化,是制备纤维状活性炭（ＣＰＡＣＦ）的优良原料。本文讨论了ＣＰＣＦ的抗拉强度和活化条件对ＣＰＡＣＦ比表面积的影响。并同石油系沥青基炭纤维（ＰＰＣＦ）进行了比较。考察了不同比表面积的ＣＰＡＣＦ、ＰＰＡＣＦ和商品用颗粒活性炭（ＡＣ）对０．１ｍｏｌ／Ｌ碘溶液、０．００５ｍｏｌ／Ｌ亚早兰溶液和２９３Ｋ下三氯甲烷饱和蒸汽的吸附性能,及以上三样品在２９３Ｋ     

A comparison of electrochemically pre-treated and spark-platinized carbon fiber microelectrode. Measurement of 8-oxo-7,8-dihydro-2′-deoxyguanosine in human urine and plasma

A novel method of carbon fiber microelectrode activation using spark discharge was demonstrated and compared to conventional electrochemical pretreatment by potential cycling. The spark discharge was performed at 800 V between the microelectrode connected to positive pole of the power supply and platinum counter electrode. Spark discharge led both to trimming of the fiber tip into conical shape and to the modification of carbon fiber microelectrode with platinum, as proven by scanning electron microscopy and electron dispersive X-ray spectroscopy. After the characterization of electrochemical properties using ferricyanide voltammetry, the activated electrodes were used for electrochemical analysis of 8-oxo-7,8-dihydro-2′-deoxyguanosine, an oxidative stress marker. Subnanomolar detection limits (0.55 nmol L⁻¹) in high-performance liquid chromatography were achieved for spark platinized electrodes incorporated into the flow detection cell.     

Determination of isoniazid and hydrazine by capillary electrophoresis with amperometric detection at a Pt-particle modified carbon fiber microelectrode

Capillary electrpphoresis (CE)/electrochemical detection (EC) for the simultane-ous determination of hydrazine and isoniazid has been developed.The electrochemical method uses a novel modified electrode dispersed with ultrafine platinum particles on the surface of a 30μm carbon fiber microelectrode.The unique characteristic of the Pt-particles modified carbon fiber microelectrode is its excellent stability.The current measurement for hydrazine is more sensitive than that of isoniazid.Selective determination of trace amount of free hydrazine in isoniazid and its formulation can be achieved at applied potential of 0.5V.     

Voltammetric Studies on the Electrochemical Reduction of Methylmercury in HCl Aqueous Medium at a Carbon Microelectrode

Fast scan voltammetry applied to methylmercury in chloride medium at a carbon fiber microelectrode has shown two cathodic peaks located at ?0.45 and ?1.1 V and a single anodic peak at ?0.33 V (vs. Ag|AgCl). It was concluded that the reoxidation process, at high sweep rates, in acidic media behaves as a reversible one‐electron transfer process coupled to a chemical reaction, with the reaction product weakly adsorbed. Good linear calibration plots for the methylmercury determinations in the concentration range from 75 to 300 μM, have been obtained using the currents of the anodic peak measured on the CVs recorded, at 10 V s^?1, at a carbon fiber microelectrode, in a stationary solution of methylmercury chloride. Data have shown that the carbon microelectrode, cycled continuously in the analyte, can replace the dropping mercury electrode (DME), with the advantages that the carbon microelectrode is a promising tool for further studies in high resistive media, such as in natural waters.     

A thermomechanical technique for characterizing pitch

Thermomechanical analysis (TMA) in a tube-compressive mode can be used to characterize pitch in a reproducible and sensitive way. In a single experiment, this technique enables simultaneous determination of the glass transition temperature, the softening temperature and the rheological behaviour of a pitch sample. Results on a typical Australian coal-tar pitch are consistent with Bingham fluid behaviour above its softening temperature with a yield stress of the order of 100 Pa. In a similar test a petroleum pitch sample exhibited no yield stress.     

煤沥青的电化学加氢──Ⅰ．原料煤沥青的预处理和组成结构分析

为选择适于作为碳纤维原料的煤沥青，对三种中低温煤沥青的预处理和组成结构进行了研究，同时对其中的太钢煤沥青进行了热缩聚制取中间相沥青的结构变化分析。研究分析结果表明，只要经过合适的工艺路线进行处理，这三种煤沥青都有可能作为沥青基碳纤维的原料。     

Quantitative analysis of polydisperse systems via solvent-free matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Quantitative analysis of partially soluble and insoluble polydisperse materials is challenging due to the lack of both appropriate standards and reliable analytical techniques. To this end, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) incorporating a solvent-free sample preparation technique was investigated for the quantitative analysis of partially soluble, polydisperse, polycyclic aromatic hydrocarbon (PAH) oligomers. Molecular weight standards consisting of narrow molecular weight dimer and trimer oligomers of the starting M-50 petroleum pitch were produced using both dense-gas/supercritical extraction (DGE/SCE) and preparative-scale, gel permeation chromatography (GPC). The validity of a MALDI-based, quantitative analysis technique using solvent-free sample preparation was first demonstrated by applying the method of standard addition to a pitch of known composition. The standard addition method was then applied to the quantitative analysis of two insoluble petroleum pitch fractions of unknown oligomeric compositions, with both the dimer and trimer compositions of these fractions being accurately determined. To our knowledge, this study represents the first successful MALDI application of solvent-free quantitative analysis to insoluble, polydisperse materials.     

Flexural properties of fiber‐reinforced polypropylene composites with and without a transcrystalline layer

The flexural properties of isotactic polypropylene (PP) matrix composites reinforced with 5–30 vol% of unidirectional pitch‐based carbon, polyacrylonitrile (PAN)‐based carbon, e‐glass or aramid fibers were measured using both static and dynamic test methods. Previous research has shown that these pitch‐based carbon and aramid fibers are capable of densely nucleating PP crystals at the fiber surface, leading to the growth of an oriented interphase termed a “transcrystalline layer” (TCL), while the e‐glass and PAN‐based carbon fibers show no nucleating ability. The PP matrices examined included unmodified homopolymers, nucleated homopolymers and PP grafted with maleic anhydride (MA). The composites based on the unmodified PP homopolymers all exhibited poor fiber/matrix adhesion, regardless of fiber type and presence or absence of a TCL. The addition of nucleating agent to the PP matrix had no measurable effect on either the amount of TCL material in pitch‐based carbon‐fiber‐reinforced composites, as measured by wide‐angle X‐ray scattering, WAXS, or the static flexural properties of the composites reinforced with either type of carbon fiber. However, MA grafting reduced the transcrystalline fraction of the matrix in pitch‐based carbon‐fiber‐reinforced composites; at the highest level of MA grafting, the TCL was completely suppressed. In addition, high levels of MA grafting improved the transverse flexural modulus of the composites containing both types of carbon fibers, and reduced the extent of fiber pull‐out, indicating an improvement in fiber/matrix adhesion. Copyright © 1999 John Wiley & Sons, Ltd.     

全固态酸度微电极组的设计与应用

以木犀草素为pH特性敏感物,碳纤维为导电基质,固体石蜡为粘合剂制成了木犀草素碳纤维酸度微电极,将该电极与自制导电凝胶型全固态微型Ag/AgCl电极和铂丝微电极联用,构成全固态酸度微电极组。 采用循环伏安法研究了该电极组对pH值为2.00~10.00的磷酸盐缓冲溶液有效酸度的响应,结果表明,循环伏安曲线上有一对可逆氧化还原峰,两峰的峰电势均随pH值呈线性变化,据此建立了方波伏安法测定溶液酸度的方法,氧化峰的峰电势(E_pa)与pH的线性回归方程为:E_pa(V)=-0.0567pH+0.603(r=0.999),体液中常见离子及蛋白质等不干扰测定。 该电极组微型、无毒、抗干扰能力强,应用于微量体表唾液和汗液酸度的测定,取得了令人满意的结果,为微量体液的实时、在体、现场检测提供了技术基础。     

煤沥青与石油沥青混合调制道路沥青的研究

采用高效剪切分散仪考察了调配温度、调配时间、搅拌方法等工艺对煤沥青混合石油沥青性能的影响,对优选的样品进行了离析实验、抗老化性能及流变性能评价。结果表明,调配工艺对煤沥青在石油沥青中的分散有重要影响,调配温度的升高、调配时间的延长能促进煤沥青在石油沥青中分散但也会导致调配沥青的老化;煤沥青粒径对调配沥青性能有重要影响,对优选样品的进一步评价表明,调配沥青有好的耐高温流变性能和抗热氧老化性能,储存稳定性可以解决。     

Determination of linuron in soil by stripping voltammetry with a carbon fiber microelectrode

A carbon fiber microelectrode was used for the electroanalytical determination of Linuron (LIN) in soil extracts. The microelectrode was subjected to an electrochemical pretreatment in order to improve the herbicide adsorption on the electrode surface. With this preconcentration step, detection limits of 80 ng ml⁻¹ and determination limits of 260 ng ml⁻¹ were reached. Optimal conditions with respect to accumulation time and potential, scan rate and pH were established. The LIN was determined in a soil sample with the method proposed and the results found were comparable to those obtained by HPLC.     

Thermoanalytical studies of pitch pyrolysis

Characterization of pitches by thermal analysis techniques is highly relevant to the practical use of these materials, as they undergo heat treatments in all of their utilization processes. The aim of this work was to improve the interpretation of the complex DTA curves of pitches by comparison with model compounds. For this, TG/DTG/DTA was used to study under identical conditions the pyrolysis of a petroleum pitch and a coal tar pitch as well as a number of polycyclic aromatic hydrocarbons. Results were interpreted as a function of the molecular structure, pyrolysis reactivity and graphitizability of cokes from the hydrocarbons. It is concluded that condensation and polymerization, which are the most likely exothermal reactions predominant in petroleum pitches, indicate the presence therein of reactive molecules. Alternatively, endothermal phenomena such as distillation, depolymerization and cracking, predominant in coal tar pitches, suggest the presence of light, little reactive aromatic molecules.Financial support from DGICYT (project PB87-0456) is gratefully acknowledged.     

中温煤焦油沥青的超临界溶剂抽提和分离

用超临界溶剂在半连续装置上对中温煤焦油沥青（ＭＣＴＰ）进行了抽提和分离，考察了抽提段的实验条件对灰分和吡啶不溶物（ＰＩ组分）脱除率的影响；在分离段使用升温和／或降压法、精馏法调节ＭＣＴＰ族组成分布，并用分步抽提法调节ＭＣＴＰ的族组成。实验表明：用甲苯为超临界溶剂抽提可脱除全部灰分，ＰＩ组分也可在较低的压力下选择性地脱除；采用升温和／或降压法对抽出物可进行一定程度的分离，但对庚烷可溶物（ＨＳ组分）分离的选择性不高；采用精馏法可选择性地脱除ＨＳ组分，但尚需改进设备进一步提高分离效率；采用分步抽提法用石油醚作一次抽提溶剂可高选择性地脱除ＨＳ组分，其选择性在９５％以上。     

Spin probes in structure studies of petroleum mesophase pitch

The ESR spectra of petroleum pitch labeled with the stable copper-porphyrin complex and changes in the spectra due to pyrolysis are analyzed. It is concluded that the functions of carriers and traps for unpaired electrons in mesophase pitch are performed by anisotropic associates or crystallites sized about 2.0 nm. The intermodular interactions between the parallel layers of anisotropic associates may be significant. They increase when the molecular associates pass to the paramagnetic state and determine the preferable packing of the paramagnetic crystallites one over another. Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 5, pp. 902–907, September-October, 1997.     

Determination of glutathione in single HepG2 cells by capillary electrophoresis with reduced graphene oxide modified microelectrode

Determination of intracellular bioactive species will afford beneficial information related to cell metabolism, signal transduction, cell function, and disease treatment. In this study, the electrochemically reduced graphene oxide modified carbon fiber microdisk electrode (ER‐GOME) was used as a detector of CZE‐electrochemical detection and developed to detect glutathione (GSH). The electrocatalytic activity of the modified microelectrode was characterized by cyclic voltammetry. Under optimized experimental conditions, the concentration linear range of GSH was from 1 to 60 μM. When the S/N ratio was 3, the concentration detection limit was 1 μM. Compared with the unmodified carbon fiber microdisk electrode, the sensitivity was enhanced more than five times. With the use of this method, the average contents of GSH in single HepG2 cells were found to be 7.13 ± 1.11 fmol (n = 10). Compared with gold/mercury amalgam microelectrode, which was usually used in determining GSH, the electrochemically reduced graphene oxide modified carbon fiber microdisk electrode was friendly to environment for free mercury. Furthermore, there were several merits of the novel electrochemical detector coupled with CE, such as comparative repeatability, easy fabrication, and high sensitivity, hold great potential for the single‐cell assay.     

Dense-gas fractionation of mixtures of petroleum macromolecules

Dense-gas extraction (DGE) was used to fractionate a petroleum pitch feedstock of broad molecular weight distribution (MWD) into selected oligomeric constituents. The DGE process was carried out in a semibatch mode using the solvent toluene (T_c = 318.6 °C, P_c = 41.1 bar) and a pitch charge of 10–15 g. A packed column with reflux produced the equivalent of several equilibrium stages. The apparatus was operated at near and supercritical temperatures, with the stillpot at 320 °C and the column temperature increasing linearly up to the reflux condenser temperature of 360 °C. Operating pressures were determined by the conditions required to extract a given oligomer and varied from 44 to 84 bar. Using a monomer-rich petroleum pitch feed (MW_n = 299, PDI = 1.10), a dimer-rich extract with a purity approaching 90% (MW_n = 521, PDI = 1.07) was obtained, with the remaining residue (MW_n = 883, PDI = 1.24) consisting of 95% trimer and higher oligomers. MALDI-TOF mass spectrometry was used to determine the MWD of the feed pitch and pitch fractions, with a unique matrix being used to enhance the response of higher MW species. The combination of DGE for separation and MALDI for accurate MW information is a powerful new technique for the molecular characterization of insoluble, high MW fossil fuels.     

Preparation and characterization of anode materials using expanded graphite/pitch composite for high-power Li-ion secondary batteries

Expanded graphite was prepared by the intercalation of natural graphite using ammonium peroxodisulfate as an oxidizing agent and a high purity of sulfuric acid as an intercalate. The amounts of oxidizing agent and intercalate were changed to determine the preparation conditions of expanded graphite as the anode material for high-power Li-ion batteries. The expanded graphite was tested as the anode material and further composited with the different amounts of petroleum pitch to improve the electrochemical properties. Although the expanded graphite anode showed the improved electrochemical properties such as initial reversible capacities of around 400 mAh/g and a charge capacity at 5 C-rate of 83 mAh/g as compared with those for the natural graphite anode of 378 and 19.4 mAh/g, respectively, it still had some weak points for a high-power anode material such as low initial efficiency and potential plateaus with the stage characteristic. The anode composites with high performance could be obtained by compositing the expanded graphite and the petroleum pitch at the ratio of 1:2, showing an improved initial efficiency of 78 % and decreased potential plateaus with 389 mAh/g of the initial reversible capacity.     

Chemical activation of carbon mesophase pitches

This paper studies the chemical activation of mesophase pitches of different origins in order to obtain activated carbons suitable for use as electrodes in supercapacitors. The effect that the activating agent (NaOH, LiOH, and KOH), the alkaline hydroxide/pitch ratio, and the activation temperature had on the characteristics of the resultant activated carbons was studied. LiOH was found to be a noneffective activating agent, while activation with NaOH and KOH yielded activated carbons with high apparent surface areas and pore volumes. The increase of the KOH/pitch ratio caused an increase of the chemical attack on the carbon, producing higher burnoffs and development of porosity. Extremely high apparent surface areas were obtained when the petroleum pitch was activated with 5:1 KOH/carbon ratio. The increase of the activation temperature caused an increase of the burnoff, although the differences were not as significant as those derived from the use of different proportions of activating agent.     

Multimembrane carbon fiber microelectrodes for amperometric determination of serotonin in human urine

An electrochemical sensor for the determination of serotonin in urine was prepared using Ni(II)-phthalocyanine and Nafion to modify the surface of a 4 mm length carbon fiber microelectrode. The resultant sensor was found to improve the response towards this neuronal amine versus the microelectrode without the polymer films. Different polymerization conditions, as well as different conditioning solutions and buffer systems, were investigated in order to optimize the response of the electrodes. Square wave voltammetry (SWV) is proposed as a direct method for determination of serotonin in human urine, after a solid-liquid extraction process. The proposed method enables a detection limit for serotonin of 0.80 +/- 0.04 microgram L-1 to be achieved at a reduction potential of 0.35 V, with an overall prediction error of 2.2% and recoveries of 93%.