石油焦与煤混合燃料热重分析研究

石油焦与煤混合燃烧是高效处理石油焦的有效方法，作者对选用的石油焦和煤不同配比的混合燃料进行了热重分析研究。使用常压高温热天平研究、分析了各配比混合燃料的热解特性和燃烧特性。并根据化学动力学方法计算了各过程的化学动力学参数，即活化能E和频率因子A0。结果表明，各混合燃料热解起始温度大致相同，随煤焦比减小，挥发分析出速率变缓，最大释放速度所对应的温度升高，最终失重率减小，挥发分释放特性指数减小；随煤焦比增大，混合燃料着火温度和燃尽温度逐渐降低，最大燃烧速率所对应的温度降低，燃烧特性指数增大；随煤焦比减小，活化能和频率因子增大。     

Thermogravimetry as a screening tool for the estimation of the vapor pressures of pure compounds

A simplified approach was developed to estimate the vapor pressure of pure compounds from experimental data obtained by isothermal thermogravimetric (TG) analysis. A numerical procedure was developed to estimate the Antoine parameters of the substance by the analysis of isothermal TG data. The results of the experimental validations carried out evidenced that at least a preliminary estimation of vapour pressures of pure substances by the analysis of TG data is possible. The limited time and the reduced amounts of sample required for the experimental runs make the technique attractive with respect to the conventional and more accurate techniques for vapor pressure assessment.     

Synthesis and properties of novel polyurethanes containing 3,4‐dioxybenzylidenecyanoacetate group as a nonlinear optical chromophore

Methyl 3,4‐di‐(2′‐hydroxyethoxy)benzylidenecyanoacetate ( 3 ) was prepared by hydrolysis of methyl 3,4‐di‐(2′‐vinyloxyethoxy)benzylidenecyanoacetate ( 2 ). Diol 3 was condensed with 2,4‐toluenediisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate, and 1,6‐hexamethylenediisocyanate to yield polyurethanes 4 – 6 containing the nonlinear optical chromophore 3,4‐dioxybenzylidenecyanoacetate. The resulting polyurethanes 4 – 6 were soluble in common organic solvents such as acetone and dimethylformamide. Polymers 4 – 6 indicated thermal stability up to 300 °C in thermogravimetric thermograms with glass‐transition temperature values obtained from differential scanning calorimetric thermograms in the range of 78–102 °C. The second‐harmonic generation coefficients (d₃₃) of the poled polymer films were around 6.9 × 10^?9 esu. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1742–1748, 2002     

烟碱分子烙印聚合物的吸附特性

利用分子烙印技术，以烟碱为烙印分子，甲基丙烯酸(MAA)为功能单体，乙二醇二甲基丙烯酸酯(EDMA)为交联剂，合成了对烟碱具有特异性作用的分子烙印聚合物P(Nic)；通过平衡吸附实验，评价了其对烟碱的亲和力和选择性。与非烙印聚合物相比，P(Nic)对烟碱表现了很高的亲和力；Scatchard分析表明在P(Nic)中存在对烟碱有不同的亲和力的两类作用位点。通过与氨基吡啶类物质在P(Nic)上的吸附行为比较，表明P(Nic)对烟碱具有很好的选择性。本工作证明了用P(Nic)作为固相萃取(SPE)材料选择性地从烟草烟雾中提取烟碱的可能性。     

Decomposition of Toluene and Acetone in Packed Dielectric Barrier Discharge Reactors

The influences of TiO₂ catalytic material and glass pellet packing on the decomposition efficiency of toluene and acetone in air by dielectric barrier discharge (DBD) reactors were experimentally investigated in this study. The effects of both packing materials on the formation of byproducts such as CO and CO₂ were also evaluated. Experimental results indicate that the introduction of glass materials into the plasma zone of a wire-tube reactor would improve the decomposition efficiency of toluene and acetone compared to a nonpacked reactor. The apparent decomposition rate constant of a glass packed-bed reactor was 4.5–4.8 times greater than that of a nonpacked reactor. The results also indicate that the decomposition rate constant of toluene was approximately 2.6 times higher than that of acetone no matter which type reactor was utilized. The application of TiO₂ coated pellets in DBD reactors will enforce the hydrocarbon byproducts to further be oxidized to CO₂, notwithstanding, it will not significantly improve the performance of the reactors in the decomposition of toluene and acetone, and in the formation of CO. The results show that the best selectivity of CO₂ for acetone decomposition in a TiO₂ coated pellets packed-bed reactor was approximately 40% higher than that in a glass packed-bed reactor.     

Influence of extractions on physicochemical characterization and bioactivity of Piper nigrum oils: Study on the non-isothermal decomposition kinetic

Black pepper oils have been investigated frequently in the recent years. However, there is a significant variation in physicochemical properties and bioactivity of oils depended on extraction techniques. In this study, the systemic investigation of four various extraction methods was performed to evaluate the physicochemical characterizations, antioxidant and antibacterial activity. The investigation of ¹H NMR, FTIR and UV–Vis spectra confirmed presence of non-volatile components in oils extracted through supercritical CO₂ and hexane-soaking extractions which induced their typical thermal properties. The isothermal behaviour of extracted oils related to evaporation was within range of 3.2–7.3% (w/w) at 27 °C. The SEM images of the black pepper confirmed different operation manners of mechanism between extractions using the solvents and heating process. The lowest MIC for both essential oils from conventional hidrodistillation and microwave-assisted hidrodistillation against two bacteria including E. coli and B. subtilis were found to be 137 µg mL⁻¹. The non-isothermal decomposition kinetics were investigated on the essential oil of microwave-assisted hydrodistillation extraction. The activation energies and pre-exponent factors of non-isothermal decomposition were found to be in range of 36.5–73.7 KJ mol⁻¹ and 4.98 × 10³–1.97 × 10⁸ s⁻¹, respectively, dependent on conversional fractions of the oil. The results revealed that chemical components, physicochemical properties and bioactivity of black pepper essential oils depended on the extraction techniques.     

Preparation, characterization and properties studies of quinine-imprinted polymer in the aqueous phase

The uniform-sized spherical molecularly imprinted polymers were successfully prepared through molecular imprinting technology by two-step seed swelling and mini-emulsion polymerization in the aqueous condition using quinine as template molecules and methacrylic acid (MAA) as functional monomer. The polymers were characterized by IR spectra, thermal-weight analysis, scanning electron microscope and laser particle size analysis. The properties of imprinted polymers were investigated in different organic phases and aqueous media. In the organic media, results suggested that polar interactions (hydrogen bonding, ionic interactions) between acidic monomer/polymer and template molecules are mainly responsible for the binding and recognition; whereas in the aqueous medium, a considerable recognition effect was also obtained where the ionic (electrostatic) interaction and hydrophobic interaction play an important role. The experiments of binding different substrates indicated that the MIPs possessed an excellent rebinding ability and inherent selectivity to quinine. __________ Translated from Zhongshan Dcocue Xuebao/Acta Scientianum Natralium University Sunyatseni, 2005, 44(3)(in Chinese)     

Polymerization of methyl methacrylate by 2‐pyrrolidinone and n‐dodecyl mercaptan

The bulk polymerization of methyl methacrylate initiated with 2‐pyrrolidinone and n‐dodecyl mercaptan (R‐SH) has been explored. This polymerization system showed “living” characteristics; for example, the molecular weight of the resulting polymers increased with reaction time by gel permeation chromatographic analysis. Also, the polymer was characterized by Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR techniques. The polymer end with the iniferter structures was found. By the initial‐rate method, the polymerization rate depended on [2‐pyrrolidinone]^1.0 and [R‐SH]⁰. Combining the structure analysis and the polymerization‐rate expression, a possible mechanism was proposed. n‐Dodecyl mercaptan served dual roles—as a catalyst at low conversion and as a chain‐transfer agent at high conversion. Finally, the thermal properties were studied, and the glass‐transition temperature and thermal‐degradation temperature were, respectively, 25 and 80–100 °C higher than that of the azobisisobutyronitrile system. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3692–3702, 2002     

On-channel base stacking in microchip capillary gel electrophoresis for high-sensitivity DNA fragment analysis

We evaluated a novel strategy for high-sensitivity DNA fragment analysis in a conventional glass double-T microfluidic chip. The microchip allows for a DNA on-channel concentration based on base stacking (BS) with a microchip capillary gel electrophoretic (MCGE) separation step in a poly(vinylpyrrolidone) (PVP) sieving matrix. Depending if low conductivity caused a neutralization reaction between the hydroxide ions and the run buffer component Tris+, the stacking of DNA fragments were processed in the microchip. Compared to a conventional MCGE separation with a normal electrokinetic injection, the peak heights of 50-2650-base pair (bp) DNA fragments on the MCGE-BS separation were increased 3.9-8.0-fold. When we applied the MCGE-BS method to the analysis of a clinical sample of bovine theileria after PCR reaction, the peak height intensity of the amplified 816-bp DNA fragment from the 18S rRNA of T. buffeli was enhanced 7.0-fold compared to that of the normal injection method.     

Sol-gel approach to in situ creation of high pH-resistant surface-bonded organic-inorganic hybrid zirconia coating for capillary microextraction (in-tube SPME)

A novel zirconia-based hybrid organic-inorganic sol-gel coating was developed for capillary microextraction (CME) (in-tube SPME). High degree of chemical inertness inherent in zirconia makes it very difficult to covalently bind a suitable organic ligand to its surface. In the present work, this problem was addressed from a sol-gel chemistry point of view. Principles of sol-gel chemistry were employed to chemically bind a hydroxy-terminated silicone polymer (polydimethyldiphenylsiloxane, PDMDPS) to a sol-gel zirconia network in the course of its evolution from a highly reactive alkoxide precursor undergoing controlled hydrolytic polycondensation reactions. A fused silica capillary was filled with a properly designed sol solution to allow for the sol-gel reactions to take place within the capillary for a predetermined period of time (typically 15-30 min). In the course of this process, a layer of the evolving hybrid organic-inorganic sol-gel polymer got chemically anchored to the silanol groups on the capillary inner walls via condensation reaction. At the end of this in-capillary residence time, the unbonded part of the sol solution was expelled from the capillary under helium pressure, leaving behind a chemically bonded sol-gel zirconia-PDMDPS coating on the inner walls. Polycyclic aromatic hydrocarbons, ketones, and aldehydes were efficiently extracted and preconcentrated from dilute aqueous samples using sol-gel zirconia-PDMDPS coated capillaries followed by thermal desorption and GC analysis of the extracted solutes. The newly developed sol-gel hybrid zirconia coatings demonstrated excellent pH stability, and retained the extraction characteristics intact even after continuous rinsing with a 0.1 M NaOH solution for 24 h. To our knowledge, this is the first report on the use of a sol-gel zirconia-based hybrid organic-inorganic coating as an extraction medium in solid phase microextraction (SPME).