THERMODYNAMIC STUDY OF ADSORPTION OF PHENOLIC COMPOUNDS FROM AQUEOUS SOLUTION BY A WATER-COMPATIBLE HYPERCROSSLINKED POLYMERIC ADSORBENT

Equilibrium data for the adsorption of phenolic compounds, i.e., phenol, p-cresol, p-chlorophenol and p-nitrophenol from aqueous solutions by a water-compatible hypercrosslinked polymeric adsorbent (NJ-8) within temperature range of 283-323 K were obtained and correlated with a Freundlich-type of isotherm equation, so that equilibrium constants KF and n were obtained. The capacities of equilibrium adsorption for all the four phenolic compounds on the NJ-8 from aqueous solutions are around 2 times as high as those of Amberlite XAD-4, which may be attributed to the unusual micropore structure and the partial polarity on the network. The values of the enthalpy (always negative) are indicative of an exothermic process, which manifests the adsorption of all the four phenolic compounds on the two polymeric adsorbents to be a process of physical adsorption. The negative values of free energy change show that the solute is more concentrated on the adsorbent than in the bulk solution. The absolute free energy values of adsorption for NJ-8 are always higher than those for Amberlite XAD-4, which indicates that phenolic compounds are preferentially adsorbed on NJ-8. The negative values of the adsorption entropy are consistent with the restricted mobilities of adsorbed molecules of phenolic compounds as compared with the molecules in solution. The adsorption entropy values of phenolic compounds for NJ-8 are lower than those for Amberlite XAD-4, which means the micropores of NJ-8 require more orderly arranged adsorbate.     

Preparation and characterization of Fully stoichiometric SrCoO3 by electrochemical oxidation

A nearly stoichiometric SrCoO₃ phase had been prepared up to now only using high oxygen pressure. A new method for preparing fully stoichiometric SrCoO₃ has been proposed using electrochemical oxidation. Brownmillerite-type SrCoO_2.50 is oxidized into a completely stoichiometric perovskite at a potential of 500 mV for 180 hours at room temperature in alkaline media (1 M KOH). The oxidized phase has a cubic unit cell (a=383.5 pm). It is metallic and, at temperatures below T=280 K, it shows ferromagnetic behavior. The magnetic moment at 0 K is 2.1 μ_B. The physical properties of SrCoO_3.00 have been explained in terms of partial occupancy of a σ*e band.     

稀土与含硫有机配体配合物的研究 Ⅳ.轻稀土元素与3-苯基-5-(呋喃-2)吡唑啉二硫代甲酸固体配合物的合成及性质

吡唑啉类化合物具有杀菌特性和植物生长调节作用,3-苯基-5-(呋喃-2)吡唑啉二硫代甲酸盐能与许多过渡金属离子形成稳定的配合物。而与稀土的配合物尚未报道。为考察稀土与含硫有机配体形成配合物的条件及该配合物的性质,我们在非水体系和保护气氛     

Effect of tetrahydrofuran on the conductance and ion-pairing of hydrogen chloride in wet and dry methanol mixtures

The molar conductance of dilute solutions of HCl in wet (68.5% methanol + 31.5% tetrahydrofurane mixtures at 25°C have been measured. The data were analyzed using the Fuoss-Hsia equation to calculate the infinite dilution molar conductances and association constants. The trend of the limiting conductances in these mixtures as a function of the water content shows, once more, the peculiar minimum due to the anomalous proton conductance mechanism. From these data the limiting molar conductance in the anhydrous binary solvent system was evaluated. The percentage excess proton mobility with respect to potassium ion has also been determined. All these data are compared to those found in a binary isodielectric methanol mixture containing as cosolvent 1,4-dioxane. This comparison shows that proton mobilities are very similar in both solvent mixtures. The dielectric constants, refractive indices, viscosities and densities of the methanol-tetrahydrofuran mixtures in the whole mole fraction range have been measured and are reported. An analysis of the excess molar volumes and viscosities shows a slight deviation of this system from ideality.     

Study of the first nucleation steps of thin films by XPS inelastic peak shape analysis

The initial steps in the formation of thin films have been investigated by analysis of the peak shape (both inelastic background and elastic contributions) of X‐ray photoelectron spectra. Surface coverage and averaged height of the deposited particles have been estimated for several overlayers (nanometre range) after successive deposition cycles. This study has permitted the assessment of the type of nucleation and growth mechanisms of the films. The experiments have been carried out in situ in the preparation chamber of an XPS spectrometer. To check the performance of the method, several materials (i.e. cerium oxide, vanadium oxide and cadmium sulfide) have been deposited on different substrates using a variety of preparation procedures (i.e. thermal evaporation, ion beam assisted deposition and plasma enhanced chemical vapour deposition). It is shown that the first deposited nuclei of the films are usually formed by three‐dimensional particles whose heights and degree of surface coverage depend on the chemical characteristics of the growing thin film and substrate materials, as well as the deposition procedure. It is concluded that XPS peak shape analysis can be satisfactorily used as a general method to characterize morphologically the first nanometric moieties that nucleate a thin film. Copyright © 2006 John Wiley & Sons, Ltd.     

单壁碳纳米管的结构修饰

由于单壁碳纳米管具有独特的结构、电学及机械等性能，可望在许多新领域得 到应用，已引起广泛的关注。但由于单壁碳纳米管不溶于水和常见的有机溶剂，极 大地制约了其应用性能的研究。随着单壁碳纳米管制备技术的不断完善，其研究方 向已开始转向结构修饰及应用性能的研究。主要介绍近年来单壁碳纳米管结构修饰 方面的最新发展状况，重点讨论化学功能化及物理吸附。     

Preparation of VPS and PVD coatings for metallographic and TEM investigations

The aim of the first part of the paper is to give some advice for the faultless metallographic preparation of vacuum plasma sprayed coatings. Several coating/substrate combinations using metals, alloys and ceramics were investigated to derive some general rules. The second part deals with a preparation technique for cross-sections- of physical vapour deposition coatings. This technique was optimized for TiN and Ti(C, N) coatings on hardmetals which were examined in an analytical transmission electron microscope.     

物理化学课程“热化学”主题学习历程研究——化学师范生知识建构的文本分析

为深入了解地方性师范院校化学师范生知识建构习惯和水平，探讨他们在大学专业基础课程中的学习历程，以物理化学课程中以“融合科学读写特色”的“热化学”学案作为研究载体，研究对象在学案引导下开展自学活动，并在阅读教材和文献基础上进行科学写作。采用量表工具针对大学生自学效果和反思活动进行评价，并采用SOLO分类评价科学写作作品，采用KWL工具评价学生的科学阅读收获。结果发现研究对象学习动机不强，不擅长在新的学科知识学习中联系已有专业课程知识，基于文本学习的建构活动水平极低，可能是因为他们在应试背景下的基础知识并未形成体系，先修课程中并未培养元认知学习策略。     

物理有机化学的现状和在我国的进展

本文评述了当前物理有机化学各个主要领域的研究工作,指出物理有机化学是甚为重要的基础学科,数十年来在深度和广度两方面皆有很大的发展。回顾了我国第一届和第二届物理有机讨论会情况,扼要地介绍了物理有机化学在我国的主要进展。     

Fouling Mitigation in a Heat Exchanger: High Cycles of Concentration for a Cooling-Tower Application

The purpose of the present study is to investigate the effect of a physical water treatment (PWT) technology on fouling mitigation in a simulated cooling tower operating at high cycles of concentration. Hard water was produced by evaporating pure water in a circulating open cooling tower, where dissolved calcium carbonate ions became concentrated with time. Heat transfer tests were conducted in a rectangular channel by varying the cycle of concentration (COC) from 5 to 10, and fouling resistances were measured over 270 hrs for each case with and without the PWT treatment. Another test was conducted with no blowdown case with and without the PWT treatment. The fouling resistance at 5 cycles with the PWT treatment was about 70% less than that in the case without the PWT treatment at the end of 270-hr tests. Even at 10 cycles, the PWT treatment reduced the fouling resistance by 60% from the value for the no treatment case. Thus, one can conclude that the PWT technology can help circulating cooling-tower water at relatively high COC for significant freshwater conservation, while keeping fouling resistances below industry standards.