CCN activation of oxalic and malonic acid test aerosols with the University of Vienna cloud condensation nuclei counter

The cloud droplet activation of monodisperse laboratory aerosols consisting of single organic and inorganic substances as well as a mixture of several substances was investigated using the University of Vienna cloud condensation nuclei counter (CCNC). The CCNC operates on the principle of a static thermal diffusion chamber. Water vapour supersaturations can be set in the range from 0.1% to 2%. Aqueous solutions of oxalic acid and malonic acid as well as solutions of inorganic compounds (NaCl and (NH₄)₂SO₄) were nebulized in a Collison atomizer and then passed through a closed-loop differential mobility particle spectrometer to produce monodispersed particles. An internally mixed aerosol consisting of ammonium sulphate, oxalic acid and malonic acid with relative concentrations resembling those found in cloud water at a mountain station [Löflund, Kasper-Giebl, Schuster, Giebl, Hitzenberger, Reischl et al. (2002) Atmos. Environ. 36, 1553] was also investigated for cloud condensation nuclei (CCN) activation. All these particles were activated at supersaturations expected from Köhler theory. Oxalic and malonic acid particles are therefore expected to be good atmospheric CCN both as pure particles and as internally mixed particles containing other chemical compounds.     

阴／非离子复合表面活性剂驱油剂的制备研究

研究了阴离子表面活性剂AES与非离子表面活性剂OP-10和阴离子表面活性剂AES与非离子表面活性剂TX分别以不同比例混合后对表面／界面张力的影响,并从机理上进行了相关探讨。实验结果表明：当AES与OP-10和AES与TX的质量比分别为8：2和6：4时,表面／界面张力均降低至最低值。二者比较来看,AES与TX的复配体系较AES与OP-10的复配体系降低表面／界面张力的效果明显。     

Effect of surface properties of activated carbons on surfactant adsorption kinetics

This research investigates the adsorption properties of three activated carbons (AC) derived from coconut, coal, and wood origin. A linear relationship exists between the number of water molecules adsorbed onto each AC and the oxygen content determined elemental analysis and XPS. An inverse linear relationship exists between the plateau amount of dodecanoic acid anionic surfactant and the oxygen content on the surface of ACs. The surface charge on each AC’s surface had a linear relationship with the plateau amount of dodecanoic acid. A plug-flow heterogeneous surface diffusion model (PFHSDM) for a fixed-bed adsorption process was developed to describe the adsorption kinetics in a fixed-bed column. The model represents axially dispersed plug-flow, external mass transfer, adsorption equilibrium on the fluid-particle interface, and intraparticle diffusion. The larger molecular dimension of the dodecanoic acid as a more hydrophobic entity than octanoic acid led to a faster external mass transfer rate but a slower surface diffusion rate as estimated from the PFHSDM. The interaction between the organic moiety of surfactant and the AC surface chemistry such as surface oxygen content and surface charge contributes to the adsorption performance in both to the adsorption equilibrium and kinetics.     

常压等离子体射流对聚乙烯醇薄膜性能的影响

用常压等离子体射流处理不同含水率聚乙烯醇（PVA）薄膜,通过扫描电镜（SEM）观察薄膜表面形态,并用红外光谱测试仪（FTIR）、X光电子能谱（XPS）、X射线衍射仪（XRD）分析了等离子体处理前后含水率为1.85%MC及41.33%MC两种 PVA化学结构及结晶结构的变化。试验结果表明:水分可加速氦气/氧气等离子体对PVA刻蚀及氧化,其中刻蚀速率达0.68μm/min,氧含量从30.8%提高到34.8％;同时,经过处理的薄膜结晶度增加了48％。     

The influence of aluminum phosphates on graphite oxidation

Aluminum phosphates are of interest for use as inhibitors for the oxidation of carbonaceous materials. This investigation analyzes three aluminum phosphates of nominal compositions, Al₂O₃ · P₂O₅, Al₂O₃ · 3P₂O₅, and Al₂O₃ · 9P₂O₅, in terms of thermal stability and efficacy to inhibit the thermal oxidation of graphite flake in pure oxygen. Temperature programmed oxidation reveals that the onset temperature for oxidation is increased by 75-100 °C as a result of the aluminum phosphate treatments. Isothermal oxidation rate measurements show that while the overall oxidation rate constants are lowered by the aluminum phosphate treatments, the apparent activation energy remains constant (54-59 kcal/mol), which indicates that the reduction in rate constant with temperature is due to a lowering of the pre-exponential term.     

The performance of surfactant on the surface characteristics of electroless nickel coating on magnesium alloy

Magnesium and its alloys corrode rapidly in the electrolyte bath. Surfactants while used extensively as surface active agents in the electrolyte bath, have been little studied on magnesium surfaces. The influence of surfactants cetyltrimethyl ammonium bromide (CTAB) and sodium lauryl sulfate (SLS) on the surface properties such as roughness, morphology and topography of electroless Ni–P deposits on magnesium alloy was researched. The research reveals that the surfactant solutions has significant influence on the composition of coating, surface roughness and surface morphology. In addition, it has marginal effect on the microhardness. Electroless coatings with addition of surfactants produce a smooth surface and average roughness value of 1.412 μm for CTAB and 1.789 μm for SLS, which are less than the value (2.98 μm) without surfactant addition. There was a significant improvement in the rate of deposition. However, the surfactants influence reached maximum at critical micelle concentration and above this value it gets stabilized. The initial structure appears to be dependent upon the percent occluded surfactants. The surface microstructures are discussed in line with the experimental observations.     

正构烷基酚热力学性质的构效关系

选取了150种正构烷基酚的热力学性质作为分析对象。为了研究热力学性质的构效关系, 引入并简化了主量子拓扑指数⁰P、¹P。考虑到分子对称性对热力学性质的影响, 为了方便量化对称程度, 将烷基作为类原子处理, 定义了烷基的折算点价和烷基相似度的计算方法, 借助矩阵形式计算了烷基酚分子对称特征指数Q。将⁰P、¹P、Q与苯环上烷基的数目T、苯环上相邻烷基的对数B作为分子描述符, 利用方差膨胀因子VIF进行筛选, 确定¹P、T、B、Q作为构效关系模型的自变量。采用最佳变量子集回归方法, 并根据Akaike信息判据、Kubinyi函数建立了热力学性质定量构效关系模型, 所有模型的相关系数均大于99%, 甚至达到100%。采用交叉验证方法对模型的稳健性和预测能力进行了检验, 结果表明所建模型具有良好的稳健性和预测能力。     

The influence of cationic surfactant CTAB on optical,dielectric and magnetic properties of cobalt ferrite nanoparticles

In the present work, the influence of cationic surfactant CTAB (cetyltrimethylammonium bromide) on size, shape and coalescence behaviour of cobalt ferrite nanoparticles (CFNPs) synthesized via hydrothermal method is reported. Pure CFNPs show no additional peaks, whereas α-Fe₂O₃ phase is observed in CTAB added CFNPs upon annealing. FT-IR analysis confirms the formation of M − O vibrational bands (metal -oxygen) at tetrahedral A-site and octahedral B-site for both samples. SEM observations reveal less agglomeration and smaller particle size for surfactant added CFNPs. Raman spectral study confirms the formation of cubic spinel structure and Raman active modes of CTAB added CFNPs. UV–Vis spectra indicate a decrease in the energy band gap with annealing. The dielectric constant of surfactant added CFNPs decreases with increasing applied frequencies for both real and imaginary, but ac conductivity increases with increasing frequencies. Two sextet patterns of Fe³⁺ trivalent ions from tetrahedral and octahedral sites are observed in Mössbauer spectra. VSM study indicate the ferrimagnetic nature of CTAB added CFNPs. The electrochemical analysis reveals the pseudocapacitive nature of working electrode prepared by CTAB added CFNPs.     

The influence of a mixed radiation environment on the properties of the passive film on tungsten

The properties of the passive film formed on the tungsten (W) in H₂SO₄ (pH 1.6) during proton irradiation (spallation) were characterized with electrochemical impedance spectroscopy (EIS), surface enhanced Raman spectroscopy (SERS), and the Mott-Schottky (MS) method. EIS data were associated with an adsorption pseudocapacitance. Observed changes in the adsorption pseudocapacitance were consistent with thinning of the outer layer of the passive film. SERS experiments found that the spallation environment had no affect on the molecular state of the oxide. Results from MS experiments found that the oxygen vacancy concentration in films formed during proton irradiation were lower than those films formed in the absence of irradiation. In accordance with the point defect model (PDM) for oxide films, a decrease in the oxygen vacancy concentration indicates proton irradiation alters the passive film by either decreasing the oxygen vacancy flux or increasing oxygen vacancy diffusion. Calculations using the LAHET and MCNP transport codes have demonstrated that spallation reactions are capable of generating numerous energetic particles such as, electrons, neutrons, protons, and photons. Each of these species is capable of generating a wide variety of defects in the oxide film altering its electronic and transport properties and, thus, explaining the observed electrochemical phenomena.     

The influence of structure order on the kinetics of dehydroxylation of kaolinite

The structural order of kaolinite is an important factor that shows a substantial effect on the processes which take place during the thermal treatment of kaolin. The influence of structural order on the dehydroxylation process was investigated by simultaneous thermogravimetry and differential thermal analysis (TG-DTA). The thermal analysis was performed on the samples with gradually decreasing structural order prepared by milling procedure. The apparent activation energy of dehydroxylation process decreases with decreasing structural order according to the exponential function. The extrapolation of experimental data leads to the estimation of apparent activation energy of 76.6 kJ mol^?1 and of frequency factor of 0.12 × 10⁴ s^?1 related to completely disordered form of kaolinite, while the ordered form shows the apparent activation energy of 216.17 kJ mol^?1 and the frequency factor of 9.26 × 10⁴ s^?1. The relationships between features such as the infrared pattern of treated material, the degree of structural order and the apparent activation energy were established.     

Role of oxygen vacancies and Sr sites in SrCo0.8Fe0.2O3 perovskite on efficient activation of peroxymonosulfate towards the degradation of aqueous organic pollutants

Metal-based perovskite oxides have contributed significantly to the advanced oxidation processes (AOPs) due to their diverse active sites and excellent compositional/structural flexibility. In this study, we specially designed a perovskite oxide with abundant oxygen vacancies, SrCo_0.8Fe_0.2O₃ (SCF), and firstly applied it as a catalyst in peroxymonosulfate (PMS) activation towards organic pollutants degradation. The result revealed that the prepared SCF catalyst exhibited excellent performance on organic compounds degradation. Besides, SCF showed much better activity than La_0.5Sr_0.5Co_0.8Fe_0.2O₃ (LSCF) in terms of reaction rate and stability for the degradation of the organic compounds. Based on the analysis of scanning electron microscope, transmission electron microscope, X-ray diffraction, N₂ adsorption–desorption, X-ray photoelectron spectroscopy and electron paramagnetic resonance, it was confirmed that the perovskite catalysts with high content of Sr doping at A-site could effectively create a defect-rich surface and optimize its physicochemical properties, which was responsible for the excellent heterogeneous catalytic activity of SCF. SCF can generate three highly active species: ¹O₂, SO^-₄· and ·OH in PMS activation, revealing the degradation process of organic compounds was a coupled multiple active species in both radical and nonradical pathway. Moreover, it was mainly in a radical pathway in the degradation through PMS activation on SCF and SO^-₄· radicals produced were the dominant species in SCF/PMS system. This study demonstrated that perovskite-type catalysts could enrich OVs efficiently by doping strategy and regulate the PMS activation towards sulfate radical-based AOPs.     

A review of the influence of humidity on photocatalytic decomposition of gaseous pollutants on TiO2-based catalysts

Humidity can have an appreciable influence on the photocatalytic degradation of volatile organic compounds (VOCs) in air. It has been proposed that there are multiple layers of water molecules on the surface of the photocatalyst, and a VOC molecule must penetrate this layer and be able to diffuse to the photocatalytic surface for a reaction to occur. An updated analysis of related literature from the past 12 years indicates that this proposed mechanism remains reasonable for explaining observed effects. According to this mechanism the VOC's hydrophilicity should dominate the influence of humidity on the photocatalytic reaction kinetics, and this effect can be seen in a categorization of literature observations based on the octanol-water partition coefficient. The frequently cited Langmuir-Hinshelwood kinetic model does not directly account for humidity effects in this way but can be adapted for this purpose. As an example, the rate of photocatalytic decomposition of chlorobenzene in air under humid conditions can be described by a modified Langmuir-Hinshelwood kinetic model, where the reaction rate coefficient is dependent on the water concentration. Understanding and considering the effect of humidity is useful for optimizing the efficacy of photocatalytic VOC treatment of air.     

The influence of the grain size distribution of raw materials on the selected surface properties of sanitary glazes

Glazes in significant way influence on most of the final properties of ceramic ware, mainly on surface parameters as colour, glossy or roughness. Usually, these properties has been changed by chemical composition and firing parameters. The results of presented works show, there is a possibility of improvement of surface proprieties by the selective milling and selection of the grain size of group of raw materials. It was shown, that in case of the sanitary glazes, an adequate selection of the grain size of quartz, feldspars, zirconium silicate and rest of raw materials, leads to improvement of whiteness and glossy as well as decreasing of roughness of surface.     

Construction of quantum-scale catalytic regions on anatase TiO2 nanoparticles by loading TiO2 quantum dots for the photocatalytic degradation of VOCs

We constructed quantum-scale catalytic regions on the surfaces of TiO₂ nanoparticles by loading TiO₂ quantum dots (QDs) with a two-step method. The removal rate and mineralization efficiency of toluene were measured and then used in evaluating the oxidation performance of the prepared samples. A home-built atmospheric surface photovoltage spectrometer and X-ray photoelectron spectrometer were used in analyzing band alignment across the interface between TiO₂ QD and TiO₂ particle and the transfer of charge carriers at the surface. Results showed that an upward band bending formed from the TiO₂ particle to the TiO₂ QD and promoted the accumulation of holes at the QD side. Moreover, the QD and surrounding substrate TiO₂ formed a quantum-scale catalytic region, improving the reaction probability of electron-hole pairs and corresponding intermediates. The mineralization efficiency of toluene in QD-loaded TiO₂ reached 95.8%. The synthetic method is green and simple, showing potential in scale production and industrial application.     

磁流体制备中表面活性剂的选择及其包裹条件的影响

讨论了表面活性剂对磁性颗粒的包裹以及pH值、温度、表面活性剂的用量和搅拌速度等包裹条件对磁性颗粒的影响。应用磁天平、粒度测试仪对磁性颗粒的粒径和磁化率进行了测定。结果表明,在十二烷基苯磺酸钠、油酸钠和乙二醇3种不同的表面活性剂中,选用油酸钠效果最好。当pH=5,温度为80℃,搅拌速度为200 r/min,油酸钠的用量大约为Fe2+的0.4~0.5倍时,包裹效果最好,得到的磁性颗粒小、磁性强。     

六硝基芪细化研究

用结晶液中表面加入活性剂及超声波处理的方法细化六硝基芪,粒径小于１μｍ的微粒可达５５％以上。     

Effect of mesogenic organic salts on vulcanization and physical properties of rubber compounds

The effect of mesogenic organic salts as reinforcing fillers for non‐ionic elastomers such as natural rubber and styrene–butadiene rubber has been investigated. The influence of cation size (thallium and sodium) and organic chain length (thallium(I) pentanoate and thallium(I) dodecanoate) on vulcanization parameters, physical and mechanical characteristics and rheological behaviour has also been analysed. In general, the maximum torque of the vulcanizates increases in the presence of the salts and is clearly manifested in a noticeable increase in tensile modulus and strength of the composites. The thallium(I) salts are more effective reinforcements than the sodium salt, and the length of the organic chain has hardly any influence on the mechanical properties. The composites based on the thallium(I) dodecanoate salt show a very peculiar rheological behaviour with a ‘plateau’ in the elastic modulus and loss modulus versus temperature plots which is related to solid phase I, existing between 83.5 and 127 °C, characterized as a plastic condis phase. This issue is especially interesting for the fabrication of devices such as sensors to control, for instance, the security (resistance of a material) as a function of temperature. © 2013 Society of Chemical Industry     

The influence of the texture and surface properties of carbon adsorbents obtained from biomass products on the adsorption of manganese ions from aqueous solution

Studies on the adsorption of manganese ions from aqueous solution on carbon obtained from a mixture of biomass products indicate the importance of acidic surface oxides for manganese ion adsorption that is predominantly site specific. The results show that oxygen remaining from the raw material participates in the formation of surface oxides and indicates the possibility of controlling the content of acidic surface sites of the carbon surface by appropriate selection of the precursor composition and surface properties modification. The surface functionalities of oxidized carbon from a mixture of biomass products resembles the behavior of an ion-exchange resin. Oxidized carbon obtained from a 50:50 mixture of tar from steam pyrolysis of apricot stones and furfural contains a balance of surface area and high surface concentration of functional groups favorable for adsorption of positively charged manganese ions.     

管道渗流对表层土壤影响的数值模拟

采用有限容积法建立埋地管道泄漏多孔介质流固耦合相变数学模型,对油品管道下侧泄漏进行压力场和体积分数的数值模拟。研究表明管道泄漏后,压力对于表层土的影响极小,可以忽略不计。体积分数经过一定时间后,等值线形成一个正苹果形。由于重力作用y轴比x轴扩散快,之后油品最外层等值线到达表层土下缘,油品开始渗入表层土,密集的等值线继续向上扩散,当等值线前锋到到表层土上缘时外界就会发现有泄漏现象发生,但是最大等值线前锋并没有到达表层土。当表层区域都向表层有油品输出,并且比较密集的等值线前锋已经处在表层土,这时地表应该会出现油品液体的流动。再经过一段时间,外层等值线到达土壤最下缘,这就意味着开始有油品开始污染地下水。