The Numerical Analysis of the Gas-Liquid Absorption Process Accompanied by Rayleigh Convection

Flow and concentration fields of liquid phase in a gas-liquid contacting system are simulated to show the Rayleigh convection by utilizing the finite-element method. The Schlieren images in CO2-ethanol system provided direct visual verification of the present simulation, and the simulated results were well consistent with the experimental observation. The influence of the Rayleigh convection on mass transfer is analyzed qualitatively and quantitatively based on the simulated and the experimental results.     

糖基化聚丙烯微孔膜表面功能化及其从水溶液中去除硼酸的研究简

Affinity membranes are fabricated for boric acid removal by the surface functionalization of microporous polypropylene membrane （MPPM） with lactose-based polyols. The affinity is based on specific complexation between boric acid and saccharide polyols. A photoinduced grafting-chemical reaction sequence was used to prepare these affinity membranes. Poly（2-aminoethyl methacrylate hydrochloride） [poly（AEMA）] was grafted on the surfaces of MPPM by UV-induced graft polymerization. Grafting in the membrane pores was visualized by dying the cross-section of poly（AEMA）-grafted MPPM with fluorescein disodium and imaging with confocal laser scanning microscopy. It is concluded that lactose ligands can be covalently immobilized on the external surface and in the pores by the subsequent coupling of poly（AEMA） with lactobionic acid （LA）. Physical and chemical properties of the affinity membranes were characterized by field emission scanning electron microscopy and Fourier Transform Infrared/Attenuated Total Refraction spectroscopy （FT-IR/ATR）. 3-Aminophenyl boric acid （3-APBA） was removed from aqueous solution by a single piece of lactose-functionalized MPPM in a dynamic filtration system. The results show that the 3-APBA removal reaches an optimal efficiency （39.5%） under the alkaline condition （pH 9.1）, which can be improved by increasing the immobilization density of LA. Regeneration of these affinity membranes can be easily realized through acid-base washing because the complexation of boric acid and saccharide polyol is reversible.     

颗粒尾涡增强湍流的大涡模拟以及气固两相流中湍流变动的数值模拟

The turbulence enhancement by particle wake effect is studied by large eddy simulation （LES） of turbulent gas flows passing a single particle. The predicted time-averaged and root-mean-square fluctuation velocities behind the particle are in agreement with the Reynolds-averaged Navier-Stokes modeling results and experimental results. A semi-empirical turbulence enhancement model is proposed by the present-authors based on the LES resuits. This model is incorporated into the second-order moment two-phase turbulence model for simulating vertical gas-particle pipe flows and horizontal gas-particle channel flows. The simulation results show that compared with the model not accounting for the particle wake effect, the present model gives simulation results for the gas turbulence modulation in much better agreement with the experimental results.     

A NEW METHOD FOR ACHIEVING DROPWISE CONDENSATION (Ⅰ) BASIC CONCEPT AND EXPERIMENTAL RESULTS

Various methods for achieving dropwise condensation (DWC) are reviewed from the point of view of surface science. The objective of the present work is stated. In the experimental study, the surfaces of stainless steel and copper tubes employed were treated with various surface techniques, steam condensation under atmospheric pressure was carried out and steady DWC observed on these surfaces, and the mechanism of DWC formation on the treated surfaces was analysed. Experimental results and photographs of DWC are presented.     

三辛胺萃取丁二酸、苹果酸、马来酸、富马酸特性的研究

Extraction equilibrium features of succinic acid, malic acid, maleic acid and fumaric acid were investigated systematically with trioctylamine (TOA) in chloroform, 4-methyl-2-pentanone (MIBK) and 1-octanol. Fourier transform-infrared (FTIR) spectroscopic analysis of organic samples loaded with the acid shows that amine forms 1:1 complex of ion-pair association with succinic acid, malic acid and maleic acid, and 1:1, 2:1 complex of ion-pair association with fumaric acid. It is proposed that the complex forms depend on the second dissociation constant of the dibasic acid, pKa2 Results of equilibrium experiments show that diluents affect extraction behavior, and depend on the solute concentration. Protic diluents, chloroform and 1-octanol, are more effective than the others when the equilibrium solute concentration is lower than 1:1 stoichiometry of TOA to acid, otherwise the extraction ability shows that MIBK>l-octanol>chloroform for malic and maleic acids, and l-octanol>MIBK>chloroform for succinic acid.     

非傅立叶热现象的理论分析和实验证实

This paper consists of two parts. (1) For a hollow sphere with sudden temperature changes on its inner and outer surfaces, the hyperbolic heat conduction equation is employed to describe this extreme thermal case and an analytical expression of its temperature distribution is obtained. According to the expression, the non-Fourier heat conduction behavior that will appear in the hollow sphere is studied and some qualitative conditions that will result in distinct non-Fourier behavior in the medium is ultimately attained. (2) A novel experiment to observe non-Fourier heat conduction behavior in porous material (mainly ordinary duplicating paper) heated by a microsecond laser pulse is presented. The conditions for observing distinct non-Fourier heat conduction behavior in the experimental sample agree well with the theoretical results qualitatively.     

液体在固体表面上的铺展动力学

Based on assuming that there is the precursor film in the front of the apparent contact line （ACL）, a model was proposed to understand the dynamic wetting process and associated dynamic contact angle. The present model indicated that a new dimensionless characteristic parameter, 2, attects the dynamic wetting process and associated dynamic contact angle as well. However, the previous model suggested that the dynamic contact angle is dependent＇on the capillary number and static contact angle only. An experimental investigation was conducted to measure the dynamic wetting behavior of silicon oil moving over glass, aluminum and stainless steel surfaces. It concluded that when the value of 2 was selected as 0.07, 0.16 and 0.35 for glass, aluminum and stainless steel, respectively, the experimental results were in good accordance with the prediction of the model. Furthermore, the comparison of the model with Strom＇s experimental data showed that 2 is independent on the species of liquids. Apparently, 2 should be interpreted as the effect of the solid surface properties on the dynamic wetting process.Meanwhile, it is found in the present experiment that the Hoffman-Voinov-Tanner law, which is valid at very low capillary number （Ca 〈〈 1 or 80〈 10°） recommend by Cazabat, still holds for higher contact angles, even up to 70°-80°. This is explained by （he present model very well.     

Progress in the Study on the Phase Equilibria of the CO2·H2O and CO2-HeO-NaCI Systems

To study the feasibility of CO2 geological sequestration,it is needed to understand the complicated mul- tiple-phase equilibrium and the densities of aqueous solution with CO2 and multi-ions under wide geological condi- tions（273.15—473.15K,0—60MPa）,which are also essential for designing separation equipments in chemical or oil-related industries.For this purpose,studies on the relevant phase equilibria and densities are reviewed and analyzed and the method to improve or modify the existing model is suggested in order to obtain more reliable predictions in a wide temperature and pressure range.Besides,three different models（the electrolyte non random two-liquid（ELECNRTL）,the electrolyte NRTL combining with Helgeson model（ENRTL-HG）,Pitzer activity coefficient model combining with Helgeson model（PITZ-HG））are used to calculate the vapor-liquid phase equilib- rium of CO2-H2O and CO2-H2O-NaCl systems.For CO2-H2O system,the calculation results agree with the experimental data very well at low and medium pressure（0—20MPa）,but there are great discrepancies above 20MPa.For the water content at 473.15K,the calculated results agree with the experimental data quite well.For the CO2-H2O-NaCl system,the PITZ-HG model show better results than ELECNRTL and ENRTL-HG models at the NaCl concentration of 0.52mol·L ^-1 .Bur for the NaCl concentration of 3.997mol·L ^-1 ,using the ELECNRTL and ENRTL-HG models gives better results than using the PITZ-HG model.It is shown that available experimental data and the thermodynamic calculations can satisfy the needs of the calculation of the sequestration capacity in the temperature and pressure range for disposal of CO2 in deep saline aquifers.More experimental data and more accurate thermodynamic calculations are needed in high temperature and pressure ranges（above 398.15K and 31.5MPa）.     

伴有Rayleigh对流的气液吸收过程数值模拟

Flow and concentration fields of liquid phase in a gas-liquid contacting system are simulated to show the Rayleigh convection by utilizing the finite-element method. The Schlieren images in C02-ethanol system provided direct visual verification of the present simulation, and the simulated results were well consistent with the experimental observation. The influence of the Rayleigh convection on mass transfer is analyzed qualitatively and quantitatively based on the simulated and the experimental results.     

Ultrasonically Assisted Extraction of Isoflavones from Stem of Pueraria lobata （Willd.） Ohwi and Its Mathematical Model

Ultrasonically assisted extraction of isoflavones from the stem of Pueraria lobata （Willd.） Ohwi has been carried out with an ultrasonic extracting apparatus （20kHz, electrical power input to the transducer in 0-650W）. The influence of the electrical power input and extraction time on the＇extraction yield is investigated in water, n-butanol, and 95% （by volume） and 50% （by volume） ethanol aqueous solution. The experimental results indicate that the yields of total isoflavones are higher in ultrasonically assisted extraction than those obtained from con-ventional extraction.Moreover,a mathematical model is proposed,by introducing the electrical power input to index the ultrsound intensity,to describe the behavior of ultrasonically assisted extraction.It is found that the model calcuations are in good agreement with the experimental data.     

基于PSO的丁二酸发酵动力学模型参数优化

丁二酸是一种重要的化工原料,对丁二酸发酵过程进行模型化研究可以为工艺放大提供必要的基础数据。根据丁二酸发酵过程的实验数据,在已有的丁二酸发酵动力学模型的基础上,采用粒子群优化算法进行模型参数优化研究,求得最优参数并利用其进行过程仿真。结果表明优化后的模型能够更好地模拟丁二酸分批发酵过程。和采用遗传算法进行的研究结果相比,粒子群算法提高了模型计算值与实验测量值的拟合程度,且算法简单,易于实现。     

A novel synthesis of succinic acid type Gemini surfactant by the functional group interconversion of Corynomicolic acid

2,3-Bis(undecyl)succinic acid, succinic acid type Gemini surfactant, was successfully synthesized from Corynomicolic acid by the functional interconversion of OH of Corynomicolic acid to COOH via (1) mesylation of OH of syn-isomer, (2) elimination of methanesulfonate group using base to E-alpha,beta-unsaturated ester, (3) Michael addition of CN(-) with 18-crown-6 and (4) hydrolysis. In most hydrolysis conditions, a mixture of syn- and anti-2,3-bis(undecyl)succinic acid was obtained, but hydrolysis in 75% H(2)SO(4) gave only anti-2,3-bis(undecyl)succinic anhydride. After converting a mixture of syn- and anti-2,3-bis(undecyl)succinic acids to corresponding acid anhydrides, syn- and anti-anhydride isomers were separated by column chromatography, and by following hydrolysis syn- and anti-2,3-bis(undecyl)succinic acid was selectively prepared. Based on the surface tension measurement, the effect of stereochemistry on surface tension isotherms was discussed in terms of the hydrophobic interaction between two alkyl groups and the electrostatic repulsion between two hydrophilic COO(-) groups.     

The Influence of Chemical Pre-treatment and Magnesium Surface Enrichment on Bonding of Succinic Acid Molecules to Aluminium Alloy

In the present study a combined Fourier Transform Infrared Reflection–Absorption Spectroscopy (FT-IR–RAS) and Auger electron spectroscopy (AES) analysis was performed to investigate the bonding of organic coatings to oxides formed on Al–Mg based alloys. The interfacial bonding of a model molecule, succinic acid, mimicking the functional groups used in practical coatings was studied in detail on various differently pre-treated aluminium alloy (AA5182, 4.8 wt% magnesium) surfaces. Besides these differently pre-treated alloy surfaces, also pure magnesium and aluminium were studied for reference. The surface and near-surface composition of the alloys was studied by Auger electron spectroscopy, ion-milling away the surface oxides to obtain a depth profile. The results show that after heat treatment, the oxides are as much enriched in magnesium as aluminium although the bulk concentration of magnesium is only 4.8 wt%. FT-IR–RAS shows that bonding of the succinic acid molecules takes place in a range of configurations, varying between bridging bidentates and unidentates. The relative portion of unidentates increases with the magnesium surface concentration. This is attributed to the difference in bond lengths of Mg–O and Al–O, forcing the carboxylic acid groups to stretch or to attach to only one oxide group (unidentate) instead of two (bidentate). Also the mixed OH/CO₃ surface after Mg enrichment at the surface has less room for bonding with two groups, thus affecting the bonding configuration in a similar way.     

Electrochemical analysis of the adsorption and desorption behaviors of carboxylic acid and anhydride monomers onto zinc surfaces

The interfacial bondings formed between succinic acid and myristic acid, as well as succinic anhydride molecules with a set of differently treated zinc substrates have been investigated using infrared reflection absorption spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The compounds were selected to model typically used carboxylic-based adhesives and coatings. Moreover, the adsorption kinetic has been evaluated by means of chronoamperometry (CA) and chronovoltammetry measurements. XPS results showed a relation between the amount of carboxylates formed by adsorption of succinic acid/myristic acid and the hydroxyl fraction presented on the surfaces as proved by a higher electron transfer in CA. On the other hand a set of oxidative/reductive interactions was detected during the adsorption of succinic anhydride, in turn proving a spontaneous ring opening and adsorption mechanism. A clear relationship between the amount of adsorbents and surface hydroxyls/carbonates was detected for the adsorption of succinic anhydride. The extent to which the formed carboxylates resisted negative potentials was also investigated by cyclic voltammetry (CV) in an aqueous solution. The coordinative bonding of a bifunctional carboxylic acid group to the oxide surface was found to be not stable in the presence of a negative potential, while a monofunctional carboxylic acid group could resist displacement by water for a prolonged period of time. On the other hand, a low double layer capacitance was obtained after the adsorption of succinic anhydride, which was related to a change in potential of zero charge (PZC) upon the adsorption.     

A comparison of the interfacial bonding properties of carboxylic acid functional groups on zinc and iron substrates

The present work investigates the molecular interfacial bonds between carboxylic functional groups and zinc and iron substrates. Succinic acid models the functionality of many commonly used adhesives and organic coatings. On the other hand, iron and zinc form the major surface composition of galvanized steel. Consequently, studying the interfacial properties of the polymer functional groups and zinc or iron substrates illuminates the correlation of the polymer bonding characteristics and surface chemical properties of galvanized steel. In this work, X-ray photoelectron spectroscopy (XPS) and fourier transform infrared reflection absorption spectroscopy (FTIR-RAS) are combined to evaluate the surface compositions, the amount of adsorbed molecules and the interaction mechanism between the succinic acid functionalities and the differently pretreated surfaces. The results show that variation of the treatments prior to succinic molecule adsorption results in different adsorption properties, which are related to the changes in chemistry and composition of the oxide layer.     

气相色谱法测定丁二酸酯化液中有机组分的含量

针对丁二酸酯化液的特点,选择强极性毛细管柱作为分析柱,优化得到了分析测试条件,利用气相色谱建立了丁二酸二甲酯、丁二酸单甲酯和甲醇的标准曲线。在测试确认模拟混合样品的分析精度的基础上,分析了丁二酸酯化反应液样品中有机组分浓度。分析结果表明,该方法快速、准确、灵敏度高、重复性好,相对标准偏差(RSDs,n=7)在2%以内,能满足丁二酸酯化反应过程特性研究的分析要求。     

聚异丁烯丁二酸失水山梨醇酯的合成及其性能

以聚异丁烯丁二酸酐、山梨醇为主要原料,经过醚化、酯化两步反应,合成了聚异丁烯丁二酸失水山梨醇酯,并用红外光谱对其进行结构表征。测定了产品的极限乳化性能与储存稳定性能,结果表明,山梨醇的失水度为1.0¹.2,聚异丁烯丁二酸酐与失水山梨醇物质的量为1.0∶1.21.2,聚异丁烯丁二酸酐与失水山梨醇物质的量为1.0∶1.2¹.0∶1.5,产品的乳化稳定性较好,产品的极限乳化性能与储存稳定性能均优于聚异丁烯丁二酰亚胺(T152),产品的成本明显低于T152,具有很好的市场推广前景。     

H-732阳离子交换树脂催化酯化反应

以H-732阳离子交换树脂为催化剂进行了酯化反应研究,合成了丁二酸单乙酯和乙酰水杨酸,通过单因素实验和正交实验优化了反应工艺。单因素实验结果表明：催化剂用量为丁二酸酐质量的20%、乙醇与丁二酸酐的摩尔比1.8∶1、反应时间2 h、反应温度90 ℃时,丁二酸单乙酯产率最高为68.76%;在丁二酸单乙酯的合成体系中加入分离出的副产物丁二酸二乙酯可以抑制副反应的发生,大大提高单酯的产率（90.79%）。正交实验结果表明：乙酸酐与水杨酸的摩尔比为3∶1,催化剂用量为水杨酸质量的14.50%,反应时间2 h、反应温度60 ℃时,乙酰水杨酸产率最高为77.57%;催化剂连续使用5次时,催化能力才有明显下降,对连续使用过5次的催化剂重新活化后催化能力无明显降低。     

Impact of the Charge-Regulated Nature of the Bacterial Cell Surface on the Activity of Adhered Cells

Since the first reported observations by Zobell in 1943, it has been recognized that the metabolic activity of adhered bacteria can differ from that of their planktonic counterparts. Many studies have been performed and the overwhelming evidence is that bacterial adhesion to surfaces can result in changes to cellular metabolic activity and that the changes are a function of the surface properties of both the bacterial and adhering surfaces. However, the mechanism that results in these observations has remained elusive. The authors have approached this problem by focusing on cellular bioenergetics, which describes how bacteria obtain, store and use energy, and how adhesion can affect this process. In a series of experimental and numerical studies, the authors developed a hypothesis linking cellular bioenergetics to the physicochemical charge-regulation effect, which causes variations in surface electrostatic properties as a surface containing acid/base functional groups (e.g., the bacterial cell surface) approaches another surface. The purpose of this paper is to synthesize these prior studies and provide a cohesive presentation of the hypothesis. If this hypothesis is ultimately shown to be true, it will provide a fundamental basis for the engineered design of surface materials and coatings that can enhance or inhibit bacterial activity and colonization, depending on the requirements of the system at hand.     

Hydrogenation of Succinic Acid to γ-Butyrolactone (GBL) Over Palladium-Alumina Composite Catalyst Prepared by a Single-Step Sol–Gel Method

Abstract  

Mesoporous palladium-alumina (Pd-A) composite catalysts prepared by a single-step sol–gel method were calcined at various temperatures to control palladium surface area and acidity. The Pd-A catalysts were characterized by XRD, BET, N₂ adsorption–desorption isotherm, H₂ chemisorption, ²⁷Al MAS NMR, NH₃-TPD, and HR-TEM analyses. Liquid-phase hydrogenation of succinic acid to γ-butyrolactone (GBL) was carried out over Pd-A catalyst in a batch reactor. The effect of calcination temperature of Pd-A catalyst on the palladium surface area and catalytic performance was investigated. In the hydrogenation of succinic acid, conversion of succinic acid increased with increasing palladium surface area of Pd-A catalyst. Selectivity for GBL depended on the formation of succinic anhydride (an intermediate product formed by acid catalysis) and by-products (formed by hydrogenolysis). Nevertheless, yield for GBL also increased with increasing palladium surface area of Pd-A catalyst. Thus, palladium surface area played an important role in enhancing the catalytic performance of Pd-A catalyst in the hydrogenation of succinic acid to GBL.