Chinese Journal of Chemical Engineering

Design, preparation and in vitro bioactivity of mono-PEGylated recombinant hirudin

HOU Beibei, LI Shirong, LI Xiaohui, XIU Zhilong

2007, 15(6): 775-780. doi:

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Hirudin, the most potent inhibitor of thrombin found in nature, has a short half-life in serum, which significantly limits its clinical application as an anticoagulant. Recently, PEGylation has been commonly used as an effective method to prolong its half-life in serum. In contrast to the nonspecific PEGylation under basic conditions that targets lysine residues randomly, PEGylation sites under mildly acidic conditions preferably targets histidine residues, and there is only one histidine residue at 51 in r-hirudin; therefore, succinimidyl carbonyl methoxy poly-ethylene glycol (SC-mPEG, 20000) was attached to r-hirudin at mildly acidic pH to favor the formation of mono- PEGylated r-hirudin. The reaction mixture with high mono-PEGylated ratio was easily separated by a one-step ion-exchange chromatographic (IEC) procedure. Approximately 79.71% of the mono-PEGylated r-hirudin was PEGylated at His51, which showed that the acidic PEGylation operation prevented the PEGylation of active center (Lys47) of r-hirudin in principle. Mono-PEGylated product with purity higher than 95% was obtained as the pre-dominant product, and 34% of the anticoagulant activity was retained in vitro. The staining method for sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was improved to obtain perfect electrophoretic pattern in less than 5min. More accurate molecular weight was deduced due to the use of PEGs as molecular weight standards.

Proteome analysis of the adaptation of a phenol-degrading bacterium Acinetobacter sp. EDP3 to the variation of phenol loadings

GENG Anli, LIM Ci Ji

2007, 15(6): 781-787. doi:

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Strain EDP3 was isolated from an industrial-activated sludge. It belonged to the gamma group of Proteobacteria with an identity of 97.0% to Acinetobacter calcoaceticus according to the 16S rRNA gene sequences. It can tolerate up to 1000mg•L－1 phenol at room temperature with a much longer lag phase. This indicates that higher phenol concentration has induced some physiological and genotypic changes in the bacterium. The aim of this study is, therefore, to investigate these responses to phenol concentration variations in strain EDP3. Proteome analysis is conducted by means of a two-dimensional polyacrylamide gel electrophoresis (2D PAGE) and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) was conducted to obtain a deeper insight into the adaptive responses inside the bacterium. Comparative analysis of the proteome profiles of strain EDP3 grown in 400mg•L－1 and 1000mg•L－1 phenol allowed us to identify that among all the proteins up-regulated under the higher phenol concentration, oxidative stress proteins were dominant. The synthesis of a heat shock protein, 60000 chaperonin GroEL, was also amplified. In addition, the expression of one membrane protein, adenosine 5′-triphosphate (ATP)-binding cassette (ABC) type sugar transporter, was found up-regulated. The inhibition of adenosine 5′-triphosphate (ATP) and RNA/protein synthesis was also observed.

Covalent assembly of penicillin acylase in mesoporous silica based on macromolecular crowding theory

WANG Anming a,b , ZHOU Cheng a , WANG Hua a , SHEN Shubao a , XUE Jianyue b , OUYANG Pingkai a

2007, 15(6): 788-790. doi:

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To improve the covalent immobilization of penicillin acylase (PA), macromolecular crowding theory was applied to its immobilization. Influence of mass ratio of enzyme to the silica, as well as, activation time with glutaraldehyde on the activity of assembled PA, was studied. In the mesopores, the effect of β-cyclodextrin (β-CD) on the immobilization of the enzyme was also investigated. It was remarkable that the coupled yield and relative activity reached 99.5% and 92.3%, respectively, when penicillin acylase assembled covalently in the mesopores. The results here indicate that mimicked macromolecule crowding could significantly ameliorate the performance of covalently immobilized PA.

Adaption of Au nanoparticles and CdTe quantum dots in DNA detection

DAI Zhao, ZHANG Jimei, DONG Quanxi, GUO Ning, XU Shichao, SUN Bo, BU Yuehua

2007, 15(6): 791-794. doi:

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A DNA fluorescence probe system based on fluorescence resonance energy transfer (FRET) from CdTe quantum dot (QD) donors to Au nanoparticle (AuNP) acceptors is presented. CdTe QDs, 2.5nm in diameter, as energy donors, were prepared in water. Au nanoparticles, 16nm in diameter, as energy acceptors, were prepared from gold chloride by reduction. CdTe QDs were linked to 5′-NH2-DNA through 1-ethyl-3-(dimethylaminopropyl)carbodiimide hydrochloride (EDC) as a linker, and the 3′-SH-DNA was self-assembled onto the surface of AuNPs. The hy-bridization of complementary double stranded DNA (dsDNA) bound to the QDs and AuNPs (CdTe-dsDNA-Au) determined the FRET distance of CdTe QDs and Au nanoparticles. Compared to the fluorescence of CdTe-DNA, the fluorescence of CdTe-DNA-Au conjugates decreased extremely, which indicated that the FRET occurred be-tween CdTe QDs and Au nanoparticles. The fluorescence change of this conjugate depended on the ratio of Au-DNA to CdTe-DNA. When the AuNPs-DNA to QD-DNA ratio was 10:1, the FRET efficiency reached a maxi-mum. The probe system would have a certain degree of fluorescence recovery when a complementary single stranded DNA was introduced into this system, which showed that the distance between CdTe QDs and Au nanoparticles was increased.

Preparation and in vitro studies of stealth PEGylated PLGA nanoparticles as carriers for arsenic trioxide

WANG Zhiqing, LIU Wei, XU Huibi, YANG Xiangliang

2007, 15(6): 795-801. doi:

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The aim of this study was to prepare arsenic trioxide (ATO)-loaded stealth PEGylated PLGA nanoparticles (PEG-PLGA-NPs) and to assess the merits of PEG-PLGA-NPs as drug carriers for ATO delivery. PEG-PLGA copolymer was synthesized with methoxypolyethyleneglycol (Mw＝5000), D, L-lactide, and glycolide by the ring-opening polymerization method. Amorphous ATO was transformed into cubic crystal form to increase its solu-bility in the organic solvent. ATO-loaded PEG-PLGA-NPs were prepared by the modified spontaneous emulsifica-tion solvent diffusion (SESD) method, and the main experimental factors influencing the characteristics of nanopar-ticles were investigated, to optimize the preparation. To confirm the escape of PEG-PLGA-NPs from phagocytosis by phagocytes, PEG-PLGA-NPs labeled rhodamine B uptake by murine peritoneal macrophages (MPM) were ana-lyzed by flow cytometry. The results showed that the physicochemical characteristics of PEG-PLGA-NPs were af-fected by the type and concentration of the emulsifiers, polymer concentration, and drug concentration. ATO-loaded PEG-PLGA-NPs, with particle size of 120.8nm, zeta potential of －10.73mV, encapsulation efficiency of 73.6%, and drug loading of 1.36%, were prepared under optimal conditions. The images of transmission electron micros-copy (TEM) indicated that the optimized nanoparticles were near spherical and without aggregation or adhesion. The release experiments in vitro showed the ATO release from PEG-PLGA-NPs exhibited consequently sustained release for more than 26d, which was in accordance with Higuchi equation. The uptake of PEG-PLGA-NPs by MPM was found to decrease markedly compared to PLGA-NPs. The experimental results showed that PEG-PLGA-NPs were potential nano drug delivery carriers for ATO.

Preparation of nitrogen-doped TiO₂ nanoparticle catalyst and its catalytic activity under visible light

YU Huang, ZHENG Xuxu, YIN Zhongyi, TAO Feng, FANG Beibei, HOU Keshan

2007, 15(6): 802-807. doi:

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N-doped TiO2 nanoparticle photocatalysts were prepared through a sol-gel procedure using NH4Cl as the nitrogen source and followed by calcination at certain temperature. Systematic studies for the preparation parameters and their impact on the structure and photocatalytic activity under ultraviolet (UV) and visible light irradiation were carried out. Multiple techniques (XRD, TEM, DRIF, DSC, and XPS) were commanded to characterize the crystal structures and chemical binding of N-doped TiO2. Its photocatalytic activity was examined by the degradation of organic compounds. The catalytic activity of the prepared N-doped TiO2 nanoparticles under visible light (＞400nm) irradiation is evidenced by the decomposition of 4-chlorophenol, showing that nitrogen atoms in the N-doped TiO2 nanoparticle catalyst are responsible for the visible light catalytic activity. The N-doped TiO2 nanoparticle catalyst prepared with this modified route exhibits higher catalytic activity under UV irradiation in contrast to TiO2 without N-doping. It is suggested that the doped nitrogen here is located at the interstitial site of TiO2 lattice.

Numerical simulation of gas holdup distribution in a standard Rushton stirred tank using discrete particle method

HAN Luchang, LIU Yuejin, LUO He'an

2007, 15(6): 808-813. doi:

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The discrete particle method was used to simulate the distribution of gas holdup in a gas-liquid standard Rushton stirred tank. The gas phase was treated as a large number of bubbles and their trajectories were tracked with the results of motion equations. The two-way approach was performed to couple the interphase momentum exchange. The turbulent dispersion of bubbles with a size distribution was modeled using a stochastic tracking model, and the added mass force was involved to account for the effect of bubble acceleration on the surrounding fluid. The predicted gas holdup distribution showed that this method could give reasonable prediction comparable to the reported experimental data when the effect of turbulence was took into account in modification for drag coefficient.

Compound heat transfer enhancement of a converging-diverging tube with evenly spaced twisted-tapes

HONG Mengna, DENG Xianhe, HUANG Kuo, LI Zhiwu

2007, 15(6): 814-820. doi:

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Pressure drop and compound heat transfer characteristics of a converging-diverging tube with evenly spaced twisted-tapes (CD-T tube) have been investigated experimentally. Swirl was generated by evenly spaced twisted-tape elements which vary in twist ratio and rotation angle. Space ratio also has an important effect on the characteristics. For comparison, experiments in a smooth circular tube and a converging-diverging (CD) tube with-out twisted-tapes were carried out. The results show that the twisted-tape with twist ratio y＝4.72 and rotation angle θ＝180° has the best performance among the four types of twisted-tapes presented in this paper. At Reynolds num-ber ranging from 3400 to 20000, when space ratio s＝48.6, the heat transfer efficiency index, which increases as the Reynolds number increases, is 0.85—1.21 and 1.07—1.15 compared to that of a smooth circular tube and a CD tube without twisted-tape inserts, respectively.

Experimental investigation of single-phase flow in structured packing by LDV

CHEN Jiangbo, LIU Chunjiang, LI Yingke, HUANG Ying, YUAN Xigang, YU Guocong

2007, 15(6): 821-827. doi:

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To date, many models have been developed to calculate the flow field in the structured packing by the computational fluid dynamics (CFD) technique, but little experimental work has been carried out to serve the vali-dation of flow simulation. In this work, the velocity profiles of single-phase flow in structured packing are meas-ured at the Reynolds numbers of 20.0, 55.7 and 520.1, using the laser Doppler velocimetry (LDV). The time-averaged and instantaneous velocities of three components are obtained simultaneously. The CFD simulation is also carried out to numerically predict the velocity distribution within the structured packing. Comparison shows that the flow pattern, velocity distribution and turbulent kinetic energy (for turbulent flow) on the horizontal plane predicted by CFD simulation are in good agreement with the LDV measured data. The values of the x-and z-velocity components are quantitatively well predicted over the plane in the center of the packing, but the predicted y-component is sig-nificantly smaller than the experimental data. It can be concluded that experimental measurement is important for further improvement of CFD model.

Quadrature method of moments for nanoparticle coagulation and diffusion in the planar impinging jet flow

YU Mingzhou, LIN Jianzhong, XIONG Hongbing

2007, 15(6): 828-836. doi:

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A computational model combining large eddy simulation with quadrature moment method was employed to study nanoparticle evolution in a confined impinging jet. The investigated particle size is limited in the transient regime, and the particle collision kernel was obtained by using the theory of flux matching. The simulation was validated by comparing it with the experimental results. The numerical results show coherent structure acts to dominate particle number intensity, size and polydispersity distributions, and it also induce particle-laden jet to be diluted by the ambient. The evolution of particle dynamics in the impinging jet flow are strongly related to the Reynolds number and nozzle-to-plate distance, and their relationships were analyzed.

Prediction of leakage rates through sealing connections with nonmetallic gaskets

GU Boqin, CHEN Ye, ZHU Dasheng

2007, 15(6): 837-841. doi:

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In this work, a model of gas leakage through nonmetallic gaskets was developed in order to predict leakage rate of gasket sealing connections. The model was verified by the leakage experiments on two types of gaskets: compressed non-asbestos fiber gasket and flexible graphite gasket reinforced with tanged metal sheet. The coefficients in the leakage rate formula were obtained by regression of experimental data for each type of gasket. The model was also validated against the experimental leakage data by other researchers and shown to produce ac-curate predications. Furthermore, the model was applied to a bolted flanged connection in service in order to assess the tightness of the connection.

The enhancement of CO₂ chemical absorption by K₂CO₃ aqueous solution in the presence of activated carbon particles

LU Sumin, MA Youguang, ZHU Chunying, SHEN Shuhua

2007, 15(6): 842-846. doi:

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The enhancement of chemical absorption of CO2 by K2CO3/H2O absorbents in the presence of activated carbon (AC) particles was investigated. The results show that the gas absorption rates can be enhanced significantly in the presence of AC particles, and the maximum enhancement factor 3.7 was observed at low stirring intensities. The enhancement factor increased rapidly with the solid loading during the initial period of absorption and then became mild gradually to a maximum value. Both the liquid-solid contact area and the probability of solid particles residing at the gas-liquid interface decreased with the increase of the particle size, leading to a negative effect on the enhancement of mass transfer. The influence of the particles on gas absorption decreased with the reaction rate. The stirring speed changed the interfacial coverage and mass transfer rate on the liquid side and consequently affected the mass transfer between the gas and liquid phases; the enhancement factor decreased with the stirring intensity. A heterogeneous two-zone model was proposed for predicting the enhancement factor and the calculated results agreed well with the experimental data.

Biosorption equilibrium and kinetics of Au(III) and Cu(II) on magnetotactic bacteria

SONG Huiping, LI Xingang, SUN Jinsheng, YIN Xiaohong, WANG Yanhong, WU Zhenhua

2007, 15(6): 847-854. doi:

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Magnetotactic bacteria (MTB) as biosorbents for the adsorption of Au(III) and Cu(II) ions from aqueous solution have been investigated. The optimum adsorption conditions for both metal ions were the initial pH scope of 1—5.5 for Au(III) and 2.0—4.5 for Cu(II), room temperature, biomass concentration of 10.0g•L－1 and sorption duration more than 10 min. When the initial metal concentration were within 500mg•L－1, the maximum biosorption capacity of 1.0g of MTB (dry mass basis) for Au(III) and Cu(II) were calculated as 505.2mg of Au(III) and 493.1mg of Cu(II) by Langmuir model in single system, respectively. The isotherm equilibrium of Au(III) and Cu(II) ions in the Au-Cu binary system reflected a unique phenomenon that the adsorption of Au(III) was reinforced and that of Cu(II) prohibited, compared respectively with their performances in the single metal system. When the concentration of Au(III) and Cu(II) were below 80mg•L－1, the wastewater after MTB treating was below 1.0mg•L－1, which is in conformity with Environmental Performance Standards (EPS) of Canada. Besides, all the kinetic data were fitted well to the pseudo second-order kinetic model with a high correlation coefficient (R2＞0.999).

Effect of ultrasound on the treatment of emulsification wastewater by ceramic membranes

SHU Li, XING Weihong, XU Nanping

2007, 15(6): 855-860. doi:

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Ultrasonic field was applied in the treatment of oil emulsification wastewater by ZrO2 ceramic membrane. The permeate flux, rejection ratio in the filtration process and recovery ratio of flux in the membrane cleaning process were measured. Great improvement in the permeate flux and rejection ratio have been observed for the membrane process enhanced by the ultrasonic field. The permeate flux of water through the membrane was about 210L•m－2•h－1 and the oil rejection ratio was over 99.9% under the optimal ultrasonic treatment conditions, which were 8W of ultrasonic power, 7cm of ultrasonic probe length introduced into the membrane channel and the same ultrasonic radiation direction as the wastewater flow. The resistance of the membrane process was compared between the cases with and without ultrasound, and the total resistance was reduced 68% by the use of ultrasound. Four methods including water cleaning, water cleaning under sonication, chemical cleaning and chemical cleaning under sonication were used to recover membrane flux. It was found that the flux recovery ratio increased with the increase of ultrasonic cleaning power. In addition, the use of chemical agents combining with ultrasonic irradiation showed a synergistic effect, which resulted in the highest cleaning efficiency and the shorter cleaning time.

Ultrasonically assisted extraction of isoflavones from stem of Pueraria lobata (Willd.) Ohwi and its mathematical model

XU Huaneng, ZHANG Yingxin, HE Chaohong

2007, 15(6): 861-867. doi:

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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 conventional extraction. Moreover, a mathematical model is proposed, by introducing the electrical power input to index the ultrasound intensity, to describe the behavior of ultrasonically assisted extraction. It is found that the model calculations are in good agreement with the experimental data.

Sorption of pyruvic acid with weakly basic polymer sorbents

HUANG Shaokai, QIN Wei, DAI Youyuan

2007, 15(6): 868-871. doi:

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Uptakes of pyruvic acid for two types of commercially available weakly basic polymer sorbents, D301G and D301R, have been measured over a wide pH range and at various salinities of MgSO4. The results show that the overloading adsorption of pyruvic acid occurs on both weakly basic polymer sorbents, and the overloading models can predict the experimental data of uptake very well. The overloading value for D301G is larger than that for D301R. The adsorption isotherm of pyruvic acid for both polymeric sorbents is greatly affected by the solution pH and MgSO4 concentration in the aqueous phase, and a high recovery efficiency of pyruvic acid from aqueous solution can be obtained at the solution pH around 2.

Macroporous resin adsorption for purification of flavonoids in Houttuynia cordata Thunb.

ZHANG Ying, LI Shufen, WU Xiwen, ZHAO Xing

2007, 15(6): 872-876. doi:

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Flavonoids are one main kind of effective components in Houttuynia cordata Thunb., which display a wide range of pharmacological activity. In this study supercritical fluid extraction (SFE) with carbon dioxide was first used as preparation step to remove the volatile components, which are also active components, from Houttuynia cordata Thunb. Then ultrasound-assisted extraction was used to obtain the crude flavonoids and the macroporous resin adsorption technology was further employed to purify the flavonoids. Nine kinds of macroporous resins with different properties were tested through static adsorption, and one macroporous resin labeled as D101 was selected. The effect of several factors, such as the ratio of column height to diameter, initial concentration and pH, on both flavonoids yield and content were explored by dynamic adsorption to obtain reasonable conditions of adsorption and desorption. The experimental results show that the content of flavonoids can be above 60% with flavonoids recovery of 93.3 % under the optimum conditions of purification. HPLC analysis of the final flavonoids product shows it contains quercitrin, hyperin, rutin and quercetin.

Supercritical carbon dioxide extraction of andrographolide from Andrographis paniculata: Effect of the solvent flow rate, pressure and temperature

A.C. Kumoro, Masitah Hasan

2007, 15(6): 877-883. doi:

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Andrographis paniculata Nees has been extensively used for traditional medicine and help against fever, dysentery, diarrhoea, inflammation, and sore throat. In this study, andrographolide, the main component of this plant was extracted from the leaves of A. paniculata using supercritical carbon dioxide. The operating pressures were varied from 7.50 to 20MPa, the temperatures were varied from 30℃ to 60℃, and the flow rates were varied from 0.5 to 4ml•min－1. The best extraction condition occurred at 10MPa, 40℃, and a flow rate of 2ml•min－1 for a 3g sample of A. paniculata ground-dried leaves. The measured extraction rate was found to be about 0.0174g of andrographolide per gram of andrographolide present in the leaves per hour of operation. The future studies must focus on the interaction between the various operating parameters such as temperature, pressure, and flow rate of supercritical carbon dioxide.

Effect of alumina particle size on Ni/Al₂O₃ catalysts for p-nitrophenol hydrogenation

CHEN Rizhi, DU Yan, XING Weihong, XU Nanping

2007, 15(6): 884-888. doi:

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The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences on physiochemical properties and catalytic activity of the resulting Ni/Al2O3 catalyst, but little influence on the selec-tivity. At a comparable amount of Ni loading, the catalytic activity of Ni/Al2O3 prepared with alumina support of smaller particle size is lower. The reduction behavior of the catalyst is a key factor in determining the catalytic ac-tivity of Ni/Al2O3 catalyst. The supported nickel catalyst 10.3Ni/Al2O3-3 improves the life span of the membrane by reducing fouling on the membrane surface compared to nano-sized nickel.

Effects of sulfur compounds on Cd partitioning in a simulated municipal solid waste incinerator

ZHANG Yanguo, LI Qinghai, MENG Aihong, CHEN Yong, ZHOU Yuqun, CHEN Changhe

2007, 15(6): 889-894. doi:

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The effect of sulfur compounds (including sulfur, sulfide, sulfite and sulfate), initial concentration of heavy metal and operating conditions on Cd emission in municipal solid waste (MSW) incineration were investigated using a simulated tubular furnace and simulated MSW spiked with Cd. The concentration of Cd was measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES) after digesting the samples including bottom ash, fly ash and flue gas according to related USEPA methods. The results show that S and Na2S tend to increase Cd partitioning in bottom ash, whereas Na2SO3 and Na2SO4 tend to reduce Cd partitioning in bottom ash. The effect of sulfur compounds on Cd partitioning in bottom ash was in the sequence of Na2S＞S＞Na2SO3＞Na2SO4. chemical equilibrium analysis is also performed to determine the effect of sorbents on Cd adsorption. The calculations show that S presents strong affinity for Cd and restrains Cd adsorption by SiO2, whereas when temperature rises to between 830℃ and 1030℃, Cd adsorption efficiency of SiO2 is over 80% and the efficiency of Al2O3 is up to 85%.

Hydroxylation of benzene with hydrogen peroxide over highly efficient molybdovanadophosphoric heteropoly acid catalysts

ZHANG Fumin, GUO Maiping, GE Hanqing, WANG Jun

2007, 15(6): 895-898. doi:

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Keggin type molybdovanadophosphoric heteropoly acids, H3+nPMo12－nVnO40 (n＝1—3), were prepared by a novel environmentally benign method, and their catalytic performances were evaluated via hydroxylation of benzene to phenol with hydrogen peroxide as oxidant in a mixed solvent of glacial acetic acid and acetonitrile. Various reaction parameters, such as reaction time, reaction temperature, ratio of benzene to hydrogen peroxide, concentration of aqueous hydrogen peroxide, ratio of glacial acetic acid to acetonitrile in solvent and catalyst concentration, were changed to obtain an optimal reaction conditions. H3+nPMo12－nVnO40 (n＝1—3) are revealed to be highly efficient catalyst for hydroxylation of benzene. In case of H5PMo10V2O40, a conversion of benzene of 34.5% with the selectivity of phenol of 100% can be obtained at the optimal reaction conditions.

Synthesis and characterization of waterborne epoxy curing agent modified by silane

LU Guangqi, SUN Jianzhong, ZHOU Qiyun

2007, 15(6): 899-905. doi:

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A novel waterborne epoxy curing agent was prepared using 3-glycidoxypropyl trimethoxysilane (GPTMS) as a termination agent of adduct, which was synthesized by triethylene tetramine (TETA) and liquid epoxy resin (E-51). The effects of the reaction temperature and time on the synthesis process were investigated experimentally. The particle size and the distribution of water dispersion of the curing agent were measured by dynamic light scattering (DLS). The structure of the products was characterized by Fourier transform infrared spectrometer (FTIR) and 1H-nuclear magnetic resonance (1H NMR). The properties of the synthesized curing agent and the epoxy resin film cured by it were also measured. The results showed that the appropriate temperature for the synthesis of adduct was at 65—75℃ and the reaction time was 4—5h, and that the suitable reaction temperature of curing agent synthesis was 75—85℃ and the reaction time was 3—4h. When the mass ratios of GPTMS and acetic acid were 3%—5% and 5%—10% respectively, the hardness, water resistance and adhesion of the cured film were improved significantly.

Fluorous biphase system of C₉F₁₈ and its use in esterification

SHI Hongxin, XIANG Juping, WU Hongke

2007, 15(6): 906-908. doi:

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Some apolar organic solvents is miscible with perfluorous nonene to form fluorous biphase systems. Perfluorous nonene could be used as a green solvent in equimolar esterification of carboxylic acids with alcohols without removal of water or ester formed. Perfluorous nonene made the esterification equilibrium to move right and the yields of esterification to enhance in different degrees as compared with that in the absence of perfluorous nonene. After esterification perfluorous nonene is easy to be recovered and recycled.

2,3,5-Triphenyl-2H-tetrazolium chloride and 2,4,6-tri(2-pyridyl)-s-triazine on the corrosion of mild steel in HCl

PANG Xuehui, HOU Baorong, LI Weihua, LIU Faqian, YU Zhigang

2007, 15(6): 909-915. doi:

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Electrochemical measurement, quantum chemical method, and scanning electron microscopy (SEM) were performed to investigate the inhibitive effect of 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) and 2,4,6-tri(2-pyridyl) -s-triazine(TPT) on the corrosion of mild steel in 1mol•L－1 HCl at room temperature. Impedance spectroscopy measurement showed that the polarization resistance increased and that double layer capacitance de-creased with the increase in the inhibitive concentration, and the results of potentiodynamic polarization showed that the inhibitors suppressed both cathodic and anodic processes of steel corrosion without change in the mecha-nism. Higher the orbital density distribution strength of the lowest unoccupied molecular orbital, higher is the molecule dipole, and lower energy gap between the energy of the highest occupied molecular orbital and the energy of the lowest unoccupied molecular orbital resulted in higher inhibitory efficiency. The results of SEM analysis showed that the metal was protected from aggressive corrosion by the addition of TTC and TPT.

Effect of magnetic field on the extraction process of acetone-water-trichloroethane system

SUN Yongli, LIU Yong, WU Songhai, JIA Shaoyi

2007, 15(6): 916-918. doi:

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In order to investigate the effect of magnetic field on the liquid-liquid extraction, the extraction in the acetone-water-trichloroethane system was studied under magnetic field with different magnetic induction intensity. The results showed that the effect of magnetic field was positive in the extraction process, and the partition coeffi-cient and the yield of acetone increased with the increasing magnetic induction intensity by 5.16%—8.35% and 1.85%—5.70% respectively. The effect of magnetic field on the extraction was intensified when the temperature became higher. The experimental data of the partition coefficient of acetone were correlated by the method of least square in terms of a power-law correlation.