Most Down Articles
Published in last 1 year | In last 2 years| In last 3 years| All| Most Downloaded in Recent Month | Most Downloaded in Recent Year|

Please wait a minute...
For Selected: Toggle Thumbnails
Pressure Drop Measurements on Distillation Columns
T.J. Cai, M. R. Resetarits
null    2011, 19 (5): 779-783.  
Abstract3228)      PDF(pc) (237KB)(22935)       Save
Pressure drops are of major importance for distillation/absorption columns. This paper mainly discusses how to correctly measure, interpret and use pressure drop data. The possible causes of incorrect pressure drop measurements are studied including the effects of pressure tap dimensions, locations, and vapor condensation etc. The effect of the static head of vapor on the pressure drop data and column pressures is evaluated. Variations of sec-tional pressure drops along the column are investigated based on the experimental data obtained from commercial size distillation columns at Fractionation Research, Inc. (FRI). For a packed column, it is found that the spacing between the liquid distributor and the top of the bed affects the overall pressure drop measurements, which is con-firmed by a fundamental fluid dynamics analysis.
Reference | Related Articles | Metrics
Isolation of Lysozyme from Chicken Egg White Using Polyacrylamide-based Cation-exchange Cryogel
YAN Luding, SHEN Shaochuan, YUN Junxian, YAO Kejian
null    2011, 19 (5): 876-880.  
Abstract6039)      PDF(pc) (339KB)(17692)       Save
An effective cation-exchange chromatographic method for lysozyme isolation from chicken egg white is presented, using supermacroporous cryogel grafted with sulfo functional groups. The chromatographic processes were carried out by one-step and sequential elution, respectively. Sodium phosphate buffer (pH 7.8) containing different concentrations of NaCl is used as elution agent. The corresponding breakthrough characteristics and elution behaviors in the cryogel bed were investigated and analyzed. Purity of lysozyme in the elution effluent was assayed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The maximum purity of the obtained lysozyme was about 96%, and the cryogel is demonstrated as a potential separation medium for purification of high-purity lysozyme from chicken egg white.
Reference | Related Articles | Metrics
Calculation of viscosities of liquid mixtures using Eyring's theory in combination with cubic equations of state
JIWeirong, D.A.Lempe
Abstract2210)      PDF(pc) (314KB)(10314)       Save
Cubic equations of state (EOS) have been combined with the absolute rate theory of Eyring to calculate viscosities of liquid mixtures. A modified Huron Vidal gE-mixing rule is employed in the calculation and in comparison with the van Laar and the Redlich-Kister-type mixing rule. The EOS method gives an accurate correlation of liquid viscosities with an overall average deviation less than 1% for 67 binary systems including aqueous solutions. It is also successful in extrapolating viscosity data over a certain temperature range using parameters obtained from the isotherm at a given temperature and in predicting viscosities of ternary solutions from binary parameters for either polar or associated systems.
Reference | Related Articles | Metrics
Preparation and Analysis of Fe3O4 Magnetic Nanoparticles Used as Targeted-drug Carriers
ZHAO Yuanbi, QIU Zumin, HUANG Jiaying
null    2008, 16 (3): 451-455.  
Abstract2407)      PDF(pc) (279KB)(9618)       Save
Fe3O4 magnetic nanoparticles were prepared by the aqueous co-precipitation of FeCl3·6H2O and FeCl2·4H2O with addition of ammonium hydroxide.The conditions for the preparation of Fe3O4 magnetic nanoparticles were optimized,and Fe3O4 magnetic nanoparticles obtained were characterized systematically by means of transmission electron microscope(TEM),dynamic laser scattering analyzer(DLS)and X-ray diffraction(XRD). The results revealed that the magnetic nanoparticles were cubic shaped and dispersive,with narrow size distribution and average diameter of 11.4 nm.It was found that the homogeneous variation of pH value in the solution via the control on the dropping rate of aqueous ammonia played a critical role in size distribution.The magnetic response of the product in the magnetic field was also analyzed and evaluated carefully.A 32.6 mT magnetic field which is produced by four ferromagnets was found to be sufficient to excite the dipole moments of 0.05 g Fe3O4 powder 2 cm far away from the ferromagnets.In conclusion,the Fe3O4 magnetic nanoparticles with excellent properties were competent for the magnetic carriers of targeted-drug in future application.
Reference | Related Articles | Metrics
Study on Kinetics of Iron Oxide Reduction by Hydrogen
HOU Baolin, ZHANG Haiying, LI Hongzhong, ZHU Qingshan
null    2012, 20 (1): 10-17.  
Abstract5212)      PDF(pc) (517KB)(8447)       Save
Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed.Influence of external diffusion,internal diffusion and heat transfer on the intrinsic reaction rate was investigated and the conditions free of internal and external diffusion resistance have been determined.In the experiments,in order to correctly evaluate the intrinsic kinetics parameters for reducing Fe2O3 to Fe3O4,the reaction temperatures were set between 440℃ and 490℃.However,in order to distinguish the reduction of Fe3O4 to FeO from that of FeO to Fe,the reaction temperature in the experiment was set to be greater than 570℃.Intrinsic kinetics of iron oxide reduction by hydrogen was established and the newly established kinetic models were validated by the experimental data.
Reference | Related Articles | Metrics
Prediction of leakage rates through sealing connections with nonmetallic gaskets
GU Boqin, CHEN Ye, ZHU Dasheng
Abstract2470)      PDF(pc) (241KB)(7583)       Save
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.
Reference | Related Articles | Metrics
SHEN Huamin, WENG Mengyan, WEI Boyi
Abstract1947)      PDF(pc) (3746KB)(7009)       Save
The solubility of NH_3 in water in multicomponent systems under high pressure is of extreme importance to the new integrated ammonia and urea process. This paper proposes a new method for calculating the vaporliquid equilibria for aqueous ammonia solutions under high pressure. Based on the experimental data of the binary system of NH_3-H_2O in the high concentration range, a model has been established for the activity coefficients of NH_3 and H_2O to describe the non-ideality of the liquid phase; and the modified SIRK equation of state for polar compounds has been used to describe the non-ideality of the vapor phase under high pressure. The reliability of this model has been examined in the light of the experimental data of the solubility of NH_3 in H_2O under high pressure in the systems of NH_3-H_2O-N_2, NH_3-H_2O-N_2-H_2-Ar-CH_4 and NH_2-H_2O-N_2-H_2, the last being from Guerreri et al. Both the accuracy of calculation and the concentration range for applicability of this model have been found to surpass those of Guerrerl’s model.
Related Articles | Metrics
Preparation of Butyl Chloride from Butanol and Hydrochloric Acid Using Ionic Liquids as Catalyst
SUN Aijun, NIE Yi, LI Chunxi, WANG Zihao
null    2008, 16 (1): 151-154.  
Abstract2767)      PDF(pc) (191KB)(6979)       Save
The catalytic performance of some quaternary ammonium salts for the liquid phase reaction of butanol and hydrochloric acid at different conditions was studied experimentally and compared with the traditional catalyst (ZnCl2). The organic ammonium catalysts investigated include ionic liquids N-butyl-N-methyl imidazolium fluobo-rate ([BMIM][BF4]) and N-butyl-N-methylimidazolium chloride ([BMIM]Cl) as well as hydrochloric salts of N-methylimidazol ([HMIM]Cl), pyridine ([HPy]Cl) and triethylamine ([HEt3N]Cl). It is shown that the intrinsic catalytic performance of all organic ammonium salts except [HEt3N]Cl is slightly superior to ZnCl2, while the selectivity of butyl chloride is nearly at the same level around 96%. The conversion of butanol increases slightly with temperature and the catalyst amount added while the variation of selectivity is not obvious. Based on the recycle experiments, the ionic liquids as catalyst for the reaction of butanol and hydrochloric acid can be used more than 5 times, which suggests great potential of using ionic liquids as novel catalyst for such reactions.
Reference | Related Articles | Metrics
The Design and Control of Distillation Column with Side Reactors for Chlorobenzene Production*
BO Cuimei, TANG Jihai, BAI Yangjin, QIAO Xu, DING Lianghui, ZHANG Shi
Chin.J.Chem.Eng.    2012, 20 (6): 1113-1120.  
Abstract4352)      PDF(pc) (408KB)(6818)       Save
The distillation column with side reactors (SRC) can overcome the temperature/pressure mismatch in the traditional reactive distillation,the column operates at temperature/pressure favorable for vapor-liquid separation,while the reactors operate at temperatures/pressures favorable for reaction kinetics.According to the smooth operation and automatic control problem of the distillation column with side reactors (SRC),the design,simulation calculation and dynamic control of the SCR process for chlorobenzene production are discussed in the paper.Firstly,the mechanism models,the integrated structure optimal design and process simulation systems are established,respectively.And then multivariable control schemes are designed,the controllability of SRC process based on the optimal steady-state integrated structure is explored.The dynamic response performances of closed-loop system against several disturbances are discussed to verify the effectiveness of control schemes for the SRC process.The simulating results show that the control structure using conventional control strategies can effectively overcome feeding disturbances in a specific range.
Reference | Related Articles | Metrics
A Study on Enhancement of Filtration Process with Filter Aids Diatomaceous Earth and Wood Pulp Cellulose
DU Lihong, CHEN Xu, LI Wenping, ZHU Qixin
null    2011, 19 (5): 792-798.  
Abstract3142)      PDF(pc) (359KB)(6703)       Save
In this paper, a study to enhance the filtration for solid/liquid materials difficult to be filtered, such as highly viscous, highly compactible or gel like materials, is presented. Filter aids diatomaceous earth and wood pulp cellulose are used to enhance the filtration by improving filter cake structure and properties in the filtration of a biological health product and a highly viscous chemical fiber polymer melt product. The property of solid/liquid systems, filtration at different flow rates, specific cake resistance, cake wetness, filtration rate, filtrate turbidity for filter aid selection and evaluation, and operation optimization are investigated. The results are successfully applied to industrial process, and can be used as a reference for similar filtration applications.
Reference | Related Articles | Metrics
Study on the Diffusion Coefficient of Sodium Chloride at Infinite Dilution in Supercritical
XIAO Ji, LU Jiufeng, CHEN Jian, LI Yigui
Abstract2315)      PDF(pc) (1370KB)(6543)       Save
The molecular dynamics (MD) was employed to simulate the diffusion coefficient of sodium
chloride at infinite dilution in supercritical water from 703.2 K to 763.2 K and from 30
MPa to 45 MPa. Based on the simulated data and the Patel-Teja(PT) equation of state and the
Liu-Ruckenstein equation, an equation for calculating the diffusion coefficient of NaCl at
infinite dilution in supercritical water is proposed. Both the agreement between the
simulated and correlated data, and that between the simulated and predicted data of
diffusion coefficients for NaCl in supercritical water ranging from 703.2 K to 803.2 K and
from 25 MPa to 50 MPa show that this equation is applicable for the calculation of
diffusion coefficients.
Reference | Related Articles | Metrics
New Development of Reverse Micelles and Applications in Protein Separation and Refolding
LIU Yang, DONG Xiaoyan, SUN Yan
null    2008, 16 (6): 949-955.  
Abstract3703)      PDF(pc) (184KB)(6237)       Save
Reverse micelles bring mild and effective microenvironments in organic solvent that contain biomolecules,which have attracted immense attention for application in the isolation of proteins,protein refolding,and enzymatic reaction.In this review,the application of reverse micelles for protein separation and refolding has been briefly summarized and various reverse micellar systems composed of different surfactants,including ionic,nonionic,mixed,and affinity-based reverse micelles,have been highlighted.It illustrates especially the potential application of the novel affinity-based reverse micelles consisting of biocompatible surfactant coupled with affinity ligands.Moreover,the importance to develop universal affinity-based reverse micelles for protein separation and refolding in the downstream processing of biotechnology has been pointed out.
Reference | Related Articles | Metrics
Effects of the supports on activity of supported nickel catalysts for hydrogenation of m-dinitrobenzene to m-phenylenediamine
LIU ,Yingxin, CHEN ,Jixiang, ZHANG ,Jiyan
Abstract2672)      PDF(pc) (196KB)(6095)       Save
The hydrogenation of m-dinitrobenzene to m-phenylenediamine in liquid phase was studied with the nickel catalysts supported on SiO2, TiO2, γ-Al2O3, MgO and diatomite carriers. Based on the experiments of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR),      temperature-programmed desorption of hydrogen (H2-TPD) and activity evaluation, the physico-chemical and catalytic properties of the catalysts were investigated. Among the catalysts tested, the SiO2 supported nickel catalyst showed the highest activity and selectivity towards m-phenylenediamine, over which 97.3% m-dinitrobenzene con-version and 95.1% m-phenylenediamine yield were obtained at 373K under hydrogen pressure of 2.6MPa after re-action for 6 h when using ethanol as solvent. Although TiO2 and diatomite supported nickel catalysts also presented high activity, they had lower selectivity towards m-phenylenediamine. As for γ-Al2O3 and MgO supported catalysts were almost inactive for the object reaction. It was shown that both the activity and selectivity of the catalysts were strongly depended on the interaction between nickel and the support. The higher activities of Ni/SiO2, Ni/TiO2 and Ni/diatomite could be attributed to the weaker metal-support interaction, on which Ni species presented as crystal-lized Ni metal particles. On the other hand, there existed strong metal-support interaction in Ni/MgO and Ni/-Al2O3, which causes these catalysts more difficult to be reduced and the availability of Ni active sites de-creased, resulting in their low catalytic activity.
Reference | Related Articles | Metrics
New Synthetic Method of Ciprofloxacin
CHEN Yingqi, DAI Liyan
Abstract2545)      PDF(pc) (1233KB)(6071)       Save
A new synthetic method of ciprofloxacin is started with 2,4-dichloro-5-fluoroacetophenone,
via oxaly lation, ethoxymethylenation, amination, cyclization, hydrolysis, decarbonylation
and piperazination. The reaction temperature is moderate and the operation is easily
controlled. Additional four new compounds are prepared by the method.
Reference | Related Articles | Metrics
Modeling and control of a continuous stirred tank reactor based on a mixed logical
dynamical model
DU Jingjing, SONG Chunyue, LI Ping
Abstract2225)      PDF(pc) (271KB)(5948)       Save
A novel control strategy for a continuous stirred tank reactor (CSTR) system, which has the
typical characteristic of strongly pronounced nonlinearity, multiple operating points, and
a wide operating range, is initiated from the point of hybrid systems. The proposed scheme
makes full use of the modeling power of mixed logical dy-namical (MLD) systems to describe
the highly nonlinear dynamics and multiple operating points in a unified framework as a
hybrid system, and takes advantage of the good control quality of model predictive control
(MPC) to design a controller. Thus, this approach avoids oscillation during switching
between sub-systems, helps to relieve shaking in transition, and augments the stability
robustness of the whole system, and finally achieves optimal (i.e. fast and smooth)
transition between operating points. The simulation results demonstrate that the presented
ap-proach has a satisfactory performance.
Reference | Related Articles | Metrics
Issues in Freeze Drying of Aqueous Solutions
WANG Wei, CHEN Mo, CHEN Guohua
null    2012, 20 (3): 551-559.  
Abstract4537)      PDF(pc) (344KB)(5836)       Save
Freeze drying or lyophilization of aqueous solutions is widely used in pharmaceutical industry.The increased importance of the process is gaining a worldwide interest of research.A growing body of literature has demonstrated that the scientific approach can result in improved product quality with minimum trial and error empiricism.Formulation and process development need a systematical understanding of the physical chemistry of freezing and freeze drying,material science and mechanisms of heat and mass transfer.This paper presents an overview on freeze drying of aqueous solutions based on publications in the past few decades.The important issues of the process are analyzed.
Reference | Related Articles | Metrics
Macroporous resin adsorption for purification of flavonoids in Houttuynia cordata Thunb.
ZHANG Ying, LI Shufen, WU Xiwen, ZHAO Xing
Abstract2682)      PDF(pc) (175KB)(5833)       Save
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.
Reference | Related Articles | Metrics
The Research Progress of CO2 Capture with Ionic Liquids
ZHAO Zhijun, DONG Haifeng, ZHANG Xiangping
Chin.J.Chem.Eng.    2012, 20 (1): 120-129.  
Abstract6821)      PDF(pc) (274KB)(5502)       Save
Due to their negligible volatility,reasonable thermal stability,strong dissolubility,wide liquid range and tunability of structure and property,ionic liquids have been regarded as emerging candidate reagents for CO2 capture from industries gases.In this review,the research progresses in CO2 capture using conventional ionic liquids,functionalized ionic liquids,supported ionic-liquids membranes,polymerized ionic liquids and mixtures of ionic liquids with some molecular solvents were investigated and reviewed.Discussion of relevant research fields was presented and the future developments were suggested.
Reference | Related Articles | Metrics
Advances in the Research and Development of Acrylic Acid Production from Biomass
XUXiaobo, LINJianping, CENPeilin
Abstract2456)      PDF(pc) (276KB)(5493)       Save
The shortage of petroleum has resulted in worldwide efforts to produce chemicals from renewable resources. Among these attempts, the possibility of producing acrylic acid from biomass has caught the eye of many researchers. Converting the carbohydrates first to lactic acid by fermentation and then dehydrating lactic acid to acrylic acid is hitherto the most effective way for producing acrylic acid from biomass. While the lactic acid fer-mentation has been commercialized since longer times, the dehydration process of lactic acid is still under devel-opment because of its low yield. Further efforts should be made before this process became economically feasible. Because of the existence of acrylic acid pathways in some microorganisms, strain improvement and metabolic en-gineering provides also a possibility to produce acrylic acid directly from biomass by fermentation.
Reference | Related Articles | Metrics
Process Characteristics of CO2 Absorption by Aqueous Monoethanolamine in a Microchannel Reactor
YE Chunbo, CHEN Guangwen, YUAN Quan
null    2012, 20 (1): 111-119.  
Abstract4754)      PDF(pc) (262KB)(5441)       Save
Process characteristics of CO2 absorption using aqueous monoethanolamine(MEA) in a microchannel reactor were investigated experimentally in this work.A T-type rectangular microchannel with a hydraulic diameter of 408 μm was used.Operating parameters,i.e.temperature,pressure and molar ratio of MEA to CO2 were studied.Under 3 MPa pressure,the mole fraction of CO2 in gas phase could decrease from 32.3% to 300×10-6 at least when gas hourly space velocity ranged from 14400 to 68600 h-1 and molar ratio of MEA to CO2 was kept at 2.2.In particular,the effects of temperature on CO2 absorption flux,mass transfer driving force,gas-liquid contact time and enhancement factor were analyzed in detail and found that mass transfer enhancement by chemical reaction was a crucial factor for the process of CO2 absorption.
Reference | Related Articles | Metrics