Table of Content

20 June 2016, Volume 16 Issue 3

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An Immerged Fibre-optic Photoimaging Method for Measurement of Bubble Size

CHEN Fang-yuan LI Ping-ping LI Xiang-yang YANG Chao MAO Zai-sha

Chin. J. Process Eng.. 2016, 16(3):  361-366.  DOI: 10.12034/j.issn.1009-606X.215417

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An immerged photoimaging system was developed to measure bubble size distribution, which mainly consisted of a fibre-optic endoscope, an image acquisition system and a light source. Bubbles generated by a microbubble generator and two ceramic microporous tubes with different pore-sizes were measured using this system, and the results were compared with those by the conventional sampling photoimaging method. The bubble sizes generated by the three generators ranged from 50 to 2000 mm. The difference between the two methods was not obvious when the bubble diameter was smaller than 200 mm. However, it became significant when the bubble diameter was larger than 200 mm. This is probably because smaller bubbles are relatively more stable, and bigger bubbles are easy to coalesce, leading to measurement errors in the sampling course. The results suggest that this new method is capable of measuring a wide range of bubble sizes reliably, and can be used for in-situ measurement of bubble size in gas-liquid systems, verification of other methods and numerical simulation.

Flow Characteristic of Particle Agglomerates in a Gas-Solid Fluidized Bed

HUANG Ya-hang LIU Meng-xi HU Juan

Chin. J. Process Eng.. 2016, 16(3):  374-379.  DOI: 10.12034/j.issn.1009-606X.215426

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Transient solid hold-up signals were registered in a cold fluidized bed and statistically analyzed. Particle agglomerates in the emulsion phase were identified from signals and the agglomerate properties were investigated. The volume fraction of the transient solid holdup signals varied from 0.05 to 0.72. Mean solid holdup of particle agglomerates in the emulsion fluctuated in the range of 0.552~0.562, barely influenced by switch of operation pattern. The volume fraction of the particle agglomerates decreased first and then increased with increasing superficial gas velocity, varying over a range of 0.01~0.5 with flow regimes. Agglomerate frequency varied over the range of 0.02~1.6 Hz and the duration time was less than 0.12 s in most cases.

Gas Dispersion Behaviors in a Cylindrical and Conical Moving Bed

JIA Hai-bing LI Chen WEI Si-chen FAN Yi-ping LU Chun-xi

Chin. J. Process Eng.. 2016, 16(3):  380-387.  DOI: 10.12034/j.issn.1009-606X.215376

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The gas dispersion behavior in the cylindrical and conical moving bed was investigated/compared by using the helium gas tracing technique. The experimental results show that radial flow of cylindrical bed assumes a plug pattern while the axial gas distribution of conical bed was non-uniform in the main flowing zone (0.110.89), the gas bypassing appears in the cylindrical moving bed and radial flow of conical bed tends to a plug pattern. Because the gas bypassing would be reduced by about 40%~50% in conical bed. According to the radial flow characteristics in the cylindrical and conical moving bed, furthermore, an empirical model for estimating the axial distribution of gas concentration was established based on the experimental data and the theoretical analysis, which agreed with the experimental data.

Preparation of Micro-droplets and Their Rising Process in Stagnant Liquid

CHENG Shi-meng DENG Chao-jun HE Xiong-yuan XU Bo-ya HUANG Wei-xing

Chin. J. Process Eng.. 2016, 16(3):  388-393.  DOI: 10.12034/j.issn.1009-606X.215409

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A co-axial microfluidic device was designed and assembled, and the micro-droplets of 100~600 mm with good spheric shape were successfully prepared. The test shows that the droplet diameter dp was mainly determined by the tapered tip Dt (40~450 mm) of the microfluidic devices. For a given tapered tip, the dp decreased with increasing flow rate Qc of the continuous phase. The increase in the flow rate of the dispersed phase only had a minor effect on the droplet diameter, but increased the frequency of micro-droplet generation. Based on the test, the correlations between dp and Qc for the device of different sizes are presented and their correlation coefficients are all above 0.99. Then the rising velocities of micro-droplets of soybean oil and toluene in stagnant liquid were measured. The results show that, unlike the millimeter-scale droplets which usually have lower drag coefficient CD than the rigid particles due to deformation, the relation of CD versus Re for micro-droplets is consistent with that for the rigid particles and the reason for this finding is given in terms of interfacial tension. Observation shows that, due to the wake effect, the bulk velocity of the droplet swarms is 30% higher than the single droplet with the same diameter.

Numerical Simulation on Erosion of Wall by Particles in a 90o Bending Duct of Ventilation Pipeline

ZHANG Li-an QIAN Fu-ping HU Jia XIA Yong-jun YANG Hong LU Jin-li HAN Yun-long

Chin. J. Process Eng.. 2016, 16(3):  394-401.  DOI: 10.12034/j.issn.1009-606X.215347

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The gas-solid two-phase flow in 90o bending duct of the ventilation and dust removal pipeline was simulated using CFD-DPM, and the erosion rate of the bending duct by anthracite coal particle was calculated, and the influence of the bend diameter R/D ratio of the bending duct, inlet gas velocity, particle size and the materials properties of the duct wall on the erosion was also analyzed. And, the results of numerical simulation were compared with those of experiment and by empirical formula in the literature. The results show that the numerical simulation results match the experimental data and empirical formula calculation values, which indicates that the numerical simulation results are probably credible. When the inlet gas velocity and the particle size are fixed, the erosion rate of the bending duct decreases first and then increases with increasing R/D. When R/D is 3~4, the erosion rate is relatively small, the relational expression between the erosion rate and the inlet gas velocity is E=KV1.08~1.32 when the bend diameter ratio is constant, and the inlet gas velocity is 0~5 m/s, the change of the erosion rate with the inlet gas velocity is small, but when the inlet gas velocity is greater than 5 m/s, the trend is opposite. The relational expression between the erosion rate and the particle size is E=Kdp2.38~3.01. The smaller the bend diameter ratio, the more obvious the erosion rate changes with the dust particle size. And when the dust particle size is smaller than 5 mm, the erosion rate is almost zero. In addition, the materials properties of the duct wall (such as brinell hardness) also influence the erosion rate, and the erosion rate of the material with the great brinell hardness is lower than that of the material with the small brinell hardness.

Numerical Simulation on Mixing Process of Sludge and Solid Particles in a Stirred Tank Equipped with Shifted Propeller

ZHU Gui-hua ZHANG Li-xin MA Kai WANG Wan-bin

Chin. J. Process Eng.. 2016, 16(3):  402-406.  DOI: 10.12034/j.issn.1009-606X.215401

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The granular sludge mentioned this paper in the 1m diameter stirred tank contains 92%(w) water and 0.01 m diameter solid granule. The numerical simulations of mixing processes of sludge and solid granule in the stirred tanks equipped with six shifted blades propeller (6SBP) and six blades propeller (6BP) were conducted respectively by using Fluent software. The numerical analysis of the concentration field distributions, the mixing times and the mixing energy per unit volume under the above two different propellers were carried out according to the simulation results, and the particles concentration distribution was demonstrated by experiment. The results show: the simulation curves of particles concentration distribution consists with the experimental one well. The mixing process is closely related to the flow pattern, and the concentration field distribution with shifted stirring blades tends to be stable faster. The 6SBP exhibits high perfomance in terms of mixing efficiency, the mixing time of six shifted blades propeller is 27 s at agitation speed of 4 r/s, while it costs 6BP 9 s more under the same condition. And the mixing energy per unit volume by six shifted blades propeller is only 79.6% of that by normal propeller.

Extraction of Propionic Acid from Fermentation Broth by Ion-exchange Chromatography

CUI Xiao-peng YANG Hai-peng XU Guo-xia WANG Zi-qiang WANG Yun-shan; ZHANG Li-ping SU Zhi-guo

Chin. J. Process Eng.. 2016, 16(3):  407-412.  DOI: 10.12034/j.issn.1009-606X.215311

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The adsorption capacity of 7 ion-exchange resins with different properties for propionic acid in the fermentation broth was investigated. The effects of fermentation broth acidification method and pH value on the resin adsorption capacity were studied. The elution processes with different concentrations of H2SO4 were analyzed. The feasibility of in series multi-column chromatography to increase the yield of propionic acid was discussed. The results showed that ZGD630, a macroporous weak-base anion exchange resin had the highest adsorption capacity for propionic acid. D001 H-type cation exchange resin acidization method was determined. When pH value decreased to 3 from 6.5, the static state adsorption capacity of ZGD630 increased from 54.34 mg/g to 110 mg/g dry beads, with a dynamic adsorption capacity of 152.5 mg/g. The highest propionic acid concentration during the elution process (4 mol/L H2SO4) reached 81.8 g/L, which was 2.12 times the original fermentation broth concentration. A recovery yield of 62.15% was obtained for propionic acid with in series three-column combined chromatography, a significant improvement compared to the one-column chromatography.

Microextraction Enrichment of Phenol in Water with [Bmim]PF6-TBP Extractant

DENG Yu-chen CHEN Yu-huan HOU An-yu SUN Yi

Chin. J. Process Eng.. 2016, 16(3):  413-417.  DOI: 10.12034/j.issn.1009-606X.215419

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1-Butyl-3-methyl imidazolium hexafluorophosphate ([Bmim]PF6) and tributyl phosphate (TBP) were combined as a binary extractant to extract phenol. Influencing variables on the enrichment performance of the binary extractant such as the volumes of [Bmim]PF6 and TBP, pH, temperature and salt were investigated. The enrichment mechanism was explored. The results showed that a high enrichment factor of 128 was achieved in 30 mL TBP-30 mL [Bmim]PF6 system at a low temperature of 273.15 K without addition of salt and buffer solution. The high enrichment performance was attributed to the interaction between P==O of TBP and ?H of phenol OH.

Chromatographic Separation of Gamma-Aminobutyric Acid

LANG Li JIANG Li-hua QIU Yong-jun ZHOU Jia-chun ZHAO Li-ming

Chin. J. Process Eng.. 2016, 16(3):  418-423.  DOI: 10.12034/j.issn.1009-606X.215384

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Eight resins were tested systematically to select the best one for the chromatography separation of gamma-aminobutyric acid (GABA) and monosodium glutamate (MSG). Then the influence of the ratio of length to diameter of column, flow rate of mobile phase and column temperature on the separation efficiency of GABA and MSG were investigated in terms of resolution and recovery. Finally, the separation efficiency of fermentation broth was concretely studied. The results showed that the resin QY-HG01 separated GABA and MSG well. The best separation efficiency was achieved under the operating conditions of ratio of length to diameter 25, flow rate of mobile phase 2.5 mL/min and column temperature 50℃ through the single factor experiments. Injected with the pretreated fermentation broth, it was found that GABA and MSG were separated well. The decolorization rate of the fermentation broth was 84.9%, and the desalinization rate was 99.2%. The purity of GABA increased from 24.9% in the broth to 80.4% in the eluent with a recovery yield of 89.3%.

Preparation of Lithium Carbonate from a Li-bearing Desorption Solution

CAO Wei SUN Shu-ying; SONG Xing-fu YU Jian-guo;

Chin. J. Process Eng.. 2016, 16(3):  424-430.  DOI: 10.12034/j.issn.1009-606X.215395

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The process of removing impurity ions from the eluent and preparation industrial grade lithium carbonate powder was investigated in this study. The eluent was obtained by eluting MnO2 ion-sieve precursor after adsorption process with HCl solution. The effects of enrichment on impurities removal efficient, NaOH consumption, size of the precipitate, and lithium loss rate of the precipitation process were systematically investigated. Na2CO3 was used to precipitate Li+ in the 5 times concentrate eluent via HPRO after removal impurity ions. The results indicate that the concentrate rate had an essential effect on impurities removal efficient, size of the precipitate, and lithium recovery rate. The optimal purification process was determined as follows: HPRO permeate of an enrichment of 5, the ending pH=12, the feed rate of NaOH was 72 mL/min, and the stirring speed is 300 r/min. Mg2+ and Mn2+ in the solution can be completely removed under the optimum operation condition, the maximum mean practical size of Mg(OH)2 and MnO2×H2O blended precipitate reached 28.05 mm and the alkali consumption [molar ratio of NaOH/(Mn2++Mg2+)] is reduced to 3.48. Li2CO3 with a purity of 99.51% and mean size of 16.38 mm was produced by adding Na2CO3 directly to the 5 times concentrated eluent after removal of impurity ions. The purity of Li2CO3 powder conformed to the national primary standards of GB/T 11075-2013 and the maximum Li+ recovery rate reached 71.26%.

Optimization of the Nickel Modified Active Carbon Used for Adsorption of Methane by Response Surface Method

ZHENG Bei-lei LIN Qin PAN Hong-yan LIU Xiu-juan ZHAO Min CHENG Zheng ZHAO Chun-liang

Chin. J. Process Eng.. 2016, 16(3):  431-437.  DOI: 10.12034/j.issn.1009-606X.215423

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The active carbon was modified by Ni(NO3)2 for adsorption methane which from the low concentration coal-bed gas. In order to optimization the conditions of nickel modified active carbon the Box-Behnken central composite design experiments which based on the univariate tests and response surface method were used. The result showed that the optimized conditions of nickel modified active carbon were Ni(NO3)2 concentration 0.21 mol/L, temperature 730℃, and time 67 min. Under the conditions, the breakthrough time was 550 s, adsorption capacity was 58.07 mL/g, the modified active carbon has superior adsorption performance.

Pyrolysis Characteristics and Kinetics of Schizochytrium-Coal Mixture

WANG Ya-bing HAO Xiao-hong YIN Hai MA Yi CUI Guo-min

Chin. J. Process Eng.. 2016, 16(3):  438-444.  DOI: 10.12034/j.issn.1009-606X.215372

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Pyrolysis process of schizochytrium-coal blends was studied by thermo-gravimetric analysis (TGA) to search the pyrolysis characteristics and interaction in the process of co-pyrolysis. The results showed that the peak width at half height of DTG curves of microalgae and coal were 225 and 68℃ respectively, and the starting temperature of devolatilization were 225 and 183℃ respectively, thus, the devolatilization of coal was slower and occurred over a wider temperature range. With the increase of the content of microalgae in blends, the release index of comprehensive characteristics of volatile D and the activity increased gradually. The interaction between microalgae and coal was related to the proportion of the sample. When the mass ratio of coal to algae was 1:1, the difference between the calculated value and the measured value of the maximum weight loss rate was 0.83%/min, which was inhibited in the process of pyrolysis. When the mass ratio of coal to algae was 3:1 or 1:3, the interaction was not obvious. The pyrolysis kinetics were investigated by Coats-Redfern integral method, and the results showed that the processes could be simplified as a first-order reaction.

Process Mechanism of Vanadium-containing Slag Roasting and Alkali Leaching

MENG Li-peng WANG Shao-na DU Hao ZHENG Shi-li

Chin. J. Process Eng.. 2016, 16(3):  445-451.  DOI: 10.12034/j.issn.1009-606X.215352

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The conversion and dissolution mechanism of vanadium in the process of blank roasting and alkali leaching were studied. The results showed that vanadium in spinel (FeV2O4) was gradually oxidized into VO2 and V2O5, and then formed vanadate by combining with Ca/Mn/Mg. Leaching process ccan be divided into low temperature leaching (T<180℃) and high temperature leaching. Low temperature leaching only extracted vanadate and vanadium oxide, while high temperature leaching (T≥180℃) extracted the vanadium in the form of solid solution in calcium silicate. Vanadium leaching rate in blank roasting and alkali leaching process reached 97.63%, while the rate of traditional process was only 80%. The application of blank roasting and alkali leaching process could realize the high efficiency and clean extraction of vanadium from vanadium-bearing slag.

Flocculation Mechanism of Synthetic Goethite Suspension Using Hydroxamated Polymer and Sodium Polyacrylate

WANG Meng HU Hui-ping CHEN Xiang-pan LIU Jin-wei CHEN Qi-yuan

Chin. J. Process Eng.. 2016, 16(3):  452-462.  DOI: 10.12034/j.issn.1009-606X.215388

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The flocculation effects of homemade hydroxamated flocculant (HPAA) and commercially available sodium polyacrylate (PAAS) on synthetic goethite suspensions with different solid contents were studied. The adsorption mechanism of HPAA or PAAS on the surfaces of goethite was investigated. The settling rate of 50 g/L goethite suspension with HPAA (1.74 m/h) was faster than that with PAAS (0.54 m/h), which indicated that HPAA exhibits better flocculation performance than PAAS does. It could be found that the stretching vibration of carbonyl band in hydroxamic acid groups of HPAA was downshifted from 1654 cm-1 to 1645 cm-1 and a new adsorption band appeared at 1455 cm-1, which demonstrated that a five-membered ring chelate may be formed among iron atoms of goethite surfaces, the hydroxyl groups and the carbonyl groups in hydroxamic acid groups of HPAA. In the case of PAAS, the separation of the asymmetric and symmetric stretches of the carboxylate groups in adsorbed PAAS was 163 cm-1, which was greater than that of unadsorbed PAAS with 157 cm-1. There was no indication of a contribution from the monodentate adsorption between iron atoms of goethite surfaces and carboxylate groups of PAAS, but there may exist a bi-dentate bridging structure. Compared with synthetic goethite, XPS curve fittings of Fe 2p spectra showed that the binding energies of the main Fe 2p3/2 and Fe 2p1/2 resolved peaks on HPAA-treated goethite surfaces were correspondingly decreased by 0.9 and 0.7 eV, while those on PAAS-treated goethite surfaces were correspondingly decreased by 0.7 and 0.3 eV. The characteristic N 1s peak of HPAA and C 1s peak of PAAS were correspondingly detected on HPAA-treated and PAAS-treated goethites, and a binding energy change of N 1s spectrum of adsorbed HPAA was observed. The relative atomic ratios of C/Fe, N/Fe and O/Fe on HPAA-treated and PAAS-treated goethite surfaces were increased. All the results suggested that HPAA or PAAS was adsorbed on the goethite surfaces by the chemisorption, and a stronger adsorption of HPAA on the goethite surfaces happened than that of PAAS.

Effects of Width and Density of Insulation Material of Expandable Polystyrene on Flame Spread and Combustion Characteristics

ZHAO Jie HUANG Xin-jie LIU Wei ZHANG Ying SUN Jin-hua

Chin. J. Process Eng.. 2016, 16(3):  463-469.  DOI: 10.12034/j.issn.1009-606X.215357

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A series of lab-scale experiments were carried out for expandable polystyrene (EPS) with the densities of 18 and 25 kg/m3 and widths of 4, 8, 12 and 16 cm respectively. The representative parameters such as the length of pool fire zone, flame height and flame spread speed, were investigated. The results showed that the flame structures of EPS during flame spread process included the typical type, the reverse type and merged type. When the width of the sample was 8 cm, the flame structures behaved almost as the reverse and merged types for the worse instability of flame during spread. The average length of pool fire wais longer for 18 kg/m3 than for 25 kg/m3 with the same width, which can be attributed to the faster flame spread speed with the lower density for EPS. The flame spread speed of EPS with the density of 18 kg/m3 was almost two times of that with the density of 25 kg/m3, due to the air in the cells which promotes combustion. It was also found that the surface flame height was mostly controlled by the width of EPS, while the flame height in the pool fire was mostly controlled by the ratio of the length to the width of the pool fire.

Effects of CO2 and Oxygen-enriched Air on Combustion of Methane and Ethylene

CHU Hua-qiang CAO Wen-jian FENG Yan REN Fei XU Jing GU Ming-yan

Chin. J. Process Eng.. 2016, 16(3):  470-476.  DOI: 10.12034/j.issn.1009-606X.215371

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The effect of dilution gas addition is an important topic in the field of gaseous fuel combustion. In the present study, the effects of CO2 addition and oxygen enrichment on the characteristics of laminar coflow methane and ethylene diffusion flames were investigated experimentally. The shape and temperature distribution of the flames under different atmospheres were analyzed. With the increase of oxygen concentration from 21% to 50%(j), the height decreased by about 70% for both flames, while the flame temperature and brightness increase. Under the same oxygen concentration, the brightness of the ethylene flame is higher than that of the methane flame. With the increase of CO2 concentration from 0 to 20%(j), the flame height increased by 28%, and the average edge temperature of the flame at each height decreased by 290℃, and the centerline temperature decreased by 132℃. The flame brightness is reduced from yellow color to dull yellow, and the visible flame base sligts down towards the burner rim. When the CO2 concentration is more than 20%(j), the flame will be lifted, and eventually blown out.

Effects of Ca2+ and Al3+ on the Polymerization of Silicic Acid without Na+

SHEN Xing-mei LI Liao-sha WU Xing-rong ZHU Jian-hua AI Jin

Chin. J. Process Eng.. 2016, 16(3):  477-481.  DOI: 10.12034/j.issn.1009-606X.215403

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To eliminate the effect of Na+ on the polymerization of silicic acid, silicic acid without any metal ions was prepared by acid hydrolysis of water-quenched calcium sillicate. After adding Ca2+, pH value of silicic acid slightly decreased, while it significantly decreased after adding Al3+. The polymerization rate of silicic acid is accelerated by Al3+ at initial pH≤2, but reduced at initial pH>2. As for Ca2+, it had no obvious effect on polymerization of silicic acid. After gelation, Al?O?Si bond was formed in the silica gel, which hindered dehydration of bound water. The crystallization process was hindered by Ca2+, and the amount of bound water decreased. The chemical formulas of silica gels with no ions, Ca2+ and Al3+ are SiO2×0.52H2O, SiO2×0.36H2O, SiO2×1.50H2O, respectively.

Preparation and in vitro Evaluation of Enrofloxacin Complex Taste-masking Microcapsules

LIU Meng-xi DENG Feng-ying FU Hua-lin YIN Dai-ping ZHANG Ji-quan LI Rui

Chin. J. Process Eng.. 2016, 16(3):  482-487.  DOI: 10.12034/j.issn.1009-606X.215385

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Solid dispersion was combined with microencapsulation technique to prepare composite taste-masking microcapsules of enrofloxacin for animals. Then, optimal preparation conditions of microcapsules were determined by a single factor and orthogonal experiments based on simulated oral release, drug loading capacity and encapsulation efficiency. Relevant properties of the composite microcapsules prepared with optimal methods were investigated. The results indicated that the optimized formulation conditions included 15 g/L sodium alginate solution, 1.0 mm aperture of adding needle, 100 g/L CaCl2 and 10 min curing time. The prepared composite microcapsules had a good appearance. The drug loading, encapsulation efficiency and average particle diameter of the prepared microcapsules were 20.3%, 89.8%, and 273.67 mm respectively. The release rate of microcapsule in the simulated oral fluid in 30 s was less than pigs' bitterness threshold to enroflloxacin. Therefore the composite microcapsules had a good taste masking effect.

Application of Red Bean Originated Carbonyl Reductase in the Preparation of (R)-Phenylethanediol

PENG Yi-qiang JU Han-xue

Chin. J. Process Eng.. 2016, 16(3):  488-493.  DOI: 10.12034/j.issn.1009-606X.215392

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Carbonyl reductasese (CR) with the ability of aromatic ketone asymmetry reduction was extracted from red bean (CRrb) by grinding, centrifigation, filtration and acetone precipitation. CRrb liquid with 5.8 fold increase in purity was achieved by rapid purification, and its enzymatic properties were examined and compared with the microbe origin CR. CRrb was coupled with formate dehydrogenase (FDH) to construct a bi-enzyme system to continuously catalyse the reaction of b-hydroxyacetophenone to (R)-phenylethanediol. The results showed that the optimal reaction pH value of CRrb was 6.0, and the optimal reaction temperature of CRrb was 45℃. It showed higher thermostability between 40~60℃ than the microbe origin CR. The kinetics parameters (Michaelis constant Km and maximum reaction velocity Vmax) of CRrb were 5.68 mmol/L and 20.21 mmol/(min×mL) respectively, which indicate its affinity with the substrate and catalysis efficiency were higher than CR from microbe origin. Under the optimization reaction conditions of coupling system, the substrate tolerance concentration reached 60 mmol/L which was higher than the microbe origin CR. The reaction efficiency of the coupling system was the highest when the enzymatic activity rate of CRrb/FDH was optimized as 1:1.5, and the acquired production mol number when 1 mol cofactor was turned of coupling system batch reaction was improved from 266 mol to 365 mol.

Immobilization of Glucoamylase onto Electrospun PAA/PVA Microfibrous Membrane by Active Ester Method

SUI Chun-hong WANG Zhao-yi WEI Yu-qing WANG Cheng

Chin. J. Process Eng.. 2016, 16(3):  494-499.  DOI: 10.12034/j.issn.1009-606X.215389

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The carboxyl groups of poly(acrylic acid) (PAA)/polyvinyl alcohol (PVA) microfibrous membranes were activated by using dicyclohexyl-carbodiimide and N-hydroxysuccinimide. The free amines of glucoamylase were reacted with the activated carboxyls to form ester bond, which immobilized the enzyme onto the electrospun PAA/PVA microfiber by covalent bonds. The enzymatic reaction of the immobilized glucoamylase was investigated. The results showed that glucoamylase was attached on the surface of electrospun PAA/PVA composite microfibrous membrane, and the diameter of the fiber was about 435 nm. The maximum reaction velocity (Vmax) and michaelis constant (Km) of the immobilized glucoamylase were 5.77 g/(L×h) and 10.45 g/L, respectively. The optimum pH range and temperature of the immobilized enzyme were similar to those of the free enzyme. Immobilized glucoamylase had higher storage stability. It retained 62% of the original activity in 12 d, as compared to about 40% for the free enzyme. The immobilized glucoamylase could be used for 10 times while retaining 40.5% of its activity.

Synthesis of Phytosterol Esters Catalyzed by Immobilized Lipase in Solvent-free System

ZHOU Hai-yan JIANG Zhen-hua REN Li-wei YU Min ZHOU Hua WEI Ping

Chin. J. Process Eng.. 2016, 16(3):  500-504.  DOI: 10.12034/j.issn.1009-606X.215298

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The aim of this work is to synthesize lauric acid phytosterol esters by lipase in solvent-free system. The lipase was immobilized on macroporous resin NKA, with addition of dextran. The reaction conditions were optimized. The results showed that under the optimized conditions of a molar ratio of lauric acid to phytosterol of 6:1, 7.5% dextra of molecular weight 10 kDa and the reaction temperature of 60℃ in solvent-free system, the esterification rate reached 96.2% after 12 h. The reaction time of the synthess of phytosterol esters decrease 4 h comparing with the immobilized lipase on a macroporous resin.

Identification and Release Behavior of Wheat Germ Protein with Mass Spectrometry

WANG Kai KONG Ying-jun KANG Ji-yao GAO Jian-ping ZHANG Ze-yu ZHANG Gui-feng WANG Ming-lin

Chin. J. Process Eng.. 2016, 16(3):  505-509.  DOI: 10.12034/j.issn.1009-606X.215370

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Release behavior of proteins from defatted wheat germ during extraction process was investigated. Proteins in wheat germ suspension were separated using high performance liquid chromatography (HPLC), and the separated proteins were identified using mass spectrometry (MS). Then, the relative release rate and release quantity of different proteins in wheat germ were compared during extraction process. The result indicated that the release rate was related to the molecular weight of the proteins. All proteins were released faster in the dynamic extraction than in the static extraction. The chromosome 3B protein with the retention time of 18.78 min during HPLC separation had the fastest release rate, and the release ratio reacheded to 90% after two extraction.

Preparation of Cu-20%W Composite Powders via in-situ Reaction

XU Yu-song TIAN Guo-jian GU Yong-zhen YUE Zhan-feng

Chin. J. Process Eng.. 2016, 16(3):  510-515.  DOI: 10.12034/j.issn.1009-606X.215377

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In-situ co-precipitation method was adopted to get precursor powder CuWO4-Cux(OH)yCO3 in which the elements content was controlled precisely by using Na2CO3 at high temperatures. Fine Cu-20%W composite powders were obtained through subsequent two-stage hydrogen reduction. The structure, phase composition, distributions of elements and particle size of the prepared powders were characterized. The results showed that the pale green precursor powders mainly consisted of CuWO4 and Cu4(OH)6CO3 under the reaction conditions of pH 5, temperature 75℃, the (NH4)2WO4/Na2CO3 molar ratio of 1/10.578 and the reaction solution 300 mL. The element recovery rate reached 95%. After two-stage hydrogen reduction of 0.5 h at 450℃ and 0.5 h at 600℃, the composite powder particle was nearly spherical in shape with a size of 400~800 nm. Copper was semi covered by tungsten and the two elements distributed uniformly.

Preparation Conditions of Semi-coke via Pyrolysis of Low-rank Coal in an Integrated Fluidization Bed

ZHOU Qi BAI Li-qiang CHEN Zhao-hui GAO Shi-qiu XU Guang-wen

Chin. J. Process Eng.. 2016, 16(3):  516-521.  DOI: 10.12034/j.issn.1009-606X.215418

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Preparation conditions of semi-coke via pyrolysis of Xinjiang Zhundong coal with different sizes were studied in an integrated fluidization bed consisting of a fluidization bed section at the bottom and a transport bed section at the top. The effects of pyrolysis temperature, excessive oxygen ratio (ER), gasification temperature and residence time on product distributions and char properties were investigated. The yield of pyrolysis gas increased with ER, gasification temperature and residence time, while the yields of char and tar decreased. The specific surface area of the char increased with the gasification temperature, while it first increased and then decreased with ER. When coal was fed into the fluidization bed, the semi-coke with the fixed carbon content over 83%(w) and volatile matter below 9%(w) was obtained under the operating conditions of ER of 0.11, gasification temperatures of 850℃ in the fluidization bed, pyrolysis temperature of 750℃ in the transport bed, and coal particle residence time of 90 s in the fluidization bed.

Catalytic Properties of Hexagonal Mesoporous Silica Supported Phosphoric Acid

GAO Liang-jun CHEN Ping

Chin. J. Process Eng.. 2016, 16(3):  522-528.  DOI: 10.12034/j.issn.1009-606X.215351

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H3PW12O40×nH2O (HPW) supported on hexagonal mesoporous silica (HMS) was prepared via impregnation method to obtain modified mesoporous HMS (HPW/HMS). The surface structure and acidty of the samples were characterised. The catalytic performance of HPW/HMS was tested through Friedel-Crafts acylations of 2-methoxynaphthalene (2-MN) with acetic anhydride (AA). The results showed that the obtained HPW/HMS catalyst displayed a typical mesoporous structure. HPW was well dispersed on the HMS support, and the acidity increased with the amount of HPW loading. Under the conditions of 120℃, 4 h, HPW/HMS 0.3 g, molar ratio of 2-MN to AA 1:2, the conversion rate of 2-MN was 75.3%(mol) and the selectivity of the main product 2-methoxy-1-acetonaphthone was up to 83.0%(mol). Repeated experiments demonstrated a slight decline in the catalytic activity.

Particle Distribution Measurement of SiO2-based Phase Change and Humidity Controlling Composite Material with Fine Particle Size by Laser Particle Size Analyzer

ZHANG Hao LIU Xiu-yu ZONG Zhi-fang ZHU Qing-ming DU Xiao-yan LIN Xiao-fei

Chin. J. Process Eng.. 2016, 16(3):  529-532.  DOI: 10.12034/j.issn.1009-606X.215406

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Using SiO2 as the carrier and hexadecanol-palmitic acid-lauric acid as a phase change material, SiO2-based phase change and humidity controlling composite materials were prepared by the sol-gel process. The effects of solute concentration, ultrasonic time, ultrasonic power and dispersing medium on the particle size measurements were investigated by using median particle diameters (d50) as an evaluation indicator. The results indicated that the laser particle size analyzer (test range 1~10000 nm) is applicable to the particle size measurement of SiO2-based phase change and humidity controlling composite materials showing high reproducibility. The dispersion effect of water is better than that of alcohol. When the solute concentrationwas 5~10 g/L, the needed ultrasonic time was longer than 15 min and ultrasonic power was higher than 400 W, optimum dispersion results of SiO2-based phase change and humidity controlling composite materials can be achieved using water as the dispersing medium.

Research Advances in the Structures of High Gravity Process Engineering Devices

FENG Zhi-rong JIAO Wei-zhou YU Li-sheng LI Xiao-xia WANG Yong-hong LIU You-zhi

Chin. J. Process Eng.. 2016, 16(3):  533-540.  DOI: 10.12034/j.issn.1009-606X.215424

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High gravity technology (HiGee) is a kind of new intensification technology in chemical process intensification which has been applied in many fields of chemical engineering. The research progress in the structures of high gravity process engineering devices in recent decades was reviewed and the structure characteristics and occasion applicable of all kinds of high gravity devices were analyzed and summarized. Structure design of impinging steam-rotating packed bed (IS-RPB)，rotating zigzag bed (RZB), splitting packing-rotating packed bed (SP-RPB), multistage spraying-rotating packed bed, rotating bed with Helix channels and so on were specifically analyzed, the advantages and disadvantages of various structures were evaluated. Finally, brief analysis of the structure development tendency in the future of high gravity device was presented.