Table of Content

20 August 2016, Volume 16 Issue 4

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Flow and Transfer

Mechanical Radial Distribution of Particles Concentration in a Riser Reactor

LI Chen FAN Yi-ping JIA Hai-bing HUANG Shi-ping FAN Han-wen

Chin. J. Process Eng.. 2016, 16(4):  541-548.  DOI: 10.12034/j.issn.1009-606X.215364

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Based on the Kutta?Joukwski lift force law in aerodynamics, the force on particles is analyzed, and the theoretical method FK?J??g(vg,Z?vp,Z)(?vp,Z/?r)r to calculate Kutta?Joukowski force on particle group in riser is proposed. Furthermore, the local solid holdup and particle velocity profile are studied by PV-6D optical fiber density apparatus via a large-scale cold-model experiment. With the former theoretical method, the radial profile of the Kutta?Joukowski force is proposed on the basis of the experiment results. The influence of solid circulation rate, superficial gas velocity and axial position on Kutta?Joukwski lift force is analyzed. The results show that when dimensionless radius r/R?0, Kutta?Joukwski lift force is 0, r/R is 0.85, Kutta?Joukwski lift force is maximized, Kutta?Joukwski lift force increases with solid circulation rate, the superficial gas velocity has no significant effect on the radial distribution of Kutta?Joukwski lift force, the value in fully developed zone is larger than accelerating zone and export restrained zone. Furthermore, the empirical formulae for the estimation of the radial distribution of Kutta?Joulowski force is set up based on the experimental data and theoretical analysis. The computed and experimental results are in good agreement.

Analysis on Evolution of Longitudinal Vortexes in Fully Developed Zone of a Kenics Static Mixer

LI Quan-shu WEI Si-yuan GONG Bin ZHANG Jing

Chin. J. Process Eng.. 2016, 16(4):  549-555.  DOI: 10.12034/j.issn.1009-606X.215413

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The large eddy simulation (LES) is used to study the fully developed flow fields in Kenics statics mixer. The formation inducement and evolution process of secondary flow is analyzed. Simulated data coincide well with experimental data. The results based on the current researched contents show that there are three kinds of longitudinal vortices in the area of the seventh twisted element. They are designated as merged-vortex, internal- vortex and detour-vortex. Merged-vortex produces by merging two vortices from the entrance of element. And internal- vortex grows by the rotation of the twisted blade. The detour-vortex is induced by the Coriolis force caused by high twist rate of the twisted blade. And the Coriolis force will lead to the unbalance pressure distribution and the separation of boundary layer, thus the induced vortices will come into being. The area of the seventh element is divided into four segments along the axial direction. There are five vortices in the first and second segments, and the values of vorticity and turbulent intensity are 23.0% and 8.93% higher than that in the third and fourth segments respectively. The vorticity increases suddenly near the pipe wall on the interface of the neighboring elements, which is 73.0% higher than the average values, because the energy dissipation is caused by breakup and coalescence of vortices.

Effect of Feed Sprays on Gas?Solid Two-phase Flow and Mixing in a Riser

CHEN Sheng YAN Zi-han WANG Wei FAN Yi-ping LU Chun-xi

Chin. J. Process Eng.. 2016, 16(4):  556-564.  DOI: 10.12034/j.issn.1009-606X.215430

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In order to improve the uneven mixing of catalyst particles and feed in a feedstock injection zone of FCC Riser, the formation mechanism of the nonuniform mixing is studied through both experiment and 3-D CFD simulation over a large-scale cold-model riser. The effects of operating conditions on the mixing behavior are further investigated. Based on the formation mechanism, a novel scheme of feedstock injection is proposed and compared with the traditional scheme. The result indicates that the traditional scheme of feedstock injection leads to the uneven mixing. A desirable operating condition [Gs?80 kg/(m2?s), Ug?3.28 m/s, Ujet?62.5 m/s] can improve the distributions of solids and feed, reduce the axial range of catalyst-feed mixing by half, but the uneven mixing persist. The novel design especially the 30o downward scheme can be expected to realize a desired mixing.

Estimation of Gas Holdup in a Gas?Liquid Stirred Vessel

FAN Bing-qiang ZHANG Yang ZHENG Shi-li FENG Xin WANG Shao-na CHEN Xiao-fang QIAO Shan

Chin. J. Process Eng.. 2016, 16(4):  565-570.  DOI: 10.12034/j.issn.1009-606X.216108

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The gas holdup in an air?water systems is measured using the method of differential pressure and the electric conductive probes. N and M are measured by the torque transducer and used to calculate the power input. A physical model was developed to predict the total gas holdup in a gas?liquid stirred vessel by dividing the gas in the liquid into two parts that A is the one entering and quitting the liquid, and B is the other recycling in the liquid, respectively, The results indicate that based on the difference between flow regimes in gas?liquid systems, it is reasonable that the total gas holdup should divided into two stages: ?total??Vs? for the flooding condition, ?total??Vs?+?PV?Vs? for the loading/completely dispersing conditions, and as for DT+DT, ??6, ??1, ??0.32, ??0.56, ??1. The results from literatures are predicted by the model reasonably. The model is reasoned for some other types of dual-impellers, in which ? is controlled by the types of the impellers.

Influence of Back Pressure on Discharge Property of U-valve

JIAO Fang-ran LI Hong-zhong ZHU Qing-shan

Chin. J. Process Eng.. 2016, 16(4):  571-576.  DOI: 10.12034/j.issn.1009-606X.216122

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In order to investigate the influence of the back pressure on the solid discharge rate of the U-valve, a setup with adjustable back pressure was established. Experimental results revealed that the solid discharge rate, as well as the effective aeration rate on the solid discharge rate decreased with increasing the back pressure. Both the back pressure and the orifice height had significant influence on the discharge behavior of the U-valve. When the back pressure fluctuation was significant, the operation of the U-valve was more stable with a smaller orifice height. The orifice height had a suitable range to obtain a stable discharge rate, i.e., the orifice height was less than 0.11 m, the back pressure was less than 7 kPa, the back pressure was greater than 13 kPa, and the orifice height was more than 0.15 m. In addition, the solid discharge rate was correlated with the back pressure, the aeration rate, and the orifice height. The average relative error was 20.9% between the calculated and the experimental data. Based on this correlation, the reasonable range of orifice height was calculated to provide the guidance for the design of U-valves.

Reaction and Separation

Leaching Kinetics of Reductively Roasted Slag with HCl

SHAO Da-wei LIU Ya-hui WANG Wei-jing CAO Cheng-bo QI Tao

Chin. J. Process Eng.. 2016, 16(4):  577-583.  DOI: 10.12034/j.issn.1009-606X.216146

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Aiming at a new type of roasted titanium slag which is prepared with a new process proposed by Institute of Process Engineering, the process of leaching roasting titaniferous slag with hydrochloric acid under pressure was using to solve the problem of low sulfuric acid decomposition rate. The effects of ratio of liquid to solid, leaching temperature, acid concentration, leaching time on Ti leaching rate were studied and the optimal reaction condition was obtained. Roasted titaniferous slag was leaching with 30%(?) hydrochloric acid which ratio of liquid to solid was equal to 8 mL/g, the whole process was keeping 2 h at 120℃, then the leaching rate of TiO2 can reach up to 95%. According to the dynamics equations of layer diffusion control model of solid product and the Arrhenius equation, kinetic equation of leaching in hydrochloric acid system at atmospheric pressure can be obtained with the effect of reaction temperature on leaching rate of Ti and Ca, which is 1+2(1?x)?3(1?x)2/3?11.4e?31.2/(RT)t. Meanwhile, its reaction apparent activation energy is Ea??31.2 kJ/(mol?K).

Recovery of Valuable Elements in Jaroaite Residue by Hot Acid Leaching

LIU Peng-fei ZHANG Yi-fei YOU Shao-wei BO Jing JIANG Xiao-duo

Chin. J. Process Eng.. 2016, 16(4):  584-589.  DOI: 10.12034/j.issn.1009-606X.216125

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Sulfuric acid and hydrochloric acid were used to research leaching process of Fe, Si, Zn, Pb in jarosite residue. The results showed that sulfuric acid leaching, leaching rate of Fe, Zn reached 80% under the optimum conditions of leaching temperature of 95℃, reaction time of 2 h, stirring speed of 300 r/min, concentration of sulfuric acid of 1.2 mol/L and mass ratio of liquid to solid of 100:5. Hydrochloric acid leaching, leaching rate of Fe, Zn, Pb reached to 83%, 89%, 99% under the optimum conditions of leaching temperature of 95℃, reaction time of 1.5 h, stirring speed 400 r/min, concentration of hydrochloric acid 2.8 mol/L and mass ratio of liquid to solid 100:5. Jarosite was used to get rid of Fe in leaching solution. Jarosite residue can be fixed treatment to finally obtain zn-rich Solution.

Leaching Kinetics of Chlorogenic Acid from Eucommia ulmoides Leaves

GU Nan-nan WANG Tian-gui XIAO Qing-gui XU Hong-bin WANG Shao-na

Chin. J. Process Eng.. 2016, 16(4):  590-595.  DOI: 10.12034/j.issn.1009-606X.216124

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Ethanol solution was employed as a solvent for extracting chlorogenic acid (CGA) from Eucommia ulmoides leaves, and HPLC was used to determine the concentration of CGA in the extraction liquid. The process variables, such as the ratio of liquid to solid, the ethanol concentration, the extraction temperature and extraction time, were investigated in detail. The optimum parameters were as follows: ratio of liquid to solid of 10 mL/g, ethanol concentration of 60%(?), extraction temperature of 60℃ and extraction time of 40 min. Under the optimum conditions, the extraction yield of CGA reached up to 90.21%. The infusion rates of CGA at different temperatures were measured and the rate constants of infusion were calculated and obtained. The results indicated that the extraction of CGA in ethanol solution was controlled by internal diffusion. The extracting process was satisfied with the internal diffusion kinetic model, and the apparent activation energy was 11.46 kJ/mol.

Separation and Recovery and Identification of Toluene Diamine from Byproduct Tar of Amine Light Gasification

BAI Fang HUA Chao, LU Ping LIANG Xiang-feng LIU Hui-zhou

Chin. J. Process Eng.. 2016, 16(4):  596-600.  DOI: 10.12034/j.issn.1009-606X.215397

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This work investigated the separation process and contents of ortho toluene diamine (O-TDA), metra toluene diamine (B-TDA) of by-product tar of amine light gasification. We discussed the effect of the pressure, temperature, speed, dripping speed on O-TDA, B-TDA contents in tar coupling with the falling film evaporation technology. The contents of TDA in the tar were quantitative identified by orthogonal experiment optimization. The results show that the optimal separation conditions are at temperature of 200℃, 15 kPa pressure, rotating speed of 30 r/min, and the feed rate of 1.5 r/min, then the separating efficiency is best with a relative standard deviation of 1.1%?1.5%.

Optimization and Evaluation on Adsorption and Desorption of ?-Poly-L-lysine on Amberlite IRC-50 Resins

GAO Yang HE Hong-gang LI Fang-liang YUAN Guang-jie CHEN Xu-sheng MAO Zhong-xian

Chin. J. Process Eng.. 2016, 16(4):  601-606.  DOI: 10.12034/j.issn.1009-606X.215434

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The adsorption capacity and elution rate of H+-form and Na+-form as well as NH4+-form Amberlite IRC-50 (IRC-50) resins for ?-poly-L-lysine (?-PL) at different pH values and eluant concentrations were evaluated by static adsorption experiment. Meanwhile, the dynamic adsorption and elution processes of three forms of IRC-50 resins were also studied. The results revealed that the optimum pH value of three forms of IRC-50 resins for ?-PL adsorption was 8.0, the saturated adsorption capacity were 238.7, 293.3 and 298.1 mg/g, respectively. In addition, the optimum concentration of the eluent for three forms of IRC-50 resin was 0.1 mol/L, and the elution rate reached more than 96%. The results of dynamic adsorption and elution experiments indicated that the purity of ε-PL obtained by Na+-form and NH4+-form resins were 12% higher than that of H+-form resin. Moreover, the kinetic adsorption rate constants for Na+-form and NH4+-form resins are nearly 2 times more than that of H+-form resin. Therefore, Na+-form and NH4+-form resins are more suitable for the separation and extraction of ?-PL than H+-form resin.

Process and Technology

Experimental Study and Mechanism Analysis of Pre-oxidation Decaking of Coal at Low Temperatures

FU Ying-hui FAN Chui-gang LI Song-geng SONG Wen-li LIN Wei-gang

Chin. J. Process Eng.. 2016, 16(4):  607-614.  DOI: 10.12034/j.issn.1009-606X.216154

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Pre-oxidation decaking experiments with a fixed bed at low temperature were carried out on a kind of strongly caking coal mined from Pingdingshan District. The results showed that longer reaction time could lower coal caking index, but temperature had complex effects on the coal caking properties. While the oxidation temperature was 200℃, the caking index of raw coal decreased from 81 to 3.49 after 8 h. Solid state 13C-NMR characterization indicated that, after oxidation, aliphatic side-chains in macromolecular structure of coal was broken and had a lower content than before, while the content of oxygen functional groups increased and the aromatic structure remained stable. At the same time, content of aliphatic carbon bonded to oxygen falO, content of aromatic carbon bonded to oxygen faP, content of carbonyl carbon faC and aliphatic hydrocarbon carbon falC?H showed a good linear dependence on coal caking index GR.I.. The equations were falO??0.012GR.I.+5.53, faP??0.013GR.I.+7.03, faC??0.014GR.I.+5.25 and falC?H?0.041GR.I.+19.46, and their coefficients of determination were 0.889, 0.722, 0.623 and 0.581, respectively.

Physico-chemical Properties of [1ChCl:2EG]/CrCl36H2O Deep Eutectic Solvents

ZHANG Xian-jie ZHANG Zhi LI Jian HUA Yi-xin XU Cun-ying LI Yan

Chin. J. Process Eng.. 2016, 16(4):  615-621.  DOI: 10.12034/j.issn.1009-606X.215425

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The melting points, density, surface tension, viscosity and conductivity of [1ChCl:2EG]/CrCl3?6H2O deep eutectic solvents (DESs) ionic liquids as a function of temperatures and concentration of CrCl3?6H2O had been studied, respectively. The results showed that [1ChCl:2EG]/CrCl3?6H2O DESs have the lowest melting points (211 K), indicating it has wider liquid range at low temperature. It shows a good linear relationship between the density and temperature, with the temperature increasing, the density increased slightly. The surface tension lower than water but higher than traditional organic solvent and increases with the concentration of the CrCl3?6H2O. As temperature increases from 293 K to 343 K, the viscosity of [1ChCl:2EG]/CrCl3?6H2O DESs decreases significantly, but the conductivity increases obviously, and the DESs have the minimum viscosity and the maximum conductivity at the concentration of 0.3 mol/L CrCl3?6H2O. The CrCl3?6H2O and [1ChCl:2EG]/(0.3 mol/L) CrCl3?6H2O DES were decomposed into CRO3 at 923 K, and could maintain stable performance below 383 K.

Experimental Investigation of the Influence of Ethanol on the Condensation Heat Transfer of Gravity Loop Thermosyphon without Vacuum

HUANG Jian SHEN Jian-biao WANG Li

Chin. J. Process Eng.. 2016, 16(4):  622-628.  DOI: 10.12034/j.issn.1009-606X.216120

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Herein we experimentally investigated the influence of ethanol on condensation heat transfer of gravity loop thermosyphon in presence of massive non-condensable gas. Investigated results revealed that addition of 0.5%?1% mass fraction of ethanol formed Marangoni effect on the surface of condensate film, promoted local condensation heat transfer, and increased 9% local heat flux of the inlet section of the condenser. When the ethanol content was greater than or equal to 1.5%, ethanol cannot fully condense to form the new non-condensable gas, the pressure of the system and temperature of evaporator could be increased, and the higher ethanol content, the higher system pressure, the system pressure of 5% condition was 64% more than pure vapor condition.

Co-gasification Characteristics of Distillery Residue with Coal Char in CO2 Atmosphere

ZHANG De-cheng AO Xian-quan CHEN Qian-lin CAO Yang XIE Yan LUO Huan-hu ZHANG Ji-fang

Chin. J. Process Eng.. 2016, 16(4):  629-633.  DOI: 10.12034/j.issn.1009-606X.215438

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Co-gasification reactivity of distillery residue and coal char with CO2 was studied by a fixed bed reactor. The pore structure, surface elemental composition and ash mineral composition of the experimental samples were investigated by scanning electron microscopy analysis methods, X-ray spectroscopy and X-ray diffraction. The results showed that the co-gasification reactivity of distillery residue and coal char with CO2 have significant synergies, and except CO2, the main production of this reactivity is CO, H2 and CH4. The highest concentration is produced of the three gases under the blending ratio of the distillery residue of 80%. The gasification temperature and the blending ratio of distillery residue are the major factors which affect the co-gasification reactivity. At the same blending ratio of distillery residue, the co-gasification reactivity increased with increasing temperature within a temperature range of 900?1100℃. At the same temperature, the co-gasification reaction activity increased with increasing of the blending ratio of distillery residue at the range of 20%?80%. Distillery residue contains volatile content as high as 69.47%, inducing a large amount of pore structure during gasification. The induced pore, the potassium and calcium contained in the distillery residue and coal char, are the main factors for improving the co-gasification reactivity.

Co-pyrolysis Characteristics of Shenmu Bituminous Coal and Huadian Oil Shale

SHI Yong LAI Deng-guo CHEN Zhao-hui GAO Shi-qiu CUI Ping XU Guang-wen

Chin. J. Process Eng.. 2016, 16(4):  634-638.  DOI: 10.12034/j.issn.1009-606X.216126

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The co-pyrolysis characteristics and related synergistic mechanism of Shenmu bituminous coal and Huadian oil shale at different blending ratios were studied in TG analyzer and fixed bed reactor. The results showed that the experimental values of weight loss from co-pyrolysis was higher than the calculated one, indicating that the possible interaction during co-pyrolysis could promote the release of volatiles and suppress the char production. The synergistic effect between coal and oil shale increased the oil yields and decreased the yields of water and char, presenting as the obvious effect of increasing oil and decreasing water in co-pyrolysis of Shenmu coal and Huadian oil shale. When the mass ratio of Huadian oil shale to Shenmu coal was 1:1, the highest oil yield was obtained of 9.84% and increased by 8.8% comparing to the calculated oil yield. Co-pyrolysis contributed to the increase of light oil content and yield. When the mass ratio of Huadian oil shale to Shenmu coal was 1:4, the light oil content higher than 80%, and yield was about 7.5%, increased by 8% and 11.2% compared with the calculated values, respectively, demonstrating that addition of a small amount of oil shale can obviously improve the pyrolysis oil quality. The hydrogen-rich components and radicals from oil shale pyrolysis helped to inhibit the polymerization of aromatics produced by coal pyrolysis and facilitated the conversion of aromatics into oil products, thus increased the pyrolysis oil yield and quality.

Biochemical Engineering

Immune Effect of HTCC Hydrogel Microspheres and the Blending Emulsion of Oil and Microspheres as New Adjuvants of Combined Vaccine against Newcastle Disease and Avian Influenza

ZOU Yong-juan LIU Yan WANG Yue-qi WU Jie GONG Fang-ling, MA Guang-hui

Chin. J. Process Eng.. 2016, 16(4):  639-646.  DOI: 10.12034/j.issn.1009-606X.216134

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Aiming to enhance the immune efficacy of the combined vaccine against newcastle disease and avian influenza, N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC) hydrogel microspheres and the blending emulsion of oil with microspheres (MPs) were investigated as vaccine adjuvants. After optimization, the maximized antigen absorption efficiency reached 90% when the antigens were incubated with 2 mg/mL microspheres with the size of 1 ?m for 2 h. In vivo experiments indicated that both the microspheres and blending emulsion significantly enhance the antigen specific HI titers. In detail, the blending emulsion group was superior to the microspheres in the enhancement of HI titers. Most importantly, both the microspheres and blending emulsion could induce robust and long-term cellular immune responses compared to oil adjuvant, and the proliferation levels of peripheral blood mononuclear cells were 1.5 folds to that of the soluble antigen group. These results suggested that the HTCC hydrogel microspheres and blending emulsion would be promising adjuvants for poultry vaccine.

Security Evaluation of N-(2-Hydroxy)propyl-3-trimethylammonium Chitosan Chloride Microspheres as Parenteral Vaccine Adjuvant

WU Jing-jing WU Nan YUE Hua WU Xing-lan NAKANISHI Hideki GAO Xiao-dong MA Guang-hui

Chin. J. Process Eng.. 2016, 16(4):  647-653.  DOI: 10.12034/j.issn.1009-606X.215427

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The safety evaluation of N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTCC) microspheres as parenteral vaccine adjuvant was carried out in mice, rats, guinea pigs, rabbits. Mouse acute toxicity test showed that they have a high tolerance for over 50 times given clinical dose (5.0 mg/dose). Even high dosage of microspheres was injected in SD rats for many times, no pathological changes were found in their organ. The symptoms of mice in abnormal toxicity test were normal after injection. And the weight of mice increased significantly. In allergy test, no allergic reaction and symptoms were found in guinea pigs. And no fester and suppuration were found in muscle stimulation test. In the hemolysis results, red blood cell did not aggregate. All the tests proved good security of the HTCC microspheres.

Separation and Characterization of Type II Collagen from Bovine Articular Cartilage

LI Sai-na KANG Ji-yao DENG Ping-ye GAO Jian-ping ZHANG Gui-feng WANG Ming-lin

Chin. J. Process Eng.. 2016, 16(4):  654-659.  DOI: 10.12034/j.issn.1009-606X.216139

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The bovine articular cartilage was pretreated using NaCl and guanidine hydrochloride to remove impurities and the proteoglycan respectively. Then the miscellaneous proteins were digested by pepsin, and the type II collagen was purified by salting out, dialysis and freeze-dried, Type II collagen was characterized. The results showed that a single band (α-chain) with a subunit molecular weight of 130 kDa. The content of Gly in amino acid composition of type II collagen was over 30%, and the total content of Pro and Hyp was over 20%. The purified type II collagen had unique supramolecular structures of collagen. The denaturation temperature of type II collagen was 43.68℃ in buffer solution with pH 7.0. Properties of collagen purified from bovine cartilage corresponded to bovine type II collagen.

Materials Engineering

Preparation of Polyurethane Hollow Microcapsules by Co-axial Electrospraying and in in-situ Encapsulation of Lipase

HU Bin ZHEN Ya-fei JI Xiao-yuan SU Zhi-guo MA Guang-hui ZHANG Song-ping

Chin. J. Process Eng.. 2016, 16(4):  660-666.  DOI: 10.12034/j.issn.1009-606X.216103

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Hollow polyurethane (PU) microcapsules were prepared by co-axial electrospraying technology, with glycerol containing certain content of water and PU dissolved in N, N-dimethylacetamide (DMAC) as internal and external phase electro-spraying solutions, respectively. The effects of the solution composition and flow rate on the morphology of the microcapsule were investigated. The results showed that uniform hollow PU microcapsules were successfully fabricated, using co-axial electrospraying of 80%(?) glycerol and DMAC solution of 10%(?) PU as internal and external phase electrospraying solution, under the conditions of the solution flow rates of 0.05 and 1 mL/h, voltage about 22 kV, distance of 48 cm between spinneret and collector, temperature of 30℃, and humility of 10%. By dissolving definite amount of Candida antarctica lipase B (CALB) in the internal phase electrospraying solution, the enzyme was in-situ encapsulated inside the hollow cavity of PU microcapsules. The original biocatalytic activity of encapsulated CALB was 76.19% of the free CALB, and about 60% after 10 times recycles. Thermal stability of CALB showed that the half-life of CALB at 60℃ was prolonged about 8 times after encapsulation.

Acidic Ionic Liquid Catalyzed Esterification of Butene for Preparation of Sec-butyl Acetate

WANG Ao-yun ZHAO Guo-ying YANG fei-fei LIU fang-fang

Chin. J. Process Eng.. 2016, 16(4):  667-672.  DOI: 10.12034/j.issn.1009-606X.216147

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A series of acidic ionic liquids such as [Bmim]HSO4, [Bmim]SbF6, Bmim]PF6, [BSmim]HSO4, [BSmim]CF3SO3, [BSN222]H2PW12O40 and [Ph3PSO3H]HSO4 were synthesized following two-step method to substitute concentrated sulfuric acid as catalyst for esterification of butene. The synthesized ionic liquids and the blending with Lewis salts were used as catalysts for the esterification of butene with acetic acid at 90℃ for 4 h, under the volume ratio of the mixture of butane & butene to acetic acid of 18:5, and the molar ratio of acetic acid to catalyst of 2. As [Ph3PSO3H]HSO4 was catalyst for the esterification of butene, the conversion rate of butene reached 88.8%, selectivity and yield of butyl acetate reached 100% and 88.8%, respectively, versus that values of sulfuric acid as catalyst of 73.5%, 77.7% and 57.1% under the same conditions. After 8 times re-use of [Ph3PSO3H]HSO4 as catalyst for the esterification of butene, the conversion rate of total butene keeps more than 88.4%, selectivity of butyl acetate more than 97.4%.

Preparation of Potassium Dichromate by Potassium Chromate Electrolytic and Crystallization

GUO Ying-chao ZHANG Yong-qiang YU Zhi-hui WEI Guang-ye LI Yong-li Qu Jing-kui QI Tao

Chin. J. Process Eng.. 2016, 16(4):  673-678.  DOI: 10.12034/j.issn.1009-606X.215394

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The cationic membrane electrolysis of potassium chromate and potassium dichromate crystallization were studied. The effects of current density, temperature, KOH concentration and K2CrO4 concentration on electrolytic process were investigated. The purity and yield were studied under different concentrations and conversions of potassium dichromate solution. The effects of stirring rate, cooling rate and seeds adding on the particle size distribution and crystal morphology were researched. The results showed that, the optimum condition was current density of 0.25 A/cm2, electrolysis temperature of 80℃, KOH of 50 g/L and K2CrO4 of 400 g/L. The purity of crystal is not less than 99.8% when the conversion rate of K2Cr2O7 more than 90%. The optimize conditions of crystallization process were K2Cr2O7 initial concentration of 500 g/L, stirring speed of 300 r/min, cooling rate of 0.5℃/min, no seed adding. Product was completely in conformity to GB 28657-2012.

Influence of HPMC on the Properties of Lightweight Aggregate Concrete by Chemical Foaming in situ

FAN Chuan-gang， WU Rui CHEN He MENG Fang-fang LI Jia-mao SHENG Yu-sheng

Chin. J. Process Eng.. 2016, 16(4):  679-683.  DOI: 10.12034/j.issn.1009-606X.215428

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The lightweight aggregate concrete (LAC) specimens were prepared by chemical foaming in situ, the sludge expanded ceramsite, hydroxy propyl methyl cellulose (HPMC), H2O2, and expanded perlite were used as the aggregate, foam stabilizer, chemical foaming agent (CFA), and carrier for CFA, respectively. The results showed that HPMC content in the range of 0.05%~0.125%(?) had the promising performance of foam stabilization and anti-segregation for the preparation of LAC. Accompanying to the slight increase of bulk density of resulting LAC specimens, the 28 d curing compressive strength, the flexural strength and the thermal conducting coefficient were increased, whereas the 48 h water absorption was decreased with the increase of HPMC content. For HPMC in the range of 0.125%~0.15%(?), the properties of resulting LAC specimens were changed with the variation of HPMC content conversely as compared with that in the range of 0.05%~0.125%(?), the slump of fresh LAC specimens was decreased slightly. For the resulting LAC specimen with HPMC content of 0.125%(?), the bulk density was 1245 kg/m3, the 28 d curing compressive strength was 31 MPa, the 28 d curing flexural strength was 6 MPa, the 48 h water absorption was 6.1%, and thermal conducting coefficient was 0.33 W/(m?K), respectively.

Preparation of Potassium Salt from Low Grade Potassium Ore with Additive-assisted Roasting, Water Leaching and Crystallization

LI Gang ZHU Yuan-yuan YI Ling-yun ZHAO Wei DU Ai-ling QI Tao

Chin. J. Process Eng.. 2016, 16(4):  684-691.  DOI: 10.12034/j.issn.1009-606X.216149

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The technology of extracting potassium salt from low grade potash feldspar was studied by adopting the process of roasting?leaching?separation, and the decomposition mechanism and leaching kinetics were analyzed. The results showed that the decomposition efficiency of ores is better by adding mixed additive agents. The leaching rate of potassium reaches up to 91.88% under the optimum conditions of Ore:CaCl2:Na2CO3?1:0.5:0.1(?), roasting 4 h at 800℃, leaching 2 h at 80℃, ratio of liquid to solid of 1 mL/g. The CaCl2?Na2CO3 mixed additive could effectively decrease the decomposed temperature of ore. The stage of leaching potassium was controlled by internal diffusion process.

Preparation of Tri-layer PDMS/POS/PAN Composite Membrane and Its Pervaporation Performance

TAN Sheng SU Yi FENG Shi-chao ZHOU Hui CHEN Xiang-rong SHEN Fei LUO Jian-quan Wan Yin-hua

Chin. J. Process Eng.. 2016, 16(4):  692-699.  DOI: 10.12034/j.issn.1009-606X.216115

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Two kinds of polyorganosiloxane (POS), DVTMS&B (DB) and TMTV&B (TB), were synthesized by copolycondensation of 1,3-divinyltetramethyldisiloxane (DVTMS) or tetravinyltetramethylcyclotetrasiloxane (TMTV) with component B in polydimethylsiloxane (PDMS), respectively. The PDMS/DB(TB)/PAN composite membranes with tri-layer, a polyacrylonitrile (PAN) support layer, a DB(TB) transition layer and a PDMS active layer were prepared by sequential coating methods and used to the separation of 1% (?) aqueous solution of n-butanol by means of pervaporation. The effects of mass ratio of DVTMS or TMTV to B and the mass content of DB and TB in casting solution on pervaporation performance were investigated. The results showed that the addition of DB or TB enhanced pervaporation performance of composite membrane with a same total thickness of separation and transition layer. To 1%(?) aqueous solution of n-butanol, the separation factor was 40.96 and permeation flux was 628.40 g/(m2?h) of PDMS/DB/PAN composite membrane, under the mass ratio of DVTMS:B of 3:1 and the concentration of DB in transition layer solution of 5%(?), and the separation factor was 41.58 and permeation flux was 540.00 g/(m2?h) of the PDMS/TB/PAN, under the mass ratio of TMTV:B of 1:1 and the concentration of TB in transition layer solution of 3%(?). Thus, the separation factors were increased by 8.5% and 10.2%, along with the permeation fluxes were increased by 29.5% and 11.3%, respectively, of PDMS/DB/PAN composite membrane and PDMS/TB/PAN composite membrane compared with the same thickness PDMS/PAN composite membrane under the optimized conditions.

Preparation of Porous Fe/C Micro-electrolysis Filter and Its Adsorptive Property to Pb2+ in Aqueous Solution

FU Ping-feng YANG Tian-wen FENG Jie

Chin. J. Process Eng.. 2016, 16(4):  700-705.  DOI: 10.12034/j.issn.1009-606X.215262

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The porous Fe/C micro-electrolysis filter was prepared from the iron ore concentrate, coal and papermaking sludge via a direct reduction method. The Fe/C filter was characterized. The adsorptive properties of Pb2+ in aqueous solution were tested by using Fe/C filter and activated carbon, respectively. The results showed that the Fe/C filter had the porosity of 32.3%~52.9%, metallic iron content of over 50% and adjustable Fe/C mass ratio. The optimized mass ratio of Fe to C was 6.8, and the largest adsorption capacity of Pb2+ was obtained at pH=3. The Pb2+ adsorption process with both the Fe/C filter and activated carbon fitted well with a pseudo-second order kinetic model. Langmuir isotherm equation could be used to evaluate the Pb2+ adsorptive capacity. The maximal adsorption capacity of Pb2+ was 112.36 and 27.94 mg/g for the Fe/C filter and activated carbon, respectively, showing the much higher adsorption capacity of the Fe/C filter.

Preparation of Fe-loaded Activated Carbon and Its Adsorption Property to Uranium Ion in Aqueous Solution

YANG Ling-fang ZHU Xia-ping QIU Yang LIU Da-qian LAI Yi

Chin. J. Process Eng.. 2016, 16(4):  706-713.  DOI: 10.12034/j.issn.1009-606X.216167

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The Fe-loaded activated carbon was prepared by liquid-phase chemical reduction procedure. The activated carbon, Fe-loaded activated before and after adsorption uranium ion were analyzed, its absorption property to uranium ion was studied. The results showed that Fe was embedded loosely as spheres in the pores of activated carbon which had a specific surface area of 10.3 m2/g, pore size of 0.0245 cm3/g and pore diameter of 10.5 nm. Some erosion and new crystals on iron surface were detected after adsorption uranium ion, contributing a rise in specific surface area of 16.7 m2/g, pore size of 0.0955 cm3/g and pore diameter of 17.9 nm. Redox, together with adsorption and precipitate, dominant the uranium ion removal efficiency. The maximum removal rate was 99% with mass ratio of FeSO4?7H2O to activated carbon of 1.25:1, Fe-AC concentration of 0.6 mg/mL , reaction time of 60 min, and pH value of 5.00. The uranium ion adsorption by Fe-loaded activated carbon matched Langmuir (R2=0.943) and Freundich (R2=0.992) models. The adsorption reaction could be described by a pseudo-second order kinetics equation (R2=0.999), and diffusion rate agreed with the membrane diffusion.

Review

Research Progress on Production Mechanism of HF and Its Fire Suppression Mechanism of Fluorine-containing Fire Extinguishing Agents as Halon Alternatives

MAO Ai-qin DING Pei-pei DING Meng-ling YU Hai-yun PAN Ren-ming

Chin. J. Process Eng.. 2016, 16(4):  714-720.  DOI: 10.12034/j.issn.1009-606X.215380

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Hydro-fluoro-carbons (HFCs) gas fire extinguishing agents, such as trifluoromethane (CHF3), pentafluoroethane (C2HF5), hexafluoropropane(C3H2F6) and heptafluoropropane (C3HF7) is the most efficient Halon alternatives, which possess the properties of high fire-fighting efficiency, reliable performance, no residue after finishing their duty. The four kinds of fluorine-containing fire extinguishing agents will produce the toxic gas HF during the fire extinguish process. The fluorine-containing free radicals resulted from the thermal decomposition of HFCs reacts with H, OH and O radicals in the flame to prevent the chemical chain reaction in the process of the combustion. The amount of HF produced could be reduced by shortening the time to reach the fire extinguishing concentration, reducing the time of interaction between fire extinguishing agent and flame, and adding additives or inhibitor. Future work should gain deep insight into studying the chemical extinguishing mechanism under different usage conditions, and obtaining a lot of real data, such as the extinguishing concentration, the toxicity, the compatibility and corrosion of such HFCs fire extinguishing agents. It provides theoretical basis and application for reducing the release of toxic gas HF, expanding the application field, and developing some new type of HFCs fire extinguishing agents with better performance.