The Chinese Journal of Process Engineering

Measurement of Liquid Circulation Velocity and Gas Holdup in a System at High Solid Concentration with an Electric Conductivity Probe

LUO Zi WU Qian WANG Tie-feng HAN Mei YU Wei SHA Zuo-liang WANG Jin-fu

. 2008, 8(5): 833-838.

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A measurement method of liquid circulation velocity and local gas holdup at high solid concentration in an airlift reactor simultaneously was developed，based on two probes of electrical conductivity tip and tracing method. Two residence time distribution (RTD) curves were obtained by measuring the concentration changes of tracer (saturated solution of KCl) injected into the riser by using two probes. The gas holdup was obtained by analyzing one RTD curve, with an average discrepancy within 5%. The liquid circulation velocity was determined by correlation of the two RTD curves after filtering bubble signals, and the results were consistent with the values measured by ultrasound Doppler velocimetry. The effects of operating conditions on gas holdup and liquid circulation velocity were investigated in an external-loop airlift reactor. The results show that the gas holdup increases with increasing superficial gas velocity, and the radial distribution of gas holdup is uniform with the superficial gas velocity less than 0.1 m/s, however, parabolic distribution with the superficial gas velocity larger than 0.1 m/s. The liquid circulation velocity increases almost linearly with increasing superficial gas velocity, and decreases with increasing solid holdup.

Solid Concentration Distribution in a Gas-Solid Fluidized Bed

CAI Jin LI Tao SUN Qin-wen YING Wei-yong FANG Ding-ye

. 2008, 8(5): 839-844.

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The experiments were conducted in a cold conventional fluidized bed using fiber optical probe as the detecting apparatus. The system compromises a replaceable gas distributor in a 0.284 m internal diameter acrylic column, a compressor, a series of knock-out drum, a freezer dryer, a rotameter, a fiber optic probe system and a series of cyclone. The experiments were carried out at ambient conditions and under different superficial gas velocities ranging from 0.3 to 0.5 m/s and different initial bed height ranging from 0.6 to 1.5 m using air as the fluidizing gas. A mixture of sands ranging from 154 to 180 mm diameter and average density of 2550 kg/m3 were used as the fluidizing particles. The effects of radial distance, axial distance, superficial gas velocity, initial bed height, porosity and shape of distributor on solid concentration in the bed were examined. The experimental results show that the time-averaged solid concentration increases in the dense phase area with the increase of superficial gas velocity. The shape of distributor does not exert much influence on the solid concentration while the smaller porosity of distributor gives rise to a lower and steeper solid concentration distribution. The initial bed height influences the solid concentration distribution contours significantly.

Local Mass Transfer Behaviour in a Three-phase Airlift Loop Reactor with Forced Circulation of Slurry Phase

MengXi Liu LU Chun-xi SHI Ming-xian

. 2008, 8(5): 845-850.

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A novel three-phase airlift loop reactor with forced slurry phase circulation was proposed. The reactor was divided into six regions. Experiment was conducted in a cold model apparatus with 300 mm ID plexiglas column and 1700 mm in height over a wide range of operation conditions with the superficial velocity in draft tube, UGr, from 0.006 to 0.19 m/s, the liquid velocity pumped into the reactor, Ucir, from 0.0307 to 0.0511 m/s, and the volumetric solid concentration, es, from 5% to 15%, respectively. The mass transfer coefficient, kLa, was measured in each flow region of the reactor by employing a new O2/air steady-state method. It was found that with kLa as high as 0.754 s-1, the downcomer affected region has a biggest mass transfer coefficient than other regions, while the annulus region, with kLa no more than 0.043 s-1, has a smallest one. Interestingly, the mass transfer coefficient of gas-liquid separation region approximately equals to that of whole reactor. In addition, the mass transfer coefficient of whole reactor increases with the increase of superficial gas velocity and superficial liquid velocity pumped into the reactor, but decreases with increasing solid loading.

Transport and Separation of Cerium(IV) in Dispersion Supported Liquid Membrane System

PEI Liang YAO Bing-hua FU Xing-long WANG Li-ming

. 2008, 8(5): 851-858.

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The transport of Ce(IV) through a dispersion-supported liquid membrane consisting of polyvinylidene fluoride membrane as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester (PC-88A) dissolved in kerosene as the membrane solution was studied. The effects of HCl concentration, initial concentration of Ce(IV) in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on transport of Ce(IV) were also investigated. The optimum transport conditions of Ce(IV) were obtained as that HCl concentration was 4.0 mol/L, carrier concentration 0.16 mol/L, volume ratio of membrane solution to stripping solution 40:20 in the dispersion phase, and HCl concentration 0.1 mol/L in the feed phase. Under the conditions, when initial concentration of Ce(IV) was 0.7′10-4 mol/L, the transport rate of Ce(IV) was up to 96.3% in 75 min. The kinetic equation was developed. The diffusion coefficient of Ce(IV) in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained, being 6.69′10-8 m2/s and 19.3 mm, respectively. The separation result of Ce(IV) in simulated samples showed that under the certain conditions, transport rate of Ce(IV) of fly ash was up to 92.8% in 125 min, transport rate of Ce(IV) of molten slag up to 92.6% in 105 min and transport rate of Ce(IV) of mixed solution of Ce(IV) and Eu(III) up to 83% in 215 min. The transport rates of other ions were extremely low.

Experimental Studies on Bacteria Leaching Mechanism of Uranium from Uraninite

DING De-xin LI Guang-yue LIU Yu-long WANG Yong-dong WANG you-tuan

. 2008, 8(5): 859-865.

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Thiobacillus ferrooxidans was used in bacteria leaching of uranium from uraninite ore leaching system with bacteria and Fe2+, the system with bacteria and without Fe2+, the system with Fe2+ and without bacteria, the system with Fe3+ and without bacteria, the system without bacteria and iron ions, and uncontrolled pH value, and the system without bacteria and iron ions, and controlled pH value of 2. The effects of pH value, redox potential (Eh), ferrous ions, total iron and uranium concentration were examined. The leaching rates for the six uraninite ore leaching systems reached 98.00%, 80.33%, 97.66%, 93.00%, 20.33% and 72.00%, respectively. The results show that bacteria play mainly an indirect role in leaching uranium from uraninite. That is to say that bacteria oxidize sulfate in reduction state, S0 Fe2+ to produce Fe2(SO4)3 and it in turn oxidizes the insoluble U(IV) to soluble U(VI) and, in this way, the uranium in uraninite ore is leached out.

Separation of Impurity from Recycled Alkaline Solution in the Clean Production Process of Titanium Dioxide

LIN Lin WANG Jing-gang WANG li-na CHU Jing-long QI Tao XUE Tian-yan

. 2008, 8(5): 866-871.

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The separation of Mn, Al and Si from the recycled alkaline solution was investigated. The results showed that approximately 99.7% of Mn(VI) in the recycled alkaline solution could be removed in the optimal conditions of temperature 90℃ and volume ratio of reductant to solution 1:200. The concentrations of Al and Si in the recycled alkiline solution could be reduced to 1 and 0.2 g/L, respectively at 70~90℃ with added adequate amount of CaO. The XRD analysis results suggested that the main product was 1.5CaO×SiO2×xH2O when aluminium was absent, while it was Ca2.93Al1.97Si0.64O2.56(OH)9.44 when aluninium was present.

Preparation of PVA-TEOS/PAN Composite Membrane and Its Application in Pervaporation Separation of Ethyl Acetate-Water Solution

YUAN Hai-kuan XU Zhen-liang MA Xiao-hua WEI Yong-ming QI Jun ZENG Yi-hong

. 2008, 8(5): 872-876.

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The composite membrane of polyvinyl alcohol (PVA)-tetraethoxysilane (TEOS)/polyacrylonitrile (PAN) (PVA-TEOS/PAN) was prepared by sol-gel reaction of mixtures of PVA and TEOS for pervaporation separation of ethyl acetate-water solution, where the support layer was PAN hollow fiber ultrafiltration membrane. FT-IR spectra and XRD patterns proved that the covalent bond Si?O?C formed and the crystallinity of PVA descended in the top layer of PVA-TEOS/PAN composite membrane of the cross-linking reaction between PVA and TEOS, respectively. In addition, the hydrophilicity of composite membrane was characterized by static contact angle for methylene iodide. The swelling degree of composite membrane in ethyl acetate aqueous solution, and the effects of TEOS concentration in coating solution, feed temperature and concentration on pervaporation performance of PVA-TEOS/PAN composite membrane for ethyl acetate-water solution were investigated. The results showed that the swelling of PVA in the solution was inhibited with addition of TEOS, leading to PVA-TEOS/PAN composite membrane with good dehydration performance. For PVA-TEOS/PAN composite membranes with 5% and 30% TEOS, their pervaporation performance of 98% ethyl acetate aqueous solution were evaluated as follows: the separation factors were 2830 and 4448, and their permeation fluxes 49.4 and 41.4 g/(m2×h) at 40℃, respectively.

Adsorption of Cr6+ in Water by Modified Lignosulfonate

LI Ai-yang SONG Chu-hua CAI Ling

. 2008, 8(5): 877-881.

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Treatment of Cr6+-containing wastewater by modified lignosulfonate was studied. The influences of quantity of modified lignosulfonate, adsorption time, pH value and temperature on its adsorption to Cr6+ in water were examined. The experimental results show that the content of Cr6+ in the treated water can be lower than the national standard of 0.5 mg/L under the following optimization conditions of the dosage of modification lignosulfonate 3 g, adsorption time 1 h, pH 4~7 and room temperature. The adsorption of modified lignosulfonat to Cr6+ agrees with Freundlich isothermal equation. The results indicate that modified lignosulfonat is a kind of good and cost effective adsorbent.

Treatment of Wastewater Containing Phosphate by Fly Ash Adsorbent Loaded with Ferrihydrite

YAO Shu-hua LIU Dan SHI Zhong-liang

. 2008, 8(5): 882-886.

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The characteristics of phosphate adsorption on fly ash loaded with ferrihydrite were investigated. The influential factors such as the dosage of adsorbent, concentration of phosphate, solution pH, co-existing anions in solution on removal of phosphate ion were examined. The adsorption isotherm of phosphate on fly ash loaded with ferrihydrite could be described by the Langmuir and Freundlich equations. The adsorption kinetic data could be described by the Lagergren second-order rate equation. The adsorbent had perfect properties in phosphate adsorption capacity, the results showed that the removal rate of phosphate could be over 97% in the conditions of adsorbent dosage 8.0 g/L, and pH=3. When the concentrations of co-existing anions were 5~30 mg/L, SO42-, NO32-, CO32- and Cl- in the solution had almost no effect on the adsorption of phosphate on fly ash loaded with ferrihydrite, but SiO32- caused greater phosphate removal rate decrease.

Effect of Scaling on Electrosorption Desalination and Its Control

ZHAO Xue-na NI Wen CHEN Zhao-lin

. 2008, 8(5): 887-891.

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The effect of scaling on electrosorption desalination was studied by using electrosorption technology to desalt feed water containing different concentrations of Ca2+ and high concentration bicarbonate (HCO3-). The experiments were carried out at three Ca2+ concentrations of 40, 144 and 350 mg/L, respectively. The results show that the desalination efficiency drops remarkably at higher Ca2+ concentrations. Analysis of changes of ion removal rate, ion desorption rate and initial working current reveals that the calcium carbonate scale formed in the electrosorption module is a result of the interaction between Ca2+ and HCO3-, which causes the decrease of electrical double layer capacitance of electrode material, and therefore affects the desalination effect. Calcium carbonate can be dissolved after using acidification-stripping as pretreatment to obtain HCO3- concentration of 100 mg/L, which results in the improvement of desalination of the module. The crystallization and dissolution mechanism of calcium carbonate in the module are also discussed based on HCO3- ion residue and pH change in the working effluent.

Roasting Pretreatment of High-sulfur Bauxite

LU guo-zhi ZHANG Ting-an BAO Li DOU Zhi-he ZHANG Wei-guang

. 2008, 8(5): 892-896.

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Roasting pretreatment of high sulfur bauxite was studied using a rotary kiln, and the effects of roasting temperature and roasting time on sulfur content and digestion performance of high sulfur bauxite were examined. Changes of microscopic appearance and crystal structure were analyzed with SEM and XRD techniques. The mechanism of desulphurization and roasting pretreatment was also studied. The experimental results indicate that the sulfur in bauxite was successfully discharged as gas form through roasting, the sulfur content of high sulfur bauxite met the industrial standard under the conditions of 750℃ roasting temperature and 60 min holding time. The digestion rate of alumina was above 97% under the conditions of 220℃ digestion temperature and 60 min holding time.

Aqueous Two-phase Extraction of 2,3-Butanediol from Fermentation Broth

ZHANG Jiang-hong JIANG Bo LI Zhi-gang SUN Li-hui SUN Ya-qin DAI Jian-ying XIU Zhi-long

. 2008, 8(5): 897-900.

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The separation of 2,3-butanediol by aqueous two-phase systems with salts and organic solvents was studied. Firstly, the phase separation ability of various salts and organic solvents was compared, and then the effect of phase composition on the extraction was investigated. According to the partition coefficient and the yield of 2,3-butanediol, the ethanol and ammonium sulphate system was proved to be the best one of four systems. The optimum phase composition was 20%(w) of ammonium sulphate and 27%(w) of ethanol for flocculated broths. The partition coefficient and yield of 2,3-butanediol were 7.4 and 90.18%, respectively. The process is simple and highly efficient.

Photocatalytic Reduction of Cr(VI) in Cr(VI)-Acetic Acid Compound System

LEI Xue-fei XUE Xiang-xin

. 2008, 8(5): 901-907.

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Using calcined sulfate-modified titanium-bearing blast furnace slag as photocatalyst, the photocatalytic reduction of Cr(VI) in Cr(VI)-acetic acid (AA) compound system was studied. The effects of initial pH value, concentration of Cr(VI), AA/Cr(VI) volume ratio, synergistic effect factor and reuse on its photocatalytic reaction performance were also investigated. The results indicate that with increase of AA/Cr(VI) volume ratio up to 0.2%, the reduction efficiency of Cr(VI) significantly increases up to 27.55%, and thereafter it decreases gradually. The acidic solutions are favorable for the photocatalytic reduction of Cr(VI), and the optimum pH for the reduction of Cr(VI) is 1.5. Under the same conditions of 110 min and pH 1.5, the photocatalytic reduction efficiency of Cr(VI) is 76.32% for single Cr(VI) system and 100% for Cr(VI)-AA system. Cr(VI) is more efficiently eliminated in Cr(VI)-AA compound system than in single Cr(VI) system, and the synergistic effect factor is always greater than 0, indicating that there exists a synergistic effect in the compound system. The photocatalytic reduction of Cr(VI) in Cr(VI)-AA system follows Langmuir-Hinshelwood kinetic model.

Preparation and Polymerization of Inverse Microemulsion System of Dimethyl Diallyl Ammonium Chloride-Acrylamide

YUE Qin-yan GAO Bao-yu

. 2008, 8(5): 908-913.

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Taking kerosene as oil phase, dimethyl diallyl ammonium chloride (DMDAAC) and acrylamide (AM) as monomers, based on the emulsifying system comprised of nonionic surfactants Span-80 and OP-10, the effects of hydrophile-lipophile balance (HLB) value of emulsifier, monomers concentration and content in water, addition of electrolyte, temperature and emulsifier concentration on the stability of the system and solubilization capacity of aqueous phase were studied by conductivity method and visual observation. The results showed that the conductivity changed slightly and the solubilization capacity was large at 7.70 of HLB value, 60%(w) of monomers concentration in water, 0.2 of molar ratio of DMDAAC to AM, and 1.25%(w) of HCOONa concentration in water. The increase of temperature had a negative effect on the systematic stability. Polymer microemulsion with high stability and clarity was obtained after polymerization. The particle size increased notably after polymerization via particle size analysis, which could be interpreted by the mechanisms of monomer diffusion and micelle collision.

Experimental Investigation on High Temperature Air Coal Gasification

CAI Jiu-ju LI Ming-jie ZHAO Zi-zhong

. 2008, 8(5): 914-919.

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The high temperature air/steam as gasifying agent was applied in gasification of coal with a 200 mm internal diameter fixed bed gasifier. The effects of process parameters such as temperature of gasifying agent, gasification temperature, ratio of air to coal and ratio of steam to coal on gasification performance were studied. The experimental results indicated that the gas heat value increased 32.5% with the temperature of air from 500℃ to 800℃. The increase in gasification temperature availed the gasification process, but its increase was limited by the melting point of ash in the condition of solid slag emission. The effects of ratio of air to coal and ratio of steam to coal on coal gasification performance were realized by changing the gasification temperature, and the two parameters had an optimum operating range for a certain fixed bed coal gasification process. In the experimental conditions, they should be controlled in the ranges from 1.55 to 1.8 Nm3/kg and from 0.25 to 0.35 kg/kg, respectively.

Properties of Green Pellets Used to Produce Al-Si Alloy from Bauxite Tail by Carbothermal Method

YANG Dong FU Da-xue WANG Yao-wu FENG Nai-xiang

. 2008, 8(5): 920-925.

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In order to measure true density of green pellets which were used to produce Al-Si alloy with bauxite tail by carbothermal method, a novel method was proposed and its feasibility testified by the volume-weight method. Based on the method, the influences of pressing pressure, dry agglomerant content, moisture content and particle size on the properties of green pellets were investigated by single-factor and orthogonal experiments using the compressing strength and pore ratio of green pellets as indexes. The optimum conditions for the properties of green pellets are obtained as fellows: pressing pressure 22.5 MPa, dry agglomerant content 9%(w), moisture content 13%(w) and particle size 0.42~0.178 mm. Under the optimum conditions, the compressing strength and pore ratio of green pellets are 27.8 MPa and 18.7%, respectively.

Ultrasonic Electro-oxidation Process of Molybdenite Concentrate

CAO Zhan-fang ZHONG Hong WEN Zhen-qian FU Jian-gang CHEN Na

. 2008, 8(5): 926-931.

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The oxidation of MoS2 concentrate in NaCl solution electrolysis environment and the impact of ultrasonic field on the leaching process of Mo were investigated. The decomposition process of MoS2 can be accelerated by ultrasonic field. When there are iron ions, anode potential is decreased about 0.7 V than that without iron ions, iron ions in the solution play an electronic transmission role by directly joining the electrode reaction of anode and oxidation leaching process. The results indicate that the leaching rate of Mo can achieve 99.5% with ultrasonic field exertion working 4 min in every 5 min under the conditions that the liquid-solid ratio is 20, mixing rate 500 r/min, iron ion concentration 6%, leaching temperature 40℃, pH (initialization) 1, and leaching time 4 h, respectively.

Optimization of Technological Conditions in Synthesis of Biodiesel from Kosteletzkya virginica Oil with Supercritical Methanol

YANG Qing-li YU shan-lin 中国科学院海洋研究所

. 2008, 8(5): 932-936.

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Supercritical methanol transesterification technology was used to produce biodiesel from Kosteletzkya virginica oil as raw material. The single factor and orthogonal experiments were adopted to study the effects of molar ratio of methanol to Kosteletzkya virginica oil, reaction pressure, agitation speed, reaction time, reaction temperature, water content and acid number on oil transesterification rate. The results indicated that the order of influential factors on the oil transesterification rate within the experimental range was obtained as follows: reaction temperature>reaction pressure>reaction time>agitation speed>molar ratio of methanol to Kosteletzkya virginica oil. The optimal technological parameters of oil transesterification from Kosteletzkya virginica oil were determined as follows: reaction temperature 300℃, reaction pressure 12 MPa, reaction time 9 min, agitation speed 300 r/min and molar ratio of methanol to Kosteletzkya virginica oil 30, and under such conditions, the total oil transesterification rate after transesterification in three times was obtained as 97.62%.

Production Process of Chlorine from HCl by Catalytic Oxidation

CHEN Zhi-tao HAN Ming-han WEI Fei JIN Yong

. 2008, 8(5): 937-940.

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In the production process of chlorine from HCl by catalytic oxidation, in order to decrease the energy consumption for separating HCl and O2 and increase the yield of chlorine, the conversion rates of both HCl and O2 must be high enough. According to thermodynamic and kinetic analysis and experiments, the optimal reaction conditions for the process are obtained, which are temperature 450℃, pressure 0.11 MPa, molar ratio of HCl to O2 4, and WHSV of HCl 0.45 h-1. Under the reaction conditions, the conversion rates of both HCl and O2 are 65%, and the dry contents of Cl2 and O2 78.8% and 21.2%, respectively.

Hydrolysis Kinetics of Agricultural Residues with Hot Liquid Water

XU Ming-zhong ZHUANG Xin-shu YUAN Zhen-hong SUN Yong-ming XU Jing-liang LI Lian-hua

. 2008, 8(5): 941-944.

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Based on a self-designed batch reactor, xylan, rice straw and palm shell were pretreated by hot liquid water for hydrolysis kinetic study under 160~220℃, 4.0 MPa, 0~60 min, mass ratio of liquid to solid 20:1 and rotation speed of 500 r/min. All experimental data were fitted to the curves, and the kinetic parameters calculated. The results indicated that the hydrolysis obeyed a first-order sequential model. The temperature and time were the main influential factors. For xylan hydrolysis, the activation energy is 65.58 kJ/mol for hemicellulose hydrolysis and 147.21 kJ/mol for reducing sugars degradation. Thus the reducing sugars are enriched in the liquid products. However, the activation energy values of rice straw and palm shell are 68.76 and 95.19 kJ/mol for hemicellulose hydrolysis and 47.08, 79.74 kJ/mol for reducing sugars degradation respectively due to their complex composition compared with xylan. Consequently, the hydrolysis time should be controlled to decrease the degradation of reducing sugars.

Control of Na2O Content in Aluminum Hydroxide from Carbonization of Sodium Aluminate Solution with High Alumina Concentration

LI Xiao-bin ZHOU Xiao-song ZHOU Qiu-sheng PENG Dian-jun LIU Gui-hua PENG Zhi-hong

. 2008, 8(5): 945-948.

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According to the mechanism of carbonization of sodium aluminate solution following the mechanism of seeded precipitation, the influences of different conditions, temperature 70~95℃, CO2 concentration 25%~60%(j), and CO2 ventilation rate 0.055~0.167 m3/(h·L), for batch carbonization of sodium aluminate solution with high alumina concentration on Na2O content in carbonization product were investigated in the self-designed carbonization tank without addition of aluminum hydroxide seed. The results show that Na2O content in carbonization product can be significantly reduced by increasing carbonization temperature and decreasing the amount of ventilated CO2 to adjust the super-saturation of liquor and control the carbonization rate of sodium aluminate solution. Na2O content in carbonization product could reach less than 0.25%(w) with low CO2 concentration and ventilation rate under the following carbonization conditions: carbonization temperature is in the vicinity of 95℃, alumina concentration in the original purified aluminate solution for carbonization varies from 170 to 180 g/L with molar ratio of Na2O to alumina 1.40~1.50, and carbonization time is about 6 h with carbonization rate 90%~93%.

Effects of Sintering Process Parameters on Physicochemical Properties of Calcium Aluminate Slag System

WANG Bo YU Hai-yan SUN Hui-lan BI Shi-wen

. 2008, 8(5): 949-952.

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The phase composition, self-disintegrating property and alumina leaching property of calcium aluminate slag obtained at different temperatures and different holding times were investigated by XRD and laser particle size analyzer when the material ratio of calcium aluminate slag is at the optimum condition. The results indicate that when the temperature is below 1450℃, the reaction of slag takes place in solid reaction area and the reaction speed is slow, and there exists quite a lot of 2CaO×Al2O3×SiO2 which decreases the self-disintegrating and leaching property of calcium aluminate slag. When the temperature is above 1450℃, liquid appears in the slag, so the reactions become fast and proceed completely. The main phases of calcium aluminate slag are g-2CaO×SiO2 and 12CaO×7Al2O3, and the properties of self-disintegrating and leaching are well. Holding time has little effect on the phase components and particle size of slag, but it decreases the leaching rate of alumina in the slag appreciably.

Strip Hot-dip Galvanizing Quality Monitoring Model Based on Neural Network Rule Extraction

WANG Jian-guo YANG Jian-hong ZHANG Wen-xing XU Jin-wu

. 2008, 8(5): 957-961.

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To overcome the difficulty of production quality monitoring model based on traditional neural network which is usually used poorly, a strip hot-dip galvanizing quality monitoring model based on neural network rule extraction is proposed. Taking the quality monitoring of zinc coating weight in strip hot-dip galvanizing as the investigated subject, the sample datasets are trained by neural network rule extraction method to obtain the quantitative relationships in the form of knowledge rules among input variables (such as the parameters of raw materials and control parameters of production) and output ones (the quality parameters), with which the production control parameters can be set and updated easily. 756 training and 376 testing examples are chosen as variables of the network. The results show that the new model has a rule-overcast-ration of 94.8% and has provided an effective tool for auto-control of product quality, because in the new model the range of each input variable can be readily set up based on the target range of the output variables.

Preparation of Berberine-loaded Chitosan Microspheres and Their Fungistasis

HOU Yao-dong GE Xi-zhen LIU Jun-feng TIAN Ping-fang TAN Tian-wei

. 2008, 8(5): 962-966.

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Berberine-loaded chitosan microspheres were prepared by emulsion-chemical crosslinking technique. The preparation conditions were optimized by orthogonal experimental design with respect to particle size distribution, embedding rate and drug loading. The prepared microspheres showed perfect spherical geometry, smooth surface and suitable size distribution while observed under optic and scanning electron microscopes. The average diameter of microspheres was 15 mm, with drug loading of 4.78% and embedding rate of 78.98%. Subsequently, their drug release in vitro was tested in the phosphate buffered saline (pH 6.8) for 30 d, and the release curve demonstrated an appropriate speed. In addition, inhibitory rates of the microspheres against Alternaria solani, Colletotrichum capsici and Botrytis cinerea were determined using growth rate method at microsphere concentration of 5 mg/mL. Exhilaratingly, the microspheres showed 65% inhibitory rate against Alternaria solani, one predominant pathogen causing post-harvest disease of tomato.

Synthesis and Anti-hydroxyl Free Radical Activity of Glucosamine-Dy Complex

REN Xiang-qun ZHAI Yu-chun GE Xin QIN Yan

. 2008, 8(5): 967-971.

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The coordination compound of glucosamine-Dy was synthesized from D-glucosamine hydrochloride with Dy3+ ion, and characterized by elemental analysis, molar conductivity, IR, UV-Vis and XPS, respectively. The scavenging effects of D-glucosamine and glucosamine-Dy complex on hydroxyl free radical produced by EDTANa2×Fe(II)-H2O2 system were studied. The results showed that Dy3+ ions were coordinated with amino groups, secondary hydroxyl groups and Cl-. D-glucosamine and glucosamine-Dy complex had significant scavenging effects on hydroxyl free radical. The glucosamine-Dy complex displayed higher scavenging effects on the hydroxyl free radical compared with glucosamine when mass concentration of the sample was 2.5 mg/mL, the removal rate of glucosamine-Dy complex on hydroxyl free radical reached 85%, and that of D-glucosamine was 77%. The removal rates of D-glucosamine and glucosamine-Dy complex on hydroxyl free radical increased with their mass concentrations.

Preparation and Characterization of Keramzite from Municipal Sewage Sludge

YUE Min YUE Qin-yan LI Ren-bo GAO Bao-yu YU Hui QI Yuan-feng

. 2008, 8(5): 972-977.

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Sewage sludge was used as principal material to sinter lightweight keramzite aggregates. The optimized preparation conditions were selected. The impacts of main factors (dry time, preheating temperature, preheating time, sintering temperature, and sintering time) on characteristics of lightweight aggregate (specific surface area, bulk density, and granule density) were studied. The results show that the optimized mass ratio of sewage sludge to additives was that sewage sludge:fly ash:clay=2:3:1. The optimized preparation conditions were as follows: dry time 1 h, preheating temperature 300℃, preheating time 20 min, sintering temperature 1100℃, and the sintering time 8 min. Under these conditions, the characteristics of lightweight keramzite aggregates were obtained as follows: specific surface area 4.222 m2/g, bulk density 635 kg/m3, granule density 1146 kg/m3, porosity 22.4%, weight loss in hydrochloric acid 0.18%, and abrasion loss 0.4%.

Effects of HCl Concentration and Calcination Temperature on Properties of Titanate Nanotubes

ZHOU Li-min ZHU Xia-ping GUANG Qun-wu

. 2008, 8(5): 978-982.

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Titanate nanotubes (TIN) were prepared with a hydrothermal method and characterized by TEM, XRD and nitrogen adsorption-desorption isotherms. The effects of HCl concentration and calcination temperature on microstructure and photocatalytic activity of TIN were investigated. The photocatclytic activity of TIN was evaluated using methyl orange as model compound. The results showed that with increasing HCl concentration from 0.001 mol/L to 0.1 mol/L, the sodium content of TIN decreased from 7.25%(w) to 0, and the TIN morphology might be destroyed. The specific surface area and pore volume of TIN decreased with increasing calcination temperature with the maximum value of 353 m2/g and 1.70 cm3/g, respectively. The amount of anatase phase and crystallization degree of TIN were also affected by calcination temperature. The dependence of photocatalytic activity of TIN on both factors can be interpreted with variations of specific surface area, pore volume, amount of anatase phase and degree of crystallization during the sodium exchange and heat treatment process. The photocatalytic activity order of TIN samples toward methyl orange was obtained as: TIN-0.01 (HCl 0.01 mol/L)>TIN-0.1 (HCl 0.1 mol/L)>TIN-0.001 (HCl 0.001 mol/L), and the maximum apparent reaction rate constant (h-1) was 0.84 for TIN-0.01, 0.55 for TIN-0.1, and 0.30 for TIN-0.001, respectively.

Preparation of Spherical LiFePO4 Particles with Combined Process of Precipitation and Calcination and Their Characterization

YAN Hong ZHOU Jian-xin SHEN Xiang-qian

. 2008, 8(5): 983-987.

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Spherical LiFePO4 particles were synthesized by combined process of precipitation and calcination from FeSO4, H3PO4, LiOH and NH3×H2O. The precursor, a mixture of spherical Fe3(PO4)2 and Li3PO4 particles, and products derived from calcination of the precursor were characterized by XRD and SEM. The formation process of LiFePO4 from the reaction of Fe3(PO4)2 and Li3PO4 was analyzed by TG-DSC. The results show that the formation process and microstructure of olivine LiFePO4 were largely influenced by the structural characteristics and mixing state of spherical Fe3(PO4)2 and Li3PO4 particles. The spherical Fe3(PO4)2 particles with a high tap density and good fluidity consist of very small sheet-like or stick-like crystallites, which are arranged radically in the sphere and form an ordered structure. After subsequent calcination of Fe3(PO4)2 and Li3PO4 at 700℃ for 3 h under atmosphere of N2 and H2, the precursor was transformed into a single olivine LiFePO4 particle material with porous structure, diameters around 1~13 mm and a tap density of 1.25 g/cm3, which would be a promising cathode material for dynamic green Li-ion batteries.

Giant Magnetoresistance of CuCo Granular Films Electrodeposited in Magnetic Field

ZHAO Lin FAN Zhan-guo GAO Peng YANG Zhong-dong

. 2008, 8(5): 988-992.

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CuCo granular film was prepared by electrodeposition in the stable magnetic field. Scanning electron microscope and XRD were used to examine the composition and structure of plated films. The giant magnetoresistance of the films was measured by the four-line method. The magnetic field could affect the composition of the granular film, the concentration of Co was higher under 0.6~0.8 T, and when the intensity of magnetic field was over 0.8 T, the concentration of Co would decrease. The crystal grains were refined under the magnetic fields. The optimal intensity of magnetic field was 0.6 T, under which the crystal grains of films were more compact, and the orientation of crystal plane (111) was promoted. The measurement result showed that the magnetoresistance of CuCo granular film prepared in 0.6 T increased 25% than that prepared without magnetic field after vacuum annealing.

Preparation and Characterization of Sb-Active Carbon Composite as Negative Electrode for Li-ion Batteries

LI Yan-hong WU Feng WU Chuan BAI Ying

. 2008, 8(5): 993-997.

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Sb-active carbon composite was prepared by carbothermal reduction from Sb2O3 and active carbon. The so-prepared material was characterized by XRD and SEM. Electrochemical lithium insertion/extraction characteristics of the material were determined by constant current charge-discharge and cyclic voltammetry methods. The results show that Sb2O3 is reduced to metallic Sb. More homogeneous composite can be obtained by increasing the molar ratio of reductant in raw materials. The Sb-active carbon composite heated for 12 h with a molar ratio of Sb2O3:C 1:4 exhibits the best electrochemical lithium insertion/extraction characteristics and possesses the initial lithium specific insertion capacity of 893 mA×h/g. Even after 8 cycles, Sb-active carbon composite still shows high lithium specific extraction capacity as 548 mA×h/g, which is 88% of initial lithium specific extraction capacity.

Fabrication and Optimization of Cathode in a Direct Microbial Fuel Cell

XU Yuan SONG Tian-shun YE Ye-jie CHEN Ying-wen ZHU she-min SHEN Shu-bao

. 2008, 8(5): 998-1002.

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A fabrication method of cathode in a direct microbial fuel cell was studied, and the primary influential factors of fabrication were investigated. The performances of cathodes obtained at different fabricating conditions were evaluated by the power density and voltage-current curves. The results showed that they were much affected by the concentration of PTFE in the impermeable layer, Nafion content in the catalyst layer and carbon content in the flattening layer. When the concentration of PTFE was 30%(w), Nafion content 2.8 mL, and carbon content 0.18 g, the best performance was obtained. The power density output was 357 mW/m2, and the COD removal rate reached 90%.

Preparation of Flake-shaped Copper Particles with PEG600 Template

CHEN Ming-wei ZHANG Wei-gang

. 2008, 8(5): 1003-1007.

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The flake-shaped crystalline copper particles with 10~40 mm in diameter and 1.5~2.5 mm in thickness were prepared by using liquid phase reduction method with NaH2PO2 as reducing agent and PEG600 as template. The effects of pH value of reductive solution, reaction temperature, concentration of CuSO4 and volume of PEG600 on the preparation of flake-shaped copper particles were studied. The optimum conditions were obtained as follows: the concentration of CuSO4 and NaH2PO2 were 0.2 and 0.14 mol/L, respectively, the volume of PEG600 8 mL, the reaction temperature 80℃, and the pH value 0.5. The prepared product was proved to be pure flake-shaped copper particles through the analysis of XRD and TEM.

Conditions and Optical Absorbency of SmBO3 Powder Synthesized by Sol-Gel Combustion Method

HE Wei HAN Peng-de MU Lei WANG Li-xin ZHANG Qi-tu

. 2008, 8(5): 1008-1012.

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The influential factors of precursor for preparation of SmBO3 powder by sol-gel combustion method were investigated. The effects of calcination temperature and time on optical absorbency of SmBO3 powder were examined. The results showed that when heating temperature was 80℃, molar ratio of H2O to the sum of Sm and B 30, pH 2 and molar ratio of citric acid to the sum of Sm and B 1:1, the gel combusted steadily at 180℃, and then changed into white fluffy precursor. SmBO3 powder was obtained when the precursor calcined at 750℃ for 2 h, with an average particle size of 100 nm. There was strong absorption in 1.05~1.15 mm wavelength range, and the reflectivity of SmBO3 powder reached a minimum value of about 0.41% at 1.07 mm wavelength. It was about 0.6% at 1.06 mm.

Preparation of Crosslinked Copolymer Microspheres of PGMA-MMA-EGDMA with Suspension Polymerization Method

ZHUANG Ru-bin GAO Bao-jiao

. 2008, 8(5): 1013-1017.

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Ternary copolymerization was performed with suspension polymerization method by using glycidyl methacrylate (GMA) as main monomer, methyl methacrylate (MMA) as comonomer, ethyl glycol dimethacylate (EGDMA) as crosslinker and polyvinyl alcohol as disperser, and crosslinked copolymer GMA-MMA-EGDMA microspheres were obtained. Their chemical structure and morphology were characterized with FT-IR and SEM. The effects of content of disperser, stirring speed, volume ratio of oil to water phase, content of crosslinker and content of NaCl on the sphericity and size of microspheres were examined. The results show that the first three factors are key factors. As the content of disperser is less than 1%(w), the stirring rate lower than 250 r/min and the ratio of oil to water greater than 1:4 (j), balling process can not be realized in the copolymerization system. Addition of electrolyte NaCl conduces the balling process, and the size of microspheres decreases with increasing the added amount of NaCl. Via controlling reaction conditions of the suspension copolymerization, the crosslinked copolymer GMA-MMA-EGDMA microspheres with excellent sphericity and controllable diameter in a range of 100~400 mm can be gained.

Effects of Heat Treatment on Structure and Static Magnetic Properties of Barium Ferrite Hollow Microspheres

CHEN Ming CHENG Xu-dong MAO Fang

. 2008, 8(5): 1018-1021.

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Barium ferrite hollow microspheres were fabricated by plasma spray pyrolysis technique. The precursor solution was synthesized by chemical co-precipitation with BaCl2×2H2O and FeCl3×6H2O as basic raw materials. Microstructure and magnetic properties of the hollow microspheres were studied by XRD, SEM, image analysis and vibration sample magnetometometer techniques after thermal treatment. The results showed that the diameters of hollow microspheres distributed in 2~5 mm, the crystals were relatively perfect, and their size and saturation magnetization gradually increased with the temperature from 900℃ to 1100℃, the saturation magnetization was up to 47 A×m2/kg at 1100℃. Coercivity increased gradually to the maximum value of 2.6′105 A/m at 1000℃ and then decreased .

Characterization and Tribological Properties of Pulse-electrodeposited Nanocrystalline Zinc Coatings

GAO Zheng-hong SUN Xiao-jun LI Jian-gong

. 2008, 8(5): 1022-1025.

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Nanocrystalline zinc coatings with the average grain size from 6 to 32 nm were prepared on copper substrate by pulse electrodeposition. Microstructure and mechanical and tribological properties of the coatings were characterized by XRD, SEM, Vickers microhardness, and pin-on-disk tribo-test. The effects of current density on average grain size and the further effects of average grain size on Vickers microhardness and friction coefficient of the coatings were investigated. The results showed that the average grain size decreased from 32 to 6 nm with current density from 0.3 to 2.4 A/cm2. While the average grain size decreasing, Vickers microhardness of the coatings increased from lower than 0.5 GPa to over 2.0 GPa, and the friction coefficient against Si3N4 ball in ambient air decreased from 0.18 to 0.05. Moreover, the variation of microhardness with average grain size exhibited a conventional Hall-Petch relationship.

Preparation and Characterization of Zr4+-doped TiO2 Photocatalyst

TANG Jian-jun ZOU Yuan DENG Ai-hua LI Rong-xian

. 2008, 8(5): 1026-1029.

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Zr4+-doped TiO2 photocatalyst was prepared by urea thermal decomposition and homogeneous co-precipitation method using TiOSO4 and ZrCl4 as precursors, the phase and photocatalytic activity of Zr/TiO2 were characterized by XRD, TEM, BET and FT-IR techniques. XRD results indicate that Zr4+-doped TiO2 has small crystal size (14 to 17 nm) and large specific surface area, and phase transformation from anatase to rutile is effectively inhibited. FT-IR results indicate that the presence of Zr4+-dopet in TiO2 accelerates its surface hydroxyl groups, and improves the adsorption characteristics of phenol. Photocatalysis results indicate that Zr4+ doping increases photocatalytic activity of TiO2, the degradation rate of phenol and removal rate of TOC after 100 min reaction reach as high as 100% and 80% respectively with 4%Zr/TiO2 photocatalyst.

Advances in Sludge Reduction Induced by Oligochaetes and Theirs Growth Kinetics

ZHU Hui WEI Yuan-song WANG Ya-wei LIU Jun-xin

. 2008, 8(5): 1030-1040.

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Advances in sludge reduction induced by oligochaetes and their growth kinetics are thoroughly reviewed. Stable presence, growth and reproduction of oligochaetes in activated sludge system, both affecting their predation on sludge and their capacity of sludge reduction, are significantly influenced by such factors as substrate characteristics, environmental conditions, population density of oligochaetes, except for their different species. Based on direct weighing, the observed sludge yield coefficient is not considered as suitable to evaluate the real capacity of sludge reduction of biomass by oligochaetes, because this method can be easily affected by lots of factors in activated sludge process. Whereas, isotope tracing provides a new way to more effectively evaluate the capacity of sludge reduction and screen worms suitable for sludge reduction of biomass. In addition, worms can improve the sludge settling, and should be considered in sludge reduction of volume.

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