The Chinese Journal of Process Engineering

La(III) Transport in Dispersion Supported Liquid Membrane Including PC-88A as the Carrier and HCl Solution as the Stripping Solution

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

. 2008, 8(6): 1041-1050.

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The transport of La(III) through a dispersion supported liquid membrane with polyvinylidene fluoride membrane as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in kerosene as the membrane solution, was studied. As a result, the optimum transport conditions of La(III) were obtained as that concentration of HCl solution was 4.0 mol/L, concentration of PC-88A 0.16 mol/L, and volume ratio of membrane to stripping solution 30:30 in the dispersion phase, and pH value 4.0 in the feed phase. Ionic strength had no obvious effect on the transport of La(III). Under the optimum conditions, when initial concentration of La(III) was 0.8′10-4 mol/L, the transport rate was up to 96.3% during the transport time of 125 min. The kinetic equation was developed based on the law of mass diffusion and theory of interface chemistry. The diffusion coefficient of La(III) in the membrane and the thickness of diffusion layer between feed and membrane phases were obtained as 3.20′10-7 m2/s and 3.22′10-5 m, respectively. The calculated results were in good agreement with experimental results.

Distributions of Solids Hold-up in the Airlift Loop Fluidized Bed of a Riser-Airlift Loop Fluidized Bed Coupled Reactor

WANG De-wu LU Chun-xi

. 2008, 8(6): 1051-1056.

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Based on olefin reduction technology with auxiliary reactor for FCC naphtha upgrading, a large-scale cold model experimental setup with a riser-airlift loop fluidized bed coupled reactor was established. The distributions of solids hold-up in the upper airlift loop fluidized bed were investigated. The effects of superficial gas velocity and outer solids flux on the radial distribution of local solids hold-up were analyzed. The fluidization quality of coupled airlift loop fluidized bed and coupled conventional one was compared in radial non-uniformity index. The results show that the solids hold-up of airlift loop fluidized bed decreased with increasing superficial gas velocity, and the solids hold-up in the bottom of draft tube increased with increasing outer solids flux, while outer solids flux had little effect on that in the middle-upper part of draft tube. The solids hold-up of annulus decreased slightly with increasing outer solids flux. When Ug,d<0.85 m/s, the uniformity of radial distributions of local solids hold-up in the draft tube gradually became well along axial direction; when Ug,d≥0.85 m/s, firstly the uniformity became well along axial direction, then became worse in the exit of draft tube. The uniformity extent of distributions of solids hold-up in the annulus is middle part of annulus > bottom part of annulus > upper part of annulus. In the same condition, the radial non-uniformity index of distributions of solids hold-up of airlift loop fluidized bed was less than that of conventional fluidized bed.

Effects of Grid Scale, Time Step and Maximum Solid Volume Fraction on CFD Simulation in a Jetting Fluidized Bed

PEI Pei WANG Qi-cheng ZHANG Kai WEN Dong-sheng

. 2008, 8(6): 1057-1063.

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Based on the Eulerian-Eulerian two-fluid model, the hydrodynamics was simulated in a two-dimensional jetting fluidized bed with 2.0 m height and 0.3 m width. Air and glass bead were chosen as gas and solid phases, respectively. The effects of grid scale, time step and maximum solid volume fraction on jetting parameters, such as jet revolution, jet penetration depth and jet frequency, were investigated numerically with CFX4.4 by adding User-defined Fortran subroutines. The computational results are independent of mesh size and time step for the gas-solid system used, when vertical grid number is 100 in the lower part of the bed and time increment 0.0005 s. The relative errors of simulated jet penetration depth and jet frequency with their corresponding experimental measurements are 5.7% and 3.8%, respectively. The influence of the maximum solid volume fraction on numerical data can be ignored in the range of this study.

Investigation on Solid-Liquid Suspension Performance in an Eccentrically Stirred Tank

YANG Feng-Ling Yang Shenjie Zhou ZHANG Cui-xun CHEN Lian-fang

. 2008, 8(6): 1064-1069.

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Solid-liquid suspension performance in an eccentrically stirred tank was numerically investigated by using Fluent software. The two-phase system studied consisted of globose glass beads and water. Solid particle volume fraction was 15%, and the particle diameter 135 mm. Standard k-e turbulent model was used to simulate the steady liquid phase flow field, and the unsteady solid-liquid suspension process was simulated with the Eulerian multiphase model. The flow pattern, solids particles concentration distribution and power consumption were extensively analyzed. The results show that, compared with the concentric agitation, the eccentric agitation led to a more homogeneous particle concentration distribution, improved the suspension performance and saved energy. Besides, the improvement of solid-liquid suspension performance varied with the eccentricity. In this work, solid particles reached the best suspension when the eccentricity, e, was 0.21. The critical suspension velocity and power consumption were about 80% and 90% of those in the concentric agitation respectively.

Minimum Fluidization Characteristics of Binary Mixtures of Particles with Significant Size Difference

LIU Wei-Wei FAN Yi-ping LU Chun-xi

. 2008, 8(6): 1070-1074.

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Minimum fluidization characteristics of binary mixture of particles with significant size difference are studied in cold model perspex experimental equipment with the dimensions of f260 mm′2000 mm. The fluidization curves and characteristic velocities including initial velocity, minimum fluidization velocity, segregated velocity and full fluidization velocity are obtained. It is indicated that fluidization curves could be divided into four zones, corresponding to three states: mixing state, intermediate state and full segregated state. Characteristic velocities of binary mixtures decrease with increasing of mass fraction of fine particles, and the trend is not obvious when mass fraction of fine particles is about 0.4~0.5. Bed voidage of binary mixtures of particles in fixed bed and full fluidization states and volume contraction ratio of binary mixtures of particles arrived at extremum when the mass fraction of fine particles is equal to 0.4.

Experimental Study on Flow Characteristics under Salt Precipitation in a Horizontal Pipe

JIA Wei-dong YANG Min-guan GAO Bo LI Hui GU Hai-fei

. 2008, 8(6): 1075-1079.

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A phase Doppler particle analyzer was used to measure salt precipitation turbulent flow of sodium carbonate solution under salt precipitation in a round pipe. Experimental results indicate that the relative count density and average diameter of particle phase show a climbing trend with temperature falling. And average diameter of particle phase increases from 40 mm to above 60 mm with the temperature from 30℃ to 15℃. The crystallized particles from salt precipitation are separated out and grow up continually when the supersaturation increases. The fluctuating intensity of liquid phase is lower than that of particle phase at the same temperature and falls down close to the wall surface, but that of particle phase becomes higher. The turbulence is obviously anisotropic during the course of salt precipitation flow. The average velocities of liquid and particle phases are symmetric basically along the horizontal direction at different temperatures. And the average velocity of liquid phase is slightly bigger than that of particle phase, the difference of average velocity between two phases is about 3% of mainstream velocity. Meanwhile, the average velocity of particle phase decreases with the temperature falling down.

Computational Fluid Dynamic Simulation of Liquid-Liquid Mixing in a Static Double-T-shaped Micromixer

E. A. MANSUR WANG Yun-dong DAI You-yuan

. 2008, 8(6): 1080-1084.

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The laminar flow structure and mixing performance of T-shaped and double-T-shaped micromixers with rectangular cross-section have been investigated using computational fluid dynamic (CFD) simulation. FLUENT software is used to evaluate the mixing efficiency. The numerical simulation results show that the presented double-T-micromixer is highly efficient over T-shaped micromixer. The performance of double-T-micromixer with and without static mixing elements (SME) is also investigated. The enhancement in mixing performance is thought to be caused by the generation of eddies and lateral velocity component when the mixture flows through these elements. Mixing efficiency as higher as 97% is reached within a mixing length of 320 mm downstream from the first T-junction with the enhancement of three SMEs.

Investigation on Pressure Oxidative Leaching of Copper Slag with High Iron and Silicon Content

JIN Bing-jie YANG Xian-wan SHEN Qing-feng

. 2008, 8(6): 1085-1091.

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The pressure oxidative leaching of copper slag with high iron and silicon content was studied systematically. The results show that the effects of leaching time, oxygen partial pressure, acid dosage, leaching temperature and agitation rate are predominant, and the initial Cu2+ concentration not remarkable. The optimal technological conditions are obtained: leaching time 2 h, oxygen partial pressure 0.8 MPa, acid concentration 46.6 g/L, temperature (150±2)℃, agitation speed 600 r/min and flocculation composite A 30~100 g/m3. Under these conditions, the extraction rate of Cu is over 95%, the concentration of Fe less than 5 g/L, the yield of S 20%~30% of total sulfur mass, and the filtration rate of magma about 0.8 m3/(m2×h).

Extraction and Separation of Titanium from Air-cooled Ti-bearing Blast Furnace Slag

XIONG Yao LIANG Bin LI Chun

. 2008, 8(6): 1092-1097.

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A two-step extracting and separating process of air-cooled Ti-bearing blast furnace slag was proposed and investigated. The slag was firstly leached with HCl, leading to a preliminary separation of titanium and silicon with other dissolvable impurities. The resulting solid residue was then subjected to high temperature treatment for further separation of titanium and silicon species. The results showed that the leaching produced a preliminarily enriched residue with 33% TiO2 and 36% SiO2, in which the titania mainly came from the H2TiO3 formed during the hydrolysis and un-reacted CaTiO3. During the heat treatment, TiO2 in the H2TiO3 was carbothermally reduced to Ti3O5 and crystallized out, and the Ti3O5 content and mean size were about 85% and 20 mm, respectively. The grain size could be further increased to 36 mm upon the addition of a small amount of anatase TiO2. Therefore, it is possible to separate the Ti3O5-rich phase from the silicon-rich phase by gravity separation method. A theoretical recovery rate of Ti was calculated as 39%.

Fractionation of Lignocellulose by Formic Acid Pretreatment

HUANG Ren-liang SU Rong-xin QI Wei ZHANG Ming-jia HE Zhi-min

. 2008, 8(6): 1103-1107.

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Based on corn cobs, a pretreatment process in modest conditions (atmospheric pressure and moderate reaction temperature) was designed to fractionate lignocellulose by using formic acid. During the pretreatment, the hemicellulose was hydrolyzed quickly and most of the lignin was dissolved in the solution, but the cellulose almost could not be hydrolyzed. After solid-liquid separation and reagent recycling, corn cobs were separated into cellulose, hemicellulose hydrolysates and lignin. The effects of reaction temperature, pretreatment time and concentration of formic acid on the separated components and the obtained hydrolysates (soluble sugars) during the fractionation were studied. The HPLC results showed that the masses of soluble sugars and lignin increased quickly at first, and then changed slowly. The effect of temperature from 50 to 75℃ was not obvious. By considering efficiency and cost, the optimal operating conditions were chosen as: reaction temperature 60℃, reaction time 3 h, and concentration of formic acid 88%(w). Under the conditions the recovery rates of cellulose, hemicelluloses and lignin could reach 91.4%, 88.5% and 63.7%, respectively.

Preparation of Zeolite from Oil Shale Residue and Its Adsorption Property to Cr6+

LIU Yan-hui XUE Xiang-xin SONG Hai

. 2008, 8(6): 1108-1111.

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The formation and Cr6+ adsorption capability of zeolite synthesized after alkaline activation of a Chinese oil shale residue, and the effects of NaOH concentration, fusion temperature, aging time and aging temperature in closed systems on its adsorption to Cr6+ were investigated. NaOH concentration and aging time affected mainly the crystallinity of zeolite formed. Cr6+ adsorption capability of synthesized products increased with increasing fusion temperature, aging time and aging temperature. Cr6+ adsorption capability of synthesized zeolite decreased with the increase of NaOH concentration, reached its maximum adsorption capacity and adsorption rate for simulated 1 mg/L Cr6+ polluted water were 1.120 mg/g and 89.6% respectively. From the economic point of view, the optimal conditions are determined as follows: NaOH concentration of 4.6 mol/L, fusion temperature of 400℃, aging time of 72 h, and aging temperature of 140℃.

Extraction of Methyl Orange from Ethanol-Water System by Foam Separation

WEI Xuan-biao WU Zhao-liang LU Ke ZHANG Fang

. 2008, 8(6): 1112-1115.

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Foam separation was applied to extraction of methyl orange from ethanol-water system with cetyltrimethylammonium bromide (CTAB) as surfactant. The effects of ethanol volume, gas flow rate, pH, methyl orange concentration and surfactant concentration on its recovery rate were studied. The possibility of foam separation as an effective technology for extracting active components from traditional Chinese medicine in ethanol-water system was discussed. The results show that the recovery rate of methyl orange is above 98.5% and the enrichment ratio 14.38 under the conditions of ethanol volume 25%, pH 6.0, gas flow rate 80 mL/min, methyl orange 35 mg/L, and 80 mg/L CTAB of aqueous solution. The results also suggest that there exists possibility of extracting active components from traditional Chinese medicine in ethanol-water system by increasing the surfactant concentration in a certain range or foam stabilizer to weaken the defoaming effect of ethanol.

Decolorization of the Wastewater Containing Crystal Violet by Foam Separation

ZHANG Xiao-long WU Zhao-liang ZHENG Hui-jie DING Hong-mei

. 2008, 8(6): 1116-1119.

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The decolorization process of wastewater by foam separation was studied by using aqueous solution of crystal violet as a research system. The influences of pH value, gas flow rate, concentration of surfactant and volume of the solution on the decolorization process were investigated by using sodium dodecyl benzene sulfonate (SDBS) as the surfactant. The optimum conditions were determinated by the orthogonal test method. The results show that under the optimum conditions of pH 11.0, gas flow rate 0.018 m3/h, concentration of SDBS 450 mg/L and volume of the solution 500 mL, the enrichment ratio of crystal violet in the solution is 10.3 and its decolorization rate 93.5%.

Synthesis of Diphenyl Carbonate by Oxidative Carbonylation of Phenol with Pd/CuO-Ce0.5Mn0.5O2 Catalyst

YUAN Hua DU Zhi-ping WU Yuan-xin

. 2008, 8(6): 1120-1125.

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CuO-Ce0.5Mn0.5O2 support was prepared with two CuO doping methods and used in direct synthesis of diphenyl carbonate by oxidative carbonylation of phenol. 0.5%Pd/CuO-Ce0.5Mn0.5O2 catalyst was prepared through precipitation method using PdCl2 as the precursor of active Pd component. The catalyst was characterized by XRD, SEM and BET techniques. The effects of preparation methods of support on the activity of catalyst were investigated. The catalytic activity test results showed that the physical structure of catalyst could be improved when CuO was doped by sol-gel method. The diphenyl carbonate yield could reach 17.06% under the conditions of CuO doped amount 9%(w), reaction temperature 75℃, pressure 5 MPa and reaction time 12 h.

Preparation of Acidified Sludge-Bentonite Granules

YUAN Ai-juan LI Qian JIA Hong-yu GAO Bao-yu DUO Xin-yi LI Jing YU Hui YU Hui

. 2008, 8(6): 1126-1131.

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Taking sludge as pore-forming agent, the optimized conditions for preparation and acidification of bentonite granules were investigated. The effects of calcination temperature, roasting time and sludge content on the porosity of granules were investigated to obtain porous samples with better mechanical strength, which were further treated with sulphuric acid activation. By altering acid type, acid concentration, ratio of liquid to solid, activation temperature and activation time, the acid activated bentonite granular adsorbent with better decoloration properties was obtained and characterized in specific surface area, lost ratio, water absorption and morphology. The results indicate that the optimal preparation conditions of porous bentonite granules are calcination temperature 700℃, calcination time 7 h, and mass ratio of sludge to bentonite 1:3. And the granules are acidized by the sulphuric acid of 6 mol/L to react for 4 h at ambient temperature and ratio of H2SO4 to granules 25 mL/g. The decoloration rate of Turquoise Blue by the prepared granules reaches 47% in 2 h, which is more excellent than that of other three granular adsorbents, irregular carbons, cylindrical carbons and raw material.

Degradation Kinetics of Xylose and Glucose in Hydrolysate Containing Dilute Sulfuric Acid

QI Wei ZHANG Su-ping XU Qing-li REN Zhen-wei YAN Yong-jie

. 2008, 8(6): 1132-1137.

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In preparation of fuel alcohol from biomass as feedstock, hydrolysis with dilute acid as catalyst is one way to produce fermentable saccharide, xylose and glucose. However, the acid is also the catalyst in degradation of xylose and glucose and the yield of sacchride is dependent on the kinetic behaviors of saccharide. The degradation kinetics of xylose and glucose in the hydrolysate was investigated under the conventional process conditions of hydrogen ion concentration from 0.05 to 0.2 mol/L and temperature from 150 to 200℃. With a numerical calculation method, the kinetic parameters were estimated, and the activation energy of xylose and glucose in the degradation reaction was obtained. The kinetic equations correlating the effect of hydrogen ion concentration on the rate constants of degradation reaction were established. Comparison between the calculated results from the equations and experimental ones proved that the established kinetic model could satisfactorily predict the degradation behavior of xylose and glucose in the acidic hydrolysate.

Degradation of Nitrobenzene by Electrochemical Catalysis with Titania-containing Slags

XUE Xiang-xin TANG Yan-hong YANG He LI Wei KANG Ze-shuang

. 2008, 8(6): 1138-1142.

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The removal efficiency of nitrobenzene (NB) catalyzed electrochemically by the slags containing titania was investigated. The results show that catalytic ability of the slags was proportional to the content of titania in slag under the same experimental conditions. 100% of NB removal could be reached after 25 min under 30 V in dimensionally stable anode (DSA) when high-titania slag was used as catalyst. The products in anode had been completely removed after 30 min on the analysis of COD value which shows no discharge of contaminants. With the extension of reaction time, the BOD5/COD value of products in cathode increased gradually and NB aqueous solution obtained capability of biotransformation after 20 min.

Vacuum Pyrolysis of Chinese Fir Sawdust for Bio-oil Production

YANG Su-wen QIU Ke-qiang

. 2008, 8(6): 1143-1147.

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Using Chinese fir sawdust as raw material, the experiments of biomass vacuum pyrolysis for production of bio-oil were carried out. The effects of pyrolysis parameters such as pyrolysis temperature, system pressure, holding time of final pyrolysis temperature and heating rate on the yield of bio-oil were investigated. The effects of pyrolysis parameters on chemical components of bio-oil were analyzed by GC-MS. Under final pyrolysis temperature set at 500℃, system pressure at 20 kPa, holding time of the final pyrolysis temperature for 60 min and heating rate of 60℃/min, the maximum yield of bio-oil reached up to 67%.

Behavior of Al and Si in Bayer Red Mud Processed by NaOH Sub-molten Salt

SUN Wang ZHENG Shi-li ZHANG Yi-fei XU Hong-bin ZHANG Yi

. 2008, 8(6): 1148-1152.

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Based on the problem of higher Al2O3/SiO2 (A/S) of Bayer red mud, the separation of Al and Si in red mud from Bayer process in digestion with NaOH sub-molten salt was investigated. The effects of digestion temperature, mass ratio of alkali to red mud from Bayer process and CaO addition on the behavior of red mud in the salt were experimentally investigated. The results show that high temperature and mass ratio of alkali to red mud lead to more alumina into the aqueous phase and the decrease of A/S in brown mud. The recovery rate of Al2O3 can reach 79.22% and A/S in the brown mud is decreased to 0.39 under the conditions of mass ratio of alkali to red mud at 6, digestion temperature at 230℃, and digestion time for 2 h. Further study shows that Si exists in the form of NaCaHSiO4 and Ca3(Al0.13Fe0.87)2(SiO4)1.65(OH)5.4. The recovery rate can not be further raised under the condition of CaO addition in sub-molten salt process when the molar ratio of CaO to SiO2 over 1.2 in the original red mud.

Synthesis of Si3N4 Powder from Iron Ore Tailing

ZHANG Shu-Hui Zhi-Qiang KANG Qing LU XUE Xiang-xin HUANG Da-wei

. 2008, 8(6): 1153-1157.

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Based on thermodynamic analysis, Si3N4 powder was prepared by carbothermal reduction-nutridation from iron ore tailing. The phase composition and microstructure of sintered products were investigated by XRD and SEM techniques. The influences of synthesis temperature and N2 flow on the reaction process were also studied. The results show that Si3N4 phase in the products rises with increasing of synthesis temperature and reaches the maximum portion at 1450℃, which is assumed to be the optimal synthesis temperature. And Si3N4 crystal mostly exists as equiaxedly columnar or shot rod-like b-Si3N4. The increase of N2 flow is favorable to the reduction-nutridation process, and the optimal flow rate of N2 is 600 mL/min. Volatilization of SiO results in obvious mass loss of the tested samples.

Crystallization Kinetics of High Purity Boric Acid in Preparation Process

GONG dian-ting LI Feng-hua FAN Zhan-guo LIU Su--lan

. 2008, 8(6): 1158-1162.

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High purity boric acid was prepared by HCl acidification of borax combined with recrystallization and ion resin exchange. Some influential factors on the crystallization process of H3BO3-NaCl-H2O system such as supersaturation, crystallization temperature and time, stirring speed, and impurity in the solution were studied. The results show that with the solution concentration at 18.26%, and final crystallization temperature 10℃ held for 480 min, stirring speed 300 r/min, and proper cooling, the formation of boric acid crystals has been optimally achieved. The rate of crystallization can be over 83%, and the crystals are fine granules. NaCl can accelerate boric acid crystallization in the system. Based on the experimental data, the curve of crystallization kinetics is gained and kinetics equation formed with the reaction order of 2.

Chemical Demulsification and Immobilization of Pd Nanoparticles in W/O Microemulsion by Conductivity Method

ZHOU Yong-hua YE Hong-qi ZHONG Hong

. 2008, 8(6): 1163-1166.

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The well dispersed palladium nanoparticles with 5~10 nm in diameter were prepared in water-Tween-80-Span-80- cyclohexane microemulsion. The mixture composed of demulsifying agent and microemulsion presents subsequently microemulsion, delamination and colloid or microemulsion with the increase of amount of demulsifying agent. The hydrophilic property and molecular structure of demulsifying agent are considered as the main property factors affecting the demulsifying behavior. Adopting the critical region of delamination and homogenous system, the immobilization of palladium nanoparticles on the surface of support can be realized by simultaneous impregnation of a-Al2O3 support and chemical demulsifying. Analytical results of TEM and XPS show that Pd nanoparticles on the surface of support have the sizes of 10~20 nm in diameter and exist in Pd metallic state.

Preparation of Bio-diesel from Jatropha curcas Oil by Transesterification with Solid Acid Catalysts

SUN Jin-feng REN Tian-rui XUE Si-jia

. 2008, 8(6): 1167-1172.

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Transesterification of Jatropha curcas oil was carried out in the presence of solid acid, the effects of types of catalysts and reaction conditions on the bio-diesel yields and the components in the process of the preparation of methyl esters (bio-diesel) were examined. Solid acid catalysts ZrO2-SO42- and K4Zn4[Fe(CN)6]3 were prepared with precipitation. Their structures and characteristics identified by XRD, FT-IR, BET and elemental analysis were compared. Their catalytic activities changed with acid value and reaction temperature. The detail components of the bio-diesel production were analyzed by GC-MS. The results showed that the ZrO2-SO42- lost its catalytic activity in high acid value Jatropha curcas oil. The yield of methyl ester declined to 84%. Otherwise, K4Zn4[Fe(CN)6]3 remained its good catalytic activity and stability. The yield of methyl ester was 93%. After it was used five times, the yield of methyl ester still reached 90%.

Enzymatic Synthesis of Ethyl Oleate by Lipase in AOT Reverse Micellar System

LI Wei-jie GAO Jing JIANG Yan-jun HUANG Zhi-hong HE Ying ZHOU Li-ya

. 2008, 8(6): 1173-1178.

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Synthesis of ethyl oleate catalyzed by Lipex lipase in AOT/isooctane reverse micellar system was studied. The influential factors on its yield were investigated. The fluorescence analysis of Lipex lipase and particle size analysis of reverse micellar system were carried out. It was confirmed that Lipex lipase had a good activation in the AOT reverse micellar system, and the best solvent was isooctane. The reaction conditions were optimized. When the temperature was 25℃, buffer pH 6.5, molar ratio of water to surfactant 10, molar ratio of alcohol to oleic acid 20, concentration of oleic acid and Lipex lipase 0.005 mol/L and 0.035 g/L respectively, agitation speed 150 r/min, and reaction time 36 h, the yield of ethyl oleate reached 71.25%. The activity of Lipex lipase was affected by the particle size of reverse micellar system and configuration of Lipex lipase. The suitable particle size of reverse micella was about 80 nm.

Preliminary Study on E. coli Microbial Fuel Cell and On-electrode Taming of the Biocatalyst

XI Ming-yue SUN Yan-ping

. 2008, 8(6): 1179-1184.

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A mediator microbial fuel cell (MFC) was constructed by using E. coli as biocatalyst and new methylene blue as electron mediator. E. coli cells were carried out in anaerobic growth prior to inoculating them into the MFC in order to pre-adapt bacterial metabolism in an anaerobic environment, the electricity generation of MFC was tested, its maximum power density reached 263.94 mW/m2 with the corresponding current density 1287.50 mA/m2, the internal resistance of MFC was 200 W, and capability of the MFC was even better than those reported so far. Moreover, on-electrode taming method was adopted to improve electrochemical activity of E. coli, namely a combination of E. coli taming and electricity generation simultaneously in the same MFC without scraping off the biofilm of MFC, after the 4th on-electrode taming, the tamed E. coli MFC showed a 54% improvement in peak current density, being 612.50 mA/m2, and a 64% improvement in the maximum power output, being 166.67 mW/m2, compared with that of parental E. coli MFC. And the maturation time of tamed biofilm was obviously reduced to 240 min, quickening up 1 times compared with that of parental E. coli biofilm.

A Rapid Screening Method of Producing Strain in Acetone-Butanol Fermentation

JIN Xiao-qing ZHOU Hua WU Xue-ming ZHANG Gan-dao HE Bing-fang

. 2008, 8(6): 1185-1189.

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A rapid screening method of producing strains in acetone-butanol fermentation was developed. Nitrogen ion beam implantation was used to breed producing strains in the fermentation. The high amylase activity mutants were obtained by using 2-deoxy-D-glucose as the antimetabolite. Then the high-yielding mutants were further screened by screening plates of bromocresol green and resazurin. It was proved that the butanol and solvent producing ability of selected mutants were significantly improved. The total solvents production and butanol production of mutant I4-28 increased by 27.96% and 40.66%, compared with the parent strain, and the ratio of butanol to total solvents was up to 71.94% from 63.39%. The mutant had good genetic stability after 8 times of subculture. The rapid screening method was simple, efficient and significantly valuable in breeding of acetone-butanol producing strains.

Activity Protection of Papain Entrapped in Sol-Gel Glass Matrix

WANG Hong-yu GAO Jing WANG Hai-ou

. 2008, 8(6): 1190-1194.

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Sugar and liposome were selected for protecting papain entrapped in sol-gel glass matrix. The activity of immobilized papain influenced by sucrose, glucose, trehalose, xylose, maltose, content of cholesterol, and ratio of lecithin to cholesterol was studied. The result showed that the immobilized enzyme prepared with 80 mL 20 mg/mL papain solution, 15 mg xylose, and 500 mL N-decane solution [the content of cholesterol was 1.5%(w), and mass ratio of lecithin to cholesterol 4.5:1] had the highest activity. The entrapment efficiency of the immobilized enzyme prepared under the optimal conditions was 42.0%, and the activity recovery rate was 61.2%. The SEM analysis showed that the immobilized enzyme appeared homogeneously in spherical shape, the inner hole in the sphere existed in honey-comb shape. The effect of membrane-breaking reagents on the enzyme activity was also investigated, among which TritionX-100 was the best reagent.

Purification and Characterization of Protease with High Stability in Organic Solvebts

YAO Zhong Sun Bei-bei LI Shuang HE Bing-fang

. 2008, 8(6): 1195-1199.

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A novel solvent-tolerant protease was produced by a solvent-tolerant Bacillus licheniformis YP1 strain isolated from soil. The protease was purified by precipitation with ammonium sulfate, hydrophobic interaction chromatography and cation exchange chromatography, leading to 37.2-fold purification with 20.8% recovery rate. The product showed eletrophoretic homogeneity, as identified by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), and the specific activity of the purified protease reached 1.18×105 U/mg. SDS-PAGE analysis indicated that the relative molecular mass of the protein was about 28 kDa. The protease was stable and active in all the tested solvents and the protease activity was significantly enhanced in the presence of 50%(j) DMSO and DMF. The protease was considered as a Zn2+-complexed enzyme with an optimal reaction temperature of 55℃. The enzyme was stable in the pH range of 8.0~13.0, with an optimum pH of 10.0. The Michaelis constant for caseinolytic activity was 0.048 g/L.

Discrimination of By-products and Analysis of Reaction Mechanism in Preparation of Dichloropropanol from Glycerol

ZHAO Zhen QIAO Xu CHEN Xian TANG Ji-hai CUI Mi-fen

. 2008, 8(6): 1198-1102.

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Dichloropropanol was synthesized by chlorination of glycerol with hydrogen chloride under catalysis of organic acids and self-made inorganic catalyst. The qualitative analysis of by-products was carried out by GC-MS and the side reaction mechanism of catalytic reaction of glycerol by carboxylic acid was studied. And the main by-products of carboxylic glycerin ester, autopolymer of carboxylic acid, carboxylic chloropropyl ester and diglycerine were identified. The advantages and disadvantages between organic acids catalyst and inorganic catalyst on chlorination of glycerol were compared, and the results showed that the total selectivity of monochloropropanediol and dichloropropanol was obtained to above 99%, being 4% higher than that of organic acid catalysis.

Enhancement of Pyruvate Production with Amino Acid Addition in Torulopsis glabrata Induced Fermentation

XU Qing-long XU Xiao-peng LIU Li-ming SHI Zhong-ping DU GUo-cheng CHEN Jian

. 2008, 8(6): 1200-1203.

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The effect of amino acid on production of pyruvate by T. glabrata CCTCC M202019 was investigated. The pyruvate production was increased 23.5%, 16.4% and 11.8%, respectively, with 0.8 g/L glutamic acid, 0.6 g/L tyrosine and 0.2 g/L methionine fed to the fermentation medium at the initial fermentation. The principle of amino acids to enhance pyruvate production is that the amount of glucose used for cell growth was reduced, but the yields of cell and pyruvate on glucose (Yx/s and Yp/s) were increased. On the other hand, the concentration of intracellular NADH was decreased by amino acid addition, which resulted in higher glycolic flux and pyruvate production.

Preparation of Low Temperature and High Activity Mn-V-Ce/TiO2 Catalyst and Its Catalytic Performance on NO Oxidation

ZHENG Zu-hong TONG Hua TONG Zhi-quan ZHANG Jun-feng HAUNG Yan

. 2008, 8(6): 1204-1212.

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A novel Mn-V-Ce/TiO2 catalyst for catalytic oxidation of nitric oxide was prepared by impregnation method. The effects of loading, carrier, calcining temperature, volume fractions of NO and O2, and space velocity on Mn-V-Ce/TiO2 catalytic oxidation of nitric oxide were studied, and the catalysts were characterized by BET and XRD analysis. The results show that the catalyst from calcination of 10%Mn-3%V2O5-20%CeO2/TiO2 at 300℃ for 6 h can obtain the optimal catalytic oxidation activity. When the volume fraction of NO is 5′10-4(j), O2 10%, space velocity 8000 or 5000 h-1, the oxidation rate (NO2/NOx) reaches 50%~60% at 200 or 175℃, respectively, and the highest absorption efficiency of NOx is gained. At the temperature of 250℃, space velocity 8000 and 5000 h-1, the oxidation rate is about 74% and 86.6%, respectively.

Preparation of Magnetically Modified Natural Zeolite and Its Adsorption to Pb2+ and Cu2+

. 2008, 8(6): 1213-1217.

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The adsorption features of natural zeolites with the magnetic properties of iron oxides were combined in a composite by chemical coprecipitation process to prepare a magnetic adsorbent. The magnetically modified zeolite (MMZ) was characterized by XRD, nitrogen adsorption isotherms, FT-IR spectroscopy, SEM and magnetization measurement. The results showed that the structure of MMZ was not manifestly changed, compared with Na-zeolite, and its specific surface area increased from 25.13 to 100.90 m2/g. The adsorption of Pb2+ and Cu2+ in simulated wastewater on MMZ was studied. The results showed that the adsorption of metal ions was dependent on pH, and at pH>4.5, the removal efficiencies of Pb2+ and Cu2+ were more than 90%. Moreover, the maximum loading capacities of Pb2+ and Cu2+ in the initial concentration range studied reached 19.44 and 6.20 mg/g, respectively.

Catalysis of Bismuth Complex Salt in Vapor Phase Hydrochlorination of Acetylene

WEI Xiao-bo WEI Fei QIAN Wei-zhong LUO Guo-hua SHI Hai-bo JIN Yong

. 2008, 8(6): 1218-1222.

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A non-merury novel catalyst with bimetallic chlorides and bimetallic phosphates based on SiO2 was prepared by dipping method and used in catalytic hydrochlorination of acetylene to vinyl chloride. The experimental results showed that reaction activity of the catalyst could be promoted obviously by introducing PO43- to it. Bimetallic phosphates of Cu and Bi based on SiO2 behaved the best in testing of catalysis, and its initial reaction activity was 1/3 time of conventional industrial HgCl2/C catalyst. The catalyst could be regenerated, but lost its activity slowly after usage and regeneration. The deactivation of the catalyst was due to the loss of Bi and carbon deposition on its surface.

Preparation of Proton Conductive Electrolyte from Poly(vinylidene fluoride-co-hexafluoropropylene) by Grafting Poly(sulfopropyl methacrylate)

XIAO Shu-qin CHEN Yi-wang ZHOU Wei-hua ZHANG Xiao-lin WEI Xiao-hui

. 2008, 8(6): 1223-1227.

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Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) grafted poly(sulfopropyl methacrylate) (PSPMA) (PVDF-HFP-g-PSPMA) copolymer as proton conductive electrolyte by atom transfer radical polymerization of sulfopropyl methacrylate (SPMA) at the secondary halogenated sites of PVDF-HFP was prepared and characterized. The structure of PVDF-HFP-g-PSPMA copolymer was verified by FT-IR spectroscopy and proton nuclear magnetic resonance spectrometry. The PVDF-HFP-g-PSPMA membrane showed the ion exchange chromatography value ranging from 0.05 to 0.59 meq/g and the proton conductivity from 2.58×10-4 to 3.09×10-3 S/cm, and its property could be modulated by controlling the polymerization time.

Effect of Titanium Substrate with Different Porosities on the Properties of RuO2-TiO2 Anode

WANG Xin SHAO Yan-qun TANG Dian

. 2008, 8(6): 1228-1232.

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RuO2-TiO2 anode coating was prepared onto industrial pure titanium (TA2) substrate with different porosities. The microstructure of substrate was investigated by optical microscope. The phase structure, density, microhardness and conductivity of substrate were also examined. The phase structure, morphology, electrocatalytic activity and electrochemical stability of anodes were compared. The results showed that the mircohardness of high porosity TA2 substrate increased about 60 Hv, the conductivity of high porosity TA2 substrate increased about 0.2 W×mm. The different substrates had obvious effect on the properties of anodes. The anode prepared with the high porosity TA2 bad corrosion resistance and the worst electrocatalytic activity, and the Cl2-evolution potential increased about 10 mV, the life-time of the coating was decreased about 100 min and peeled off easily.

Controllable Synthesis of Hexagonal Prism and Hollow Anatase TiO2 Microstructures

ZHAMG Sen LIU Chun-yan LIU Yun ZHANG Zhi-ying

. 2008, 8(6): 1233-1236.

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Anatase TiO2 nanocrystals with hexagonal prism and hollow microstructures were synthesized by heating titanium oxide oxalate hydroxide hydrate microstructures obtained by refluxing at 90℃ using tetrabutyl titanate [Ti(OC4H9)4] as a precursor. Bubbles produced in the synthesis processes played an important role in the evolution of product morphology. Hexagonal prism and hollow microstructures of the final products formed in the absence and presence of bubbles, respectively. XRD patterns combined with SEM and TEM images indicated that the hexagonal prism TiO2 microstructure with the average size of 2.5 mm (diameter)×5 mm (length) and the hollow TiO2 microstructure with 200 nm wall thickness were highly crystalline and pure.

Preparation and Microwave Absorption Properties of Ni0.5Zn0.5Fe2O4 Doped with Lanthanum

WU Xiao-juan ZHAO Hai-tao ZHANG Gang MA Rui-ting

. 2008, 8(6): 1237-1240.

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Ni0.5Zn0.5LaxFe2-xO4 (x=0, 0.05, 0.1) ferrite was prepared using polyacrylamide gel method. Its structural characteristics, morphology, electromagnetic and microwave absorption properties were analyzed by XRD, TEM, and HP8510 network analyzer. The results indicated that a pure spinel structure of Ni0.5Zn0.5La0.05Fe1.95O4 formed at 600℃. La3+ had limited solid solubility in the spinel lattice of La-doped Ni-Zn ferrites. The tandm values of La-doped Ni-Zn ferrites were lower than that of the sample without La, but the tande values of La-doped Ni-Zn ferrites were higher than that without La doping in the X band. The microwave absorbing property was worse for the specimen at x=0.1 than that without doping, but better for the specimen at x=0.05 than that without doping. Its minimum reflection loss was -15.6 dB with a -10 dB bandwidth over the extended frequency range of 2.7 GHz.

Synergistic Enhancement of Sodium Chloride and Sodium Hexametaphosphate in Ceria Slurry to Material Removal Rate in Polishing of ZF7 Glass

WEI Liang-hua FU Maosheng LI Yan-hua ZHOU Xue-zhen ZHOU Mu-xin JIAO Xiao-yan LI Yong-xiu

. 2008, 8(6): 1241-1244.

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NaCl and (NaPO3)6 were adopted as dispersants of ceria slurry to enhance the polishing performance of ZF7 glass in terms of material removal rate and surface quality. The addition of NaCl into ceria slurry resulted in MRR decreasing, whereas the introduction of (NaPO3)6 evidently increased MRR. However when NaCl and (NaPO3)6 were co-added into ceria slurry, synergistic enhancement to MRR was observed. MRR for the slurries of pure ceria and ceria with 0.5 mol/L NaCl and 1.05%(w) (NaPO3)6 were 199.36 and 351.26 nm/min. The corresponding surface roughness Ra of as-polished ZF7 optical glass was 0.754 and 0.799 nm, which can meet the need of optical application. The linear relationship between MRR and Zeta potential of ceria particles in slurries shows that the increase of MRR is attributed to the increase of minus surface Zeta potential, indicating that the polishing ability of ceria can be greatly enhanced by adjusting surface Zeta potential of abrasive particles using sodium chloride and sodium hexametaphosphate as dispersants.

Preparation of Dendrimer/Poly(N-isopropyl acrylamide) Nanoparticles

. 2008, 8(6): 1245-1248.

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Polypropylenimine dendrimer (DAB-32, generation 4.0) was converted into the macroinitiator DAB-32-Br via reaction with bromoacetyl bromide. Dendrimer/poly(N-isopropyl acrylamide) nanoparticles with diameters between 60-150 nm were prepared by atom transfer radical polymerization of N-isopropyl acrylamide in H2O and H2O/CH3CH2OH media, using the DAB-32-Br/CuBr/Bpy as initiating system. Compared with in the H2O medium, the nanoparticles prepared by ATRP in H2O/CH3CH2OH medium were more regular and the aggregations between nanoparticles were less.

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