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Study on enzymatic hydrolysis of steam exploded
straw by using shaking ball
SUN Zhanwei, FU Xiaoguo, CHEN Hongzhang, WANG Yanhui, MA Runyu
Front. Chem. Sci. Eng.. 2008, 2 (1): 22-27.
https://doi.org/10.1007/s11705-008-0002-7
A novel method of enzymatic hydrolysis was developed in this paper to produce a high conversion yield and hydrolysis rate. A comparison was described by using three methods of enzymatic hydrolysis and adsorption of steam exploded straw (SEWS): shaking ball in the regime, shaking with stirrer bed, and static state. The most adequate filter-paper activity, speed and reaction time were 3.6 × 10-7 mol/(smL), 150 r/min and 24 h, respectively, with the reducing sugar yield of 0.43. The results showed that the method of shaking ball produced the highest adsorption, conversion yields and hydrolysis rate of the enzyme. This might be due to the continuous frequency increase of enzyme adsorption and desorption on the substrate surface as well as the relieved end-product inhibition. The morphological variation of SEWS was characterized by environmental scanning electron microscopy (ESEM).
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Bio-modification of eucalyptus chemithermomechanical
pulp
YANG Qifeng, ZHAN Huaiyu, FU Shiyu, WANG Shuangfei, LI Kecheng
Front. Chem. Sci. Eng.. 2008, 2 (1): 28-33.
https://doi.org/10.1007/s11705-008-0007-2
Eucalyptus chemithermomechanical pulp (CTMP) was modified with the white-rot fungus 19-6 in a stationary culture condition. Different factors that influence the effect of white-rot fungus treatment, including additional nutrition, pH value, temperature, treatment time and oxygen input were investigated. The results show that the energy consumption of post refining of CTMP treated by white-rot fungus 19-6 was lower than that of untreated pulp and the strength properties also obviously improved. At a freeness level of about 330 mL, compared to the untreated pulp, the tensile index, tear index and internal bonding strength increased by 21.3%, 27.4% and 33.1%, respectively. Unfortunately, the treatment with white-rot fungus substantially decreased all optical properties except for opacity, which was essentially unchanged. Brightness and light scattering coefficient were reduced to as much as 25% and 21% compared to the untreated pulps. However, after a tow-stage “Na2S2O4–H2O2” bleaching, the final brightness can reach 70.3% ISO, which is similar to that of the untreated CTMP.
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Cell carrier function of hollow-fiber membrane
in rotating wall vessel bioreactor
SONG Kedong, LIU Tianqing, ZHAO Hu, LI Xiangqin, MA Xuehu, CUI Zhanfeng
Front. Chem. Sci. Eng.. 2008, 2 (1): 34-39.
https://doi.org/10.1007/s11705-008-0022-3
Large-scale expansion of the osteoblasts of a Sprague-Dawley (SD) rat was studied in a rotating wall hollow-fiber membrane bioreactor (RWHMB) by using hollow-fiber membrane as the carrier. For the sake of contrast, cells were also expanded in a T-flask using a hollow-fiber membrane as carrier and in a rotating wall vessel bioreactor (RWVB) using a microcarrier. During the culture period, the cells were sampled every 12 h, and after 5 days, the cells were harvested and evaluated with scanning electron microscopy (SEM), hematoxylin-eosin (HE) staining and alkaline phosphatase (ALP) staining. Moreover, von-Kossa staining and Alizarin Red S staining were carried out for mineralized nodules formation. The results show that in RWHMB, the cells present better morphology and vitality and secrete much more extracellular matrix. It is concluded that the RWHMB combines the advantages of the rotating wall vessel and hollow-fiber membrane bioreactors. The hydrodynamic stimulation within it accelerates the metabolism of the osteoblast and mass transfer, which is propitious to cell differentiation and proliferation.
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Preparation of D-lysine by chemical reaction
and microbial asymmetric transformation
LIU Yi, JIAO Qingcai, YIN Xiaoxing
Front. Chem. Sci. Eng.. 2008, 2 (1): 40-43.
https://doi.org/10.1007/s11705-008-0023-2
The DL-lysine crystals from the racemization of L-lysine was treated as substrate with Hafnia alvei AS1.1009 intact cells as biocatalysts to produce crystalline D-lysine with a yield of 56.6% from the reaction mixture after simple purification. In the presence of 0.10 molar equivalent of salicylaldehyde, L-lysine racemization can be completed within 4 h in 1.0 mol/L of NaOH at 100°C. The activation energy of the processes was 62187.86 J/mol. The characteristics of Hafnia alvei AS1.1009 decarboxylase were studied. Under the conditions of pH 8.0, temperature 37°C, cell concentration 10 g/L, tween-80 0.5 g/L, substrate concentration 30 g/L, and the specific activity of up to 3840 U, L-lysine can be completely degraded by the decarboxylase for 12 h under the optimal conditions.
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Preparation and property of porous hydroxyapatite
as an inorganic dispersant used in suspension polymerization
XU Kaqiu, XU Jiale, WANG Yuhong
Front. Chem. Sci. Eng.. 2008, 2 (1): 49-54.
https://doi.org/10.1007/s11705-008-0004-5
The porous hydroxyapatite (HAP) for suspension polymerization dispersant was prepared using calcium carbonate and phosphoric acid as raw materials. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET nitrogen adsorption. The results show that the prepared HAP has a porous structure, low particle density, large specific surface area, uniform particle size and does not agglomerate easily between the particles. The preparation conditions for the HAP were optimized as follows: solid content of calcium carbonate aqueous suspension 90 g/L, concentration of phosphoric acid 1.0 mol/L, reaction/aging temperature 50°C, and aging time 3 h. The HAP prepared under optimal preparation conditions has 106.8 m2·g-1 of specific surface area, which is about 1.5–1.8 times as much as that of Japanese HAP or commercial HAP. Its application result in the suspension polymerization of styrene show that the porous HAP dispersant has high surface activity, excellent suspension dispersibility and stability and can markedly improve the quality of polystyrene beads.
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Modification of acidity of Mo-Fe/HZSM-5 zeolite
via argon plasma treatment
ZHU Xinli, YU Kailu, CHENG Dangguo, XIA Qing, LIU Changjun, ZHANG Yueping
Front. Chem. Sci. Eng.. 2008, 2 (1): 55-58.
https://doi.org/10.1007/s11705-008-0005-4
The NH3-TPD characterization was conducted to confirm that the acidity of Mo-Fe/HZSM-5 zeolite could be selectively modified via the glow discharge plasma treatment. The plasma catalyst treatment could totally change the distribution of aromatic products with higher methane conversion compared to the untreated catalyst. Some polycyclic aromatics such as anthracene, pyrene and phenanthrene were also produced over the plasma treated catalyst, in addition to benzene, toluene and naphthalene, which were normally obtained over the untreated catalyst.
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Kinetics of halogen-exchange fluorination of
2,6-dichlorobenzaldehyde
LIANG Zhengyong, LI Bindong, FENG Chao
Front. Chem. Sci. Eng.. 2008, 2 (1): 59-62.
https://doi.org/10.1007/s11705-008-0008-1
Under the conditions of phase transfer catalysis and nitrobenzene as the solvent, the halogen-exchange fluorination of 2,6-dichlorobenzaldehyde using KF as fluorinating agent was studied. The kinetics was investigated and the reaction rate constants were obtained under the optimum conditions of n(KF):n(2,6-dichlorobenzaldehyde):n(Ph4PBr):n(acetone-furan crown ether) = 4:1:0.1:0.05 and temperatures of 433 K, 443 K, 453 K and 463 K. The results illustrated the activation energy of the first and the second step is 4.57 × 104 J·mol-l and 3.53 × 104 J·mol-1, respectively. The pre-exponential factor is 4.50 × 105 h-1 and 1.08 × 104 h-1, respectively. Thus a reliable kinetics data could be obtained for further research.
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Study on reformulation of fluid catalytic cracking
gasoline and increasing production of light olefins
YAN Pingxiang, MENG Xianghai, GAO Jinsen, XU Chunming, SUI Zhiyu
Front. Chem. Sci. Eng.. 2008, 2 (1): 74-79.
https://doi.org/10.1007/s11705-008-0016-1
The effects of reaction temperature, mass ratio of catalyst to oil, space velocity, and mass ratio of water to oil on the product distribution, the yields of light olefins (light olefins including ethylene, propylene and butylene) and the composition of the fluid catalytic cracking (FCC) gasoline upgraded over the self-made catalyst GL in a confined fluidized bed reactor were investigated. The experimental results showed that FCC gasoline was obviously reformulated under appropriate reaction conditions. The olefins (olefins with C atom number above 4) content of FCC gasoline was markedly reduced, and the aromatics content and octane number were increased. The upgraded gasoline met the new standard of gasoline, and meanwhile, higher yields of light olefins were obtained. Furthermore, higher reaction temperature, higher mass ratio of catalyst to oil, higher mass ratio of water to oil, and lower space velocity were found to be beneficial to FCC gasoline reformulation and light olefins production.
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Improvement in the synthesis of 2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(Z)-methoxyiminoacetic
acid 2-benzothiazolyl thioester
GAO Shihao, SUN Chenghui, ZHAO Xinqi, GAO Changquan
Front. Chem. Sci. Eng.. 2008, 2 (1): 80-84.
https://doi.org/10.1007/s11705-008-0017-0
2-(5-Amino-1,2,4-thiadiazol-3-yl)-2-(Z)-methoxyiminoacetic acid 2-benzothiazolyl thioester(III), an important intermediate of the fourth generation cephalosporins, was efficiently synthesized by reacting 2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(Z)-methoxyiminoacetic acid (I) with 2,2′-dibenzothiazole disulfide (II) in the presence of triphenylphosphine. Effects of reaction time, temperature, solvents, catalysts and feeding molar ratio on the yield and quality of products were investigated, and an improved procedure suitable for industrial production was established. Using 1,2-dichloroethane as solvent, triphenylphosphine as reducer, and triethylamine as catalyst, n(I) : n(II) : n(triphenylphosphine) = 1.0 : 1.0 : 1.0, the product was obtained at room temperature in 98.1% yield. The purity of the product without further purification is 98.7% determined by HPLC method. This procedure could be a suitable alternative to the traditional processes because of its easy handling, high yield and low cost.
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Control on self-assembly structures of rod-coil-rod
(PANI)-(PEG)-(PANI) triblock copolymer
YANG Zhifang, WU Jingao, YANG Yingkui, ZHOU Xingping, XIE Xiaolin
Front. Chem. Sci. Eng.. 2008, 2 (1): 85-88.
https://doi.org/10.1007/s11705-008-0003-6
The self-assembly behaviors of the rod-coil-rod (PANI)98-(PEG)136-(PANI)98 triblock copolymer are investigated in different solvents, such as N-methyl-2-pyrrolidone (NMP), dimethyl formamide (DMF), ethanol and water. The effects of solvents, concentration and ultrasonic irradiation on self-assembly are discussed. The results indicate that the triblock copolymer forms particles, rods, fiber, networks and fiber bands in the above solvents, respectively. Especially, the triblock copolymer can form a multi-layer, tri-dimensional fibrous network and a petaline structure from the mono-layer fibrous network with the increase of its concentration in ethanol. Also, the ultrasonic irradiation has a great effect on the self-assembly of the triblock copolymer.
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Sulfonated poly(ether ether ketone)/zirconium
tricarboxybutylphosphonate composite proton-exchange membranes for
direct methanol fuel cells
GAO Qijun, HUANG Mianyan, WANG Yuxin, CAI Yuquan, XU Li
Front. Chem. Sci. Eng.. 2008, 2 (1): 95-101.
https://doi.org/10.1007/s11705-008-0012-5
Sulfonated poly(ether ether ketone) (SPEEK) is a very promising alternative membrane material for direct methanol fuel cells. However, with a fairly high degree of sulfonation (DS), SPEEK membranes can swell excessively and even dissolve at high temperature. This restricts membranes from working above a high tolerable temperature to get high proton conductivity. To deal with this contradictory situation, insolvable zirconium tricarboxybutylphosphonate (Zr(PBTC)) powder was employed to make a composite with SPEEK polymer in an attempt to improve temperature tolerance of the membranes. SPEEK/Zr(PBTC) composite membranes were obtained by casting a homogeneous mixture of Zr(PBTC) and SPEEK in N,N-dimethylacetamide on a glass plate and then evaporating the solvent at 60°C. Many characteristics were investigated, including thermal stability, liquid uptake, methanol permeability and proton conductivity. Results showed significant improvement not only in temperature tolerance, but also in methanol resistance of the SPEEK/Zr(PBTC) composite membranes. The membranes containing 30 wt-% ∼ 40 wt-% of Zr(PBTC) had their methanol permeability around 10-7 cm2·s-1 at room temperature to 80°C, which was one order of magnitude lower than that of Nafion ¯115. High proton conductivity of the composite membranes, however, could also be achieved from higher temperature applied. At 100% relative humidity, above 90°C the conductivity of the composite membrane containing 40 wt-% of Zr(PBTC) exceeded that of the Nafion ¯115 membrane and even reached a high value of 0.36 S·cm-1 at 160°C. Improved applicable temperature and high conductivity of the composite membrane indicated its promising application in DMFC operations at high temperature.
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Synthesis and characterization of macromolecular
surface modifier PP--PEG for polypropylene
CHEN Hanjia, SHI Xuhua, ZHU Yafei, ZHANG Yi, XU Jiarui
Front. Chem. Sci. Eng.. 2008, 2 (1): 102-108.
https://doi.org/10.1007/s11705-008-0018-z
A novel macromolecular surface modifier, polypropylene-grafted-poly(ethylene glycol) copolymer (PP-g-PEG), was synthesized by coupling polypropylene containing maleic anhydride with monohydroxyl-terminated poly(ethylene glycol). The effects of the reaction condition on the graft reactions were studied. The copolymers were characterized by IR, 1H NMR, thermogravimetry (TG) and differential scanning calorimetry (DSC). The results indicated that the graft reactions were hindered by increasing the molecular weight of PP or PEG. The graft copolymer was found to have a higher initial thermal degradation temperature and lower crystallization capacity as compared with pure PP, and the side chain of PEG hindered the PP chain from forming a perfect ? crystal. The thermal stability of PP-g-PEG decreased with the increasing content or molecular weight of PEG. The copolymers were blended with polypropylene to modify the surface hydrophilicity of the products. The results of attenuated total reflectance FTIR spectroscopy (ATR-FTIR) showed that PP-g-PEG could diffuse preferably onto the surface of the blends and be suitable as an effectual macromolecular surface modifier for PP.
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Selective removal of Cu(II) from contaminated
water using molecularly imprinted polymer
QI Jingyao, LI Xin, LI Ying, ZHU Jianhua, QIANG Liangsheng
Front. Chem. Sci. Eng.. 2008, 2 (1): 109-114.
https://doi.org/10.1007/s11705-008-0019-y
A synthetic molecularly imprinted polymer (MIP) was prepared by noncovalent imprinting technique for the selective removal of Cu2+ from aqueous solutions. In the preparation of imprinted polymer, Cu2+ was used as the template, oleic acid as the functional monomer and divinylbenzene as the cross-linker. The surface morphologies and characteristics of the MIP were determined by BET, scanning electron microscopy (SEM), FTIR and energy dispersive X-ray spectrometer (EDS). The proper adsorption and selective recognition ability of the MIP were studied by an equilibrium-adsorption method. In general, the removal efficiency of Cu2+ increased rapidly with pH from 2 to 7 and decreased at a pH 8. The removal efficiency of Cu2+ increased with temperature from 25°C to 50°C. Competitive adsorption studies showed that the coexisting cations have no obvious influence on the adsorption of Cu2+. In addition, the variation in the adsorption ability of the MIP that was repeatedly used was investigated, and it showed excellent reproducibility.
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23 articles
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