Frontiers of Chemical Science and Engineering

ISSN 2095-0179

ISSN 2095-0187(Online)

CN 11-5981/TQ

Postal Subscription Code 80-969

2018 Impact Factor: 2.809

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, Volume 6 Issue 4

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RESEARCH ARTICLE
Comparison of the morphology and structure of WO3 nanomaterials synthesized by a sol-gel method followed by calcination or hydrothermal treatment
Diah Susanti, Stefanus Haryo N, Hasnan Nisfu, Eko Prasetio Nugroho, Hariyati Purwaningsih, George Endri Kusuma, Shao-Ju Shih
Front Chem Sci Eng. 2012, 6 (4): 371-380.  
https://doi.org/10.1007/s11705-012-1215-3

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Tungsten (VI) oxide (WO3) nanomaterials were synthesized by a sol-gel method using WCl6 and C2H5OH as precursors followed by calcination or hydrothermal treatment. X-Ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) equipped with energy dispersive X-ray spectroscopy (EDX) were used to characterize the structure and morphology of the materials. There were significant differences between the WO3 materials that were calcinated and those that were subjected to a hydrothermal process. The XRD results revealed that calcination temperatures of 300°C and 400°C gave hexagonal structures and temperatures of 500°C and 600°C gave monoclinic structures. The SEM images showed that an increase in calcination temperature led to a decrease in the WO3 powder particle size. The TEM analysis showed that several nanoparticles agglomerated to form bigger clusters. The hydrothermal process produced hexagonal structures for holding times of 12, 16, and 20 h and monoclinic structures for a holding time of 24 h. The SEM results showed transparent rectangular particles which according to the TEM results originated from the aggregation of several nanotubes.

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Preparation of a Pb loaded gas diffusion electrode and its application to CO2 electroreduction
Ang LI, Hua WANG, Jinyu HAN, Li LIU
Front Chem Sci Eng. 2012, 6 (4): 381-388.  
https://doi.org/10.1007/s11705-012-1216-2

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A Pb loaded gas diffusion electrode was fabricated and used for the electroreduction of CO2 to formic acid. The Pb/C catalyst was prepared by isometric impregnation. The crystal structure and morphology of the Pb/C catalyst were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The preparation conditions of the gas diffusion electrode were optimized by adjusting the amounts of polytetrafluoroethylene (PTFE) in the gas diffusion layer and acetylene black in the catalytic layer. The electrochemical performance of the as-prepared gas diffusion electrode was studied by chronoamperometry and cyclic voltammetry. The optimized gas diffusion electrode showed good catalytic performance for the electroreduction of CO2. The current efficiency of formic acid after 1 h of operation reached a maximum of 22% at -2.0 V versus saturated calomel electrode (SCE).

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One-step synthesis of ?-caprolactam via the liquid phase catalytic nitrosation of cyclohexane in the presence of concentrated sulfuric acid
Kuiyi YOU, Fangfang ZHAO, Xueyan LONG, Pingle LIU, Qiuhong AI, Hean LUO
Front Chem Sci Eng. 2012, 6 (4): 389-394.  
https://doi.org/10.1007/s11705-012-1218-0

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A simple and efficient approach for the synthesis of ?-caprolactam via the liquid phase nitrosation of cyclohexane and nitrosyl sulfuric acid in the presence of concentrated sulfuric acid has been developed. A series of novel AlVPO composites were prepared by an impregnation method and the composites were then employed to catalyze the nitrosation reaction of cyclohexane and nitrosyl sulfuric acid. Compared to the reaction using fuming sulfuric acid, the selectivity for the desired product was significantly improved using this one-step catalytic process. This method affords a shortcut to prepare ?-caprolactam and its analogs from cyclohexane.

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Dispersion of a novel phenolic rigid organic filler in isotactic polypropylene matrix by solution-mixing and melt-mixing
Dongming QI, Xiaoli ZHAO, Zhijie CHEN, Peng HUANG, Jun CAO
Front Chem Sci Eng. 2012, 6 (4): 395-402.  
https://doi.org/10.1007/s11705-012-1269-2

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A novel phenolic rigid organic filler (named KD) with a high melting point was dispersed in an isotactic polypropylene (iPP) matrix by solution-mixing and/or melt-mixing. A series of KD/iPP blends was prepared with or without addition of maleic anhydride-grafted polypropylene (MAPP) as a compatibilizer. Influences of MAPP and mixing methods on the filler dispersion were studied using polaried optical microscope (POM), scanning electron microscope (SEM) and tensile test. The filler particles are always inclined to form large irregular aggregates in the iPP matrix due to their significant differences in polarity and solubility in solvent. However, an iPP/MAPP/KD (PMK) blend containing filler particles with a quasi-spherical shape (~97.8 nm in diameter) and narrow particle size distribution (polydispersity index= 1.076) was successfully prepared by incorporating MAPP to reduce the interfacial tension and surface free energy between the dispersion phase and the continuous phase, and adopting a spray-drying method after solution-mixing to suppress the increase of the size of the dispersed phase during the removal of solvent.

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Metakaolinite as a catalyst for biodiesel production from waste cooking oil
Jorge RAMIREZ-ORTIZ, Merced MARTINEZ, Horacio FLORES
Front Chem Sci Eng. 2012, 6 (4): 403-409.  
https://doi.org/10.1007/s11705-012-1224-2

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The use of metakaolinite as a catalyst in the transesterification reaction of waste cooking oil with methanol to obtain fatty acid methyl esters (biodiesel) was studied. Kaolinite was thermally activated by dehydroxylation to obtain the metakaolinite phase. Metakaolinite samples were characterized using X-ray diffraction, N2 adsorption-desorption, simultaneous thermo-gravimetric analyse/differential scanning calorimetry (TGA/DSC) experiments on the thermal decomposition of kaolinite and Fourier-transform infrared spectrometer (FTIR) analysis. Parameters related to the transesterification reaction, including temperature, time, the amount of catalyst and the molar ratio of waste cooking oil to methanol, were also investigated. The transesterification reaction produced biodiesel in a maximum yield of 95% under the following conditions: metakaolinite, 5 wt-% (relative to oil); molar ratio of oil to methanol, 1∶23; reaction temperature, 160°C; reaction time, 4 h. After eight consecutive reaction cycles, the metakaolinite can be recovered and reused after being washed and dried. The biodiesel thus obtained exhibited a viscosity of 5.4?mm2?s–1 and a density of 900.1 kg?m–3. The results showed that metakaolinite is a prominent, inexpensive, reusable and thermally stable catalyst for the transesterification of waste cooking oil.

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Effect of alkyl nitrite decomposition on catalytic performance of CO coupling reaction over supported palladium catalyst
Zhenhua LI, Weihan WANG, Dongxue YIN, Jing LV, Xinbin MA
Front Chem Sci Eng. 2012, 6 (4): 410-414.  
https://doi.org/10.1007/s11705-012-1213-5

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The syntheses of dimethyl oxalate (DMO) and diethyl oxalate (DEO) by CO coupling reaction in gaseous phase were investigated in a fixed bed reactor over Pd-Fe/Al2O3 catalyst. The catalytic performance was characterized by CO conversion, space-time yield (STY) and selectivity of DMO (or DEO). The results showed that over Pd-Fe/Al2O3 catalyst, the STY of DMO was higher than that of DEO under the same reaction conditions. The optimum reaction temperatures for synthesizing DMO and DEO were 403 K and 393 K, respectively, at the molar ratio 1 ∶ 1 of alkyl nitrite to CO. The difference in synthesizing DMO and DEO on the same catalyst was attributed to the decomposition performances of methyl nitrite (MN) and ethyl nitrite (EN), as density functional theory (DFT) calculation showed that EN decomposed more easily than MN.

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Influence of crystalline phase of Li-Al-O oxides on the activity of Wacker-type catalysts in dimethyl carbonate synthesis
Yadong GE, Yuanyuan DONG, Shengping WANG, Yujun ZHAO, Jing LV, Xinbin MA
Front Chem Sci Eng. 2012, 6 (4): 415-422.  
https://doi.org/10.1007/s11705-012-1214-4

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The catalysts supported on LiAl5O8 (spinel) for vapor phase synthesis of dimethyl carbonate (DMC) from methyl nitrite (MN) have been studied. Their catalytic activities on supports prepared by different methods were evaluated in a continuous reactor. The samples were characterized by powder X-ray diffraction, N2 adsorption-desorption isotherms, fourier transform infrared spectroscopy and temperature-programmed reduction of H2. Li/Al molar ratio and calcination temperature greatly influence the structure of crystalline phase of Li-Al-O oxides. Desirable LiAl5O8 (spinel) was formed at 800°C, while LiAl5O8 (primitive cube) formed at 900°C is undesirable for the reaction. A high Li/Al molar ratio, which was related with LiAlO2, also slowed the reaction rate. The electron transfer ability and the interaction with active component are the important properties of the spinel-based supports. The CuCl2-PdCl2/LiAl5O8 (spinel) with better electron transfer ability and low Pd2+ reduction temperature exhibited a better catalytic ability.

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Control of the agglomeration of crystals in the reactive crystallization of 5-(difluoromethoxy)-2-mercapto-1H-benzimidazole
Yongli WANG, Shuyuan MA, Xiaodong Lü, Chuang XIE
Front Chem Sci Eng. 2012, 6 (4): 423-431.  
https://doi.org/10.1007/s11705-012-1211-7

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5-(Difluoromethoxy)-2-mercapto-1H-benzimidazole (DMB) was precipitated by adding acetic acid to the DMB sodium salt solution. The spherical agglomeration of DMB during the reactive crystallization in a batch crystallizer was monitored by real-time Particle Video Microscope (PVM). We found that the low feeding rate of acetic acid, high crystallization temperature, low agitation rate or adding seed crystal can facilitate the formation of spherical agglomerates. By using a simple model, the mean crystal agglomerate size of DMB thus predicted is generally in agreement with the experimental data. In addition, the crystallization process of DMB was optimized by a new control strategy of supersaturation to avoid disadvantages brought by agglomeration.

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COMMUNICATION
Preconcentration of trace elements by adsorption onto a niobium wire for electrothermal atomization atomic absorption spectrometry with a tungsten tube atomizer
Satoshi KANECO, Hiroaki KITANAGA, Hideyuki KATSUMATA, Tohru SUZUKI
Front Chem Sci Eng. 2012, 6 (4): 432-435.  
https://doi.org/10.1007/s11705-012-1219-z

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In the present work, a new preconcentration method of trace elements by adsorption onto a niobium wire has been developed for electrothermal atomization atomic absorption spectrometry (ETAAS) with a tungsten tube atomizer. Detection limits (pg·mL–1) by this method combined with ETAAS were 45 for bismuth, 7.0 for cadmium, 20 for copper, 1.3 for gold, 36 for lead, 65 for manganese, 9.5 for rhodium and 19 for silver.

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RESEARCH ARTICLE
LC/MS/MS and radioisotope method combined for recognizing the affinity between catalpol and OCT2 transporter
Zhiyu ZHANG, Changxiao LIU, Duanyun SI, Rong LU, Xiulin YI
Front Chem Sci Eng. 2012, 6 (4): 436-442.  
https://doi.org/10.1007/s11705-012-1222-4

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More and more herbal medicines are found to be the substrates of drug transporters. In this paper, chromatography/tandem mass spectrometry (LC/MS/MS) combined with radioisotope method was used for the quantification of catalpol, a traditional Chinese medicine, to study the affinity relationship between herbal medicines and transporters. Catalpol uptake experiment was carried out by using several transporters (OAT1, OCT2, OAT3, OATP1B1 and OATP2B1). And samples were precipitated with methanol and quantified with LC/MS/MS. The results show that catalpol has a good affinity with OCT2-transfected S2 cells. After studying drug-drug interaction between catalpol and 14C-tetraethylammonium (TEA), we found that catalpol is able to facilitate TEA transport mediated by OCT2, suggesting that catalpol could probably be a new promoter of OCT2.

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Optimization of cellulase production using Trichoderma reesei by RSM and comparison with genetic algorithm
Saravanan P, Muthuvelayudham R, Rajesh Kannan R, Viruthagiri T
Front Chem Sci Eng. 2012, 6 (4): 443-452.  
https://doi.org/10.1007/s11705-012-1225-1

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The potential of Trichoderma reesei for cellulase production using pineapple waste as substrate has been investigated. A maximum cellulase activity of 9.23 U/mL is obtained under the optimum experimental conditions: pH (5.5), temperature (37.5°C), initial substrate concentration (3%), inoculum concentration (6.6 × 108?CFU/mL), and culture time (6 days). Box-Behnken design (BBD) statistical tool and genetic algorithm (GA) are used to optimize the process parameters. The BBD study of linear and quadratic interactive effects of experimental variables on the desired response of cellulase activity showed that the second order polynomial is significant (R2 = 0.9414). The experimental cellulase activity under the optimal conditions identified by the BBD is 9.23 U/mL and that by GA is 6.98 U/mL. This result indicates that the BBD model gives better result than GA in the present case.

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Repeated batch fermentation with water recycling and cell separation for microbial lipid production
Yumei WANG, Wei LIU, Jie BAO
Front Chem Sci Eng. 2012, 6 (4): 453-460.  
https://doi.org/10.1007/s11705-012-1210-8

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Large waste water disposal was the major problem in microbial lipid fermentation because of low yield of lipid. In this study, the repeated batch fermentation was investigated for reducing waste water generated in the lipid fermentation of an oleaginous yeast Trichosporon cutaneum CX1 strain. The waste fermentation broth was recycled in the next batch operation after the cells were separated using two different methods, centrifugation and flocculation. Two different sugar substrates, glucose and inulin, were applied to the proposed operation. The result showed that at least 70% of the waste water was reduced, while lipid production maintained satisfactory in the initial four cycles. Furthermore, it is suggested that T. cutaneum CX1 cells might produce certain naturally occurring inulin hydrolyzing enzyme(s) for obtaining fructose and glucose from inulin directly. Our method provided a practical option for reducing the waste water generated from microbial lipid fermentation.

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Comparative lipidomic analysis of S. cerevisiae cells during industrial bioethanol fermentation
Bin QIAO, Hong-Chi TIAN, Ying-Jin YUAN
Front Chem Sci Eng. 2012, 6 (4): 461-469.  
https://doi.org/10.1007/s11705-012-1223-3

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Variations in the composition and level of phospholipids (PLs) in yeast cells during industrial ethanol fermentation processes were analyzed. A comparative lipidomic method was used to investigate the changes in total cellular PLs during continuous and fed-batch/batch processes. The phospholipid metabolism in yeast changed during both processes, mainly due to the presence of long-chain poly unsaturated fatty acids (PUFA) that contained phosphatidyglycerol (PG), phosphatidylethanolamine (PE) and phosphatidylserine (PS). The complexity of the media affected the growth of the yeast and the membrane composition. Yeast incorporated lots of exogenous saturated and PUFAs from the feedstock during the fermentations. During the continuous fermentation, there was an increase in PLs with shorter chains as the fermentation progressed and early in process there were more long-chains. During the fed-batch/batch process, the PG species increased as the fermentation progressed. This is probably due to an inositol deficiency in the earlier part of the fermentation.

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REVIEW ARTICLE
Progress of three-dimensional macroporous bioactive glass for bone regeneration
Lijun JI, Yunfeng SI, Ailing LI, Wenjun WANG, Dong QIU, Aiping ZHU
Front Chem Sci Eng. 2012, 6 (4): 470-483.  
https://doi.org/10.1007/s11705-012-1217-1

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Bioactive glasses (BGs) are ideal materials for macroporous scaffolds due to their excellent osteoconductive, osteoinductive, biocompatible and biodegradable properties, and their high bone bonding rates. Macroporous scaffolds made from BGs are in high demand for bone regeneration because they can stimulate vascularized bone ingrowth and they enhance bonding between scaffolds and surrounding tissues. Engineering BG/biopolymers (BP) composites or hybrids may be a good way to prepare macroporous scaffolds with excellent properties. This paper summarizes the progress in the past few years in preparing three-dimensional macroporous BG and BG/BP scaffolds for bone regeneration. Since the brittleness of BGs is a major problem in developing macroporous scaffolds and this limits their use in load bearing applications, the mechanical properties of macroporous scaffolds are particularly emphasized in this review.

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Heat, mass, and work exchange networks
Zhiyou CHEN, Jingtao WANG
Front Chem Sci Eng. 2012, 6 (4): 484-502.  
https://doi.org/10.1007/s11705-012-1221-5

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Heat (energy), water (mass), and work (pressure) are the most fundamental utilities for operation units in chemical plants. To reduce energy consumption and diminish environment hazards, various integration methods have been developed. The application of heat exchange networks (HENs), mass exchange networks (MENs), water allocation heat exchange networks (WAHENs) and work exchange networks (WENs) have resulted in the significant saving of energy and water. This review presents the main works related to each network. The similarities and differences of these networks are also discussed. Through comparing and discussing these different networks, this review inspires researchers to propose more efficient and convenient methods for the design of existing exchange networks and even new types of networks including multi-objective networks for the system integration in order to enhance the optimization and controllability of processes.

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15 articles