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Progress in Chemistry 2012, No.04 Previous issue Next issue

In this issue:

Review
Vanadium-Based Catalysts for the Selective Catalytic Reduction of NOx with NH3
Liu Fudong, Shan Wenpo, Shi Xiaoyan, He Hong
2012, 24 (04): 445-455 |
Published: 24 April 2012
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Abstract
Selective catalytic reduction of NOx with NH3 or urea (NH3/Urea-SCR) as reducing agents over catalytic materials in oxygen-rich conditions is one of the most efficient and widely-used techniques for the removal of NOx from stationary and mobile sources. The most important catalyst system for NH3-SCR process is vanadium-based catalyst. In this review, the composition and NH3-SCR performance, the activity improvement of vanadium-based catalysts and the corresponding NH3-SCR reaction mechanisms are summarized. The possible developing orientations in the field of NH3-SCR technique are also prospected. The conventional V2O5-WO3 (MoO3)/TiO2 catalyst and corresponding improved vanadium-based catalysts usually show excellent deNOx efficiency and SO2 durability in the medium temperature range. On these catalysts, the highly dispersed V5+ species and poly-vanadate species are confirmed to be the active phases for NH3-SCR reaction. Over vanadium-based catalysts prepared by different methods or with different compositions, a majority of researchers consider that the NH3-SCR reaction follows an Eley-Rideal (E-R) mechanism and some researchers prefer to a Langmuir-Hinshelwood (L-H) mechanism, which might be related to the vanadium loading amount and reaction temperature. During the subsequent work in further study, the researchers should combine multiple characterization methods aiming at different catalyst systems, and pay more attention to the influence of temperature on the reaction mechanism together with the effect of surface acid/basic property on the adsorption and activation of NH3/NOx. Accordingly, much more comprehensive and authentic reaction mechanism can be concluded. The systematic understanding of the research progress in vanadium-based catalysts is beneficial to the development of highly efficient, stable vanadium-based SCR catalytic converters at the present stage, and also important for the design and synthesis of novel, efficient, environmentally-friendly vanadium-free SCR catalysts with high resistance to poisoning.
Contents
1 Introduction
2 Composition and NH3-SCR performance of vanadium-based catalysts
3 Improvement of vanadium-based catalysts
4 NH3-SCR reaction mechanism over vanadium-based catalysts
5 Comments and outlook
Anionic Wormlike Micelles
Zhao Jianxi, Xie Danhua
2012, 24 (04): 456-462 |
Published: 24 April 2012
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Abstract
The molecular geometry and the driving factor of Gibbs free energy are acted as the preconditions for wormlike micelle construction. Bearing this in mind, the formation and properties of the wormlike micelles by conventional anionic surfactants are summarized. The reasons restricting the wormlike micelle formation and high viscoelasticity in conventional anionic surfactant systems are illustrated. The molecular structure advantage of Gemini surfactant in forming wormlike micelles is introduced. Recent advances in anionic wormlike micelle construction, especially for those formed by anionic Gemini surfactants with long and rigid spacer are described in detail. Finally, as a conclusion, it is specially pointed out that based on the superiority of novel molecular structures, Gemini surfactants could become main candidates in constructing wormlike micelles.
Contents
1 Introduction
2 Mechanism of wormlike micelle formation
3 Wormlike micelle systems formed by conventional anionic surfactants
4 Advantage of Gemini surfactant in forming wormlike micelles
5 Wormlike micelle systems constructed by anionic Gemini surfactants
6 Conclusions
Biomimetic Smart Nanochannels for Energy Conversion
Zhang Minghui, Zhai Jin
2012, 24 (04): 463-470 |
Published: 24 April 2012
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Abstract
Biomimetic smart nanochannels show great potential in the field of energy conversion due to the special structure and responsive property. This article describes the recent progress in the biomimetic energy conversion systems and consists of four parts based on the different mechanisms of energy conversion: the chemoelectrical conversion system to mimic the electrical eel, the photochemical conversion system to mimic the green leaf, the photoelectrical system to mimic the bacteriorhodopsin, the electrochemomechanical conversion system to mimic the hydroelectric power. These biomimetic energy conversion systems can help people to better understand the energy conversion processes in nature. Furthermore, they can inspire the scientists to develop artificial energy devices with better performance. Among them the eel-inspired chemoelectrical conversion system shows the most promising future due to its high energy conversion efficiency and widespread energy input from mixing river water with sea water. The leaf-inspired photochemical conversion system is difficult to utilize with its energy output in the form of ATP. The bacteriorhodopsin-inspired photoelectrical system shows a bright future regardless of its relatively low energy conversion efficiency. The hydroelectric-inspired electrochemomechanical conversion system is in its infancy and needs further investigation. The performance of these systems is influenced by the geometric structure and the charge densities of the nanochannel, as well as the external environment such as the type and concentration of the solution, the concentration or pressure difference, pH and so on.
Contents
1 Introduction
2 The application of smart nanochannels in the field of energy conversion
2.1 The chemoelectrical conversion system to mimic the electrical eel
2.2 The photochemical conversion system to mimic the green leaf
2.3 The photoelectrical system to mimic the bac-teriorhodopsin
2.4 The electrochemomechanical conversion system to mimic the hydroelectric power
3 Conclusions and outlook
Controlled Fabrication and Application of Platelet SBA-15 Materials
Ma Liqun, Zhai Shangru, Liu Na, Zhai Bin, An Qingda
2012, 24 (04): 471-482 |
Published: 24 April 2012
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Abstract
Ordered SBA-15 materials are of great importance in the materials field due to the tunable pore size within 5-30 nm and excellent mechanical and hydrothermal stability in comparison with other siliceous mesostructures. More recently, platelet SBA-15 with short channels have attracted great attention because of the favorable effect for molecular delivery and mass transfer. Platelet SBA-15 materials have been synthesized using various effective synthesis pathways including co-solvent effect of alkane molecules, inducing effect of metal ions and syngeristic effect of multi-surfactants. Based on different assembly mechanisms, the current progress in designed assembly and applications of platelet SBA-15 in catalysis, adsorption and biomedical molecule immobilization are reviewed, and the perceptive on potentiality of this newcomer with fascinating characteristics is also prospected.
Contents
1 Introduction
2 Designed synthesis of platelet SBA-15 with short channels
2.1 Co-solvent effect of alkane molecules
2.2 Inducing effect of metal ions
2.3 Prompting effect of inorganic salts
2.4 Other methods
3 Advanced applications of platelet SBA-15
3.1 Favorable catalysts
3.2 Favorable supports
3.3 Adsorption of biomedical molecules
3.4 Other applications
4 Conclusion and outlook
Ionic Liquids-Mediated Formation of 5-Hydroxymethylfurfural
Hu Lei, Sun Yong, Lin Lu
2012, 24 (04): 483-491 |
Published: 24 April 2012
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Abstract
5-Hydroxymethylfurfural (5-HMF) is considered as a very important biomass-based platform compound that can be used to synthesize a broad range of liquid fuels and chemicals, which are mainly derived from fossil resources so far. The study of the production of 5-HMF in the presence of ionic liquids has increasingly attracted more attention. In this review, the recent achievements of ionic liquids-mediated formation of 5-HMF are systematically summarized, including applications of ionic liquids as reaction solvents and catalysts in the production of 5-HMF, influence factors and formation mechanisms in the ionic liquids-mediated formation of 5-HMF. The future research trends of ionic liquids-mediated formation of 5-HMF are suggested.
Contents
1 Introduction
2 Production of 5-HMF using ionic liquids as reaction solvents
2.1 Fructose as feedstock
2.2 Glucose as feedstock
2.3 Sucrose as feedstock
2.4 Cellulose, starch and inulin as feedstock
3 Production of 5-HMF using ionic liquids as catalysts
3.1 Ionic liquids as base catalysts
3.2 Ionic liquids as acid catalysts
4 Mechanisms of ionic liquids-mediated formation of 5-HMF
5 Influence factors of ionic liquids-mediated formation of 5-HMF
5.1 Reaction temperature
5.2 Heating method
5.3 Reaction time
5.4 Catalyst loading
5.5 Substrate loading
5.6 Water content
5.7 Co-solvent
5.8 Extraction method
6 Conclusions and perspectives
Preparation of Vertically Oriented Mesoporous Thin Films
Zhang Qian, Shan Feng, Lu Xuemin, Lu Qinghua
2012, 24 (04): 492-500 |
Published: 24 April 2012
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Abstract
The macroscopic alignment of mesochannels in films and its control are quite significant for advanced materials with controlled functions. However, the direction of mesochannels in almost all mesoporous/mesostructured films is parallel to the substrate. The films containing vertically oriented mesochannels in uniform direction are of wide prospects due to their huge potential applications including catalysis, adsorption and separation, high-sensitive chemical sensors, solar cells and so forth. Here some important characterization techniques are presented, such as cross-sectional TEM, X-ray diffraction and grazing-incident small-angle X-ray scattering. Simultaneously, various preparation methods of vertically oriented mesoporous thin films in recent years are reviewed including template-based method, using external fields, modification of substrate and other methods. We also briefly summarize its applications in selective membrane, preparation of vertically oriented metal films and electrochromic display devices. In addition, the development of vertically oriented mesoporous thin films in the future is expected.
Contents
1 Introduction
2 Key characterization techniques of vertically oriented mesoporous thin films
2.1 Cross-sectional electron microscope
2.2 X-ray diffraction
2.3 Grazing-incident small-angel X-ray scattering
3 Methods to prepare vertically oriented mesoporous thin films
3.1 Template-based method
3.2 External field
3.3 Modification of substrate
3.4 Other methods
4 Applications of vertically oriented mesoporous thin films
4.1 Selective membrane
4.2 Preparation of vertically oriented metal films as hard template
4.3 Electrochromic display devices
5 Conclusion and outlook
Transparent Conductive Graphene Films
Tang Jingjing, Di Feng, Xu Xiao, Xiao Yinghong, Che Jianfei
2012, 24 (04): 501-511 |
Published: 24 April 2012
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Abstract
Graphene, a novel two-dimensional atomic thin crystalline material, first discovered in 2004, has become one of the hottest research areas all over the world. Its unique monolayer atomic structure has exhibited fantastic physical and chemical properties, which give rise to the great performance of transparent conductive graphene films. Compared with indium tin oxide (ITO) films, transparent conductive graphene films exhibit more outstanding performance in mechanical strenght, transparency(light transmittance) and chemical inertness. In this review, we briefly summarized the optoelectronic properties of graphene, synthesis of graphene precursors and preparing methods of the transparent conductive graphene films, then discussed the unsolved problems and prospected the future developments in the end.
Contents
1 Introduction
2 Optoelectronic property of graphene
3 Precursors to transparent conductive graphene films
3.1 Graphene oxide
3.2 Reduced graphene oxide
3.3 Exfoliated graphene
3.4 Graphene hybrid material
4 Preparation methods of transparent conductive graphene films
4.1 Vacuum filtration
4.2 Spin coating
4.3 Spray coating
4.4 Chemical vapor deposition(CVD)
4.5 Other preparation methods
5 Conclusions and prospects
Preparation and Modification of Graphene on Substrate
Tian Yuan, Zhao Qianying, Hu Jing, Zhou Chen, Miao Ling, Jiang Jianjun
2012, 24 (04): 512-522 |
Published: 24 April 2012
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Abstract
Since the successful isolation of the single atomic layer of graphite in 2004, graphene has drawn great interests due to its unique properties, including high mechanical strength, outstanding conductivity, high coefficient of thermal conductivity, etc. It is significant to manufacture large-scale and high-quality graphene on various substrates for the study of the characteristics of graphene and the research of the nano-devices basing on graphene. This paper selectively reviews recent experiment advances in graphene made on different substrates, SiC, SiO2, Cu, Ni, Co, Ru, for instance. Nowadays, we can obtain large area of high quality graphene by using different methods, such as CVD, epitaxial growth, mechanical separation, etc. We can manufacture graphene on nonmetals including SiC, GaAs, SiO2, and metals covering Cu, Ni, Co, Ru, Au, Ag, etc. This article especially reviews the interaction between the graphene and the substrates. The mechanism of interaction is closely related to the mismatch of the lattice, weakness of the bonds, the transformation of the electrons between the few layer graphene and substrates. Also, the interaction between them has great influences on geometry, energy band, and coefficient of thermal conductivity, phonon dispersion, optical waveguide performances and the properties of electrons of the graphene. The combination of the experiment and the calculation (such as density functional theory, tight-binding method, molecular dynamics simulation, etc.) can make a deeper understanding of the mechanism of the effects between graphene and different substrates, which can be served as a guide for further study.
Contents
1 Introduction
2 Experiment progresses of manufacturing graphene on various substrates
2.1 Developing graphene on nonmetal substrates
2.2 Developing grephene on metal substrates
3 Interactions between graphene and substrates
3.1 Interactions between graphene and nonmetal substrates
3.2 Interaction between graphene and metal substrates
3.3 Role of metal steps
3.4 Interactions between few layers graphene and substrates
4 Modification of graphene by substrates
4.1 Effects on geometry of graphene
4.2 Effects on bandgap of graphene
4.3 Effects on thermal conductivity
4.4 Other effects
5 Outlook
Direct Oxidative Coupling Between Unfunctionalized Arene and Olefin
Weng Jianquan, Yu Zhiqin, Zhang Guofu
2012, 24 (04): 523-544 |
Published: 24 April 2012
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Abstract
The direct oxidative coupling reaction between unfunctionalized arene and alkene, owing to its simple, efficient and environmentally friendly workup, has attracted much interest in organic synthesis. This green protocol can provide great advantages when compared with traditional Heck reaction, that it reduces the reaction steps and avoids the formation of waste inorganic salts. Especially when oxygen or air is used as the terminal oxidant in the process, the only by-product water is harmless to the environment. In this paper, new advances in transition metal-catalyzed direct oxidative coupling reaction between unfunctionalized arene and olefin are reviewed, which is presented on the basis of the different catalysts, the substrates with various types of directing groups. Moreover, some mechanisms of these novel reactions are also discussed in details.
Contents
1 Introduction
2 The system of palladium-catalyzed
2.1 Palladium-catalyzed intermolecular direct oxidative coupling
2.2 Palladium-catalyzed intramolecular direct oxidative coupling
3 The system of other catalysts
3.1 The system of rhodium-catalyzed
3.2 The system of ruthenium-catalyzed
3.3 The system of iron-catalyzed
3.4 The system of copper-catalyzed
4 Conclusions and outlook
Biomimetic Synthesis of Oligostilbenes
Li Wenling, Zang Peng, Li Hongfu, Yang Shixia
2012, 24 (04): 545-555 |
Published: 24 April 2012
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Abstract
Natural oligostilbenes are a class of plant polyphenols widely distributed in nature, and have received considerable attention in the chemical and biological fields because of their structural complexity as well as their diverse bioactivities. These oligomers and their derivatives are potentially useful leading compounds for drug development. Further investigations of structure-activity of oligostilbenes to screen active drugs were limited for their scarce availability in natural raw materials. Biosynthetic strategies towards these oligomers are studied widely and intensively by a number of chemists in recent years and has been a hot research topic. In this paper, the progress in the studies on the biomimetic synthesis of oligostilbenes over the past thirty years is reviewed in detail, including oxidative coupling reactions catalyzed by enzymes or metallic oxidants in various reaction mediums, isomerization under UV irradiation and cyclization induced by several strong acids. Diverse complex molecular architectures of oligostilbenes are thus constructed from a wide array of stilbene precursors through biomimetic routes. The future synthetic trend of oligostilbenes is also prospected.
Contents
1 Introduction
2 Biomimetic synthesis of oligostilbenes
2.1 Enzyme induced oxidative coupling reactions
2.2 Photochemical isomerization of oligostilbenes
2.3 Metallic oxidants catalyzed oligomerization
2.4 Cyclic dimerization catalyzed by acids
3 Conclusions and outlook
Chemistry and Application of Dicarbadodecaborane and Its Derivatives
Zhao Juan, Huang Pengcheng, Chen Gong, Zhan Maosheng
2012, 24 (04): 556-567 |
Published: 24 April 2012
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Abstract
Dicarba-closo-dodecaborane (carborane, C2B10H12) containing two carbon atoms and ten boron atoms adopts nearly icosahedral geometry in which the carbon and boron atoms are hexacoordinate. The compound exists as ortho-, meta-and para-isomers. Due to the strong electron-acceptor properties of the cluster, massive bulk and three-dimensional rigidity, carborane and its derivatives possess remarkable thermal and chemical stability. Besides, the ready solubility makes the compound and its derivatives widely applied. There are two common methods for synthesis of carborane and carborane derivatives, including the “alkyne insertion” methodology and the method based on the substitution reaction with carboranyl lithium. In this paper, the chemical reactions and functionalization of carborane and its derivatives are summarized, especially the substitution reactions on carbon atoms and boron atoms, the cycloaddition reaction and metal-carborane complexation. Futhermore, due to the excellent heat stability and high electronic delocalization, the carborane derivatives can be utilized as functional materials. Also, carborane derivatives can be applied in boron neutron capture therapy (BNCT) for the high boron content of carborane. Meanwhile, the metal-carborane complexes containing bulky carborane as ligands are reported to be available as the efficient catalysts. Herein, the advances in the application of the carborane derivatives in recent years are reviewed.
Contents
1 Introduction
2 Preparation, structure and properties of carborane
3 Chemical reaction of carborane
3.1 C-H functionalization
3.2 B-H functionalization
3.3 Cycloaddition reaction
3.4 Metal-carborane complexes
4 Application of carborane and its derivatives
4.1 Functional materials
4.2 Biological medicine
4.3 Catalysts
4.4 Others
5 Conclusion and outlook
Electrochemical Glucose Biosensors
Shi Wentao, Di Jing, Ma Zhanfang
2012, 24 (04): 568-576 |
Published: 24 April 2012
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Abstract
As one of the most important researches of electrochemical biosensors, electrochemical glucose biosensors obtained great achievements in the last several decades. The main research is reviewed in this paper, which focused on designing new electrochemical glucose biosensors based on nanotechnology in recent years. It was clarified by the dimensionality of the nanomaterials. Among them, zero-dimensional nanomaterials involving gold nanoparticles, silver nanoparticles, and other metal nanoparticles, one-dimensional nanomaterials involving metal or metal oxide nano wires or tubes by template methods and single wall or multi wall carbon nanotubes, two-dimensional nanomaterials involving graphene and other plate-like metal nanomaterials are discussed. The effects of nanomaterials on the electrochemical glucose biosensors are mainly focused on the biocompatibility, enhancement of sensitivity and selectivity, enzyme immobilization, etc. Additionally, the prospects of future development of electrochemical glucose biosensors is also given.
Contents
1 Introduction
2 Zero-dimension nanomaterials based glucose biosensors
2.1 Gold nanoparticles
2.2 Silver nanoparticles
2.3 Other nanoparticles
3 One-dimension nanomaterials based glucose biosensors
3.1 Nanowires prepared by template methods
3.2 Carbon nanotubes
4 Two-dimension nanomaterials based glucose biosensors
5 Conclusion and outlook
New Strategies for Protein Functionalization: Inserting Unnatural Amino Acids into Proteins
Zhang Chunqiu, Luo Quan, Liu Junqiu, Shen Jiacong
2012, 24 (04): 577-588 |
Published: 24 April 2012
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Abstract
Although 20 natural amino acids served as the building blocks of proteins contain several functional groups including carboxylic acids, amides, thiols, thiol ethers, alcohols, basic amines, and alkyl and aryl groups, they are still unable to carry out all of the natural functions. In order to improve the precision and diversity of protein to perform the biological processes, organisms have provided a variety of posttranslational modifications including phosphorylation, methylation, acetylation, and hydroxylation, even evolved novel translational machinery to incorporate either selenocysteine or pyrrolysine. Inspired by biological system, many biological or chemical methods have been developed to alter or insert new building blocks into protein, which enable protein to perform relevant functions or have some special properties, even create a new kind of enzyme. Here, we give a brief overview of the strategies for protein modification and the latest progress in this field.
Contents
1 Introduction
2 Chemical approaches
2.1 Chemical modification of proteins
2.2 Chemical synthesis
2.3 Semisynthesis
3 Biosynthetic approaches in vitro
4 Biosynthetic approaches in vivo
4.1 Incorporating unnatural amino acids into proteins using auxotrophic bacterial strains
4.2 Expanding genetic code
5 Functionalization and applications
5.1 'Click’ chemistry
5.2 Alkyne and azide functionalization
5.3 Keto and aldehyde functionalization
5.4 Alkene functionalization
5.5 Other functional unnatural amino acids
6 Conclusion and prospects
Cytochrome b5-Protein Interactions
Lin Yingwu
2012, 24 (04): 589-597 |
Published: 24 April 2012
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Abstract
Protein-protein interactions play crucial roles in biological processes, especially for heme proteins. Cytochrome b5 (Cyt b5) is a typical heme protein, which functions in vivo through various protein-protein interactions. As reviewed herein, the currently revealed interactions associated with Cyt b5 include Cyt b5-Cyt b5 reductase, Cyt b5-Cyt P450, Cyt b5-Cyt c, Cyt b5-myoglobin or hemoglobin, Cyt b5-fusion proteins (glutathione S-transferase, GST, and green fluorescence protein, GFP), and Cyt b5-tansporters (sucrose transporter, SUT1, and sorbital transporter, SOT6), etc. The fact that a single protein can interact with various proteins makes us realize the biological importance of some particular proteins. On the other hand, the study of a single protein interacting with various proteins will further our understanding of protein structure-function relationship, as well as guide rational design of novel proteins for ultimate applications.
Contents
1 Introduction
2 Cytochrome b5
2.1 Structure
2.2 Function
3 Cytochrome b5-protein interactions
3.1 Cytochrome b5-cytochrome b5 reductase
3.2 Cytochrome b5-cytochrome P450
3.3 Cytochrome b5-cytochrome c
3.4 Cytochrome b5-myoglobin or hemoglobin
3.5 Cytochrome b5-fusion protein
3.6 Cytochrome b5-transporter
4 Conclusions and outlook
Indication of Electrochemical Measurements of Magnesium Alloys in vitro for Their Degradation Behavior in vivo
Wang Jiali, Tang Jian, Zhang Peng, Wang Jue, Li Yangde, Qin Ling
2012, 24 (04): 598-605 |
Published: 24 April 2012
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Abstract
As a novel orthopaedic implants in biomedical fields, biodegradable magnesium and its alloys have shown great potential and advantages due to their excellent biocompatibility and mechanical properties. The key factor to limit their further industrialization in the medical field is the rapid degradation behavior, which has become the focus of many researchers. In this paper, the research of corrosion resistance of magnesium-based alloys was summarized based on electrochemical measurements in vitro, and the effects of simulated corrosion system in vitro on corrosion behavior of magnesium and its alloys were also analyzed. Moreover, feasibility and limitation of the electrochemical methods as the fast and efficient indication of degradation behavior of magnesium alloys in vivo is evaluated. Finally, possible means and perspectives for more logic indication of degradation behavior of magnesium alloys in vivo are also proposed.
Contents
1 Introduction
2 Electrochemical measurements in vitro
2.1 Electrochemical corrosion mechanisms of magnesium
2.2 Evaluation of corrosion resistance using electrochemical measurements
2.3 Feasibility of electrochemical results for indication of corrosion behavior of magnesium and its alloys in vivo
3 Outlook
Environmental Behavior and Toxicological Effects of Polycyclic Musks
Li Zhuona, Zhou Qunfang, Liu Jiyan, Shi Yali, Cai Yaqi, Jiang Guibin
2012, 24 (04): 606-615 |
Published: 24 April 2012
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Abstract
Polycyclic musks (PCMs) are important synthetic fragrances widely used in personal care products. Due to their continuous release into the environment and bioaccumulation, environmental behaviors of PCMs are similar to persistent organic pollutants. PCMs are new emerging pollutants and have attracted remarkable attention due to their ubiquitous distribution in the environment. In this paper, the characteristics, pollution sources, analytical methods and pollution status of PCMs are described. Then the degradation, transformation and bioaccumulation are summarized. Toxicological effects such as acute toxicity, subchronic toxicity, endocrine disrutpting toxicity and other potential toxic effects are also introduced. Finally, the existing problems and future research directions are proposed. In the future, standard analytical methods should be established to systematically understand pollution situation, migration and transformation law, and metabolic pathways of PCMs. The impacts of PCMs exposure pathways on bioavailability should also be investigated to assess potential risks. In addition, studies are also needed to explore single and combined toxic effects of PCMs at long-term low-dose exposure in vivo assay.
Contents
1 Introduction
2 Physical and chemical properties
3 Sources of PCMs in environment
4 Analytical methods
4.1 Sample extraction
4.2 Sample clean-up
4.3 Sample analysis
5 The pollution status of PCMs in environment
5.1 PCMs in water
5.2 PCMs in sewage sludge and sediment
5.3 PCMs in human being
5.4 PCMs in biota
5.5 PCMs in air
6 Degradation and transformation
7 Bioaccumulation
8 Toxicological effects
8.1 Acute toxicological effects
8.2 Subchronic toxicological effects
8.3 Other toxicological effects
8.4 Endocrine disrupting effects
9 Conclusion and prospects
Electrochemical Sensors and Biosensors Based on Nanomaterials: A New Approach for Detection of Organic Micropollutants
Wei Yan, Liu Zhonggang, Gao Chao, Wang Lun, Liu Jinhuai, Huang Xingjiu
2012, 24 (04): 616-627 |
Published: 24 April 2012
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Abstract
The presence of organic micropollutants in an aquatic ecosystem impacts directly or indirectly to biota and human being, which results in an increasing demand for the detection of organic micropollutants. In this review we examine recent development and current status of electrochemical detection of organic micropullutants using electrochemical sensors and biosensors based on nanomaterials, and discuss the sensing principles of the nanomaterials modified electrodes in these sensors. Emphasis is given to the important effect of related nanomaterials on the detection of organic micropullutants. Finally, key challenges and opportunities on the directions toward future development are outlined.
Contents
1 Introduction
2 Organophosphate and carbamate pesticides
2.1 Detection by electrochemical enzyme biosensors based on nanomaterials
2.2 Detection by electrochemical non-enzyme sensors based on nanomaterials
3 Phenolic compounds
3.1 Detection by electrochemical enzyme biosensors based on nanomaterials
3.2 Detection by electrochemical non-enzyme sensors based on nanomaterials
4 Nitroaromatic compounds
5 Other targets of organic micropollutants
6 Conclusions and outlook
Electrochemical Anodic Materials Used for Degradation of Organic Pollutants
Zhuo Qiongfang, Yang Bo, Deng Shubo, Huang Jun, Wang Bin, Yu Gang
2012, 24 (04): 628-636 |
Published: 24 April 2012
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Abstract
In recent years, researchers plunged to find efficient solutions to remove contaminants in water. Electrochemical oxidation methods were studied extensively because of the simple, clean energy and no secondary pollution. The refractory organic pollutants can be converted to biodegradable substances or direct mineralization by electrochemical oxidation method. The present review summarized the progress on electro-chemical oxidation mechanism, the recent development of anode materials, and proposed the research trend in the future. In electro-chemical oxidation mechanism aspect, the direct and indirect approaches are discussed. Some parameters which could impact the direct and indirect processes were considered. Apart from parameters, the dependence of anodic materials on the direct and indirect processes was also discussed. With the progress of anodic materials, carbon electrode, elemental metal electrode and dimensionally stable anode were summarized. All of the anodes were made to prolong the lifespan and improve the catalysis activity by adding the interlayer and adulterating the active components. The removal rates were collected to compare these anodes. For some typical anodes, the life span, the contact angle, the oxygen evolution potential (OEP) and the impedance were also listed. At last, the research trend was proposed. To achieve the commercial application of electrochemical oxidation method, the problems of the cost, the passivation membrane on the anode, and current density should be resolved.
Contents
1 Introduction
2 The mechanism of electro-chemical oxidation of organic pollutants
2.1 Direct electrochemical oxidation on the surface of anode
2.2 Indirect electrochemical oxidation by oxidative intermediates
3 Anodic materials
3.1 Carbon electrode
3.2 Elemental metal electrode
3.3 Dimensionally stable anode (DSA)
4 Summary and prospect
Chemical Mechanism During Chinese Medicine Processing
Cai Baochang, Qin Kunming, Wu Hao, Cai Hao, Lu Tulin, Zhang Xingde
2012, 24 (04): 637-649 |
Published: 24 April 2012
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Abstract
Chinese medicine processing is a traditional Chinese pharmaceutical technology, and it is also the main characteristic property that distinguish traditional Chinese medicine and natural medicine. There are complex chemical changes during the process of Chinese medicine processing, and these chemical constituents which changed during processing maybe the basis of clinical efficacy changes. To clarify the changes of the chemical constituents and the chemical reactions in Chinese medicine during the processing process is the main purpose of the chemical mechanism research of Chinese medicine processing. In recent years, many research institutions at home and abroad have done deeply research in chemical mechanism during the process of Chinese medicine processing. The chemaical reactions and chemical mechanisms ocurred in some traditional Chinese medicines during the process of Chinese medicine processing were initially clarified. The main chemical reactions occurred in the Chinese medicine processing are hydrolysis reaction, oxidation reaction, replacement reaction, isomerization reaction, decomposition reaction,etc. The main achievements in the chemical mechanism research during the process of Chinese medicine processing are reviewed. The research directions and future in the chemical mechanism research of Chinese medicine processing are prospected.
Contents
1 Introduction
2 Chemical composition change and its mechanism during Chinese medicine processing
2.1 Hydrolysis reaction
2.2 Isomerization reaction
2.3 Oxidation reaction
2.4 Replacement reaction
2.5 Decomposition reaction
2.6 Condensation reaction
2.7 Others
3 Problems and countermeasures
3.1 Application of modern analytical techniques to explore the Chinese medicine processing mechanism
3.2 Combinational research of chemical analysis and pharmaceutical efficacy mechanism during Chinese medicine processing
3.3 Exploration and establishment of new methods to clarify the mechanisms of Chinese medicine processing
4 Conclusion
Controlled Hydrogen Generation by Reaction of Aluminum with Water
Ma Guanglu, Zhuang Dawei, Dai Hongbin, Wang Ping
2012, 24 (04): 650-658 |
Published: 24 April 2012
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Abstract
Aluminum is the most abundant crustal metallic element on the earth and 100% recycled in theory. Controlled hydrogen generation (HG) by reaction of aluminum with water could provide a renewable energy cycle to address the global energy problem. In this perspective, we present the state of art in the principle, mechanism, approaches, and hydrogen generator of HG from the reaction of aluminum with water, and further discuss some remaining problems in the development of aluminum-based HG system. The key to the HG by the reaction of aluminum with water is how to disrupt/inhibit a native/regeneration coherent and adherent passivation film of aluminum surface. The fast kinetics is desirable in developing the aluminum-based HG system for the practical application. The design of hydrogen generator should focus on the utilization of reaction heat to preheat fuel, the recycle of water from the fuel cell, the fuel cartridges and the process of separation by the membrane. The use of recycled scrap aluminum will provide a reasonable hydrogen cost, thus promoting its commercial applications.
Contents
1 Introduction
2 The principle and mechanism of hydrogen generation from reaction of aluminum with water
3 Approaches of hydrogen generation from reaction of aluminum with water
3.1 Hydroxide promoters
3.2 Oxide/salt promoters
3.3 Aluminum alloying
3.4 Combined hydroxide and oxide/salt promoters
4 Design of hydrogen generator of hydrogen generation of reaction of aluminum with water
5 Cost and recycling of spent fuel of hydrogen generation from reaction of aluminum with water
6 Conclusions and outlook