短程硝化-厌氧氨氧化工艺的挑战与对策

短程硝化-厌氧氨氧化（PN/A）工艺与传统生物脱氮工艺相比，具有能耗低、设备简单、污泥产率低等诸多优点，在污水脱氮领域备受关注。本文首先总结了PN/A工艺在实际应用中存在的一些挑战，比如，处理高C/N废水效果不佳、亚硝酸盐氧化细菌（NOB）抑制困难、启动缓慢等。然后，针对上述挑战，提出了一些PN/A工艺的改进措施。可使用多种预处理技术来降低废水有机物含量，以减弱高C/N比废水的负面影响；根据NOB、厌氧氨氧化菌（AnAOB）、氨氧化细菌（AOB）之间生长条件的差异，通过调控温度、pH、溶解氧等环境条件或添加抑制剂来抑制NOB的生长。接着，总结了PN/A工艺快速启动的方法，即通过添加化学物质、物理场、外加AnAOB种泥，并给予AnAOB最佳生长条件等方法，实现PN/A工艺的快速启动。最后，展望了PN/A工艺未来有待深入研究的方向。     

A Three-Step Model for Submicron W/O Emulsion Formation in a Transitional-Phase Inversion Process

A three-step model of the transitional phase inversion (TPI) process for the formation of water-in-oil (W/O) emulsions is presented. Three types of emulsions exist in an emulsification process at different oil–water ratios and hydrophilic–lipophilic balance (HLB). A stable W/O emulsion was obtained using Sorbitan oleate (Span 80) and polyoxyethylenesorbitan monooleate (Tween 80) with a specified HLB and oil volume fraction. Oil was added into water, which contained the water-soluble surfactant, to dissolve the oil-soluble surfactant. This route allowed TPI to occur, and an interesting emulsification process was observed by varying the HLB, which corresponded to the change in the oil–water ratio. Two types of emulsions in the emulsification process were found: transition emulsion 1 (W/O/W high internal phase emulsion) and target emulsion 2 (W/O emulsion with low viscosity). This study describes the changes that occurred in the emulsification process.     

An epiisopicropodophyllin aza analogue via palladium-catalyzed pseudo-domino cyclization

A new aza analogue of epiisopicropodophyllin (the C-3 epimer of podophyllotoxin) has been synthesized exploiting two original strategic steps. Rings A/B and E are entered at an early stage via a cationic benzhydrylation process. A palladium-catalyzed pseudo-domino (Pd-PDOM) intramolecular process generates rings C/D in a single synthetic operation.     

‘Hierarchical self-assembly’ of helical amylose/SWNTs complex

Helical amylose/SWNTs complexes (A/S-C) of various sizes, a single nanotube wrapped by amylose in particular, were demonstrated. The formation process of the helical A/S-C was further explained by a novel hierarchical self-assembly model, including the wrapping of amylose chains around SWNT and the hierarchical self-assembly of wrapped-SWNTs into the superstructural A/S-C. Besides the hydrophobic interaction, the hydrogen bonding also plays a certain role in the self-assembly process.     

Reduced graphene oxide wrapped hollow molybdenum trioxide nanorod for high performance lithium-ion batteries

Reduced graphene oxide wrapped hollow molybdenum trioxide nanorods have been fabricated as a high performance anode material for lithium batteries.     

‘Hierarchical self-assembly’ of helical amylose/SWNTs complex

Helical amylose/SWNTs complexes (A/S-C) of various sizes, a single nanotube wrapped by amylose in particular, were demonstrated. The formation process of the helical A/S-C was further explained by a novel hierarchical self-assembly model, including the wrapping of amylose chains around SWNT and the hierarchical self-assembly of wrapped-SWNTs into the superstructural A/S-C. Besides the hydrophobic interaction, the hydrogen bonding also plays a certain role in the self-assembly process. Supported by the National Natural Science Foundation of China (Grant No. 60577049) and Shanghai Municipal Science and Technology Commission (Grant Nos. 034319224 and 0652nm017)     

纳米金修饰玻碳电极对鸟嘌呤的催化氧化

采用电化学沉积法制备了纳米金修饰玻碳电极,并用循环伏安法和电化学阻抗法进行了表征,以此建立了一种直接测定鸟嘌呤的电分析方法。在磷酸盐缓冲溶液(pH 6.0)中,研究了鸟嘌呤在纳米金修饰电极上的电化学行为,实验结果表明,纳米金修饰电极可以增强鸟嘌呤在电极表面的吸附,并加快鸟嘌呤在电极表面的电子传输,使其电化学信号明显增大,检测灵敏度大大提高,该修饰电极对鸟嘌呤表现出良好的电催化性能。在优化实验条件下对鸟嘌呤进行测定,方法的线性范围为8.0×10-7~6.0×10-5mol/L,检出限为1.0×10-8mol/L,在鸟嘌呤浓度为1.0×10-5mol/L时测得RSD(n=10)为2.5%。     

A photoelectrochemical cell for pollutant degradation and simultaneous H2 generation

A PEC cell with nanostructured BiVO₄ photoelectrode film presents outstanding azo dye degradation and simultaneous H₂ production performance.     

Effect of removing silica in rice husk for the preparation of activated carbon for supercapacitor applications

The significant influence of silica inside rice husk in the preparation and electrochemical performances of activated carbon are investigated. The removing of silica results in high mesoporous ratio and good rate capability.     

Oxidative Conversion of Methane/Natural Gas into Higher Hydrocarbons

Oxidative coupling of methane (OCM) to ethylene and ethane is a futuristic process of great practical importance for the effective utilization of methane/natural gas. A brief summary of the work carried out at National Chemical Laboratory (Pune) for the development of catalyst and catalytic process for OCM, particularly addressing the major issues/limitations of the OCM process and efforts made to overcome the problems is presented. This review particularly covers the development of a number of highly active/selective and stable unsupported and supported (using commercial catalyst carriers) catalysts for the OCM process and also the process of improvements/modifications to overcome most of the limitations of OCM.     

Effect of Polymerization Condition on Particle Size Distribution in St/BA/MAA Emulsion Polymerization Process

IntroductionIn the last decade of this century, the carboxylation of latexes has received more andmore attention because of their practical application[']. The application includes adhesives,coatings, etc.. Many studies on the theory of carboxylation emulsion polymerization havebeen carried out. Most of these studies have focused on ideal monomer and single emulsifier inorder to simplify the system['J. But in practicable application, mixed monomers and mixedemulsifiers are often usedL3j. The…     

Investigations on the semi-batch precipitation of silica

The semi-batch precipitation process of silica from sodium silicate and sulphuric acid has been structured into a primary particle production stage, an aggregation process until the gel point is reached and finally a gel fragmentation and compaction process. The progress of aggregation was analyzed by photon correlation spectroscopy. The reaction limited aggregation kernel was found to be proportional to B'(t)(q(p - q))A/2, where A assumes the value of one. The quantity B'(t) varies between 3.4 x 10(-20) and 2.6 x 10(-20) 1/min and is only a weak function of time. The stability ratio W for the aggregation process decreases with increasing aggregate size. During the period after the gel point the gel fragmentates. The gel clusters have an initial fractal dimension of approximately 1.8 which rapidly increases to 2.4 and stays roughly constant until the end of the process. The specific surface area decreases from 480 to 300 m2/g. The primary particles have a uniform size of 22.7 nm.     

非对称结构的CO2分离膜成膜过程的研究

采用干/湿相转化法制备了一系列非对称结构的气体分离膜。动态监测成膜过程的不同阶段,用傅立叶变换红外光谱仪来研究干相转化的蒸发过程,采用数码相机连续照相的方法,用光学显微镜来研究湿相转化的凝胶过程,并探讨成膜动力学过程对膜的最终结构及性能的影响。结果表明,对流蒸发和凝胶过程溶剂/非溶剂的交换速率对形成非对称结构的高渗透性能气体分离膜有着重要的影响。     

改进层次分析法在污水处理工艺选择中的应用

采用传统的层次分析方法(Analytic Hierarchy Process,AHP)进行污水生化处理工艺的选择时,其科学性和可操作性均较低,而改进的AHP法采取三标度法,判定矩阵较易构造,且无需进行一致性检验。本研究采用改进的AHP法,建立了4层10指标4方案的污水处理工艺综合评价体系,分别对MBR、A~2/O、A/O和氧化沟工艺的经济效益、环境影响及技术性能进行分析。结果表明,MBR、A~2/O、A/O和氧化沟工艺的评价体系公式计算结果分别为0.3137、0.3379、0.2085和0.1552。因此,在我国东北地区,综合考虑经济效益、环境影响及技术性能,A~2/O工艺为最适宜的生化处理工艺,其次是MBR工艺和A/O工艺,而氧化沟工艺为最不推荐的工艺。改进的AHP法可对现有污水处理工艺的经济效益、环境影响及技术性能进行直观的评价,从而为现有工艺的运行管理以及新工艺的设计提供理论及实践依据。     

A New Manufacturing Process to Obtain Thermoluminescent Dosimeters Using Sol-Gel Method

A new manufacturing process using sol-gel method to obtain thermoluminescent dosimeters—TLDs is described. A LiF/SiO₂ thermoluminescent dosimeter in the form of reusable solid chip was prepared using an acid-catalyzed sol-gel process, with tetramethoxysilane (TMOS) and LiF powder as precursors. In comparison with the manufacturing process of typical lithium fluoride based dosimeters, the method optimizes the manufacturing process. The new dosimeter has a dose response over a dose range varying from 0.1 Gy to 160 Gy and can be used to detect higher doses using the typical commercial TLD readers without special adjustments. Furthermore, the process may be used for the preparation of other TLDs using a simple chemical processing.     

Identification of the main by-products of the developing agent N-hydroxyethyl-N-ethyl-3-methyl-p-phenylenediamine in photographic effluents by liquid chromatography/mass spectrometry

N-Hydroxyethyl-N-ethyl-3-methyl-p-phenylenediamine (CD(4)) is commonly used as a developing agent in color photographic processes. The main by-products formed in developer baths used in the process were separated and identified by liquid chromatography/electron ionization mass spectrometry (LC/EI-MS) and liquid chromatography/atmospheric pressure ionization mass spectrometry (LC/API-MS). A number of side reactions, in addition to the main reactions involved in the developing process, were found to occur. Such side reactions involved in the formation of CD(4) by-products included oxidation, hydroxylation, sulfonation and the formation of coupling products. A reaction pathway for the degradation of CD(4) based on the nature of the by-products identified is proposed and discussed.     

Thermally produced biodegradable scaffolds for cartilage tissue engineering

A novel process was developed to fabricate biodegradable polymer scaffolds for tissue engineering applications, without using organic solvents. Solvent residues in scaffolds fabricated by processes involving organic solvents may damage cells transplanted onto the scaffolds or tissue near the transplantation site. Poly(L-lactic acid) (PLLA) powder and NaCl particles in a mold were compressed and subsequently heated at 180 degrees C (near the PLLA melting temperature) for 3 min. The heat treatment caused the polymer particles to fuse and form a continuous matrix containing entrapped NaCl particles. After dissolving the NaCl salts, which served as a porogen, porous biodegradable PLLA scaffolds were formed. The scaffold porosity and pore size were controlled by adjusting the NaCl/PLLA weight ratio and the NaCl particle size. The characteristics of the scaffolds were compared to those of scaffolds fabricated using a conventional solvent casting/particulate leaching (SC/PL) process, in terms of pore structure, pore-size distribution, and mechanical properties. A scanning electron microscopic examination showed highly interconnected and open pore structures in the scaffolds fabricated using the thermal process, whereas the SC/PL process yielded scaffolds with less interconnected and closed pore structures. Mercury intrusion porosimetry revealed that the thermally produced scaffolds had a much more uniform distribution of pore sizes than the SC/PL process. The utility of the thermally produced scaffolds was demonstrated by engineering cartilaginous tissues in vivo. In summary, the thermal process developed in this study yields tissue-engineering scaffolds with more favorable characteristics, with respect to, freedom from organic solvents, pore structure, and size distribution than the SC/PL process. Moreover, the thermal process could also be used to fabricate scaffolds from polymers that are insoluble in organic solvents, such as poly(glycolic acid). Cartilage tissue regenerated from thermally produced PLLA scaffold.     

High surface area of porous silicon drives desorption of intact molecules

The surface structure of porous silicon used in desorption/ionization on porous silicon (DIOS) mass analysis is known to play a primary role in the desorption/ionization (D/I) process. In this study, mass spectrometry and scanning electron microscopy (SEM) are used to examine the correlation between intact ion generation with surface ablation and surface morphology. The DIOS process is found to be highly laser energy dependent and correlates directly with the appearance of surface ions (Si(n)(+) and OSiH(+)). A threshold laser energy for DIOS is observed (10 mJ/cm(2)), which supports that DIOS is driven by surface restructuring and is not a strictly thermal process. In addition, three DIOS regimes are observed that correspond to surface restructuring and melting. These results suggest that higher surface area silicon substrates may enhance DIOS performance. A recent example that fits into this mechanism is the surface of silicon nanowires, which has a high surface energy and concomitantly requires lower laser energy for analyte desorption.     

Removal of fluoride from water by electrocoagulation using Mild Steel electrode

Electrocoagulation process was used for defluoridation of synthetic fluoride containing water. In the process Mild Steel (MS) was used as sacrificial electrode and experiments were performed with different varying parameters such as pH and current density (CD). The fluoride removal efficiency was found to be maximum at pH 6 and CD 75.44 A/m² (2 A). At these conditions fluoride concentration reduces from initial concentration of 50 ​mg/dm³ to 5.2 ​mg/dm³. Kinetic study of electrocoagulation process revealed that the order of the reaction was in the range 1.61–1.64 with respect to fluoride concentration. It was observed that fluoride removal efficiency of the present MS electrode is comparable to the other electrodes used in electrocoagulation process available in the literature.     

Treatment of sugar processing industry wastewater using copper electrode by electrocoagulation: Performance and economic study

This paper demonstrates the use of copper electrode for the treatment of sugar processing industry wastewater (SPIW) in terms of chemical oxygen demand (COD) by applying electrocoagulation (EC) method. EC process was carried out in batch mode with electrode effective area of 0.0112 m², supplied current intensity (CI) of 44.64 A/m² - 223.21 A/m², electrode gap (EG) of 0.5–2.5 cm, electrolyte (NaCl) dose (ED) of 0.5–2.5 g/L to treat SPIW with initial chemical oxygen demand (COD) of 6000 mg/L. The maximum COD removal 73% of SPIW is achieved at optimized condition of SPIW pH: 7, CI: 89.28 A/m², EG: 1.5 cm & ED: 1.5 g/L. Sludge and scum generated during EC process were characterized by FTIR, TGA/DTA/DTG, proximate & ultimate analysis to find its applicability and their disposal. Additionally, economic study of EC treatment process at optimum condition suggest treatment cost was 11.2 US$/m³ and it indicate economic results as comparison to other available treatment processes.