水热/溶剂热法合成不同形貌结构光催化剂BiVO4的研究进展

BiVO4光催化剂的颗粒粒径、物相及形貌结构等因素都对其催化性能有显著影响,因此制备粒径、物相及形貌结构可控的BiVO4光催化剂具有重要意义。水热/溶剂热法是目前合成光催化剂BiVO4的一种重要方法,从影响水热/溶剂反应体系的因素方面概述了水热反应温度、反应时间、反应液pH值、表面活性剂以及反应溶剂等对终产物BiVO4的颗粒尺寸、物相结构以及形貌的影响。     

不同晶型BiVO_4微球的制备及其对光催化性能的影响

以Bi（NO3）3、NH4VO3为原料,NaOH为pH调节剂,采用微波水热法在180℃制备了BiVO4微球,分析了不同煅烧温度对晶型、形貌的影响,并进一步探讨了BiVO4晶型与其光催化性能的关系。采用XRD、SEM和UV-Vis吸收光谱对产品进行了分析表征,并以光催化降解亚甲基蓝为模型反应研究BiVO4的光催化性能。结果表明所制备的BiVO4微球是四方相结构,球的直径在1～3μm之间,将其在500℃煅烧后发生晶型转变,600℃煅烧可得到纯单斜相BiVO4微球,且具有良好的可见光催化活性。而且,不同晶型的BiVO4影响亚甲基蓝的降解效果。     

球形SrSnO3∶Eu3+纳米晶的水热合成及其发光性能研究

采用水热合成法,以四水钨酸钠(Na_2SnO_3·4H_2O)和氯化锶(SrCl_2)为原料,酒石酸钾钠为表面活性剂,在pH=12、温度为200℃条件下,通过调控反应时间制备出球形锡酸锶(SrSnO_3)∶Eu~(3+)纳米晶。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)及荧光光谱仪对水热反应时间不同条件下制备的产物物相、形貌以及荧光性质进行了表征,考察了反应时间对产物形貌及发光性能的影响。结果表明:不同水热反应时间下制备的产物均为纯相钙钛矿结构SrSnO_3∶Eu~(3+)纳米晶;球形SrSnO_3∶Eu~(3+)纳米晶的最佳合成条件为pH=12、反应温度200℃、水热反应时间24h;球形SrSnO_3∶Eu~(3+)纳米晶在393nm波长激发下,在614nm处均有很强发射峰。     

溶液浓度对低温水热制备BiVO4形貌及光催化性能的影响

采用低温水热法合成了一系列BiVO4样品,以XRD、SEM、UV-Vis DRS、BET等测试技术对样品的晶相结构、形貌、吸光性能以及比表面积等进行了表征,以MB染料分子模拟环境污染物,考察了样品的光催化性能。探讨了不同起始溶液浓度对样品的形貌及其光催化性能的影响。结果表明,水热反应中,起始溶液浓度对BiVO4样品的形貌和尺寸有很大影响,当起始溶液浓度为0.01mol/L时,所得样品呈"海藻头"形;浓度为0.05和0.1mol/L时,所得BiVO4均呈"鹅卵石"形;浓度为0.5mol/L时,所得BiVO4呈"土豆"形。光催化实验结果表明,"海藻头"和"鹅卵石"形BiVO4具有较高的光催化降解能力,光催化反应180min后,对MB溶液脱色率达到75%左右,而"土豆"形BiVO4仅达到45%。此外,对低温水热反应过程中BiVO4样品的形成机理进行了探讨。     

前驱溶液的碱浓度对BiVO4粉体的微波水热法制备及光催化性能的影响

以Bi(NO3)3·5H2O和NH4VO3为原料,采用微波水热法在200℃不同前驱液碱浓度下制备了BiVO4粉体。利用XRD、FE-SEM、BET、UV-Vis等手段研究了前驱液碱浓度对BiVO4晶型、结构及形貌的影响,并对不同前驱液碱浓度下合成粉体的光催化性能进行了研究。溶于纯水获得的粉体是单斜相和四方相1～3μm八面体结构的BiVO4混晶。溶于HNO3和NaOH溶液时制得粉体为纯单斜相3μm大小球状BiVO4,NaOH增加到4mol/L时为2μm大小鱼排骨状BiVO4的混晶。光催化结果表明,紫外光下光催化活性顺序为:BiVO4(纯水)>BiVO4(4mol/L NaOH)>BiVO4(2mol/L NaOH),可见光下光催化活性顺序为:BiVO4(4mol/L NaOH)>BiVO4(纯水)>BiVO4(2mol/L NaOH)。     

水热合成单斜晶系BiVO4可见光催化剂及其性能

采用水热法合成了纯单斜晶系的可见光催化剂BiVO4,考察了水热温度、水热时间和体系的pH值对BiVO4结构和光催化性能的影响。利用XRD、SEM、BET和UV-VIS对样品进行了表征,结果表明:获得的BiVO4具有中空棒状结构,升高水热温度、提高反应溶液的pH值、延长水热时间有利于单斜晶系BiVO4的生成。确定了BiVO4的最优合成条件为:水热温度140℃,水热时间6h,反应体系pH=9。选择亚甲基蓝溶液作为光催化降解物质,研究BiVO4的可见光催化性能和催化机理。结果表明,最优条件下制备的BiVO4具有较好的可见光催化性能;同时,增加降解体系的pH值提高了催化剂对亚甲基蓝的吸附能力和活化电子的利用效率,有利于提高BiVO4的光催化性能。     

金属复合氧化物BiVO4的制备及其光催化降解含酚废水的研究

以Bi(NO3)3.5H2O和NH4VO3为原料,采用水热法合成了金属复合氧化物BiVO4,并对其进行扫描电子显微镜(SEM)、X射线粉末衍射(XRD)、紫外-可见漫反射(UV-Vis DRS)以及N2的吸附-脱附表征,探讨了合成条件(温度、时间、pH值)对BiVO4的结构、晶型、形貌、孔性质等方面的影响。以苯酚水溶液为目标降解物,研究了在可见光照射作用下BiVO4的光催化性能,结果表明BiVO4具有良好的可见光催化活性。     

BiVO4晶体的制备及其光学性能

在无氨水调节pH值条件下采用液相沉淀法制备了纳米晶BivO4粉体。通过XRD、SEM、紫外-可见分光光度计、色差仪和FITR等手段综合分析了煅烧前后BiVO。相结构和微粒形貌及其光学性能。结果表明：未煅烧的BiVO4具有四方相和单斜相两种结构，而500℃煅烧后为单一的等轴状的单斜相结构。与混合相粉体相比，纯单斜相的BiVO4具有较好的光学性能，亮度值81．7、黄品值85．9及色饱和度86．5％。     

pH值对基于TTAB的BiVO_4晶体形貌及光催化性能的调控

以十四烷基三甲基溴化铵(TTAB)为模板,采用水热合成法可控制备BiVO4微晶。利用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、比表面测定仪和紫外可见漫反射(UV-Vis DRS)等技术,表征了水热反应前驱液的pH值(pH=1.5-9)对BiVO4的晶体结构、形貌、比表面积和光学性能的影响,并在可见光照射下考察了BiVO4样品对罗丹明B的光催化降解活性。结果表明,随着pH值的增大,所得产物由单斜晶系向单斜晶系与四方晶系的混晶转变,且形貌由多面体向多孔微球转变。当pH为5~7时,所制备的BiVO4样品具有独特的形貌、较大的比表面积和良好的多孔结构,表现出优越的光催化活性,对罗丹明B降解率可高达90.4%。。     

Mn~(2+)(Co~(2+)Ni~(2+))O_4材料制备中前驱物的影响

采用水热合成法,以Mn、Co、Ni的有机或无机盐和氨水为反应原料,通过调控前驱物配方、浓度等工艺参数在一定水热反应条件下,制备纳米粉体材料,利用XRD、TEM等手段分析了该粉体的晶相及杂质组成等性能参数.实验结果表明,采用硝酸盐和沉淀剂配制、中等盐溶液浓度的前驱物,在合适的条件下进行水热反应,合成了单一尖晶石结构、晶粒尺寸集中在20～50nm间的Mn~(2+)(Co~(2+)Ni~(2+))O_4粉体材料.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.