五种作物秸秆生物炭对重金属Pb^(2+)的吸附性的比较北大核心CSCD

为探讨小麦、玉米、水稻、花生壳和稻壳制备生物炭的差异,本文对这些植物纤维在不同预成型压力下制备的生物质炭的结构和性能进行了测定和分析,并研究了其对铅离子(Pb^(2+))的吸附性。结果表明:玉米、小麦和水稻三种秸秆生物质炭对溶液中Pb^(2+)的吸附性能较好,且在不同初始浓度下对Pb^(2+)的吸附符合Langmuir等温吸附模型,吸附量分别为141.310、121.226和122.753mg·g^(-1)。而花生壳和稻壳生物炭对Pb^(2+)的吸附性能较差,吸附量分别为62.914和51.037mg·g^(-1)。玉米秸秆生物质炭的-OH、-C-H、C=C等表面官能团较多,可通过表面官能团的络合作用吸附溶液中的Pb^(2+)。小麦和水稻秸秆制备生物炭由于含有较高的碳酸盐、磷酸等无机矿物形成化学沉淀。不同初始压力下制备生物质炭对溶液中Pb^(2+)的吸附影响较小。     

微波辅助碳酸钾活化制备玉米秆基活性生物炭

以碳酸钾为活化剂、少量活性炭为吸波剂,在氩气保护下对玉米秸秆进行微波加热制备活性生物炭。采用比表面积(BET)、扫描电镜和能谱(SEM和EDS)及化学检测的方法,研究了微波加热过程中生物炭孔隙度的变化规律,考察了温度、活化剂(K2CO3)配量、微波功率和保温时间对生物炭吸附性能及产率的影响。结果表明,微波加热制备活性生物炭的最佳条件为:温度650℃、活化剂(K2CO3)配量150%、微波功率700W、保温时间5min。此条件下获得产率为28.1%的活性生物炭,具有发达的多级孔隙结构,比表面积1036.7m2/g;而且此生物炭吸附性能较好,其中碘吸附值1238.7mg/g,亚甲基蓝吸附值254mg/g,优于木质净水用活性炭国家一级标准(GB/T 13804.3-1999)。     

物理活化白酒糟制备多孔炭材料

白酒糟是典型的富含纤维素生物质过程残渣,以水蒸气及CO2为活化剂研究了制备白酒糟多孔炭(活性炭)的各种操作条件,包括炭化温度、活化温度、活化剂流量对多孔炭样品性能的影响规律,证明了利用白酒糟制备多孔炭材料的技术可行性。基于SEM、XRD、N2吸附对材料表面和孔隙的表征,并结合制备过程气相产物的实时监测,解析了白酒糟多孔炭制备过程的活化反应历程。结果表明,低温炭化和高温活化有利于提高多孔炭对碘和亚甲基蓝的吸附,水蒸气比CO2具有更高的反应活性。制备多孔炭的比表面积和孔体积分别达到了371.6 m2/g和0.34 cm3/g,对应的碘和亚甲基蓝吸附值分别是580 mg/g和90 mg/g。同时揭示了活化反应中活化剂首先与炭化料的H、O官能团发生反应形成初级孔隙,进而和C物种反应形成石墨微晶的堆垛和层错,形成多孔结构。     

巴旦木壳基生物炭的制备及其吸附性能表征

为控制环境污染领域提供新材料,分别在300、400和500℃条件下制备了巴旦木壳(BC)和干炒巴旦木壳(BCF)生物炭,并用不同浓度的HCl和NaOH对生物炭进行了改性。用国标法表征了生物炭的真密度、灰分、钙镁含量、pH值、焦糖脱色率、亚甲基蓝吸附量、碘吸附值及比表面积等基本性质,并对溶液中Pb²⁺和Zn²⁺的吸附特性进行了研究。实验结果显示,随着炭化温度的升高,两种生物炭的产率降低,灰分、钙镁含量、真密度、比表面积、孔体积、碘吸附值和pH值增加;BC500和BCF500的比表面积分别达到了199.97和295.44m²/g。BCF的灰分明显高于BC;酸碱及其浓度对不同参数产生的影响不一致。400℃碳化的两种生物炭的亚甲基蓝吸附值较高,酸碱改性后吸附值均增高;高温热解有利于制备碘吸附值高的生物炭,碱改性能提高碘吸附值,BC500和BCF500及其碱改性产物的碘吸附值达到330mg/g以上;两种生物炭及其改性产物的焦糖脱色率变化没有明显规律;高浓度酸碱改性显著降低了高温制备的BC和BCF的Pb吸附量;酸改性降低了、碱改性提高了两种生物炭的Zn吸附量。总之,两种巴旦木壳生物炭对不同物质的吸附特性不同,建议根据污染物的种类选择不同的生物炭制备工艺和改性剂。     

沙柳基磁性多孔炭的制备及其吸附亚甲基蓝性能研究

采用水热法原位改性沙柳生物炭制备磁性多孔炭复合材料,利用SEM、XRD、FT-IR、XPS和BET分别对多孔炭的形貌、结构表征,并研究磁性多孔炭吸附去除废水中亚甲基蓝性能。系列表征分析结果表明磁性复合材料表面疏松多孔,比表面积为63.01 m²/g,含有-COOH、-OH等丰富的官能团。在亚甲基蓝初始质量浓度为50 mg/L、初始pH值为11,投加量为2 g/L、25℃吸附120 min时,亚甲基蓝的吸附率可达88.52%,最大吸附量为218.08 mg/g;吸附过程与Langmuir吸附等温模型拟合较好,符合准二级吸附动力学模型。吸附以化学吸附为主,吸附稳定,无二次污染,吸附剂廉价易得,便于分离,是理想的亚甲蓝废水处理试剂。     

凹凸棒石/炭对低浓度亚甲基蓝的吸附性能(英文)

通过水热处理凹凸棒石和纤维素获得凹凸棒石/炭纳米复合材料,研究该复合材料对亚甲基蓝的吸附性能。考察吸附条件对吸附行为的影响,以及吸附动力学和热力学研究。亚甲基蓝的吸附行为符合二级吸附速率方程,吸附等温方程符合Langmuir方程。吸附热力学参数的计算值表明,亚甲基蓝在该复合材料上的吸附是自发、吸热的过程。     

不同原料烘焙炭的理化特性及对亚甲基蓝的吸附性能

选择四种生物质为原料,经300℃热裂解制成生物质烘焙炭,研究生物烘焙炭理化特性对亚甲基蓝的吸附特性以及动力学、热力学特性,分析了pH值、吸附时间、溶液初始质量浓度、生物质投加量对吸附效果的影响。同时对吸附动力学以及吸附机制进行研究。结果表明:生物质烘焙炭对亚甲基蓝的吸附约60 min即达平衡;适宜pH值为8～12,平衡吸附量随着初始浓度的增加而增加。四种生物质烘焙炭对亚甲基蓝的等温吸附均可用Langmuir方程和Frcundlich方程拟合,木粉烘焙炭属于单分子层吸附,而壳类生物质烘焙炭以多分子层吸附为主,吸附过程符合准二级动力学方程,即以化学吸附为主,吸附过程由膜扩散和颗粒内扩散共同控制,颗粒内扩散为主要吸附速率控制步骤,吸附过程为吸热反应,高温有利于吸附体系的自发进行。最终得到四种原料烘焙炭吸附能力的强弱顺序为:核桃壳烘焙炭木粉烘焙炭椰子壳烘焙炭橡胶籽壳烘焙炭。     

淀粉/蒙脱土复合多孔炭材料的制备及其吸附性能研究

以玉米淀粉和蒙脱土为原料,组合溶胶-凝胶和催化炭化技术制得多孔炭材料。通过扫描电镜(SEM)、X射线衍射(XRD)和红外光谱分析(FT-IR)对材料进行表征。考察了复合炭材料对亚甲基蓝的吸附性能及其离子交换性能。结果表明:蒙脱土和淀粉以插层形式复合,形成片层状结构,所得复合材料对亚甲基蓝有更高的吸附速率和吸附量,同时拥有优良的离子交换性能,具有广阔的应用前景。     

磷酸活化鱼鳞活性生物炭的制备及表征

以鱼鳞为原料,通过磷酸活化法制备具有较高比表面积并含大量微孔的活性生物炭。利用傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)、X射线光电子能谱(XPS)、Boehm滴定法对制备的鱼鳞活性生物炭的结构特征和表面的组成及性质等进行了表征。结果表明:在85%的磷酸、浸渍比(磷酸与鱼鳞质量比)为2、550℃活化1.0 h条件下制备的鱼鳞活性生物炭的得率为26.74%,亚甲基蓝吸附值为213 mg/g,碘吸附值为936.46 mg/g,比表面积为498.162 cm~2/g,总孔容为0.266 cm~3/g,平均孔径为2.138 nm。Boehm滴定法总酸度为1.678 mmol/g,总碱度为0.433 mmol/g,其表面含有两性官能团。其中酸性官能团为羟基、羧酸基、内酯基等多种含氧类官能团和含磷官能团,碱性官能团为酰胺、内酰胺、吡啶型和吡咯型等含氮官能团。     

离子液体辅助纳米纤维素吸附剂的制备及其吸附性能

以脱脂棉纤维素(Cellulose,Ce)为原料,以丙烯酸(AA)和丙烯酰胺(AM)为单体,使用酸性离子液体1-丁基-3-甲基咪唑硫酸氢盐([Bmim]HSO₄)为溶剂和水解催化剂对纤维素进行水解和改性,然后对改性纤维素进行高压均质处理制备出纳米纤维素吸附剂(AA/AM-g-NC)。对AA/AM-g-NC的结构和性能进行表征,并以亚甲基蓝为吸附质研究了对AA/AM-g-NC的吸附性能。结果表明,离子液体辅助高压均质处理脱脂棉后得到纤丝交联网状结构的AA/AM-g-NC吸附剂。这种吸附剂的晶型保持了纤维素Ⅰ型结构,结晶度略有提高;AA/AM-g-NC吸附剂表面接有丙烯酸和丙烯酰胺官能团,对亚甲基蓝的吸附受pH值的影响且为自发放热过程,并符合Langmuir吸附等温式;吸附过程接近准二级动力学方程,由颗粒的内扩散和表面扩散共同控制。     

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...     

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.……     

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.     

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.     

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.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.