烯丙基胺-细菌纤维素的制备及其动力学研究

基于Ce4+引发自由基接枝共聚机理,制备了新型的烯丙基胺-细菌纤维素(al-BC)吸附剂;考察了细菌纤维素(BC)和烯丙基胺加入量、硝酸铈铵(CAN)浓度等对接枝共聚反应的影响并探讨了其接枝动力学过程;以al-BC为吸附剂,研究其对重金属离子Pb2+的吸附性能。结果表明:在CAN浓度25mmol/L、硝酸浓度0.16mol/L、烯丙基胺及BC加入量分别为24mL/L和8g/L、温度40℃、反应时间4h的最优接枝条件下,al-BC接枝率为18.22%;根据实验结果拟合出了反应初期接枝反应动力学方程;在最优吸附条件下,al-BC对Pb2+的吸附能力比BC提高了37.53%。     

聚乙烯亚胺-羧甲基纤维素的合成及对金属离子的吸附性能

以羧甲基纤维素(CMC)为基质,用戊二醛(GA)做交联剂,将聚乙烯亚胺(PEI)交联到羧甲基纤维素上制得聚乙烯亚胺-羧甲基纤维素吸附剂(PEI-CMC)。采用傅里叶变换红外光谱、扫描电镜、X射线光电子能谱对PEI-CMC的结构进行了表征,测定了其对Cu2+、Pb2+和Cd2+的吸附性能,并研究了pH值、时间、金属离子的初始浓度对吸附的影响。结果表明,当CMC、PEI和GA的反应比为1 g∶5 mL∶20 mL,反应温度为25℃,反应时间为3 h时,合成的PEI-CMC的含氮量为13.23%。当CMC和PEI的反应比为1 g∶5 mL时,随着戊二醛(质量分数2.5%)的加入量增加,PEI-CMC的产率先增大后降低。在pH值1~14的范围内,溶液酸碱度的变化对PEI-CMC的交联度没有影响。PEI-CMC吸附剂对Cu2+、Pb2+和Cd2+的吸附量在实验范围内随pH升高而增加。PEI-CMC对Pb2+和Cu2+、Cd2+的吸附在90 min和180 min后分别达到平衡,吸附动力学符合准二级反应动力学模型。随着Cu2+、Pb2+和Cd2+初始浓度的增加,PEI-CMC对Cu2+、Pb2+和Cd2+的吸附量开始时快速增加,而后达到饱和,吸附等温数据符合Freundlich模型,最大吸附容量分别为Cu2+250.0mg/g、Pb2+635.9 mg/g、Cd2+142.8 mg/g。     

羧甲基纤维素纱布对水溶液中Cu~(2+)的吸附动力学研究

以棉纱布为原料制备了羧甲基纤维素纱布(CMC纱布),研究了其对Cu2+的吸附性能。对不同Cu2+浓度、不同吸附时间的吸附曲线用3种动力学模型(一级动力学方程、二级动力学方程和粒子扩散方程)进行分析,探讨了CMC纱布对Cu2+的吸附机理。结果表明,吸附动力学过程可用二级动力学模型描述,相关性系数R2均达到0.99。CMC纱布对Cu2+的吸附过程是一个复杂的非均相扩散的化学吸附过程,达到吸附平衡后没有明显的解吸附现象。粒子扩散模型分析表明,吸附过程由表面络合和吸附剂内部扩散共同控制。     

多乙烯多胺胺化GMA-TAIC共聚物大孔树脂的合成及对重金属离子的吸附

用自由基悬浮聚合制备了甲基丙烯酸缩水甘油醚(GMA)-三烯丙基异尿氰酸酯(TAIC)(80/20)共聚物大孔树脂,通过环氧基与多乙烯多胺的反应得到了相应的胺化树脂。在GMA-TAIC共聚物大孔树脂上键合多乙烯多胺会导致树脂孔体积和孔隙率的下降。合成的胺化树脂对重金属Cu(II)、Co(II)、Ni(II)、Zn(II)、Cd(II)、Mn(II)和Pb(II)离子有相当高的吸附容量,其中对Cu(II)离子吸附容量最大、吸附速率最快,吸附速率次序为:Cu(II)Cd(II)Zn(II)Pb(II)=Co(II)Mn(II),胺化树脂对这些重金属离子的吸附符合伪二级速率方程。     

活性炭孔隙结构对重金属离子吸附性能的影响

对活性炭进行孔结构调控,系统地对Cr(Ⅵ)、Pb(Ⅱ)和Cd(Ⅱ)3种重金属离子的吸附特性进行研究,考察活性炭孔隙结构对吸附的影响。采用模板法制备出平均孔径2.23~3.37nm、中孔率45.1%~91.9%的中孔活性炭,制得的中孔活性炭可几孔径范围与这3种重金属水合离子直径相匹配。将中孔活性炭用于水溶液中Cr(Ⅵ)、Pb(Ⅱ)和Cd(Ⅱ)的静态吸附,考察了pH值、温度、时间等吸附工艺条件的影响。研究发现,对吸附Cr(Ⅵ)、Pb(Ⅱ)和Cd(Ⅱ)适宜的pH值分别为3.0、6.0、6.0,吸附是一个吸热过程。吸附过程符合拟二级动力学模型。活性炭中孔率的增大有利于提高对Cr(Ⅵ)、Pb(Ⅱ)和Cd(Ⅱ)的吸附效果,表明对具有较大尺寸的重金属离子吸附过程中活性炭中孔所起的重要作用。     

多胺型阴离子交换纤维吸附Cr(Ⅵ)的热力学

采用自制的多胺型阴离子交换纤维,研究其对Cr(Ⅵ)的吸附特性.在研究的温度及浓度范围内,该纤维对Cr(Ⅵ)的平衡吸附量及吸附速率随温度的升高而增大.吸附是一个快速吸附过程,20min内即可达到吸附平衡,且该吸附过程符合Boyd液膜扩散模式.纤维对Cr(Ⅵ)吸附的平衡数据符合Langmuir和Freundlich吸附等温方程,且为优惠型吸附.测试了Cr(Ⅵ)在该多胺型阴离子交换纤维上的吸附焓、自由能和吸附熵,并对此吸附行为作了合理解释.结果表明,该吸附为吸热过程,升温有利于吸附的进行;多胺型阴离子交换纤维对Cr(Ⅵ)的吸附过程以化学吸附为主.     

木质纤维素基纳米复合材料对Pb~(2+)、Cd~(2+)的吸附研究

以原位插层共聚法制备木质纤维素-g-丙烯酸/丙烯酰胺/蒙脱土(LNC-g-AA/AM/MMT)纳米复合材料,采用X射线衍射(XRD)、扫描电镜(SEM)对其结构进行表征。研究在金属离子初始浓度、吸附时间、吸附温度、pH值等不同吸附条件下,LNC-g-AA/AM/MMT纳米复合材料对Pb2+、Cd2+吸附性能的影响。结果表明,当Pb2+、Cd2+初始浓度分别为0.04和0.06mol/L,吸附时间分别为120和60min,吸附温度分别为40和30℃,pH值为5.5时,LNC-g-AA/AM/MMT纳米复合材料对Pb2+、Cd2+的吸附量分别高达504.2和246.9 mg/g。整个吸附过程均符合Langmuir吸附等温线模型和伪二级动力学模型,且是个自发放热的反应过程。同时对最佳条件下吸附饱和的LNC-g-AA/AM/MMT纳米复合材料进行解吸研究,脱附率分别为93.4%和92.9%。     

三乙烯四胺基蔗渣纤维素对Cr(Ⅵ)的吸附性能研究

通过对蔗渣纤维素进行胺化改性,合成新型三乙烯四胺基蔗渣纤维素吸附剂,并对Cr(Ⅵ)废水进行处理。根据对三乙烯四胺基蔗渣纤维素的结构和形貌表征,发现引入三乙烯四胺可以提高蔗渣纤维素的比表面积,并形成适于吸附的多孔结构。利用热力学、动力学及脱附再生实验研究其对于Cr(Ⅵ)的吸附性能。结果表明,三乙烯四胺基蔗渣纤维素对Cr(Ⅵ)的吸附效果良好,其吸附过程符合Langmuir等温方程和准二级动力学方程。而且,该吸附剂热稳定性高,可重复使用。     

镁铝金属氧化物对共存Cu~(2+)/Cr(Ⅵ)的协同去除效应

以Mg Al-CO32–水滑石(LDH)焙烧产物(LDO)为重金属离子去除剂,在单一Cu2+、Cr(Ⅵ)体系和Cu2+/Cr(Ⅵ)共存体系中探究了LDO对重金属离子的去除性能,并结合对金属-LDO复合体的XRD、FT-IR和SEM表征阐明了双金属(Cr(Ⅵ)阴离子+Cu2+阳离子)在LDO上的去除机理。结果表明,Cr(Ⅵ)和Cu2+在LDO上的吸附表现为多重相互作用的协同吸附效应。除了Cu2+的"Jahn-Teller"效应和氢键协同多体效应外,Cu2+-Cr O42–-LDO体系还发生静电作用、水合作用、配位作用以及共沉淀和继沉淀作用,形成了Mg-Al-Cu三元复合体。     

蒙脱土/海藻酸钠接枝丙烯酸高吸水性复合物的制备及吸附性能研究

以过硫酸胺(APS)为引发剂,N,N-亚甲基双丙烯酰胺(MBA)为交联剂,采用插层聚合法制备了蒙脱土/海藻酸钠接枝丙烯酸(MMT/SA-g-PAA)高吸水性复合物。通过红外光谱(FT-IR)、扫描电镜(SEM)、热重分析(TGA)对MMT/SA-g-PAA的结构和性能进行了表征。研究了MMT/SA-g-PAA对重金属离子的吸附性能,结果表明室温下MMT/SA-g-PAA对Pb2+、Cu2+、Ni 2+的最大吸附量分别为968.9、231.0及236.0mg/g,其中对Pb2+和Cu2+的吸附符合Langmuir吸附模型,而对Ni 2+的吸附符合Freundlich吸附模型。     

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.     

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.     

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...     

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.……     

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.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...