TiO2离子筛的合成及锂吸附性能研究

以离子筛型氧化物为关键材料的锂离子选择性吸附技术是近年来盐湖卤水提锂的重要研究方向.采用商品TiO2经过研磨、焙烧浸锂、酸洗脱锂和干燥过程制备得到立方晶相尖晶石结构的TiO2离子筛,通过XRD和SEM对样品晶相结构和表面形貌进行了表征,探索了焙烧温度和Li/Ti比对离子筛前驱体结构的影响,进一步对Li+吸附性能进行了研究.结果表明,当Li/Ti摩尔比为0.9,TiO2和Li2CO3在1173K焙烧24h后得到了近乎为纯晶相的尖晶石结构Li4Ti5O12前驱体,经酸脱锂后得到对Li+具有记忆效应的TiO2离子筛,对Li+的平衡吸附量为2.530 mmol/g.     

锰钛系复合锂离子筛的制备及其吸附性能研究

以LiOH·H2O为锂源、锰钛共沉物作为锰源和钛源,采用共沉淀-水热合成法合成掺钛复合锂离子筛。研究了合成条件对复合锂离子筛的结构和性能的影响,使用X射线衍射(XRD)对合成样品进行表征,通过酸浸和吸附实验研究了合成样品吸附锂的性能和溶损率。研究结果表明:当Ti、Mn物质的量比为0.03,水热反应母液中锂浓度为3.2mol/L,反应温度为230℃,反应时间为12h时合成的离子筛具有较好的吸附性能和稳定性,对Li+的最大饱和吸附容量达到19.71mg·g-1,同时,Mn和Ti保持了较低的溶损率。     

铬铁复合掺杂锂离子筛的制备及其吸附性能研究

利用具有选择性高、吸附容量大、吸附速率快的锂离子筛从低浓度液相中吸附和分离锂已成为最有前途的方法之一,但锂锰氧化物锂离子筛因其Mn溶损率大、循环性能差在工业应用中受到限制。以LiOH·H₂O、MnO₂、Fe₂O₃、Cr₂O₃为原料,通过高温固相法制备了尖晶石型铬铁复合掺杂锂离子筛。重点研究了Cr掺杂量和煅烧温度对锂离子筛结构、吸附性能和Mn溶损率的影响。结果表明,当锂、锰、铁、铬的摩尔比为1∶2∶0.05∶0.05、煅烧温度为550℃时,合成的锂离子筛饱和吸附容量为27.30 mg/g, Mn溶损率仅为0.43%。选择吸附实验表明该锂离子筛对Li⁺具有优异的选择性能。此外,经过5次循环实验后,铬铁复合掺杂锂离子筛的饱和吸附容量仍能保持第二次循环的89%,为18.51 mg/g,优于未掺杂锂离子筛的56%。     

尖晶石型LiMn2O4酸洗提锂机理研究

以高温固相法合成的尖晶石型LiMn2O4前驱体为研究对象,通过对离子筛和离子筛吸附产物的化学分析、X射线衍射图谱分析、热重分析、红外分析和滤液中锂交换量与锰损失量分析,提出并验证了离子筛和吸附产物化学组成式可由LixMn2O4(0≤x≤1)表达,其结构依然保持尖晶石结构,阐明了以盐酸为洗脱剂离子筛提锂过程的氧化还原反应机理,给出了完善的洗脱过程与吸附过程反应式。实验结果表明,洗脱和吸附过程不彻底是导致离子筛吸附量与饱和吸附量相差较大的原因,离子筛中Mn3+歧化是离子筛发生溶损的主因;提出了关于尖晶石型离子筛提锂深入研究关键问题的建议。     

一种提锂杂化膜的制备及其提锂性能研究

将提锂吸附剂前驱体尖晶石型锰氧化物（Spinel-type manganese oxide,SMO）Li_1.6-Mn_1.6O₄与聚氯乙烯（PVC）杂化,采用溶剂-非溶剂交换法成功制备了用于海水提锂的平板膜.该杂化膜用酸处理抽出其中的锂得到具有提锂性能的膜,对膜进行了一系列提锂性能测试.实验结果表明,酸洗处理后的膜对富锂溶液中锂的吸附约6 h达平衡,最大吸附量为29 mg/g,之后采用0.5 mol/L HCl溶液脱锂约1 h锂的脱出基本达到平衡,Li⁺的脱附率在95%左右,锰的溶损率在3.5%左右.该膜在含有Li⁺、Na⁺、K⁺、Mg²⁺、Ca²⁺离子的竞争吸附过程中对Li⁺表现出很好的选择性,同时重复实验也表明,这种提锂杂化膜具有很好的稳定性.     

基于不同洗脱剂的单斜晶系钛基锂离子筛的制备及其吸附性能

采用高温固相法,以碳酸锂和二氧化钛为原料合成了锂离子筛前驱体,并分别考察了0.5mol/L盐酸和0.8mol/L过硫酸钠溶液对前驱体的洗脱及产物锂离子筛的吸锂过程。结果表明,0.5mol/L的盐酸作洗脱剂,循环洗脱-吸附5次后离子筛在含锂溶液(等体积0.01mol/L LiCl和0.01mol/L LiOH混合液)中的吸锂量稳定在18mg/g左右;0.8mol/L的过硫酸钠作洗脱剂,5次循环洗脱-吸附后对锂的吸附量约为16mg/g;吸锂过程适宜用伪二级动力学模型描述,且过硫酸钠的洗脱及所得离子筛的吸附动力学性能均优于盐酸作为洗脱剂的情况;过硫酸钠作洗脱剂有助于改善单斜晶系钛基锂离子筛的动力学性能。研究结果有助于拓宽锂离子筛的制备及应用。     

锰基锂离子筛前体及其掺杂和表面修饰进展

锰基锂离子筛是一种极具发展前景的提锂吸附材料。对其晶体结构及影响其结构稳定性的因素进行了总结,重点讨论了阴离子、阳离子以及复合3种掺杂修饰和以包覆为主的表面修饰的研究概况;指出两类修饰可在一定程度上提高锰基锂离子筛的结构稳定性、抑制Jahn-Teller效应,进而降低Mn的溶损、提高循环应用的稳定性,但修饰未能从根本上解决离子筛提锂过程中溶损的关键问题,而且修饰元素的引入也为后续的分离带来新问题。最后,从以原子量低于锰的元素为掺杂对象和应用过程涉及的洗脱剂筛选两方面,对锰基锂离子筛的发展前景进行了展望。     

低维纳米立方相Li_4Mn_5O_(12)的制备及锂吸附性能

以MnSO4·H2O和(NH4)2S2O8为原料通过控制水热反应条件合成了纯的四方相β-MnO2纳米氧化物,进一步通过低温固相法制备了立方相Li4Mn5O12,经酸浸脱锂后得到对Li+具有特殊选择性的MnO2离子筛.用XRD、HRTEM、SAED、吸附等温线、吸附动力学及共存金属离子的分配系数等手段对产物的晶相结构和Li+选择性吸附性能进行了研究.HRTEM和SAED图像表明氧化物MnO2、前驱体Li4Mn5O12和离子筛MnO2均为低维纳米棒.离子筛的最大吸附量达到6.6mmol/g,且当Li+初始浓度仅为5.0mmol/L时,离子筛的吸附量即可达到约5.0mmol/g,这对于在海水或锂离子浓度极低的盐湖卤水提锂具有重要的实用意义.     

PVDF为成膜材料制备锂离子筛膜的性能研究

将锂锰氧化物(Li1.6Mn1.6O4)添加到聚偏氟乙烯(PVDF)铸膜液中,通过相转化法制备了掺杂Li1.6Mn1.6O4的锂离子筛前驱体膜,经过盐酸处理洗脱锂离子后制得锂离子筛膜。采用X射线衍射、扫描电镜、吸附实验等手段对膜的结构和吸附性能进行表征。吸附实验表明,随着Li1.6Mn1.6O4含量的增加,锂离子筛膜的吸附量先增加后减小。当添加Li1.6Mn1.6O4的质量分数为15%时,锂离子筛膜的吸附量最高为6.98×102 mg/cm2。     

锂离子筛前驱体LiMn2O4的制备及锂吸附性能研究

以氢氧化锂和乙酸锰为主要原料,采用溶胶-凝胶法合成了尖晶石型LiMn2O4前驱体,经酸浸脱锂后得到对Li+具有特殊选择性吸附的离子筛,采用XRD、SEM、吸附动力学等手段对前驱体及相应离子筛的晶相结构及吸附性能进行了研究。结果表明,由550℃煅烧10h制备出的前驱体LiMn2O4中表现出最好的结构稳定性,酸浸转型之后锂离子筛能够保持尖晶石锂锰氧化物的结构,离子筛的最大吸附容量达到32mg/g。     

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.     

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.……     

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 ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.