美国铼合金公司开发高能电子管冷源用的钼铼合金

美国铼合金公司 (ＲＡＩ)的Ｄ .Ｂｏｒｉｓ及其同事曾经指出 ,铼含量超过 4 0 %的钼铼合金具有高温强度大、高温塑性好、室温可成形性优良和能够经受住热震等优点 ,人们很有兴趣把它们应用在许多高技术领域中 ;例如 ,用作高能电子管的冷源 ,而深拉伸则是加工这种器件的普通技术。所以 ,评价钼铼合金显微组织和化学成分的影响对这类用途来说是至关重要的。对业已得到的关于Ｍｏ - 41Ｒｅ和Ｍｏ - 48/5 0Ｒｅ合金可成形数据所做的分析表明 ,必须全面探查和研究钼铼合金在这类尖端用途中的潜力。在第 14届国际普兰西研讨会上 ,美国铼合金公司宣…     

D302-Ⅱ树脂吸附铼的性能研究及应用

针对地浸采铀浸出液低含量铼的回收,研究了D302-Ⅱ弱碱性阴离子交换树脂吸附和解吸铼的性能和机制。通过静态试验考察温度、酸度、时间对树脂吸附的影响;通过动态试验考察了溶液酸度和流速的影响,并进行了解吸剂及其浓度影响试验、抗干扰试验及树脂再生的试验;用地浸采铀浸出液通过D302-Ⅱ树脂,进行模拟回收铼试验。结果表明,D302-Ⅱ树脂对铼的吸附速率快,吸附反应速率常数k=1.6×10-3s-1,半交换期t1/2=433 s。吸附酸度在pH 2.0～5.0范围内,有利于铼的吸附。吸附平衡服从Freundish吸附等温式,吸附反应放热,反应可在常温下进行。动态上柱酸度选择为pH 2.0～5.0,流速1～2 ml.min-1,铼的吸附率可达95%以上;洗脱液选择NH4OH,25倍树脂床体积的3 mol.L-1NH4OH溶液可将铼洗脱完全。地浸采铀浸出液中的共存离子不影响铼的吸附和解吸,0.5 mol.L-1H2SO4溶液可使树脂再生。树脂对铼的静态和动态吸附容量分别为166和162 mg.g-1干树脂,对浓度低至0.03 mg.L-1铼溶液吸附和解吸,回收率可达96%～102%,表明该树脂有较好的应用前景。     

IPN弱碱树脂吸附铼的行为及热力学性质

本文研究了IPN弱碱树脂从弱碱性介质中吸附铼的行为和热力学性质。实验结果表明,在PH=9.0—10.0范围内,该树脂能有效地吸附铼,而钼仅有少量被吸附,铼钼分离系数高达1506;树脂对铼的静态平衡交换容量和动态操作容量分别为804、805.3mg/g树脂;被吸附的铼用8％HN_3·H_2O+10％NH_4NO_3混合液淋洗,淋洗率为99.32％。树脂以阴离子交换机理吸附ReO_4~-。测定并求算了吸附过程的热力学函数。其值分别为ΔH~0=-9.62kJ/mol,ΔG~0=-10.00kJ/mol,ΔS~0=1.3J/mol·K。     

硫脲光度法测定粗铼酸钾中铼时钼干扰的消除

探讨了盐酸羟胺-钼(Ⅴ)-EDTA络合物掩蔽钼,硫脲-铼-氯化亚锡分光光度法选择性测定含钼粗铼酸钾中铼含量的方法。对盐酸羟胺-钼(Ⅴ)-EDTA掩蔽钼的体系及对硫脲-铼(Ⅱ)-氯化亚锡络合物显色的条件进行了优化。结果表明:于弱盐酸介质中,80℃水浴35min条件下,4mLEDTA溶液和3mL盐酸羟胺溶液能够掩蔽3.0mg钼,且络合掩蔽体系对显色络合物无影响：于3.0mol/L盐酸介质中,在吸收波长λ₄₄₀nm处,铼质量浓度在0～20μg/mL范围内符合比尔定律,检出限为1.91×10^-8μg/mL。方法用于含钼40%～50%的粗铼酸钾样品中10%～20%的铼含量测定,相对标准偏差(RSD,n=7)为0.15%～0.25%,回收率为100%。     

丁二酮肟分光光度法测定富铼渣中铼

称取0.20 g样品于高铝坩埚中,置于马弗炉中升温至250 ℃,恒温30 min以驱除硫和砷,再加入3.5 g过氧化钠于730 ℃熔解7 min,以水浸出熔融物后,加热微沸约5 min以促进过氧化钠产生的过氧化氢分解完全,加水定容后,过滤,加入1滴对硝基酚溶液,滴加盐酸(1+6)至溶液黄色刚褪去(pH≈1),加水至20 mL,再加入5 mL 400 g/L柠檬酸溶液、5 mL盐酸(1+3)、5 mL 10 g/L丁二酮肟乙醇溶液、5 mL 250 g/L氯化亚锡溶液进行显色测定,建立了丁二酮肟分光光度法测定富铼渣中铼含量的方法。实验表明:铼的质量浓度在100～600 μg/100 mL范围内与其吸光度符合比尔定律,方法检出限为11.3 μg/mL。干扰试验表明样品中共存离子不干扰测定。将方法用于两个富铼渣管理样品及两个实际样品中铼的测定,测定值与参考值相符,相对标准偏差(RSD,n=22)为0.69%～1.1%,回收率为99%～100%。     

聚乙烯醇存在下高铼酸根与乙基紫光度法测定钼样中痕量铼

提出用高铼酸根-乙基紫-聚乙烯醇体系直接光度法测定铼的方法。在表面活性剂存在下,乙基紫与高铼酸根形成的离子缔合物分散在水相中而进行的显色反应,不但解决了乙基紫与高铼酸根缔合物水溶性差的问题,而且提高了显色反应的灵敏度。显色反应的最大吸收波长为647nm,采用摩尔比、等摩尔连续变化和平衡移动法测定了该离子缔合物中乙基紫与高铼酸根的组成比为1∶1。在10mL溶液中铼的线性范围为0～10.0μg,ε647=1.36×105L.mol-1.cm-1,检出限为1.4×10-3μg/mL。适量的柠檬酸或酒石酸存在下,     

处理钼精矿时附带提取铼

钼精矿是提取铼的主要原料.精矿中的铼含量(决定于矿床)为10~(-3)%～10~(-4)%.原苏联处理的钼精矿与中矿含铼较富(0.2～0.7kg Re/t精矿). 氧化焙烧是处理钼精矿的主要方法.国外氧化焙烧主要在多层焙烧炉内进行,只有某些小企业在管状回转炉内进行.原苏联多层炉仅用于某些所得焙砂含硫不大于0.2%的     

铼的提取与市场

1 铼的提取 铼在地壳中的含量很少,仅为1×10~(-7)%,居第80位属最稀有元素。它没有单独矿石,年生于某些钼、铜等矿物中,以辉钼矿居多,含量约0.0001%～0.3%。铼的综合回收主要以处理钼精矿、铜精矿的烟尘、母液、洗涤液和炼渣等为原料。提取方法有氧化焙烧-沉铼法、萃取法、离子交换法、高     

W-5%Re/W-26%Re钨铼偶丝氧化行为

为了解钨铼热电偶丝在空气中的氧化过程、氧化产物成分、氧化膜生长情况,进行了DSC/TG、XRD、SEM等实验.通过填充惰性物质、脱氧、造氢、密封等实体化技术对钨铼热电偶进行了防氧化保护,利用SEM观察了保护后的钨铼偶丝的形貌.结果表明:在空气中,钨铼偶丝高温氧化产物主要为WO3;W-5%Re偶丝873℃时已经可以观察到氧化,W-26%Re的氧化温度可低至681℃;钨铼偶丝氧化层开裂并呈放射状生长,不能形成保护性氧化膜;经防护后的钨铼偶丝断面保持完整,未出现明显氧化膜.     

氢还原重量法测定铼酸铵制备铼粉产品中铼

通过先测定铼粉产品中杂质元素总含量,再用差减法计算铼含量的方法较为繁琐。根据低温氢还原时,除了铼氧化物Re_2O_7、ReO_2,共存金属杂质元素和他们的氧化物均被还原为金属单质而不挥发外,其余非金属元素和他们的氧化物,以及水分、铵盐均会被挥发除去这一基本原理,实验提出了采用低温氢还原样品,以氢还原前后样品质量之比计算铼的含量,最终实现了氢还原重量法测定铼酸铵制备铼粉中铼的方法。确定的实验条件如下:样品量约1.0g;采用分段升温方式进行氢还原,其程序为先室温升温至200℃,恒温30min后升温至400℃,接着恒温30min后升温至600℃,最后再恒温30min;将盛有氢还原后铼粉的石英舟置于干燥器中冷却30min,恒重1次。实验方法适用于铼粉中不挥发杂质元素总质量分数不大于0.010%时铼的测定。将实验方法用于3个铼粉管理样品、4个铼粉实际样品中99.824%~99.995%铼的测定,测定值与参考值基本一致,相对标准偏差(n=9~22)为0.001 2%~0.003 3%,加标回收率99.99%~100.01%。     

Characterization of CeO2-ZrO2 mixed oxides prepared by two different co-precipitation methods

A series of cerium zirconium mixed oxides were prepared by two co-precipitation methods using magnesium hydrogen carbonate(MHC)and mixed ammonia-ammonia hydrogen carbonate(AAHC)as precipitant respectively.The crystal structure,BET surface area and morphology of the produced cerium zirconium mixed oxides were characterized by X-ray diffraction(XRD),Brumauer-Emmett-Teller(BET)and scanning electron microscopy(SEM)techniques.The reduction-oxidation behavior and oxygen storage capacity(OSC)performance were also studied by temperature programmed reduction(TPR)and oxygen pulse chemical adsorption methods.The XRD results demonstrated that the cerium zirconium mixed oxides obtained by both methods possessed structure of cubic solid solution phase.The fresh surface area calcinated at 600℃,aged surface area after 1000℃ and OSC at 500 ℃ of cerium zirconium mixed oxides were determined to be 89.337,34.784 m2/g,and 567 μmol O2/g for MHC method and 122.010,46.307 m2/g,and 665 μmol O2/g for AAHC method,respectively.     

湿法炼锌深度净化硫酸锌电解液中痕量锑的测定

采用孔雀绿分光光度法测定硫酸锌电解液(50～150 g/L)中的锑。在6.5 mol/L的盐酸介质中,用氯化亚锡将锑还原为三价,再用亚硝酸钠氧化为新生态五价,用尿素除去过量的亚硝酸钠,1.55mol/L的盐酸溶液中加入孔雀绿显色,用甲苯萃取有色络合物,于分光光度计波长640nm处测量吸光度。此方法对硫酸锌电解液(50～150 g/L)中0.02mg/L以上的锑进行定量测定时,锑的浓度与吸光度呈良好的线性,相关系数r为0.9994,标准偏差为0.12,相对标准偏差为5.63%,加标回收率为95.00%～105.00%。     

混合碳酸稀土热分解过程的研究

用 DTA热分析技术研究混合碳酸稀土焙烧过程中的脱水过程、分解过程 .用 Freeman-Carroll法、Piloyan法和 Kissinger法对其脱水及热分解的动力学参数进行计算 ,并对计算的结果进行比较和验证 ,得到了混合碳酸稀土脱水过程的反应活化能和反应级数分别为 80 6.9J/mol、0 .78,热分解过程的反应活化能和反应级数分别为 8.52 9k J/mol、 0 .95.用 XRD分析方法研究了不同焙烧温度对焙烧产物的影响 ,论证高温下焙烧可能产生 Ce0 .75Nd0 .2 5O1.875相     

Responses of ramie (Boehmeria nivea L.) to increasing rare earth element (REE) concentrations in a hydroponic system

A number of studies have focused on the effects of rare earth elements (REEs) on crop plants, while little attention has been paid on how tolerant plant species respond to increasing mixed REE concentrations. In this study, ramie (Boehmeria nivea L.) was exposed to a series of REE concentrations prepared with equimolar mixtures of 16 REEs (i.e. 0, 1.6, 8, 16, 80, 160, 400, 800 μmol/L) in order to explore REE accumulation and fractionation characteristics in ramie and the responses of this plant to mixed REEs. Results show that ramie root and shoot biomasses are unaffected under lower REE concentrations (1.6–80 μmol/L), while the growth of ramie and the uptake of nutrients especially Ca and Mn are largely inhibited under higher REE concentrations (160–800 μmol/L). The P and Mo concentrations in the roots increase with the increasing REE concentrations in the solution, suggestive of an involvement of P and Mo in dealing with the high concentrations of REEs in this plant. The preferential uptake of Ce and heavy REEs (HREEs) and the preferential transport of HREEs within the plant lead to a positive Ce anomaly and a HREE enrichment in ramie leaves. Our study suggests that ramie could be a good candidate for the phytoremediation of heavily REE-contaminated soils (e.g., REE mine tailings in southern China). Our results also shed light on points of taking into account phytoremediation management strategies of REE-contaminated soils (e.g., P and Mo fertilization).     

TOA-TBP从铁合金萃钯余液中协同萃取分离铂

以等离子炉富集产出的铂钯铑铁合金溶解造液萃钯后的余液为原料,选择TOA-TBP混合萃取剂萃取分离铂。研究单一TBP、TOA以及混合体系对铂的萃取行为。结果表明,对于贱金属较高的溶液体系,100%TBP对铂的萃取率仅有80.9%,单一TOA在高浓度下铂的萃取率接近100%,但铑的共萃率也随之上升,最高可达到82.86%。而95%TBP-5%TOA的混合体系在0.5 mol/L HCI,相比为1,旋转速度100 r/min条件下,铂的萃取率达到99.9%以上,铑的共萃率仅为0.2%。选择稀盐酸洗涤负载有机相,10 mol/L盐酸反萃,铂的反萃率达到97.2%。TOA-TBP混合体系可以实现铂铑高效分离,且该体系对铂的萃取具有协同效应。     

Impact of Initial pH and Linoleic Acid (C18:2) on Hydrogen Production by a Mesophilic Anaerobic Mixed Culture

Hydrogen production from glucose using a mixed anaerobic culture was assessed under batch conditions by adjusting the initial pH and adding linoleic acid (LA). At an initial pH of 5.0, hydrogen (1.9?mol?H2?mol?1 glucose) was detected after the first glucose injection in the controls (no LA added). At the latter initial pH and in cultures fed 2,000?mg?l?1 LA, the yield reached a maximum of 2.4?mol?H2?mol?1 glucose when glucose was injected again. Hydrogen was detected after the second glucose injection in cultures with the initial pH adjusted to 5.0 and 6.0. In cultures receiving LA and adjusted to pH 7.6, the hydrogen yield reached 1.4?mol?H2?mol?1 glucose when glucose was injected again. Acetate, propionate, and butyrate were detected under all conditions; however, the quantities were variable and dependent on the conditions examined. In comparison to the amount of volatile fatty acids produced, relatively low quantities of alcohols (ethanol, i-propanol, n-butanol, and i-butanol) were detected during the initial lag phase of 96?to?120?h.     

Kinetics of dissolution of sulfur in tetrachloroethylene

The kinetic regularities of the dissolution of sulfur in tetrachloroethylene (TCE), which depend on the temperature, hydrodynamic conditions, and TCE concentration, are presented. Using the rotating disc method, it is revealed that this process occurs in a mixed mode; its diffusion and kinetic components are revealed. The reaction order of the kinetic component of the dissolution rate of sulfur by TCE is 1.5, while the experimental activation energy of the process is 39.2 ± 2.0 kJ/mol. The activation energy of the diffusion component of the convective mass transfer during the dissolution of sulfur in TCE is 28.0 ± 2 kJ/mol.     

Molecular forces between membranes displaying neutral glycosphingolipids: evidence for carbohydrate attraction

The surface force apparatus was used to determine the fundamental forces governing the adhesion between mixed bilayer membranes comprising lactosyl ceramide (LacCer) and di-tridecanoyl-phosphatidyl choline. Forces between membranes were quantified as a function of the glycolipid surface densities, which ranged from 0 to 30 mol %. Control measurements of the forces between pure phosphatidylcholine membranes and mixed bilayers of lactosyl ceramide with phosphocholine showed that the steric thickness of the carbohydrate headgroups increased from 19 to 25 A when the glycolipid density increased from 10 to 20 mol %. The layer compressibility also decreased with increasing carbohydrate coverage, but the corresponding adhesion between lactosyl ceramide-containing membranes increased with increasing amounts of glycosphingolipid in them. The nonspecific van der Waals forces accounted for the attraction measured in the control experiments and that between identical 10 mol % LacCer bilayers. However, the increase in the adhesion with increasing glycolipid density was 2-4 times greater than predicted by Lifschitz theory. Additionally, the forces measured during separation of membranes containing 20 and 30 mol % glycosphingolipid indicated that the headgroups bind and rearrange during bilayer detachment. The interactions between the carbohydrates are weak and apparently dynamic, and they generate an additional density-dependent intermembrane attraction that is on the order of the van der Waals force.     

铝阳极在NaOH-乙醇有机体系中的腐蚀与电化学行为

采用腐蚀失重、塔菲尔曲线、恒电流放电等方法研究了纯铝在4mol/L NaOH-乙醇体系以及添加了酒石酸钾钠体系中的腐蚀与电化学行为。结果表明,4mol/L NaOH+50%乙醇体系能极大地降低析氢含量,缓蚀率可以达到53.09%,添加酒石酸钾钠后析氢腐蚀进一步降低。     

Kinetics of manganous oxide sulfidization in carbonyl sulfide (COS) contaminated atmospheres

To contribute to the mitigation of man-made emission of sulfurous compounds, the susceptibility of manganous oxide for carbonyl sulfide under reducing atmospheres (C-O-S system) has been investigated over the temperature range 700 to 1010 °C (973 to 1283 K). The kinetic investigation employed thermogravimetry and anin situ solid electrolyte oxygen probe to follow the topochemical reaction of spherical MnO pellets under various experimental conditions. The apparent activation energy of sulfidization of manganous oxide, under measured oxygen potentials in the C-O-S system, was determined to be 12.06 (±1.5) kcal/mol (52.33 (±6.28) kJ/mol). Overall sulfidization appeared to proceed by mixed control involving convective mass transfer of COS across the boundary layer and diffusion through the product layer. Formerly with the Department of Theoretical Metallurgy, Royal Institute of Technology, Stockholm