分光光度法测定铼回收溶液中的铼含量

提出了铼回收、提取过程中产生的各种含铼溶液中铼的丁二酮肟分光光度法.考察了吸收波长,显色酸度,共存离子干扰等条件对测定结果的影响.试液不需分离,经分取后可直接进行铼量的测定,测定范围0.005-20g/L.方法已应用于钼冶炼喷淋液、离子交换解析液及其浓缩液中铼量的测定,结果与ICP-AES测定结果相一致,方法的RSD(n=7)均小于3％,加标回收率在98％-105％之间.方法简便、快速,能够满足铼回收、提纯生产需要.     

ICP-AES法测定DD2单晶合金中的铼和铪

本文采用ICP－AES法对DD2单晶合金中铼、铪的测定进行了研究，着重考察了DD2合金中基体及共存元素对铼，铪测定的影响，采用基体匹配法消除基体干扰，测定了DD2合金中的铼，铪含量，得到了较好的精密度和准确度。方法简便快速，可获得满意的分析结果。     

超声波辅助溶剂萃取-电感耦合等离子体质谱法测定生物样品中的总汞和甲基汞

建立了超声波辅助溶剂萃取联用电感耦合等离子体质谱法(ICP-MS)测定生物样品中总汞(T-Hg)和甲基汞(MeHg)的分析方法。实验优化了萃取溶剂种类,溶剂浓度,各种辅助方法和超声波振荡时间等各种萃取条件。选择6 mol·L-1 HCl作为溶剂,超声2 h, 以有机溶剂萃取,再以水反萃,稀释后直接进行测量MeHg的含量。此方法可用于同时测定T-Hg和MeHg, 检出限为0.01 ng·mL-1,相对标准偏差为3.44％,线性范围为1～50 ng·mL-1,加标回收率为80%～97%。在此条件下测定了5种不同类型生物标准参考物质的T-Hg和MeHg,测定值与标准值吻合。该法综合了超声波辅助萃取和溶剂微萃取以及ICP-MS的优点,操作简便快速,灵敏度高,适合于各种生物样品中痕量MeHg快速萃取分离和分析。     

FAAS法测定千年不烂心中硒的含量

探讨了湖北恩施产千年不烂心中硒含量的测定方法,采用APDC-MIBK体系络合萃取,分离富集后,以火焰原子吸收光度法进行测定。本法克服了硒原子化效率低以及稳定剂铜对测定的干扰。方法的相对标准偏差为4.90%,回收率为96.0%—98.5%。     

电感耦合等离子体原子发射光谱法测定高纯铼酸铵中Ca、Cd、Mn、Fe、Mg、Al、Cu、Co、Mo、Pb、Sn和Ni

本文介绍了电感耦合等离子体发射光谱法（ICP－AES）测定高纯铼酸铵中12个杂质元素的方法。采用挥发健康基体，探讨了高铼酸铵基体的干扰及其消除办法。ICP－AES测定结果的准确度和精密度均能满足分析要求。     

ELTA萃取分离氨水反萃取原子吸收光谱法测定铸铁中的钼

本文介绍了利用ELTA为萃取剂,萃取分离铸铁中微量钼的条件以及采用1%(V/V)氨水进行反萃取后应用AAS测定水相中钼的分析方法。试验表明:钼在0～100μg/g浓度范围内呈良好线性关系,相关系数为0.9992。方法的相对误差为-3.31～-7.80%,相对标准偏差为3.39%～3.90%。     

八氧化三铀中锆的测定

采用萃取色层分离电感耦合等离子体-原子发射光谱法(ICP-AES)测定八氧化三铀中Zr,试样中铀用HCl转化为氯化铀酰后,经CL-TBP萃淋树脂分离,一次性使基体铀与Zr元素分离,测定铀化合物中Zr的质量分数。并对影响测定的各种因素进行了较详细的试验研究,确定了测定的最佳条件。方法平均回收率在96.8%—99.4%之间,相对标准偏差(RSD,n=6)优于5.3%。     

盐湖卤水中微量钒的浓度测定

为了测定盐湖卤水中微量钒的浓度,开发了一个钒的分离纯化流程来降低大量的共存离子的基质效应。该分离纯化流程包括萃取和反萃两个步骤。详细地研究了影响钒纯化效率的各种因素,得到钒的最佳分离纯化条件为:以正己烷为稀释剂,有机相中D2EHPA和TBP的体积百分比分别为30%及20%,在pH为3.0时萃取30 min;然后用3 mol/L H₂SO₄反萃 10 min。基于此分离纯化流程,将两个实际盐湖卤水样品中的微量钒纯化后,再用电感耦合等离子体质谱仪(ICP-MS)测定其浓度,该ICP-MS对51V 的检测灵敏度和检测限别为53 171 cps/(μg/L) 和1.88 ng/L。所得实际盐湖卤水钒测定结果的加标回收率接近100%而相对标准偏差低于0.6%,表明该方法可用于实际复杂体系中微量钒的浓度测定,例如海水和盐湖卤水。     

7402季胺萃取色层分离-ICP-AES法测定八氧化三铀中痕量铌、钽、锆、钛

本文选用我所合成的萃取剂7402季胺,选择性好;利用7402季胺-kel-F粉萃取色层分离技术,使铀与待测杂质元素得到定量分离。用750ICP光量计同时测定U_3O_8中Nb、Ta、Zr、Ti。取样0.5克时,测定下限Zr、Ti为0.2ppm;Nb、Ta为0.8ppm。对U_3O_8样品作了加量回收,回收率为98—102%,相对标准偏差优于±6%。     

基于原子光谱法的元素形态分析技术进展

元素的形态分析在环境和生物分析中极其重要,因为元素在生物体内的作用及其代谢过程在很大程度上取决于元素存在的化学形态,而不仅仅是元素的总量。形态分析是指测定样品中构成元素总量的单独物理化学形式的浓度。最先进的形态分析方法是色谱分离和光谱检测的联用技术,特别是色谱和电感耦合等离子-质谱(ICP-MS)的联用。但是,联用技术的设备投入大、运行成本高,难以在常规实验室中的推广应用。在许多情况下,采用非色谱分离方法对样品进行处理,也可以得到足够的元素形态信息。基于非色谱分离、原子光谱测定的元素形态分析方法的费用低、操作简单、易于推广应用。本文总结了元素形态分析的样品前处理方法,综述了基于原子光谱法的元素形态分析中比较常用的非色谱分离技术,对溶剂萃取、浊点萃取、单滴微萃取、分散液液萃取等分离技术的原理、应用和优缺点进行了评述,介绍了固相萃取中常用的吸附剂及其在元素形态分离中的应用,以及氢化物发生、共沉淀等分离方法。相比于色谱分离方法,非色谱方法是快速、灵敏、廉价的分离技术。     

Nipponium as a new element (Z=75) separated by the Japanese chemist, Masataka Ogawa: a scientific and science historical re-evaluation

This review article deals with a new element 'nipponium' reported by Masataka Ogawa in 1908, and with its scientific and science historical background. Ogawa positioned nipponium between molybdenum and ruthenium in the periodic table. From a modern chemical viewpoint, however, nipponium is ascribable to the element with Z=75, namely rhenium, which was unknown in 1908. The reasons for this corrected assignment of nipponium are (1) its optical spectra, (2) its atomic weight when corrected, (3) its relative abundance in molybdenite, the same being true with rhenium. Recently some important evidence was found among the Ogawa's personal collection preserved by his family. Deciphering the X-ray spectra revealed that the measured spectra of the nipponium sample that Ogawa brought from University College, London clearly showed the presence of the element 75 (rhenium). Thus was resolved the mysterious story of nipponium, which had continued for almost a century. It is concluded that nipponium was identical to rhenium.     

The study of structure and work function of barium oxide films and the BaO double system on the (0001) face of rhenium: I. Barium oxide on rhenium (0001) face

The structure of barium oxide films on the (0001) face of rhenium has been investigated by the techniques of low energy electron diffraction (LEED) and contact potential difference method in a wide range of coverages. The changes in surface structure of the BaO films have been observed after annealing at various temperatures. It was shown that the structure and orientation of the films depended essentially on the interaction of barium oxide with the substrate. The result of this interaction was equivalent to the oxidation of the (0001) face of rhenium. This fact was confirmed by experiments with the adsorption of BaO films on an oxidized substrate. The structures observed after heating to high temperatures (900°–1000°C) seem to be formed by the products of chemical interaction of barium oxide with rhenium (rhenates).     

Inhibition of catalytic activity of rhenium

The activity of rhenium as a hydrogen isotope equilibrium catalyst is inhibited by preadsorbed oxygen. The nearly linear decline in efficiency at 380 K and 980 K with increased oxygen coverage is matched by a similar decrease in the room temperature saturation uptake and initial sticking probability of hydrogen. In this rhenium closely resembles tungsten, and the conclusion is drawn that as far as hydrogen is concerned “patches” of high catalytic activity are not important. However, and unlike tungsten, the oxygen-saturated rhenium filament retained some catalytic and adsorptive capacity.     

Anderson-grüneisen parameter δ, bulk modulus and the compression curves of rhenium

The third-order elastic (TOE) constants of rhenium obtained from a model based on Keating's approach have been used to calculate the Anderson-Grüneisen (AG) parameter δ for this metal following the procedure suggested by Ramji Rao. The temperature dependence of the bulk modulus of rhenium has been calculated using Anderson's theory. The agreement with the experimental results of Fisher and Dever is good. The AG parameter has also been used to calculate the second Grüneisen constant q for rhenium. The variation of the lattice parameters of rhenium with hydrostatic pressure upto 500 kbars has been calculated using the theoretical TOE constants and Thurston's extrapolation formula. There is very good agreement with the experimental results of Liu et al.     

Scanning tunneling microscopy with atomic resolution on ReS2 single crystals grown by vapor phase transport

Atomic resolution images of layered transition metal-dichalcogenide ReS₂ single-crystals (n-type semiconductor) were obtained using a scanning tunneling microscope with a positive tip. In most cases only unresolved clusters of four rhenium atoms could be seen. Occasional images with higher resolution showed that these bright structures consist of four separated atoms. The symmetry of the imaged atoms is identical to that of the rhenium sublattice but not to that of the sulfur atoms. We conclude therefore that the main contribution to the tunneling current is due to the rhenium atoms, although the sulfur atoms are placed by about 0.15 nm closer to the tip. Thus for our positive bias of the tip the tunneling electrons originate from occupied rhenium states in the valence band of the semiconductor.     

High pressure generation using double-stage diamond anvil technique: problems and equations of state of rhenium

We have developed a double stage diamond anvil cell (ds-DAC) technique for reproducible pressure by precisely fabricating 2nd stage anvils using a focused ion beam system. We used 2nd stage micro-anvils made of ultra-fine (V/V₀?=?0.633 for the smallest d-spacing. The calculated pressure for this minimum volume varies from 430 to 630?GPa, depending on the choice of the equation of state of rhenium. We conclude that the most likely pressure achieved for the minimum volume of rhenium is in a range of 430–460?GPa based on a calibration using the platinum pressure scale to 280?GPa and the latter value of 630?GPa is unreasonably high, suggesting that the pressures in an earlier study for the equation of state of rhenium would have been significantly overestimated.     

Chemical shifts of the LIII absorption discontinuity of rhenium

Chemical shifts of the X-ray L_III absorption discontinuities of rhenium in some of its binary and ternary compounds have been studied using a bent crystal X-ray spectrograph. The chemical shifts (ΔE) are found to be governed by the effective charges (q) on the absorbing ions, which have been calculated using Suchet's theory. For the compound ReCl₅, however, the effective ionic charge cannot be calculated since the pentavalent radius of rhenium is not known. The ΔE, q plot has been used to determine the charges on the rhenium ions in ReCl₅ as well as in two ternary compounds KReO₄ and NaReO₄. Our work has enabled us to determine the ionic radius of pentavalent rhenium.     

Interactions du rhénium à haute température avec N2O sous basse pression

Starting at room temperature, N20 adsorption on rhenium proceeds dissociatively. Oxygen atoms remain on the surface while nitrogen molecules are desorbed. The overall process is characterized by an initial sticking coefficient value equal to 0.3 at 298 °K. In stationary conditions, and in a higher temperature range (> 1200°K) rhenium trioxide and oxygen atoms are the reaction products, depending on oxygen coverage on the surface. When the oxygen coverage is low, atomization, characterized by a reactive sticking probability of 0.2 is the only observable process. All the results are consistent with a model, previously proposed for the system oxygen-rhenium and oxygen-transition metals. The main differences in reaction rates between rhenium and oxygen or N₂O are interpreted in terms of saturation coverages.     

Lattice dynamics,third order elastic constants and thermal expansion of rhenium

A systematic investigation of the lattice dynamics, second and third order elastic constants and thermal expansion has been carried out in rhenium using Keating's approach. The ten third-order elastic constants of rhenium are calculated using four anharmonic parameters. The present model reproduces the measured pressure derivatives of the second order elastic constants well. The low and high temperature limits γ̄L and γ̄H of the lattice thermal expansion are calculated. The agreement between the calculated γ̄H and that obtained by Gschneidner from the thermal expansion and specific heat data of rhenium is satisfactory.     

Effects of the structural state of a W — Re solid solution on the Fe-57 Mössbauer spectrum

Mössbauer spectra for iron-57 are reported for alloys containing up to 27 at.% rhenium. The cobalt-57 was introduced by diffusion annealing as the parent isotope for the iron-57. Diffusion annealing at 1080°C for 16 hr causes the cobalt to diffuse mainly along lattice defects (dislocations and grain boundaries). These defects give rise to regions whose electronic structure differs from that of the matrix. The precise type of structure and the number of such regions are complex functions of the alloy composition and structural state. Results are given on the iron-57 spectra for tungsten, rhenium, the σ phase, and an alloy in the two-phase region.