贵金属元素电化学分析研究(Ⅻ)——离子交换富集分离阳极溶出伏安法测定微量铱

单独铱与其它贵金属和贱金属的有效分离方法仍属少见^[1,2],作者^[3]采用15%三烷基氧化膦-苯溶液分离过大量铱,可达理想的效果。     

分离富集技术在形态分析中应用进展

对十年来分离富集技术在形态分析中应用进展进行了评述,引用1991～2001年文献67篇。     

巯基化合物分离富集技术的应用进展

根据负载(或鳌合)巯基的物质不同,分别对巯基棉、巯基葡聚糖凝胶、巯基纸、巯基活性炭和巯基树脂等分离富集剂的制备、应用及机理进行了综述。     

活性炭分离富集技术的应用新进展

对活性炭分离富集技术的应用新进展进行综述。重点评述了活性炭的结构和吸附机理,活性炭对有机物的分离和吸附,活性炭对金属离子的分离和富集,共引用文献３５篇。     

分离富集技术在现代发射光谱分析中的应用与进展

近年来,在运用原子发射光谱法(AES)进行地质、生物、环保、农业和工业等样品的分析时,经常要求测定μg·ml~(-1),ng·ml~(-1)甚至pg·ml~(-1)级的痕量元素,而且分析对象也日益复杂多样,常用的ICP-AES虽然有很高的灵敏度,但要直接测定痕量元素,也是很困难的。因此,必须采用分离富集技术与之相配合。在发射光谱分析中,分离富集技术的采用,可使分析检出限、精密度和准确度获得有效改善,并使方法的应用范围得到扩大。广义地讲,现代发射光谱分析应该是一系列分析操作(包括物理的、化学的处理过程,仪器的和非仪器的分析过程)的总称,远非单纯的仪器测定。     

共沉淀分离富集法的应用与进展

对共沉淀分离富集法的应用与进展进行了综述。近年来,由于其与固体进样分析仪器的结合而得到了迅速发展,从自然水样到高纯和其它特殊材料的分析,从金属元素到非金属乃至有机物的测定,越来越多,越来越好的有机和无机的共沉淀体系正被研究和广泛应用。     

铊的分离富集技术

对近二十年来重金属铊的重要的和最新的分离富集技术作了系统总结和评述，并提出了在不同情况下铊分离富集方法的最优化选择，对其未来发展趋势进行了展望。     

泡沫塑料分离富集技术的应用现状

对１９９２－１９９９年泡沫塑料分离富集技术的应用进行了综述 ;根据泡沫塑料的结构特性,对其负载,吸附和解脱过程的机理进行了探讨。     

表面活性剂体系萃取分离贵金属离子的研究

研究了在TritonX 100 (NH4)2SO4 络合剂体系中,贵金属离子的萃取分离行为。考察了金属络合物的液 液两相间的分配行为及影响络合物萃取行为的各种因素,优化了萃取分离条件。实验结果表明,在pH7.0～7.5的溶液中,络合剂PAR能与Pd(Ⅱ)形成稳定的络合物,可被定量萃取,实现了Pd(Ⅱ)与Pt(Ⅵ)、Ir(Ⅵ)、Mo(Ⅵ)等混合离子间的定量分离。混合离子分离中,Pd(Ⅱ)的回收率为97.5%～100.8%。     

贵金属元素电化学分析研究VI.黄原酸钠纤维素酯富集,分离锇,钌样品中的银及其阳极溶出伏安法测定

Cellulose xanthate cotton was used for enrichment and separation of Ag from bulk Os and Ru from 0.65 mol HNO3/L solution The adsorbed Ag was eluted with 8-10 4M HNO3. Submicrogram quantity of Ag can be enriched and separated from the cotton with a recovery of 98%. Trace Ag was determine on glass carbon electrode by anodic stripping voltammetry in the electrolytic system of 0.1 mol KSCN/L-0.2 mol HNO3/L-2.5 mol CyDTA/L. The linear range between the concentration and the peak current of Ag is 10-11 to 10-7 g/mL. The detection limit reaches 10 parts per trillion for 10 min electrolysis. The relative standard deviation is 4.2% for Os sample with 6 replicate detns. The results agree with those obtained by atomic absorption spectrometry.     

Referee analysis of precious metal sweeps and related materials

Sweeps samples are often complex mixtures containing from trace amounts to 20% of one or more precious metals distributed in matrices consisting of widely varying mixtures of base metals or their oxides. Three collection procedures are described that are suitable for the isolation of precious metals from base substances. One is based on direct fusion of the sample (high-grade sweeps) with sodium peroxide, and the others on collection of the precious metals by fire-assay techniques using either nickel sulphide or silver. The precious metals are then determined either gravimetrically or by atomic-absorption or plasma-emission spectrometry.     

Application of carbon sorbents for the concentration and separation of metal ions.

Solid-phase extraction is an attractive approach in the preparation of many kinds of samples prior to analysis; highly selective sorbents are desirable for this purpose. The objective of this review is to provide updated information about carbon-based sorbents, their interaction modes and potential application for the concentration and separation of metal ions from environmental samples prior to their determination. New selective phases such as fullerenes and carbon nanotubes are described. Selected examples illustrate the potential of these sorbents.     

Proficiency testing on the analytical control of precious metal production

Our experience of executing proficiency testing programs on the analysis of precious metals and precious metal bearing materials is summarized. Six proficiency testing programs of the ”distributed sample testing” type were carried out using samples essentially distinct from each other: (I) certified samples of fine gold and fine silver, and (II) recoverable raw (scrap and catalyst waste) containing precious metals of unknown contents. The test results were assessed using the London Bullion Market Association (LBMA) rules and by Z-criteria using the ISO/IEC Guide 43 scale. Satisfactory results were presented by all participants for the analysis of certified samples of fine gold and fine silver. The results of catalyst waste analysis agreed rather well, whereas the scrap analysis revealed an essential discrepancy in the data for some samples. The reasons for such discrepancies are discussed. Received: 9 June 2000 Accepted: 21 November 2000     

Biosorption of precious metal ions by chicken feather

Chicken feather (C-feather) is an intricate network of stable and water-insoluble protein fibers with high surface area and is an abundant bioresource. C-feather protein was found to accumulate various precious metal ions (gold and platinum metals) selectively from their dilute aqueous solutions in high yield and in short contact time, depending on pH and characteristics of the individual precious metal ions. Under certain condition, the sequestering level of precious ions, Au(III), Pt(II), and Pd(II) approaches about 17, 13, and 7% of dry wt of C-feather, respectively. Gold(III) potassium cyanade was also accumulated up to 5.5% at pH 2.0. The presence of 100-fold (mol) of coexisting cations, such as Na⁺, Fe(III), Cu(II), and Ni(II), did not show a discernible effect on the precious metal uptake rate and capacity of C-feather. Experiment suggested C-feather is promising for use in the removal/recovery of precious metals as well as water pollution control. A qualitative discussion is given about the excellent adsorption behavior of C-feather.

     

Trace elements in precious and common opals using neutron activation analysis

Neutron activation analysis (NAA) was used to determine the concentration of trace elements in 44 precious and 52 common opals sampled from a number of recognised fields within Australia. The purpose of this study was to determine if precious and common opals of the same colour and location have the same or a different trace element profile. Similar numbers of black, white and grey samples were studied in each case. In most cases common opals had a significantly higher concentrationof certain trace elements when compared with precious opals.     

Recent progress in fluorescent and colorimetric chemosensors for detection of precious metal ions (silver, gold and platinum ions)

Due to the wide range of applications and biological significance, the development of optical probes for silver, gold and platinum ions has been an active research area in the past few years. This tutorial review focuses on the recent contributions concerning the fluorescent or colorimetric sensors for these metal ions, and is organized according to their structural classifications (for Ag(+) detection) and unique mechanisms between the sensors and metal ions (for Au(3+) and Pt(2+) detection).     

Colloidal surfactant-free syntheses of precious metal nanoparticles for electrocatalysis

The successful study, understanding, optimization, and ultimately scaling up of electroactive and stable electrodes strongly rely on the careful design and preparation of electrocatalytic materials. In particular, precious metal nanoparticles are key electrocatalysts for a wide range of reactions. Colloidal syntheses offer several advantages to develop precious metal nanoparticles but unfortunately often require capping agents to stabilize the nanoparticles. These ligands or surfactants often block the surface active sites and need to be removed by time and/or energy demanding steps. These extra steps potentially (unnecessarily) complicate studies, might impair reproducibility and limit a direct transfer of fundamental breakthroughs to real-life applications. Fortunately, a range of surfactant-free syntheses have been reported and are well-suited to develop electrocatalysts with improved activity. Surfactant-free syntheses also bear promising features towards high-throughput screening of multi-metallic nanomaterials to explore new concepts in electrode design.     

Paper chromatography in the separation of ions : Separation of precious metals

A study of the separation of the precious metals. Pd⁺², Pt⁺⁴, Ir⁺⁴, Rh⁺³, Ru⁺³, Os⁺⁴ and Au⁺³, by ascending paper chromatography, using different solvents and a number of complexing agents, clearly shows that microgram amounts of the elements, when present in a mixture of five, are best separated from each other in the presence of thiourea. The Rl, Rrt values and the sequences of separation are recorded in tables to show whether a good separation of a particular mixture of ions is possible.