Adsorption behaviour of a number of metals on weakly basic ion-exchangers in methanol-hydrochloric acid mixtures

Many metals are not strongly adsorbed on DEAE-cellulose from aqueous hydrochloric acid media. However, some metals can be adsorbed on DEAE-cellulose from methanol-hydrochloric acid media. Distribution coefficients of Zn, Cd, Hg(II) and Bi(III), which show pronounced adsorption, are presented as functions of the methanol and the acid concentrations. Differences in the distribution coefficient between the four metals and a considerable number of other metals are large enough to permit good separations on columns. Among the platinum group metals, Pd(II), Ir(IV) and Pt(IV) are adsorbed from the mixed solvents and may be separated from large quantities of base metals such as Fe(III), Co(II), Ni and Cu(II).     

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.     

Spectrophotometric determination of traces of several metals in ferrous and nonferrous metals and alloys after isolation by iodide extraction

Methods are presented for the determination of traces of lead, cadmium, indium, bismuth, copper, and antimony in most of the important metals and alloys used in industry. The trace metals are isolated by hexone extraction of their iodides from 5% hydrochloric acid solution and then determined spectrophotometrically. The attractive feature of the proposed procedures is that the method used for each of the trace metals is applicable to all of the matrix metals and alloys being considered.     

New trends in sustainable nanocatalysis: Emerging use of earth abundant metals

Noble metals are well-known to afford highly active, selective and durable catalysts, and have thus been at the core of the development of greener processes. In recent years, however, growing concerns about their scarcity, cost and toxicity has triggered research efforts towards the development of earth-abundant catalysts. In this Current Opinion, recent examples of the use in catalysis of pure earth-abundant metals, earth-abundant metals with minute quantities of noble metals, or earth-abundant metals activated by light are presented. This highlight article showcases the current trends in sustainable organic transformations, catalyzed by nanomaterials.     

Occurrence of Selected Metals in Wastewater Effluent and Surface Water in Ireland

Metals occur naturally in the environment and as constituents of the Earth’s crust. They have many uses, and metals such as iron, copper, and zinc are widely used in industries. Elevated levels of metals in the environment also occur as a result of human activities (municipal, residential, and traffic–related activities). A list of 15 metals chosen for this study included priority substances and those listed in the European Union Water Framework Directive 2000/60/EC. The concentrations of heavy metals in the environment are affected by several factors that must be taken into account when monitoring heavy metals released into the environment through wastewater treatment plants (WWPTs). This work examines the concentrations of metals found in WWPTs and the effects of treatment type on dissolved metal concentrations. Effluent samples were collected from the outflow of nine WWPTs in Dublin and Cork, Ireland from July 2009 to June 2011. All samples were found to contain priority metals that exceeded environmental quality standards in several cases. We present the frequency of occurrence and concentrations of metals in effluents of studied WWPTs and discuss relationships between the occurrence of heavy metals, the influence of factors such as industrial inputs, levels of treatment at WWPTs, and percentage urban area in an agglomeration. The results of this study are an indication that WWPTs may be contributing to the high levels of heavy metals found at discharge points back into river systems.     

金属的生物甲基化作用和环境输送

讨论了生命体与重金属间的相互关系、重金属生物甲基化作用的环境输送及生物富集，评述了重金属的生态危害么及微生物在其环境输送过程中所起的作用。     

Low-temperature synthesis of phthalocyanine and its metal complexes

Conditions for synthesizing unsubstituted phthalocyanine and its metal complexes from phthalonitrile at low temperatures (0–50°C) are optimized. Phthalocyanine and phthalocyaninates are produced under these conditions using activated Rieke metals, metals on inert substrate, sources of “soluble” metals in the form of unstable metal complexes, zeolites, solid-phase electrosynthesis of phthalonitrile, and UV irradiation. The use of pyrophoric metals is found to be the most efficient due to a large number of defects in their structure favoring the initial stage of phthalonitrile cyclization on a metal matrix. The suggested mechanism of formation of phthalocyanine macrocycle assumes participation of metal agglomerates occurring in activated metals.     

Kinetics of loss of platinum group metals in catalytic oxidation of ammonia

Basic characteristics of ammonia oxidation catalysts based on platinum metals, their composition, wire diameter, and specific mass are presented. An irrecoverable loss of the catalyst in manufacture of regular nitric acid is demonstrated. The loss of catalysts based on platinum-group metals and the effect of various factors on this loss are considered. The effect of various parameters on the ammonia oxidation process is analyzed and an equation describing the process in which platinum-group metals are lost is derived.     

Determination of noble metals by neutron-activation analysis

The scope and limitations of neutron-activation analysis in the field of the platinum metals are discussed. Special attention is given to interferences that occur in determination of noble metals in platinum metals and in natural samples. The problem of standards, carriers and chemical yield determination is emphasised. A recommendation is given of modern techniques for counting radionuclides formed by neutron activation of the platinum metals.     

Effect of metals on melt oxidation of polyethylene

Oxidation of polyethylene (PE) melts in contact with metals (Cu, Pb, Au, Al, Zn, Ag) has been studied by infrared spectroscopy and differential thermal analysis (DTA). These metals may be divided into two groups, depending on their activity for oxidizing PE: namely, high-activity metals (Cu, Pb, Ag, Zn) and low-activity metals (Al, Au). During the oxidation of PE in contact with high-activity metals dissolution of the surface layer of metal is observed with accumulation of metal-containing compounds (salts of carboxylic acids) in the bulk of the polymer. With low-activity metals these phenomena are not observed. The rate of oxidation of PE on low-activity metals approaches the oxidation rate of nonmetals (polytetrafluoroethylene and inorganic glass). With certain high-activity metals (Cu, Pb) the process of oxidation is accelerated only in the early stage of oxidation; then the oxidation rate slows down and the oxidation process ceases. PE films separated from metal after being oxidized on it possess chemical memory, i.e., their oxidation rate depends on the nature of the metal with which they had been in contact, and on the duration of the contact oxidation. The effect of salts of carboxylic acids (metal stearates) on the oxidation of PE melts was also studied. Based on the data obtained, it is concluded that the rate of oxidation of PE melts on high-activity metals is controlled by metal-containing compounds which are the products of contact reactions.     

西南山地煤矿区耕地土壤-农作物重金属富集及健康风险评价

为了解西南某典型山地煤矿区周边农田土壤、农作物重金属的富集情况及对当地人群健康的影响程度,采集矿区周边农田土壤样品和对应的农作物样品,测定重金属Cr、Mn、Zn、As、Pb的含量。运用Nemero指数法、潜在风险指数法对土壤重金属的污染程度进行评价;采用靶标危害系数法(THQ)评价农作物重金属对人体的健康风险。结果显示,Cr、Mn、Zn、As、Pb分别是背景值的1.81、1.90、2.89、1.30、0.86倍,处于轻度污染级别,轻微危害程度。农作物重金属Cr、Pb和As含量的超标情况较严重,Zn的含量超标相对较小。各农作物富集的重金属对人体的健康风险大小为：高粱>玉米>白菜>葱>辣椒。农作物重金属对儿童健康的危害均达到了慢性中毒;对成人健康的影响,高粱处于慢性中毒,其它农作物重金属处于产生较大影响的危害程度。农作物重金属与土壤重金属的相关性分析表明,农作物重金属的含量与土壤重金属全量并无线性关系;各重金属在农作物中的转移能力不同;Pb,As在农作物中的转移能力较大,而Cr相对较小。鉴于矿区重金属的富集情况,应尽快采取修复治理措施,为保证当地人群健康,建议当地居民不再食用和种植富集重金属严重的高粱、玉米农作物。     

Thin-layer chromatographic behavior of a number of metals on carboxymethyl-cellulose in sulfuric acid and ammonium sulfate media

Summary The thin-layer chromatographic behavior of 57 metals on a weakly acidic cation exchanger, carboxymethyl (CM) cellulose, has investigated systematically in sulfuric acid (0.01–1.0 M) and the acidic ammonium sulfate media. Thin-layer plates of a microcrystalline cellulose, Avicel SF, were also used to compare with the chromatographic behavior of the metals in the acidic sulfate system. The Rf values obtained for many metals tested on CM-cellulose plates increase with increasing concentration of sulfuric acid. Most of metals tested are distributed chromatographically on the CM-cellulose in the low acid concentration. The characteristic retention of many metals, including sulfato-complexes forming metals, on the CM-cellulose can be observed in ammonium sulfate solutions of a low concentration of the acid. Useful multicomponent separations of analytical interest on CM-cellulose layers are presented to demonstrate the use of Rf measurements for predicting separations in the acid and the acidic ammonium sulfate systems.     

Sorption preconcentration in combined methods for the determination of noble metals

Combined methods for the determination of noble metals with the use of sorption preconcentration with complexing, anion-exchange, and other sorbents are reviewed. Characteristics of sorbents, techniques of sorption preconcentration, and techniques for the preparation of a concentrate for determination are considered. Features of instrumental methods for the determination of noble metals in the analysis of different materials are discussed. Examples of the use of sorption preconcentration in combined methods for the determination of noble metals are given from publications between 1996–2005.     

Application of new types of fibrous sorbents for sampling of dissolved species of heavy metals in natural waters

The article discusses the importance and specific features of the preparatory stages in ecoanalytical monitoring of natural water, aimed to determine the content of heavy metals. A procedure was developed for sampling of dissolved species of heavy metals with sorbents. The influence of humic substances on the sorption of heavy metals was elucidated. The results obtained with the technique suggested are reported.     

Proteomics of metal transport and metal-associated diseases

Proteomics technology has the potential to identify groups of proteins that have similar biological function. However, few attempts have been made to identify and characterize metal-binding proteins by using proteomics strategies. Many transition metals are essential to sustain life. Copper, iron, and zinc are the most abundant transition metals relevant to biological systems. In addition to their important biological functions, metals can also catalyze the formation of damaging free radical species. Hence, their intracellular transport is tightly regulated. Despite recent insights into the intracellular transport of copper and other metals, our overall understanding of intracellular metal metabolism remains incomplete and it is likely that many metal-binding proteins remain undiscovered. Furthermore, the protein targets for metals during metal-associated disease states or during exposure to toxic levels of environmental metals are yet to be unravelled. A proteomics strategy for the analysis of metal-transporting or metal-binding proteins has the potential to uncover how a large number of proteins function in normal or metal-associated diseased states. Here we discuss the principal aspects of metal metabolism, and the recent developments in the area of the proteomics of metal transport.     

Surface Atomic Regulation of Core–Shell Noble Metal Catalysts

Core–shell noble metal catalysts have gained significant attention in the past few decades, as they not only reduce the use of noble metals effectively but also exhibit unique properties derived from the synergistic effect between core and shell metals. In particular, regulating the surface structure of shells to maximize the atomic utilization efficiency of noble metals is critically important. Controlling the shell thickness of noble metal catalysts at the atomic level as an efficient approach to realize this goal has been attracting growing attention; this approach involves the formation of ultrathin shells (typically 2–6 atomic layers), monolayers, or even atomically dispersed noble metals embedded in the host metal. These strategies drive the core/support metals to improve the number of active sites and the intrinsic activity of the deposited noble metals remarkably, meanwhile minimizing the usage of noble metals. Herein, recent advances regarding atomic control of the core–shell noble metal catalysts is reviewed, with focus on the surface regulation. First, synthesis methods and surface structures are summarized, and then catalytic applications of these architectures are highlighted.     

Effect of external pressure on the Kβ/Kα X-ray intensity ratios of 3d metals

The occupation numbers of the 3d transition metals are calculated as a function of pressure by means of the linear muffin-tin-orbital method. This data is used with the multiconfiguration Dirac-Fock (MCDF) X-ray intensity ratios (R) to estimate the variation of the intensity ratios of 3d metals with pressure. It is found that R decreases with pressure for the early 3d metals whereas it increases for the heavier 3d transition metals.     

Flotation of traces of heavy metals coprecipitated with aluminum hydroxide from water and sea water

Microgram quantities of heavy metals in 1-l samples of water and sea water are quantitatively coprecipitated with aluminum hydroxide at pH 9.5. The precipitate is floated with the aid of sodium oleate and small nitrogen bubbles, separated and dissolved in 2 M nitric acid, and the heavy metals are determined by atomic-absorption spectrometry. The method is rapid and applicable to 9 heavy metals at the low p.p.b. level.     

燃烧过程中碱/碱土金属对重金属迁移转化影响的研究进展

碱/碱土金属广泛存在于各种固体燃料中，在燃烧过程中碱/碱土金属与燃料中重金属及其他矿物发生复杂的物理化学反应，从而影响重金属的迁移和转化。本研究主要介绍了碱/碱土金属对As、Se、Pb和Cr四种重金属迁移转化的影响规律，包括碱金属和碱土金属对重金属迁移转化的影响，颗粒物团聚与黏结对重金属排放的影响三个方面。碱/碱土金属能够抑制重金属的挥发：碱金属与Cl元素的结合，降低了PbCl₂的生成；碱金属的存在有利于提升高岭土对Pb的吸附效率；碱/碱土金属可以与As和Se形成稳定的化合物。但同时需要注意碱/碱土金属与Cr的部分结合产物中，Cr以六价态存在，具有较高的毒性。碱/碱土金属对于团聚现象发生，分别起到了促进和抑制作用，适当含量的碱金属有利于减少重金属的释放。通过总结碱/碱土金属对重金属迁移转化的影响规律，以期为降低重金属的危害提供思路。     

准东煤中碱金属的赋存形式及其在燃烧过程中的迁移规律实验研究

对新疆煤采用三步化学提取实验(蒸馏水洗、醋酸铵洗、稀盐酸洗)以分析其碱金属赋存特性,对水溶的阴离子进行了离子色谱分析。分别检测了在不同温度、不同停留时间下准东煤灰的碱金属量,并用Factsage软件模拟该煤灰中碱金属的析出形式。结果表明,煤中的钠主要是水溶钠,钾主要以不可溶钾存在,水溶碱金属主要以水合离子形式的氯化物存在。准东煤中碱金属在400~600℃析出最快,主要是水溶态碱金属的释放,碱金属的释放主要发生在燃烧后期。灰中碱金属在高温下会与烟气中的成分发生反应,主要产物是氯化物以及氢氧化物。在700℃钠对准东煤中低温共融物的形成有很大贡献。