Concentration of precious metals during their recovery from electronic waste.

PubMed

Cayumil, R; Khanna, R; Rajarao, R; Mukherjee, P S; Sahajwalla, V

2016-11-01

The rapid growth of electronic devices, their subsequent obsolescence and disposal has resulted in electronic waste (e-waste) being one of the fastest increasing waste streams worldwide. The main component of e-waste is printed circuit boards (PCBs), which contain substantial quantities of precious metals in concentrations significantly higher than those typically found in corresponding ores. The high value and limited reserves of minerals containing these metals makes urban mining of precious metals very attractive. This article is focused on the concentration and recovery of precious metals during pyro-metallurgical recycling of waste PCBs. High temperature pyrolysis was carried out for ten minutes in a horizontal tube furnace in the temperature range 800-1350°C under Argon gas flowing at 1L/min. These temperatures were chosen to lie below and above the melting point (1084.87°C) of copper, the main metal in PCBs, to study the influence of its physical state on the recovery of precious metals. The heat treatment of waste PCBs resulted in two different types of solid products, namely a carbonaceous non-metallic fraction (NMFs) and metallic products, composed of copper rich foils and/or droplets and tin-lead rich droplets and some wires. Significant proportions of Ag, Au, Pd and Pt were found concentrated within two types of metallic phases, with very limited quantities retained by the NMFs. This process was successful in concentrating several precious metals such as Ag, Au, Pd and Pt in a small volume fraction, and reduced volumes for further processing/refinement by up to 75%. The amounts of secondary wastes produced were also minimised to a great extent. The generation of precious metals rich metallic phases demonstrates high temperature pyrolysis as a viable approach towards the recovery of precious metals from e-waste. Copyright © 2015 Elsevier Ltd. All rights reserved.

41 CFR 109-45.1002-3 - Precious metals recovery program monitor.

Code of Federal Regulations, 2010 CFR

2010-07-01

... program monitor. 109-45.1002-3 Section 109-45.1002-3 Public Contracts and Property Management Federal... UTILIZATION AND DISPOSAL 45-SALE, ABANDONMENT, OR DESTRUCTION OF PERSONAL PROPERTY 45.10-Recovery of Precious Metals § 109-45.1002-3 Precious metals recovery program monitor. The DPMO shall be the precious metals...

Precious Metals Recovery from Electroplating Wastewater: A Review

NASA Astrophysics Data System (ADS)

Azmi, A. A.; Jai, J.; Zamanhuri, N. A.; Yahya, A.

2018-05-01

Metal bearing electroplating wastewater posts great health and environmental concerns, but could also provide opportunities for precious and valuable metal recovery, which can make the treatment process more cost-effective and sustainable. Current conventional electroplating wastewater treatment and metal recovery methods include chemical precipitation, coagulation and flocculation, ion exchange, membrane filtration, adsorption, electrochemical treatment and photocatalysis. However, these physico-chemical methods have several disadvantages such as high initial capital cost, high operational cost due to expensive chemical reagents and electricity supply, generation of metal complexes sludge which requires further treatment, ineffective in diluted and/or concentrated wastewater, low precious metal selectivity, and slow recovery process. On the other hand, metal bio-reduction assisted by bioactive phytochemical compounds extracted from plants and plant parts is a new found technology explored by several researchers in recent years aiming to recover precious and valuable metals from secondary sources mainly industrial wastewater by utilizing low-cost and eco-friendly biomaterials as reagents. Extract of plants contains polyphenolic compounds which have great antioxidant properties and reducing capacities, able to reduce metal ions into zerovalent metal atoms and stabilize the metal particles formed. This green bio-recovery method has a value added in their end products since the metals are recovered in nano-sized particles which are more valuable and have high commercial demand in other fields ranging from electrochemistry to medicine.

Current advances in precious metal core-shell catalyst design.

PubMed

Wang, Xiaohong; He, Beibei; Hu, Zhiyu; Zeng, Zhigang; Han, Sheng

2014-08-01

Precious metal nanoparticles are commonly used as the main active components of various catalysts. Given their high cost, limited quantity, and easy loss of catalytic activity under severe conditions, precious metals should be used in catalysts at low volumes and be protected from damaging environments. Accordingly, reducing the amount of precious metals without compromising their catalytic performance is difficult, particularly under challenging conditions. As multifunctional materials, core-shell nanoparticles are highly important owing to their wide range of applications in chemistry, physics, biology, and environmental areas. Compared with their single-component counterparts and other composites, core-shell nanoparticles offer a new active interface and a potential synergistic effect between the core and shell, making these materials highly attractive in catalytic application. On one hand, when a precious metal is used as the shell material, the catalytic activity can be greatly improved because of the increased surface area and the closed interfacial interaction between the core and the shell. On the other hand, when a precious metal is applied as the core material, the catalytic stability can be remarkably improved because of the protection conferred by the shell material. Therefore, a reasonable design of the core-shell catalyst for target applications must be developed. We summarize the latest advances in the fabrications, properties, and applications of core-shell nanoparticles in this paper. The current research trends of these core-shell catalysts are also highlighted.

40 CFR 471.40 - Applicability; description of the precious metals forming subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... precious metals forming subcategory. 471.40 Section 471.40 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS FORMING AND METAL POWDERS POINT SOURCE CATEGORY Precious Metals Forming Subcategory § 471.40 Applicability; description of the...

40 CFR 421.260 - Applicability: Description of the secondary precious metals subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... secondary precious metals subcategory. 421.260 Section 421.260 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Secondary Precious Metals Subcategory § 421.260 Applicability: Description of the secondary...

40 CFR 421.250 - Applicability: Description of the primary precious metals and mercury subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... primary precious metals and mercury subcategory. 421.250 Section 421.250 Protection of Environment... POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421.250 Applicability: Description of the primary precious metals and mercury subcategory. The provisions of this subpart are...

40 CFR 421.250 - Applicability: Description of the primary precious metals and mercury subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... primary precious metals and mercury subcategory. 421.250 Section 421.250 Protection of Environment... POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421.250 Applicability: Description of the primary precious metals and mercury subcategory. The provisions of this subpart are...

40 CFR 421.250 - Applicability: Description of the primary precious metals and mercury subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... primary precious metals and mercury subcategory. 421.250 Section 421.250 Protection of Environment... POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421.250 Applicability: Description of the primary precious metals and mercury subcategory. The provisions of this subpart are...

40 CFR 421.250 - Applicability: Description of the primary precious metals and mercury subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... primary precious metals and mercury subcategory. 421.250 Section 421.250 Protection of Environment... POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421.250 Applicability: Description of the primary precious metals and mercury subcategory. The provisions of this subpart are...

Recovery of high purity precious metals from printed circuit boards.

PubMed

Park, Young Jun; Fray, Derek J

2009-05-30

Waste printed circuit boards (WPCB) have an inherent value because of the precious metal content. For an effective recycling of WPCB, it is essential to recover the precious metals. This paper reports a promising method to recover the precious metals. Aqua regia was used as a leachant and the ratio between metals and leachant was fixed at 1/20 (g/ml). Silver is relatively stable so the amount of about 98 wt.% of the input was recovered without an additional treatment. Palladium formed a red precipitate during dissolution, which were consisted of Pd(NH(4))(2)Cl(6). The amount precipitated was 93 wt.% of the input palladium. A liquid-liquid extraction with toluene was used to extract gold selectively. Also, dodecanethiol and sodium borohydride solution were added to make gold nanoparticles. Gold of about 97 wt.% of the input was recovered as nanoparticles which was identified with a high-resolution transmission electron microscopy through selected area electron diffraction and nearest-neighbor lattice spacing.

48 CFR 1845.607-2 - Recovering precious metals. (NASA supplements paragraph (b)).

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Recovering precious metals. (NASA supplements paragraph (b)). 1845.607-2 Section 1845.607-2 Federal Acquisition Regulations System..., Redistribution, and Disposal of Contractor Inventory 1845.607-2 Recovering precious metals. (NASA supplements...

48 CFR 1845.607-2 - Recovering precious metals. (NASA supplements paragraph (b)).

Code of Federal Regulations, 2014 CFR

2014-10-01

... 48 Federal Acquisition Regulations System 6 2014-10-01 2014-10-01 false Recovering precious metals. (NASA supplements paragraph (b)). 1845.607-2 Section 1845.607-2 Federal Acquisition Regulations System..., Redistribution, and Disposal of Contractor Inventory 1845.607-2 Recovering precious metals. (NASA supplements...

48 CFR 1845.607-2 - Recovering precious metals. (NASA supplements paragraph (b)).

Code of Federal Regulations, 2011 CFR

2011-10-01

... 48 Federal Acquisition Regulations System 6 2011-10-01 2011-10-01 false Recovering precious metals. (NASA supplements paragraph (b)). 1845.607-2 Section 1845.607-2 Federal Acquisition Regulations System..., Redistribution, and Disposal of Contractor Inventory 1845.607-2 Recovering precious metals. (NASA supplements...

48 CFR 1845.607-2 - Recovering precious metals. (NASA supplements paragraph (b)).

Code of Federal Regulations, 2013 CFR

2013-10-01

... 48 Federal Acquisition Regulations System 6 2013-10-01 2013-10-01 false Recovering precious metals. (NASA supplements paragraph (b)). 1845.607-2 Section 1845.607-2 Federal Acquisition Regulations System..., Redistribution, and Disposal of Contractor Inventory 1845.607-2 Recovering precious metals. (NASA supplements...

48 CFR 1845.607-2 - Recovering precious metals. (NASA supplements paragraph (b)).

Code of Federal Regulations, 2012 CFR

2012-10-01

... 48 Federal Acquisition Regulations System 6 2012-10-01 2012-10-01 false Recovering precious metals. (NASA supplements paragraph (b)). 1845.607-2 Section 1845.607-2 Federal Acquisition Regulations System..., Redistribution, and Disposal of Contractor Inventory 1845.607-2 Recovering precious metals. (NASA supplements...

Impact of global financial crisis on precious metals returns: An application of ARCH and GARCH methods

NASA Astrophysics Data System (ADS)

Ismail, Mohd Tahir; Abdullah, Nurul Ain; Abdul Karim, Samsul Ariffin

2013-04-01

This paper is focusing on seeing the resilient of precious metals returns in facing the global financial crisis and provides a new guide for the investors before making investment decisions on precious metals. Four types of precious metals returns which are the variables selected in this study. The precious metals are gold, silver, bronze and platinum. All the variables are transferred to natural logarithm (ln). Daily data over the period 2 January 1995 to 30 December 2011 is used. Unit root tests that involve Augmented Dickey-Fuller (ADF) and Kwiatkowski-Phillips-Schmidt-Shin (KPSS) tests have been employed in determining the stationarity of the variables. Autoregressive Conditional Heteroscedasticity (ARCH) and Generalized Autoregressive Conditional Heteroscedasticity (GARCH) methods have been applied in measuring the impact of global financial crisis on precious metals returns. The result shows that investing in platinum is less risky compared to the other precious metals because it is not influence by the crisis period.

Simplified process for leaching precious metals from fuel cell membrane electrode assemblies

DOEpatents

Shore, Lawrence [Edison, NJ; Matlin, Ramail [Berkeley Heights, NJ

2009-12-22

The membrane electrode assemblies of fuel cells are recycled to recover the catalyst precious metals from the assemblies. The assemblies are cryogenically embrittled and pulverized to form a powder. The pulverized assemblies are then mixed with a surfactant to form a paste which is contacted with an acid solution to leach precious metals from the pulverized membranes.

Matrix elimination method for the determination of precious metals in ores using electrothermal atomic absorption spectrometry.

PubMed

Salih, Bekir; Celikbiçak, Omür; Döker, Serhat; Doğan, Mehmet

2007-03-28

Poly(N-(hydroxymethyl)methacrylamide)-1-allyl-2-thiourea) hydrogels, poly(NHMMA-ATU), were synthesized by gamma radiation using (60)Co gamma source in the ternary mixture of NHMMA-ATU-H(2)O. These hydrogels were used for the specific gold, silver, platinum and palladium recovery, pre-concentration and matrix elimination from the solutions containing trace amounts of precious metal ions. Elimination of inorganic matrices such as different transition and heavy metal ions, and anions was performed by adjusting the solution pH to 0.5 that was the selective adsorption pH of the precious metal ions. Desorption of the precious metal ions was performed by using 0.8 M thiourea in 3M HCl as the most efficient desorbing agent with recovery values more than 95%. In the desorption medium, thiourea effect on the atomic signal was eliminated by selecting proper pyrolysis and atomization temperatures for all precious metal ions. Precision and the accuracy of the results were improved in the graphite furnace-atomic absorption spectrometer (GFAAS) measurements by applying the developed matrix elimination method performing the adsorption at pH 0.5. Pre-concentration factors of the studied precious metal ions were found to be at least 1000-fold. Detection limits of the precious metal ions were found to be less than 10 ng L(-1) of the all studied precious metal ions by using the proposed pre-concentration method. Determination of trace levels of the precious metals in the sea-water, anode slime, geological samples and photographic fixer solutions were performed using GFAAS clearly after applying the adsorption-desorption cycle onto the poly(NHMMA-UTU) hydrogels.

Urinary excretion of platinum from South African precious metals refinery workers.

PubMed

Linde, Stephanus J L; Franken, Anja; du Plessis, Johannes L

2018-03-30

Urinary platinum (Pt) excretion is a reliable biomarker for occupational Pt exposure and has been previously reported for precious metals refinery workers in Europe but not for South Africa, the world's largest producer of Pt. This study aimed to quantify the urinary Pt excretion of South African precious metals refinery workers. Spot urine samples were collected from 40 workers (directly and indirectly exposed to Pt) at two South African precious metals refineries on three consecutive mornings prior to their shifts. Urine samples were analysed for Pt using inductively coupled plasma-mass spectrometry and were corrected for creatinine content. The urinary Pt excretion of workers did not differ significantly between sampling days. Urinary Pt excretions ranged from <0.1 to 3.0 µg Pt/g creatinine with a geometric mean of 0.21 µg Pt/g creatinine (95% CI 0.17 to 0.26 µg Pt/g creatinine). The work area (P=0.0006; η 2 =0.567) and the number of years workers were employed at the refineries (P=0.003; η 2 =0.261) influenced their urinary Pt excretion according to effect size analyses. Directly exposed workers had significantly higher urinary Pt excretion compared with indirectly exposed workers (P=0.007). The urinary Pt excretion of South African precious metals refinery workers reported in this study is comparable with that of seven other studies conducted in precious metals refineries and automotive catalyst plants in Europe. The Pt body burden of workers is predominantly determined by their work area, years of employment in the refineries and whether they are directly or indirectly exposed to Pt. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Metal molybdate nanorods as non-precious electrocatalysts for the oxygen reduction

NASA Astrophysics Data System (ADS)

Wu, Tian; Zhang, Lieyu

2015-12-01

Development of non-precious electrocatalysts with applicable electrocatalytic activity towards the oxygen reduction reaction (ORR) is important to fulfill broad-based and large-scale applications of metal/air batteries and fuel cells. Herein, nickel and cobalt molybdates with uniform nanorod morphology are synthesized using a facile one-pot hydrothermal method. The ORR activity of the prepared metal molybdate nanorods in alkaline media are investigated by using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperomety in rotating disk electrode (RDE) techniques. The present study suggests that the prepared metal molybdate nanorods exhibit applicable electrocatalytic activities towards the ORR in alkaline media, promising the applications as non-precious cathode in fuel cells and metal-air batteries.

Surface-Functionalized Electrospun Titania Nanofibers for the Scavenging and Recycling of Precious Metal Ions.

PubMed

Dai, Yunqian; Formo, Eric; Li, Haoxuan; Xue, Jiajia; Xia, Younan

2016-10-20

Precious metals are widely used as catalysts in industry. It is of critical importance to keep the precious metal ions leached from catalysts at a level below one part per million (ppm) in the final products and to recycle the expensive precious metals. Here we demonstrate a simple and effective method for scavenging precious metal ions from an aqueous solution and thereby reduce their concentrations down to the parts per billion (ppb) level. The key component is a filtration membrane comprised of titania (TiO 2 ) nanofibers whose surface has been functionalized with a silane bearing amino or thiol group. When operated under continuous flow at a rate of 1 mL min -1 and at room temperature, up to 99.95 % of the Pd 2+ ions could be removed from a stock solution with an initial concentration of 100 ppm. This work offers a viable strategy not only for the removal of precious metal ions but also for recovering and further recycling them for use as catalysts. For example, the captured Pd 2+ ions could be converted to nanoparticles and used as catalysts for organic reactions such as Suzuki coupling in a continuous flow reactor. This system can be potentially applied to pharmaceutical industry and waste stream treatment. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Precious-Metal Salt Coatings for Detecting Hydrazines

NASA Technical Reports Server (NTRS)

Dee, Louis A.; Greene, Benjamin

2004-01-01

Substrates coated with a precious-metal salt KAuCl4 have been found to be useful for detecting hydrazine vapors in air at and above a concentration of the order of 0.01 parts per million (ppm). Upon exposure to air containing a sufficient amount of hydrazine for a sufficient time, the coating material undergoes a visible change in color.

High performance, high durability non-precious metal fuel cell catalysts

DOEpatents

Wood, Thomas E.; Atanasoski, Radoslav; Schmoeckel, Alison K.

2016-03-15

This invention relates to non-precious metal fuel cell cathode catalysts, fuel cells that contain these catalysts, and methods of making the same. The fuel cell cathode catalysts are highly nitrogenated carbon materials that can contain a transition metal. The highly nitrogenated carbon materials can be supported on a nanoparticle substrate.

48 CFR 252.208-7000 - Intent to furnish precious metals as Government-furnished material.

Code of Federal Regulations, 2010 CFR

2010-10-01

...-furnished silver is mandatory when the quantity required is one hundred troy ounces or more. The precious... quantity in whole troy ounces of precious metals required in the performance of this contract (including...

41 CFR 109-27.5103 - Precious Metals Control Officer.

Code of Federal Regulations, 2010 CFR

2010-07-01

... regulatory responsibilities. (d) Insuring that physical inventories are performed as required by, and in accordance with, these regulations. (e) Witnessing physical inventories. (f) Performing periodic unannounced inspections of a custodian's precious metals inventory and records. (g) Conducting an annual review of...

41 CFR 109-27.5103 - Precious Metals Control Officer.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Precious Metals Control Officer. 109-27.5103 Section 109-27.5103 Public Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS SUPPLY AND...

Identification of carbon-encapsulated iron nanoparticles as active species in non-precious metal oxygen reduction catalysts

PubMed Central

Varnell, Jason A.; Tse, Edmund C. M.; Schulz, Charles E.; Fister, Tim T.; Haasch, Richard T.; Timoshenko, Janis; Frenkel, Anatoly I.; Gewirth, Andrew A.

2016-01-01

The widespread use of fuel cells is currently limited by the lack of efficient and cost-effective catalysts for the oxygen reduction reaction. Iron-based non-precious metal catalysts exhibit promising activity and stability, as an alternative to state-of-the-art platinum catalysts. However, the identity of the active species in non-precious metal catalysts remains elusive, impeding the development of new catalysts. Here we demonstrate the reversible deactivation and reactivation of an iron-based non-precious metal oxygen reduction catalyst achieved using high-temperature gas-phase chlorine and hydrogen treatments. In addition, we observe a decrease in catalyst heterogeneity following treatment with chlorine and hydrogen, using Mössbauer and X-ray absorption spectroscopy. Our study reveals that protected sites adjacent to iron nanoparticles are responsible for the observed activity and stability of the catalyst. These findings may allow for the design and synthesis of enhanced non-precious metal oxygen reduction catalysts with a higher density of active sites. PMID:27538720

Recovery of Precious and Base Metals from Waste Printed Circuit Boards Using a Sequential Leaching Procedure

NASA Astrophysics Data System (ADS)

Batnasan, Altansukh; Haga, Kazutoshi; Shibayama, Atsushi

2018-02-01

This paper considers the issue of recycling of waste printed circuit boards (WPCBs) containing precious and base metals in appreciable amounts. High-pressure oxidative leaching (HPOL) with dilute sulfuric acid resulted in removal of a significant amount of base metals from a WPCB ash sample obtained by incineration at 800°C. The parameters investigated in the precious metal leaching from WPCB residue after HPOL included the sulfuric acid concentration, thiourea concentration, oxidant concentration, leaching temperature, and leaching time. Recovery of gold, silver, and palladium of 100%, 81%, and 13% from the WPCB residue sample was achieved by thiourea leaching under optimized conditions. The results show that the efficiency of precious metal dissolution from the WPCB sample using thiourea solution depended strongly on the concentration of both thiourea and oxidant.

Recovery of Precious and Base Metals from Waste Printed Circuit Boards Using a Sequential Leaching Procedure

NASA Astrophysics Data System (ADS)

Batnasan, Altansukh; Haga, Kazutoshi; Shibayama, Atsushi

2017-12-01

This paper considers the issue of recycling of waste printed circuit boards (WPCBs) containing precious and base metals in appreciable amounts. High-pressure oxidative leaching (HPOL) with dilute sulfuric acid resulted in removal of a significant amount of base metals from a WPCB ash sample obtained by incineration at 800°C. The parameters investigated in the precious metal leaching from WPCB residue after HPOL included the sulfuric acid concentration, thiourea concentration, oxidant concentration, leaching temperature, and leaching time. Recovery of gold, silver, and palladium of 100%, 81%, and 13% from the WPCB residue sample was achieved by thiourea leaching under optimized conditions. The results show that the efficiency of precious metal dissolution from the WPCB sample using thiourea solution depended strongly on the concentration of both thiourea and oxidant.

40 CFR 421.250 - Applicability: Description of the primary precious metals and mercury subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... applicable to discharges resulting from the production of gold, silver, or mercury by primary precious metals... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability: Description of the... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING...

The removal of precious metals by conductive polymer filtration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cournoyer, M.E.

The growing demand for platinum-group metals (PGM) within the DOE complex and in industry, the need for modern and clean processes, and the increasing volume of low-grade material for secondary PGM recovery has a direct impact on the industrial practice of recovering and refining precious metals. There is a tremendous need for advanced metal ion recovery and waste minimization techniques, since the currently used method of precipitation-dissolution is inadequate. Los Alamos has an integrated program in ligand-design and separations chemistry which has developed and evaluated a series of water- soluble metal-binding polymers for recovering actinides and toxic metals from varietymore » of process streams. A natural extension of this work is to fabricate these metal-selective polymers into membrane based separation unites, i.e., hollow-fiber membranes. In the present investigation, the material for a novel hollow-fiber membrane is characterized and its selectivity for PGM reported. Energy and waste savings and economic competitiveness are also described.« less

One step bioconversion of waste precious metals into Serratia biofilm-immobilized catalyst for Cr(VI) reduction.

PubMed

Yong, P; Liu, W; Zhang, Z; Beauregard, D; Johns, M L; Macaskie, L E

2015-11-01

For reduction of Cr(VI) the Pd-catalyst is excellent but costly. The objectives were to prove the robustness of a Serratia biofilm as a support for biogenic Pd-nanoparticles and to fabricate effective catalyst from precious metal waste. Nanoparticles (NPs) of palladium were immobilized on polyurethane reticulated foam and polypropylene supports via adhesive biofilm of a Serratia sp. The biofilm adhesion and cohesion strength were unaffected by palladization and catalytic biofilm integrity was also shown by magnetic resonance imaging. Biofilm-Pd and mixed precious metals on biofilm (biofilm-PM) reduced 5 mM Cr(VI) to Cr(III) when immobilized in a flow-through column reactor, at respective flow rates of 9 and 6 ml/h. The lower activity of the latter was attributed to fewer, larger, metal deposits on the bacteria. Activity was lost in each case at pH 7 but was restored by washing with 5 mM citrate solution or by exposure of columns to solution at pH 2, suggesting fouling by Cr(III) hydroxide product at neutral pH. A 'one pot' conversion of precious metal waste into new catalyst for waste decontamination was shown in a continuous flow system based on the use of Serratia biofilm to manufacture and support catalytic Pd-nanoparticles.

Effects of different production technologies on mechanical and metallurgical properties of precious metal denture alloys

NASA Astrophysics Data System (ADS)

Ferro, Paolo; Battaglia, Eleonora; Capuzzi, Stefano; Berto, Filippo

2017-12-01

Precious metal alloys can be supplied in traditional plate form or innovative drop form with high degree of purity. The aim of the present work is to evaluate the influence of precious metal alloy form on metallurgical and mechanical properties of the final dental products with particular reference to metal-ceramic bond strength and casting defects. A widely used alloy for denture was selected; its nominal composition was close to 55 wt% Pd - 34 wt% Ag - 6 wt% In - 3 wt% Sn. Specimens were produced starting from the alloy in both plate and drop forms. A specific test method was developed to obtain results that could be representative of the real conditions of use. In order to achieve further information about the adhesion behaviour and resistance, the fracture surfaces of the samples were observed using `Scanning Electron Microscopy (SEM)'. Moreover, material defects caused by the moulding process were studied. The form of the alloy before casting does not significantly influence the shear bond strength between the metal and the ceramic material (p-value=0,976); however, according to SEM images, products from drop form alloy show less solidification defects compared to products obtained with plate form alloy. This was attributed to the absence of polluting additives used in the production of drop form alloy. This study shows that the use of precious metal denture alloys supplied in drop form does not affect the metal-ceramic bond strength compared to alloys supplied in the traditional plate form. However, compared to the plate form, the drop form is found free of solidification defects, less expensive to produce and characterized by minor environmental impacts.

A new strain for recovering precious metals from waste printed circuit boards.

PubMed

Ruan, Jujun; Zhu, Xingjiong; Qian, Yiming; Hu, Jian

2014-05-01

A new strain, Pseudomonas Chlororaphis (PC), was found for dissolving gold, silver, and copper from the metallic particles of crushed waste printed circuit boards (PCBs). The optimized conditions that greatly improved the ability of producing CN- (for dissolving metals) were obtained. Dissolving experiments of pure gold, silver, and copper showed that the metals could be changed into Au+, Ag+, and Cu2+. PC cells and their secreta would adsorb metallic ions. Meanwhile, metallic ions destroyed the growth of PC. Dissolving experiments of metallic particles from crushed waste PCBs were performed by PC. The results indicated that 8.2% of the gold, 12.1% silver, and 52.3% copper were dissolved into solution. This paper contributed significance information to recovering precious metals from waste PCBs by bioleaching. Copyright © 2014 Elsevier Ltd. All rights reserved.

Recovery of precious metals from space

NASA Technical Reports Server (NTRS)

Freiser, Henry

1991-01-01

The overall objective is to develop efficient and economical separation and recovery methods for the platinum group and other precious metals. The separation of Pd(II) from Pt(II), Ir(III), and Rh(III) with trioctylphosphine oxide (TOPO) in heptane using centrifugal partition chromatography (CPC) was investigated. Activities to achieve this objective focussed on selection and evaluation of extraction systems for the PGM and modification of selected systems for multistage operation with a view to scaling up to desired macro levels. On the basis of preliminary evaluation of a series of simple metal complexing agents and chelating agents, the TOPO in heptane was selected as a likely system for isolating of Pd(II) and Pt(II) from the other PGM. A multistage apparatus capable of configuration as a simple rugged device, a centrifugal partition chromatograph (CPC), was shown to be effective. The extraction of Pd(II) was studied by CPC and batch solvent extraction. The distribution ratios for Pd(II) determined by both methods agree well. In low HCl concentrations (less than 0.1 M), the extracted species was PdCl2.(TOPO)2, irrespective of the chloride concentration, while at acid concentrations above 0.1 M, the Pd was extracted as the ion pair, 2(TOPO.H+).(PdCl4)2-. Base line separation of Pd(II) and Pt(II) in CPC was obtained under a variety of chloride and HCl concentration. It was demonstrated that the efficiency of CPC for metal separation was limited by chemical kinetic factors rather than instrumental factors, strongly suggesting that dramatic improvements can be achieved by studying reaction kinetics of formation and dissociation of the extractable metal complex.

A new approach to precious metals recovery from brown coals: Correlation of recovery efficacy with the mechanism of metal-humic interactions

NASA Astrophysics Data System (ADS)

Bratskaya, Svetlana Yu.; Volk, Alexandra S.; Ivanov, Vladimir V.; Ustinov, Alexander Yu.; Barinov, Nikolay N.; Avramenko, Valentin A.

2009-06-01

The presence of gold and platinum group elements (PGE) in low-rank brown coals around the world has promoted interest in the industrial exploitation of this alternative source of precious metals. However, due to low efficacy of the methods traditionally used for the processing of mineral ores, there exists a high demand for new strategies of precious metal recovery from refractory carbonaceous materials that could significantly increase the economic potential of gold- and PGE-bearing organic resources. Here we discuss the possibility of gold and PGE recovery from alkaline extracts of brown coals using the difference in colloidal stability of bulk organic matter and its fractions enriched with precious metals. This approach enables one to avoid complete oxidation or combustion of brown coals prior to gold recovery, to minimize organic content in gold concentrate, and to obtain a valuable by-product - humic extracts. Using gold-bearing brown coals from several deposits located in the South Far East of Russia, we show that up to 95% of gold can be transferred to alkaline extracts of humic acids (HA) and up to 85% of this gold can be recovered by centrifugation at pH 4.0-6.0, when only 5-15% of HA precipitated simultaneously. We have shown that the high efficacy of gold recovery can be attributed to the occurrence of fine-dispersed elemental gold particles stabilized by HA, which differ significantly in colloidal stability from the bulk organic matter and, thus, can be separated by centrifugation.

A Novel Method for Depositing Precious Metal Films on Difficult Surfaces

NASA Technical Reports Server (NTRS)

Veitch, L. C.; Phillip, W. H.

1994-01-01

A guanidine-based vehicle was developed to deposit precious metal coatings on surfaces known to be difficult to coat. To demonstrate this method, a platinum coating was deposited on alumina fibers using a guanidine-platinum solution. X-ray diffraction confirmed that the only species present in the coating was platinum and that all of the carbon species had been removed upon heat treatment. SEM results showed that some porosity was present but that the coatings uniformly covered the fiber surface and adhered well to the finer.

A Novel Designed Bioreactor for Recovering Precious Metals from Waste Printed Circuit Boards

PubMed Central

Jujun, Ruan; Jie, Zheng; Jian, Hu; Zhang, Jianwen

2015-01-01

For recovering precious metals from waste printed circuit boards (PCBs), a novel hybrid technology including physical and biological methods was developed. It consisted of crushing, corona-electrostatic separation, and bioleaching. Bioleaching process is the focus of this paper. A novel bioreactor for bioleaching was designed. Bioleaching was carried out using Pseudomonas chlororaphis. Bioleaching experiments using mixed particles of Au and Cu were performed and leachate contained 0.006 mg/L, 2823 mg/L Au+ and Cu2+ respectively. It showed when Cu existed, the concentrations of Au were extremely small. This provided the feasibility to separate Cu from Au. The method of orthogonal experimental design was employed in the simulation bioleaching experiments. Experimental results showed the optimized parameters for separating Cu from Au particles were pH 7.0, temperature 22.5 °C, and rotation speed 80 r/min. Based on the optimized parameters obtained, the bioreactor was operated for recovering mixed Au and Cu particles. 88.1 wt.% of Cu and 76.6 wt.% of Au were recovered. The paper contributed important information to recover precious metals from waste PCBs. PMID:26316021

Market value of asteroidal precious metals in an age of diminishing terrestrial resources

USGS Publications Warehouse

Kargel, Jeffrey S.; ,

1996-01-01

In the next century Mankind may have to choose from two options for our supply and usage of some nonrenewable natural resources, such as gold, platinum metals, and fossil fuels: learn to live with diminishing supplies of these materials obtained at ever increasing economic and environmental cost, or reach into difficult places and develop new technologies to give us what we need to sustain economic growth. Either prospect faces formidable technological and economic challenges. Exploitation of asteroids for precious and strategic metals is a possible environmentally friendly remedy for impending shortages of some resources. Certain types of asteroids could completely replace terrestrial sources of platinum metals. Asteroid metal mining may become a 21st-century space industry worth ten to fifty billion dollars annually (1995 dollars). Asteroids could make the United States and other countries self sufficient in many strategic metals, and it could usher new technologies and increase our applications of existing technologies that depend on these metals.

Self-assembly synthesis of precious-metal-free 3D ZnO nano/micro spheres with excellent photocatalytic hydrogen production from solar water splitting

NASA Astrophysics Data System (ADS)

Guo, Si-yao; Zhao, Tie-jun; Jin, Zu-quan; Wan, Xiao-mei; Wang, Peng-gang; Shang, Jun; Han, Song

2015-10-01

A simple and straightforward solution growth routine is developed to prepare microporous 3D nano/micro ZnO microsphere with a large BET surface area of 288 m2 g-1 at room temperature. The formation mechanism of the hierarchical 3D nano/micro ZnO microsphere and its corresponding hydrogen evolution performance has been deeply discussed. In particular, this novel hierarchical 3D ZnO microspheres performs undiminished hydrogen evolution for at least 24 h under simulated solar light illumination, even under the condition of no precious metal as cocatalyst. Since the complex production process of photocatalysts and high cost of precious metal cocatalyst remains a major constraint that hinders the application of solar water splitting, this 3D nano/micro ZnO microspheres could be expected to be applicable in the precious-metal-free solar water splitting system due to its merits of low cost, simple procedure and high catalytic activity.

Bio-extraction of precious metals from urban solid waste

NASA Astrophysics Data System (ADS)

Das, Subhabrata; Natarajan, Gayathri; Ting, Yen-Peng

2017-01-01

Reduced product lifecycle and increasing demand for electronic devices have resulted in the generation of huge volumes of electronic waste (e-waste). E-wastes contain high concentrations of toxic heavy metals, which have detrimental effects on health and the environment. However, e-wastes also contain significant concentrations of precious metals such as gold, silver and palladium, which can be a major driving force for recycling of urban waste. Cyanogenic bacteria such as Chromobacterium violaceum generate cyanide as a secondary metabolite which mobilizes gold into solution via a soluble gold-cyanide complex. However, compared to conventional technology for metal recovery, this approach is not effective, owing largely to the low concentration of lixiviants produced by the bacteria. To overcome the challenges of bioleaching of gold from e-waste, several strategies were adopted to enhance gold recovery rates. These included (i) pretreatment of e-waste to remove competing metal ions, (ii) mutation to adapt the bacteria to high pH environment, (iii) metabolic engineering to produce higher cyanide lixiviant, and (iv) spent medium leaching with adjusted initial pH. Compared to 7.1 % recovery by the wild type bacteria, these strategies achieved gold recoveries of 11.3%, 22.5%, 30% and 30% respectively at 0.5% w/v pulp density respectively. Bioleached gold was finally mineralized and precipitated as gold nanoparticles using the bacterium Delftia acidovorans. This study demonstrates the potential for enhancement of biocyanide production and gold recovery from electronic waste through different strategies, and extraction of solid gold from bioleached leachate.

Non-precious metal catalysts prepared from precursors comprising cyanamide and polyaniline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, Hoon Taek; Zelenay, Piotr

A catalyst for oxygen reduction reaction (ORR) for a fuel cell was prepared by pyrolyzing a mixture of polyaniline, cyanamide, carbon black, and a non-precious metal salt under an inert atmosphere. The pyrolyzed product was treated to remove acid soluble components and then pyrolyzed again. The resulting powder was used to prepare a cathode for a membrane electrode assembly that was used in a fuel cell. When iron(III) chloride was used as the salt, the resulting catalyst was porous with a web-shaped structure. It displayed a maximum power density of 0.79 W/cm at 0.4 V in H.sub.2/O.sub.2 at 1.0 barmore » back pressure.« less

Photochemical changes in cyanide speciation in drainage from a precious metal ore heap

USGS Publications Warehouse

Johnson, C.A.; Leinz, R.W.; Grimes, D.J.; Rye, R.O.

2002-01-01

In drainage from an inactive ore heap at a former gold mine, the speciation of cyanide and the concentrations of several metals were found to follow diurnal cycles. Concentrations of the hexacyanoferrate complex, iron, manganese, and ammonium were higher at night than during the day, whereas weak-acid-dissociable cyanide, silver, gold, copper, nitrite, and pH displayed the reverse behavior. The changes in cyanide speciation, iron, and trace metals can be explained by photodissociation of iron and cobalt cyanocomplexes as the solutions emerged from the heap into sunlight-exposed channels. At midday, environmentally significant concentrations of free cyanide were produced in a matter of minutes, causing trace copper, silver, and gold to be mobilized as cyanocomplexes from solids. Whether rapid photodissociation is a general phenomenon common to other sites will be important to determine in reaching a general understanding of the environmental risks posed by routine or accidental water discharges from precious metal mining facilities.

A new method for promoting adhesion between precious metal alloys and dental adhesives.

PubMed

Ohno, H; Araki, Y; Endo, K

1992-06-01

A new, simple method of modifying the adherend metal surface by a liquid Ga-Sn alloy (Adlloy) was applied to dental precious and base-metal alloys for adhesion with 4-META adhesive resin. Adhesions of 4-META resin to three other surface states--as-polished, oxidized at high temperature, and electroplated tin--were also performed for comparison with the adhesion on Adlloy-modified surfaces. Bond strength measurements were made, and the durability against water at the adhering interface was evaluated. The Adlloy-modified gold alloys (Type IV and 14 K) and silver-based alloys (Ag-Pd and Ag-Cu) showed not only high bond strengths but also excellent water durability at the adhesion interface. Surface modification by Adlloy, however, did not affect adhesion to Ag-In-Zn and base-metal (SUS, Co-Cr, and Ni-Cr) alloys. Adhesion to the tin-electroplated specimens was comparable with that to the Adlloy-modified specimens.

Precious metal recovery from waste printed circuit boards using cyanide and non-cyanide lixiviants--A review.

PubMed

Akcil, Ata; Erust, Ceren; Gahan, Chandra Sekhar; Ozgun, Mehmet; Sahin, Merve; Tuncuk, Aysenur

2015-11-01

Waste generated by the electrical and electronic devices is huge concern worldwide. With decreasing life cycle of most electronic devices and unavailability of the suitable recycling technologies it is expected to have huge electronic and electrical wastes to be generated in the coming years. The environmental threats caused by the disposal and incineration of electronic waste starting from the atmosphere to the aquatic and terrestrial living system have raised high alerts and concerns on the gases produced (dioxins, furans, polybrominated organic pollutants, and polycyclic aromatic hydrocarbons) by thermal treatments and can cause serious health problems if the flue gas cleaning systems are not developed and implemented. Apart from that there can be also dissolution of heavy metals released to the ground water from the landfill sites. As all these electronic and electrical waste do posses richness in the metal values it would be worth recovering the metal content and protect the environmental from the pollution. Cyanide leaching has been a successful technology worldwide for the recovery of precious metals (especially Au and Ag) from ores/concentrates/waste materials. Nevertheless, cyanide is always preferred over others because of its potential to deliver high recovery with a cheaper cost. Cyanidation process also increases the additional work of effluent treatment prior to disposal. Several non-cyanide leaching processes have been developed considering toxic nature and handling problems of cyanide with non-toxic lixiviants such as thiourea, thiosulphate, aqua regia and iodine. Therefore, several recycling technologies have been developed using cyanide or non-cyanide leaching methods to recover precious and valuable metals. Copyright © 2015 Elsevier Ltd. All rights reserved.

Single-Atom Catalysts of Precious Metals for Electrochemical Reactions.

PubMed

Kim, Jiwhan; Kim, Hee-Eun; Lee, Hyunjoo

2018-01-10

Single-atom catalysts (SACs), in which metal atoms are dispersed on the support without forming nanoparticles, have been used for various heterogeneous reactions and most recently for electrochemical reactions. In this Minireview, recent examples of single-atom electrocatalysts used for the oxygen reduction reaction (ORR), hydrogen oxidation reaction (HOR), hydrogen evolution reaction (HER), formic acid oxidation reaction (FAOR), and methanol oxidation reaction (MOR) are introduced. Many density functional theory (DFT) simulations have predicted that SACs may be effective for CO 2 reduction to methane or methanol production while suppressing H 2 evolution, and those cases are introduced here as well. Single atoms, mainly Pt single atoms, have been deposited on TiN or TiC nanoparticles, defective graphene nanosheets, N-doped covalent triazine frameworks, graphitic carbon nitride, S-doped zeolite-templated carbon, and Sb-doped SnO 2 surfaces. Scanning transmission electron microscopy, extended X-ray absorption fine structure measurement, and in situ infrared spectroscopy have been used to detect the single-atom structure and confirm the absence of nanoparticles. SACs have shown high mass activity, minimizing the use of precious metal, and unique selectivity distinct from nanoparticle catalysts owing to the absence of ensemble sites. Additional features that SACs should possess for effective electrochemical applications were also suggested. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The use of precious-metal-modified nickel-based superalloys for thin gage applications

NASA Astrophysics Data System (ADS)

Ballard, Donna L.; Pilchak, Adam L.

2010-10-01

Precious-metal-modified nickel-based superalloys are being investigated for use in thin gage applications, such as thermal protection systems or heat exchangers, due to their strength and inherent oxidation resistance at temperatures in excess of 1,050°C. This overview paper summarizes the Air Force Research Laboratory (AFRL) interest in experimental two-phase γ-Ni + γ'-Ni3Al superalloys. The AFRL is interested in alloys with a based composition of Ni-15Al-5Cr (at. %) with carbon, boron, and zirconium additions for grain-boundary refinement and strengthening. The alloys currently being evaluated also contain 4-5 at.% of platinum-group metals, in this case platinum and iridium. The feasibility of hot rolling these alloys to a final thickness of 0.12-0.25 mm and obtaining a nearly fully recrystallized microstructure was demonstrated.

Quantifying the density and utilization of active sites in non-precious metal oxygen electroreduction catalysts

PubMed Central

Sahraie, Nastaran Ranjbar; Kramm, Ulrike I.; Steinberg, Julian; Zhang, Yuanjian; Thomas, Arne; Reier, Tobias; Paraknowitsch, Jens-Peter; Strasser, Peter

2015-01-01

Carbon materials doped with transition metal and nitrogen are highly active, non-precious metal catalysts for the electrochemical conversion of molecular oxygen in fuel cells, metal air batteries, and electrolytic processes. However, accurate measurement of their intrinsic turn-over frequency and active-site density based on metal centres in bulk and surface has remained difficult to date, which has hampered a more rational catalyst design. Here we report a successful quantification of bulk and surface-based active-site density and associated turn-over frequency values of mono- and bimetallic Fe/N-doped carbons using a combination of chemisorption, desorption and 57Fe Mössbauer spectroscopy techniques. Our general approach yields an experimental descriptor for the intrinsic activity and the active-site utilization, aiding in the catalyst development process and enabling a previously unachieved level of understanding of reactivity trends owing to a deconvolution of site density and intrinsic activity. PMID:26486465

Antimicrobial precious-metal nanoparticles and their use in novel materials.

PubMed

Senior, Katharina; Müller, Stefanie; Schacht, Veronika J; Bunge, Michael

2012-12-01

Nanotechnology offers powerful new approaches to controlling unwanted microorganisms and other potential biohazards. Engineered nanoparticles with antifungal, antimicrobial, and antiviral properties are now being developed for a variety of applications, including manufacture and maintenance of sterile surfaces, prevention and control of biological contamination, food and water safety, and treatment of infectious diseases and cancer. The great potential of antimicrobial precious-metal nanoparticles is reflected by the high number of recent publications and patent applications, which is summarized, at least in part, in this paper. This review should provide an overview and offer guidance to the scientific community interested in nano(bio)technology, nanomedicine, and nanotoxicology, and may also be of interest to a broader scientific audience. Furthermore, this review covers specific topics in research and development addressing the effects of nanoparticles on microorganisms as well as novel nanotechnology-based approaches for controlling potentially pathogenic microorganisms.

Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska

USGS Publications Warehouse

Bundtzen, Thomas K.; Miller, Marti L.; Goldfarb, Richard J.; Miller, Lance D.

1997-01-01

Placer gold and precious metal-bearing lode deposits of southwestern Alaska lie within a region 550 by 350 km, herein referred to as the Kuskokwim mineral belt. This mineral belt has yielded 100,240 kg (3.22 Moz) of gold, 12, 813 kg (412,000 oz) of silver, 1,377,412 kg (39,960 flasks) of mercury, and modest amounts of antimony and tungsten derived primarily from the late Cretaceous-early Tertiary igneous complexes of four major types: (1) alkali-calcic, comagmatic volcanic-plutonic complexes and isolated plutons, (2) calc-alkaline, meta-aluminous reduced plutons, (3) peraluminous alaskite or granite-porphyry sills and dike swarms, and (4) andesite-rhyolite subaerial volcanic rocks.About 80 percent of the 77 to 52 Ma intrusive and volcanic rocks intrude or overlie the middle to Upper Cretaceous Kuskokwim Group sedimentary and volcanic rocks, as well as the Paleozoic-Mesozoic rocks of the Nixon Fork, Innoko, Goodnews, and Ruby preaccretionary terranes.The major precious metal-bearing deposit types related to Late Cretaceous-early Tertiary igneous complexes of the Kuskokwim mineral belt are subdivided as follows: (1) plutonic-hosted copper-gold polymetallic stockwork, skarn, and vein deposits, (2) peraluminous granite-porphory-hosted gold polymetallic deposits, (3) plutonic-related, boron-enriched silver-tin polymetallic breccia pipes and replacement deposits, (4) gold and silver mineralization in epithermal systems, and (5) gold polymetallic heavy mineral placer deposits. Ten deposits genetically related to Late Cretaceous-early Tertiary intrusions contain minimum, inferred reserves amounting to 162,572 kg (5.23 Moz) of gold, 201,015 kg (6.46 Moz) silver, 12,160 metric tons (t) of tin, and 28,088 t of copper.The lodes occur in veins, stockworks, breccia pipes, and replacement deposits that formed in epithermal to mesothermal temperature-pressure conditions. Fluid inclusion, isotopic age, mineral assemblage, alteration assemblage, and structural data indicate that

High-performance hydrogen fuel cell using nitrate reduction reaction on a non-precious catalyst.

PubMed

Han, Sang-Beom; Song, You-Jung; Lee, Young-Woo; Ko, A-Ra; Oh, Jae-Kyung; Park, Kyung-Won

2011-03-28

The H(2)-NO(3)(-) electrochemical cell using nitrate reduction on a non-precious cathode catalyst shows much improved efficiency despite ∼75% reduction of Pt metal loading as compared to typical PEMFCs using typical ORR on precious catalysts.

Replacing precious metals with carbide catalysts for hydrogenation reactions

DOE PAGES

Ruijun, Hou; Chen, Jingguang G.; Chang, Kuan; ...

2015-03-03

Molybdenum carbide (Mo₂C and Ni/Mo₂C) catalysts were compared with Pd/SiO₂ for the hydrogenation of several diene molecules, 1,3- butadiene, 1,3- and 1,4-cyclohexadiene (CHD). Compared to Pd/SiO₂, Mo₂C showed similar hydrogenation rate for 1,3-butadiene and 1,3-CHD and even higher rate for 1,4-CHD, but with significant deactivation rate for 1,3-CHD hydrogenation. However, the hydrogenation activity of Mo₂C could be completely regenerated by H₂ treatment at 723 K for the three molecules. The Ni modified Mo₂C catalysts retained similar activity for 1,3-butadiene hydrogenation with significantly enhanced selectivity for 1-butene production. The 1-butene selectivity increased with increasing Ni loading below 15%. Among the Nimore » modified Mo₂C catalysts, 8.6%Ni/Mo₂C showed the highest selectivity to 1-butene, which was even higher selectivity than that over Pd/SiO₂. Compared to Pd/SiO₂, both Mo₂C and Ni/Mo₂C showed combined advantages in hydrogenation activity and catalyst cost reduction, demonstrating the potential to use less expensive carbide catalysts to replace precious metals for hydrogenation reactions.« less

Macrocyclic Receptor for Precious Gold, Platinum, or Palladium Coordination Complexes.

PubMed

Liu, Wenqi; Oliver, Allen G; Smith, Bradley D

2018-06-06

Two macrocyclic tetralactam receptors are shown to selectively encapsulate anionic, square-planar chloride and bromide coordination complexes of gold(III), platinum(II), and palladium(II). Both receptors have a preorganized structure that is complementary to its precious metal guest. The receptors do not directly ligate the guest metal center but instead provide an array of arene π-electron donors that interact with the electropositive metal and hydrogen-bond donors that interact with the outer electronegative ligands. This unique mode of supramolecular recognition is illustrated by six X-ray crystal structures showing receptor encapsulation of AuCl 4 - , AuBr 4 - , PtCl 4 -2 , or Pd 2 Cl 6 -2 . In organic solution, the 1:1 association constants correlate with specific supramolecular features identified in the solid state. Technical applications using these receptors are envisioned in a wide range of fields that involve precious metals, including mining, recycling, catalysis, nanoscience, and medicine.

The Benefits of Recycling Silver - A Precious Metal.

DTIC Science & Technology

1985-09-01

recovery and refinement. Defense Logistics Agency (DLA): Agency responsible for providing, through DLA centers, the most effective and economical support...because of restrictive laws and regulations, mining is either prohibited or economically unfeasible. 5. The stockpile of strategic and critical materials...to maximize recovery efforts. DPDM-R also maintains overall responsibility to conduct the PMRP. The PMRP promotes the economic recovery of precious

Recovery of Rare Earths, Precious Metals and Other Critical Materials from Geothermal Waters with Advanced Sorbent Structures

DOE Data Explorer

Pamela M. Kinsey

2015-09-30

The work evaluates, develops and demonstrates flexible, scalable mineral extraction technology for geothermal brines based upon solid phase sorbent materials with a specific focus upon rare earth elements (REEs). The selected organic and inorganic sorbent materials demonstrated high performance for collection of trace REEs, precious and valuable metals. The nanostructured materials typically performed better than commercially available sorbents. Data contains organic and inorganic sorbent removal efficiency, Sharkey Hot Springs (Idaho) water chemsitry analysis, and rare earth removal efficiency from select sorbents.

A new approach for the recovery of precious metals from solution and from leachates derived from electronic scrap.

PubMed

Macaskie, L E; Creamer, N J; Essa, A M M; Brown, N L

2007-03-01

A new approach is described for the recovery of precious metals (PMs: Au, Pd and Ag) with >99% efficiency from aqueous solution utilising biogas produced during the aerobic growth of Klebsiella pneumoniae. Gold was recovered from electronic scrap leachate ( approximately 95%) by this method, with some selectivity against Cu. The recovered PM solids all contained metal and sulphur as determined by energy dispersive X-ray microanalysis (EDX). X-ray powder diffraction analysis (XRD) showed no crystalline metal sulphur compounds but a crystalline palladium amine was recorded. Silver was recovered as a sulphide (found by EDX), carbonate and oxide (found by XRD). EDX analysis of the Au-precipitate showed mainly gold and sulphur, with some metallic Au(0) detected by XRD. The gold compound was shock-sensitive; upon grinding it detonated to leave a sooty black deposit.

Transition-Metal-Controlled Inorganic Ligand-Supported Non-Precious Metal Catalysts for the Aerobic Oxidation of Amines to Imines.

PubMed

Yu, Han; Zhai, Yongyan; Dai, Guoyong; Ru, Shi; Han, Sheng; Wei, Yongge

2017-10-09

Most state-of-art transition-metal catalysts usually require organic ligands, which are essential for controlling the reactivity and selectivity of reactions catalyzed by transition metals. However, organic ligands often suffer from severe problems including cost, toxicity, air/moisture sensitivity, and being commercially unavailable. Herein, we show a simple, mild, and efficient aerobic oxidation procedure of amines using inorganic ligand-supported non-precious metal catalysts 1, (NH 4 ) n [MMo 6 O 18 (OH) 6 ] (M=Cu 2+ ; Fe 3+ ; Co 3+ ; Ni 2+ ; Zn 2+ , n=3 or 4), synthesized by a simple one-step method in water at 100 °C, demonstrating that the catalytic activity and selectivity can be significantly improved by changing the central metal atom. In the presence of these catalysts, the catalytic oxidation of primary and secondary amines, as well as the coupling of alcohols and amines, can smoothly proceed to afford various imines with O 2 (1 atm) as the sole oxidant. In particular, the catalysts 1 have transition-metal ion core, and the planar arrangement of the six Mo VI centers at their highest oxidation states around the central heterometal can greatly enhance the Lewis acidity of catalytically active sites, and also enable the electrons in the center to delocalize onto the six edge-sharing MO 6 units, in the same way as ligands in traditional organometallic complexes. The versatility of this methodology maybe opens a path to catalytic oxidation through inorganic ligand-coordinated metal catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Elucidating Oxygen Reduction Active Sites in Pyrolyzed Metal-Nitrogen Coordinated Non-Precious-Metal Electrocatalyst Systems.

PubMed

Tylus, Urszula; Jia, Qingying; Strickland, Kara; Ramaswamy, Nagappan; Serov, Alexey; Atanassov, Plamen; Mukerjee, Sanjeev

2014-05-01

Detailed understanding of the nature of the active centers in non-precious-metal-based electrocatalyst, and their role in oxygen reduction reaction (ORR) mechanistic pathways will have a profound effect on successful commercialization of emission-free energy devices such as fuel cells. Recently, using pyrolyzed model structures of iron porphyrins, we have demonstrated that a covalent integration of the Fe-N x sites into π-conjugated carbon basal plane modifies electron donating/withdrawing capability of the carbonaceous ligand, consequently improving ORR activity. Here, we employ a combination of in situ X-ray spectroscopy and electrochemical methods to identify the various structural and functional forms of the active centers in non-heme Fe/N/C catalysts. Both methods corroboratively confirm the single site 2e - × 2e - mechanism in alkaline media on the primary Fe 2+ -N 4 centers and the dual-site 2e - × 2e - mechanism in acid media with the significant role of the surface bound coexisting Fe/Fe x O y nanoparticles (NPs) as the secondary active sites.

Electron-band theory inspired design of magnesium-precious metal bulk metallic glasses with high thermal stability and extended ductility.

PubMed

Laws, Kevin J; Shamlaye, Karl F; Granata, Davide; Koloadin, Leah S; Löffler, Jörg F

2017-06-13

Magnesium-based bulk metallic glasses (BMGs) exhibit high specific strengths and excellent glass-forming ability compared to other metallic systems, making them suitable candidates for next-generation materials. However, current Mg-based BMGs tend to exhibit low thermal stability and are prone to structural relaxation and brittle failure. This study presents a range of new magnesium-precious metal-based BMGs from the ternary Mg-Ag-Ca, Mg-Ag-Yb, Mg-Pd-Ca and Mg-Pd-Yb alloy systems with Mg content greater than 67 at.%. These alloys were designed for high ductility by utilising atomic bond-band theory and a topological efficient atomic packing model. BMGs from the Mg-Pd-Ca alloy system exhibit high glass-forming ability with critical casting sizes of up to 3 mm in diameter, the highest glass transition temperatures (>200 °C) of any reported Mg-based BMG to date, and sustained compressive ductility. Alloys from the Mg-Pd-Yb family exhibit critical casting sizes of up to 4 mm in diameter, and the highest compressive plastic (1.59%) and total (3.78%) strain to failure of any so far reported Mg-based glass. The methods and theoretical approaches presented here demonstrate a significant step forward in the ongoing development of this extraordinary class of materials.

Nickel oxide and carbon nanotube composite (NiO/CNT) as a novel cathode non-precious metal catalyst in microbial fuel cells.

PubMed

Huang, Jianjian; Zhu, Nengwu; Yang, Tingting; Zhang, Taiping; Wu, Pingxiao; Dang, Zhi

2015-10-15

Comparing with the precious metal catalysts, non-precious metal catalysts were preferred to use in microbial fuel cells (MFCs) due to the low cost and high oxygen reduction reaction (ORR) efficiency. In this study, the transmission electron microscope and X-ray diffraction as well as Raman investigation revealed that the prepared nanoscale NiO was attached on the surface of CNT. Cyclic voltammogram and rotating ring-disk electrode tests showed that the NiO/CNT composite catalyst had an apparent oxygen reduction peak and 3.5 electron transfer pathway was acquired under oxygen atmosphere. The catalyst performance was highly dependent on the percentage of NiO in the CNT nanocomposites. When 77% NiO/CNT nano-sized composite was applied as cathode catalyst in membrane free single-chamber air cathode MFC, a maximum power density of 670 mW/m(2) and 0.772 V of OCV was obtained. Moreover, the MFC with pure NiO (control) could not achieve more than 0.1 V. All findings suggested that NiO/CNT could be a potential cathode catalyst for ORR in MFCs. Copyright © 2015 Elsevier B.V. All rights reserved.

Advanced Sorbent Structure Recovery of REEs, Precious Metals and Other Valuable Metals from Geothermal Waters and Its Associated Technoeconomics

DOE Data Explorer

Addleman, Shane; Chouyyok, Wilaiwan; Palo, Daniel; Dunn, Brad M.; Brann, Michelle; Billingsley, Gary; Johnson, Darren; Nell, Kara M.

2017-05-25

This work evaluates, develops and demonstrates flexible, scalable mineral extraction technology for geothermal brines based upon solid phase sorbent materials with a specific focus upon rare earth elements (REEs). The selected organic and inorganic sorbent materials demonstrated high performance for collection of trace REEs, precious and valuable metals beyond commercially available sorbents. This report details the organic and inorganic sorbent uptake, performance, and collection efficiency results for La, Eu, Ho, Ag, Cu and Zn, as well as the characterization of these select sorbent materials. The report also contains estimated costs from an in-depth techno-economic analysis of a scaled up separation process. The estimated financial payback period for installing this equipment varies between 3.3 to 5.7 years depending on the brine flow rate of the geothermal resource.

Rapid Computer Aided Ligand Design and Screening of Precious Metal Extractants from TRUEX Raffinate with Experimental Validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, Aurora Sue; Wall, Nathalie; Benny, Paul

2015-11-16

Rhodium is the most extensively used metal in catalytic applications; it occurs in mixed ores with platinum group metals (PGMs) in the earth’s crust in low concentrations (0.4 - 10 ppb). It is resistant to aerial oxidation and insoluble in all acids, including aqua regia, making classical purification methods time-consuming and inefficient. To ensure adequate purity, several precipitation and dissolution steps are necessary during separation. Low abundance, high demand, and extensive processing make rhodium the most expensive of all PGMs. From alternative sources, rhodium is also produced in sufficient quantities (0.47 kg per ton initial heavy metal (tIHM)) during themore » fission of U-235 in nuclear reactors along with other PGMs (i.e., Ag, Pd, Ru). A typical power water reactor operating with UO 2 fuel after cooling can generate PGMs in quantities greater than found in the earth’s crust (0.5-2 kg/tIHM). This currently untapped supply of PGMs has the potential to yield $5,000-30,000/tIHM. It is estimated that by the year 2030, the amount of rhodium generated in reactors could exceed natural reserves. Typical SNF processing removes the heavier lanthanides and actinides and can leave PGMs at ambient temperatures in aqueous acidic (Cl⁻ or NO 3⁻; pH < 1) solutions at various activities. While the retrieval of these precious metals from SNF would minimize waste generation and improve resource utilization, it has been difficult to achieve thus far. Two general strategies have been utilized to extract Rh(III) from chloride media: ion pairing and coordination complexation. Ion pairing mechanisms have been studied primarily with the tertiary and quaternary amines. Additionally, mixed mechanism extractions have been observed in which ion pairing is the initial mechanism, and longer extraction equilibrium time generated coordination complexes. Very few coordination complexation extraction ligands have been studied. This project approached this problem through the

A new model for simulating microbial cyanide production and optimizing the medium parameters for recovering precious metals from waste printed circuit boards.

PubMed

Yuan, Zhihui; Ruan, Jujun; Li, Yaying; Qiu, Rongliang

2018-04-10

Bioleaching is a green recycling technology for recovering precious metals from waste printed circuit boards (WPCBs). However, this technology requires increasing cyanide production to obtain desirable recovery efficiency. Luria-Bertani medium (LB medium, containing tryptone 10 g/L, yeast extract 5 g/L, NaCl 10 g/L) was commonly used in bioleaching of precious metal. In this study, results showed that LB medium did not produce highest yield of cyanide. Under optimal culture conditions (25 °C, pH 7.5), the maximum cyanide yield of the optimized medium (containing tryptone 6 g/L and yeast extract 5 g/L) was 1.5 times as high as that of LB medium. In addition, kinetics and relationship of cell growth and cyanide production was studied. Data of cell growth fitted logistics model well. Allometric model was demonstrated effective in describing relationship between cell growth and cyanide production. By inserting logistics equation into allometric equation, we got a novel hybrid equation containing five parameters. Kinetic data for cyanide production were well fitted to the new model. Model parameters reflected both cell growth and cyanide production process. Copyright © 2018 Elsevier B.V. All rights reserved.

N, S co-doped carbon spheres with highly dispersed CoO as non-precious metal catalyst for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Chen, Linlin; Guo, Xingpeng; Zhang, Guoan

2017-08-01

It is still a great challenge in preparing non-precious metal catalysts with high activity and long-term stability to substitute for precious metal catalysts for oxygen reduction reaction (ORR) in fuel cells. Herein, we report a novel and facile catalyst-N, S co-doped carbon spheres with highly dispersed CoO (CoO@NS-CSs), where biomass glucose spheres act as carbon precursor and H2S, NH3 derived from the decomposition of thiourea not only provide N, S sources but also can etch carbon spheres to produce nanoporous structure. CoO@NS-CSs catalyst exhibits excellent ORR activity with a high onset potential of 0.946 V vs. RHE (reversible hydrogen electrode) and a half-wave potential of 0.821 V vs. RHE through a four-electron pathway in alkaline solution, which is comparable to commercial Pt/C catalyst (onset potential: 0.926 V vs. RHE, half-wave potential: 0.827 V vs. RHE). Furthermore, both the long-term stability and methanol-tolerance of CoO@NS-CSs catalyst are superior to those of commercial Pt/C catalyst. The excellent ORR performance of CoO@NS-CSs catalyst can be attributed to its micro-mesopore structure, high specific surface area (667 m2 g-1), and highly dispersed CoO. This work manifests that the obtained CoO@NS-CSs catalyst is promising to be applied to fuel cells.

Modeling Hierarchical Non-Precious Metal Catalyst Cathodes for PEFCs Using Multi-Scale X-ray CT Imaging

DOE PAGES

Komini Babu, S.; Chung, H. T.; Wu, G.; ...

2014-08-18

This paper reports the development of a model for simulating polymer electrolyte fuel cells (PEFCs) with non-precious metal catalyst (NPMC) cathodes. NPMCs present an opportunity to dramatically reduce the cost of PEFC electrodes by removing the costly Pt catalyst. To address the significant transport losses in thick NPMC cathodes (ca. >60 µm), we developed a hierarchical electrode model that resolves the unique structure of the NPMCs we studied. A unique feature of the approach is the integration of the model with morphology data extracted from nano-scale resolution X-ray computed tomography (nano-CT) imaging of the electrodes. A notable finding is themore » impact of the liquid water accumulation in the electrode and the significant performance improvement possible if electrode flooding is mitigated.« less

Chalcopyrite—bearer of a precious, non-precious metal

USGS Publications Warehouse

Kimball, Bryn E.

2013-01-01

The mineral chalcopyrite (CuFeS2) is the world's most abundant source of copper, a metal component in virtually every piece of electrical equipment. It is the main copper mineral in several different ore deposit types, the most important of which are porphyry deposits. Chalcopyrite is unstable at the Earth's surface, so it weathers from sulphide outcrops and mine waste piles, contributing acid and dissolved copper to what is known as acid rock drainage. If not prevented, dissolved copper from chalcopyrite weathering will be transported downstream, potentially harming ecosystems along the way. Pristine areas are becoming targets for future copper supply as we strive to meet ever-increasing demands for copper by developed and developing nations. Additionally, our uses for copper are expanding to include technology such as solar energy production. This has lead to the processing of increasingly lower grade ores, which is possible, in part, due to advances in bio-leaching (i.e. metal extraction catalysed by micro-organisms). Although copper is plentiful, it is still a nonrenewable resource. Future copper supply promises to fall short of demand and the volatility of the copper market may continue if we do not prioritize copper use and improve copper recycling and ore extraction efficiency.

Maps showing mineral resource assessment for vein and replacement deposits of base and precious metals, barite, and fluorspar, Dillon 1 degree by 2 degrees Quadrangle, Idaho and Montana

USGS Publications Warehouse

Pearson, R.C.; Trautwein, C.M.; Berger, B.R.; Hanna, W.F.; Jenson, S.K.; Loen, J.S.; Moll, S.H.; Purdy, T.L.; Rowan, L.C.; Ruppel, E.T.; Segal, D.B.

1992-01-01

This report is one of several that assess the mineral resources in the Dillon quadrangle. For the purpose of the assessment, the deposits that are known in the quadrangle, or suspected to be present from a knowledge of the geologic setting, have been grouped into 30 deposit types on the basis of the mineralogy or commodity in the ore and the structural or depositional setting of the deposit. The emphasis in these assessment reports is on metallic minerals, but some important nonmetallic minerals are also considered. Fossil fuels are beyond the scope of this investigation, phosphate and uranium have been investigated previously (Swanson, 1970; Wodzicki and Krason, 1981 ), and certain nonmetallic minerals, including bulk commodities such as sand and gravel, are in large supply and thus are not considered. The mineral resource assessment discussed in this report concentrates on a single deposit type (of the total of 30 types) that we call "vein and replacement deposits of base and precious metals." Base and precious metals produced from such deposits are copper, lead, zinc, gold, and silver. Vein deposits of barite and fluorspar are also discussed, but because they seem to be of minor importance, they are treated briefly. Vein and replacement deposits of base and precious metals are classified as a single deposit type rather than as numerous possible subordinate types that might be distinguished on the basis of mineralogy, metal content, or other factors, because the characteristics of the ore, the ore bodies, and the structural setting are not sufficiently well known to yield a consistent detailed classification for the entire quadrangle. Furthermore, the criteria used here to explain the localization of deposits are too general to allow discrimination among subordinate types at a scale of 1 :250,000 or smaller. In assessing mineral resources, we have adopted a general philosophy similar to that of Harrison and others ( 1986). We attempt to identify parts of the

Mineral Deposit Data for Epigenetic Base- and Precious-metal and Uranium-thorium Deposits in South-central and Southwestern Montana and Southern and Central Idaho

USGS Publications Warehouse

Klein, T.L.

2004-01-01

Metal deposits spatially associated with the Cretaceous Boulder and Idaho batholiths of southwestern Montana and southern and central Idaho have been exploited since the early 1860s. Au was first discovered in placer deposits; exploitation of vein deposits in bedrock soon followed. In 1865, high-grade Ag vein deposits were discovered and remained economically important until the 1890s. Early high-grade deposits of Au, Ag and Pb were found in the weathered portions of the veins systems. As mining progressed to deeper levels, Ag and Pb grades diminished. Exploration for and development of these vein deposits in this area have continued until the present. A majority of these base- and precious-metal vein deposits are classified as polymetallic veins (PMV) and polymetallic carbonate-replacement (PMR) deposits in this compilation. Porphyry Cu and Mo, epithermal (Au, Ag, Hg and Sb), base- and precious-metal and W skarn, W vein, and U and Th vein deposits are also common in this area. The world-class Butte Cu porphyry and the Butte high-sulfidation Cu vein deposits are in this study area. PMV and PMR deposits are the most numerous in the region and constitute about 85% of the deposit records compiled. Several types of syngenetic/diagenetic sulfide mineral deposits in rocks of the Belt Supergroup or their equivalents are common in the region and they have been the source of a substantial metal production over the last century. These syngenetic deposits and their metamorphosed/structurally remobilized equivalents were not included in this database; therefore, deposits in the Idaho portion of the Coeur d'Alene district and the Idaho Cobalt belt, for example, have not been included because many of them are believed to be of this type.

Mineral resource of the month: platinum-group metals

USGS Publications Warehouse

Hilliard, Henry

2003-01-01

The precious metals commonly referred to as platinum-group metals (PGM) include iridium, osmium, palladium, platinum, rhodium and ruthenium. PGM are among the rarest of elements, and their market values — particularly for palladium, platinum and rhodium — are the highest of all precious metals.

Ages and sources of components of Zn-Pb, Cu, precious metal, and platinum group element deposits in the goodsprings district, Clark County, Nevada

USGS Publications Warehouse

Vikre, Peter G.; Browne, Quentin J.; Fleck, Robert J.; Hofstra, Albert H.; Wooden, Joseph L.

2011-01-01

The Goodsprings district, Clark County, Nevada, includes zinc-dominant carbonate replacement deposits of probable late Paleozoic age, and lead-dominant carbonate replacement deposits, copper ± precious metal-platinum group element (PGE) deposits, and gold ± silver deposits that are spatially associated with Late Triassic porphyritic intrusions. The district encompasses ~500 km2 although the distribution of all deposits has been laterally condensed by late Mesozoic crustal contraction. Zinc, Pb, and Cu production from about 90 deposits was ~160,000 metric tons (t) (Zn > Pb >> Cu), 2.1 million ounces (Moz) Ag, 0.09 Moz Au, and small amounts of PGEs—Co, V, Hg, Sb, Ni, Mo, Mn, Ir, and U—were also recovered.Zinc-dominant carbonate replacement deposits (Zn > Pb; Ag ± Cu) resemble Mississippi Valley Type (MVT) Zn-Pb deposits in that they occur in karst and fault breccias in Mississippian limestone where the southern margin of the regional late Paleozoic foreland basin adjoins Proterozoic crystalline rocks of the craton. They consist of calcite, dolomite, sphalerite, and galena with variably positive S isotope compositions (δ34S values range from 2.5–13‰), and highly radiogenic Pb isotope compositions (206Pb/204Pb >19), typical of MVT deposits above crystalline Precambrian basement. These deposits may have formed when southward flow of saline fluids, derived from basinal and older sedimentary rocks, encountered thinner strata and pinch-outs against the craton, forcing fluid mixing and mineral precipitation in karst and fault breccias. Lead-dominant carbonate replacement deposits (Pb > Zn, Ag ± Cu ± Au) occur among other deposit types, often near porphyritic intrusions. They generally contain higher concentrations of precious metals than zinc-dominant deposits and relatively abundant iron oxides after pyrite. They share characteristics with copper ± precious metal-PGE and gold ± silver deposits including fine-grained quartz replacement of carbonate minerals

Elucidating Oxygen Reduction Active Sites in Pyrolyzed Metal–Nitrogen Coordinated Non-Precious-Metal Electrocatalyst Systems

PubMed Central

2015-01-01

Detailed understanding of the nature of the active centers in non-precious-metal-based electrocatalyst, and their role in oxygen reduction reaction (ORR) mechanistic pathways will have a profound effect on successful commercialization of emission-free energy devices such as fuel cells. Recently, using pyrolyzed model structures of iron porphyrins, we have demonstrated that a covalent integration of the Fe–Nx sites into π-conjugated carbon basal plane modifies electron donating/withdrawing capability of the carbonaceous ligand, consequently improving ORR activity. Here, we employ a combination of in situ X-ray spectroscopy and electrochemical methods to identify the various structural and functional forms of the active centers in non-heme Fe/N/C catalysts. Both methods corroboratively confirm the single site 2e– × 2e– mechanism in alkaline media on the primary Fe2+–N4 centers and the dual-site 2e– × 2e– mechanism in acid media with the significant role of the surface bound coexisting Fe/FexOy nanoparticles (NPs) as the secondary active sites. PMID:24817921

Textural, mineralogical and stable isotope studies of hydrothermal alteration in the main sulfide zone of the Great Dyke, Zimbabwe and the precious metals zone of the Sonju Lake Intrusion, Minnesota, USA

USGS Publications Warehouse

Li, C.; Ripley, E.M.; Oberthur, T.; Miller, J.D.; Joslin, G.D.

2008-01-01

Stratigraphic offsets in the peak concentrations of platinum-group elements (PGE) and base-metal sulfides in the main sulfide zone of the Great Dyke and the precious metals zone of the Sonju Lake Intrusion have, in part, been attributed to the interaction between magmatic PGE-bearing base-metal sulfide assemblages and hydrothermal fluids. In this paper, we provide mineralogical and textural evidence that indicates alteration of base-metal sulfides and mobilization of metals and S during hydrothermal alteration in both mineralized intrusions. Stable isotopic data suggest that the fluids involved in the alteration were of magmatic origin in the Great Dyke but that a meteoric water component was involved in the alteration of the Sonju Lake Intrusion. The strong spatial association of platinum-group minerals, principally Pt and Pd sulfides, arsenides, and tellurides, with base-metal sulfide assemblages in the main sulfide zone of the Great Dyke is consistent with residual enrichment of Pt and Pd during hydrothermal alteration. However, such an interpretation is more tenuous for the precious metals zone of the Sonju Lake Intrusion where important Pt and Pd arsenides and antimonides occur as inclusions within individual plagioclase crystals and within alteration assemblages that are free of base-metal sulfides. Our observations suggest that Pt and Pd tellurides, antimonides, and arsenides may form during both magmatic crystallization and subsolidus hydrothermal alteration. Experimental studies of magmatic crystallization and hydrothermal transport/deposition in systems involving arsenides, tellurides, antimonides, and base metal sulfides are needed to better understand the relative importance of magmatic and hydrothermal processes in controlling the distribution of PGE in mineralized layered intrusions of this type. ?? Springer-Verlag 2007.

Metallurgical recovery of metals from electronic waste: a review.

PubMed

Cui, Jirang; Zhang, Lifeng

2008-10-30

Waste electric and electronic equipment, or electronic waste, has been taken into consideration not only by the government but also by the public due to their hazardous material contents. In the detailed literature survey, value distributions for different electronic waste samples were calculated. It is showed that the major economic driver for recycling of electronic waste is from the recovery of precious metals. The state of the art in recovery of precious metals from electronic waste by pyrometallurgical processing, hydrometallurgical processing, and biometallurgical processing are highlighted in the paper. Pyrometallurgical processing has been a traditional technology for recovery of precious metals from waste electronic equipment. However, state-of-the-art smelters are highly depended on investments. Recent research on recovery of energy from PC waste gives an example for using plastics in this waste stream. It indicates that thermal processing provides a feasible approach for recovery of energy from electronic waste if a comprehensive emission control system is installed. In the last decade, attentions have been removed from pyrometallurgical process to hydrometallurgical process for recovery of metals from electronic waste. In the paper, hydrometallurgical processing techniques including cyanide leaching, halide leaching, thiourea leaching, and thiosulfate leaching of precious metals are detailed. In order to develop an environmentally friendly technique for recovery of precious metals from electronic scrap, a critical comparison of main leaching methods is analyzed for both economic feasibility and environmental impact. It is believed that biotechnology has been one of the most promising technologies in metallurgical processing. Bioleaching has been used for recovery of precious metals and copper from ores for many years. However, limited research was carried out on the bioleaching of metals from electronic waste. In the review, initial researches on the

Recovery of precious metals from low-grade automobile shredder residue: A novel approach for the recovery of nanozero-valent copper particles.

PubMed

Singh, Jiwan; Lee, Byeong-Kyu

2016-02-01

The presence of precious metals (PMs) in low-grade automobile shredder residue (ASR) makes it attractive for recycling. This study investigated the leaching and recovery characteristics of two PMs (Cu and Ag) and two heavy metals (Mn and Co) from ASR. The effects of H2O2, leaching temperature, liquid to solid (L/S) ratio, and particle size on metal leaching were determined in an aqueous solution of 0.5M nitric acid. The metal leaching rate was increased with increasing nitric acid concentration, amount of H2O2, L/S ratio and temperature. The leaching kinetics was analyzed by using a second-order reaction model. In the analysis of leaching kinetics, the metal leaching data were well fitted (R(2)⩾0.99) with the second-order reaction model. The activation energy (kJ/mol) for metal leaching was 39.6 for Cu, 17.1 for Ag, 17.3 for Mn and 29.2 for Co. Metal recovery was carried out by fractional precipitation with the addition of advanced Fenton's regent. Metal recovery efficiency was increased to 99.95% for Cu, 99.8% for Mn, 90.0% for Ag and 96.46% for Co with the advanced Fenton's regent. In particular, a novel finding of the PM recovery is that Cu can also be recovered directly from the leachate of ASR in the form of zero-valent copper (ZVC) nanoparticles (NPs). Hydrometallurgical recovery of the metals from ASR using nitric acid is highly efficient. Copyright © 2015 Elsevier Ltd. All rights reserved.

In-Situ through-Plane Measurements of Ionic Potential Distributions in Non-Precious Metal Catalyst Electrode for PEFC

DOE PAGES

Komini Babu, S.; Chung, H. T.; Zelenay, P.; ...

2015-09-14

This manuscript presents micro-scale experimental diagnostics and nano-scale resolution X-ray imaging applied to the study of proton conduction in non-precious metal catalyst (NPMC) fuel cell cathodes. NPMC’s have the potential to reduce the cost of the fuel cell for multiple applications. But, NPMC electrodes are inherently thick compared to the convention Pt/C electrode due to the lower volumetric activity. Thus, the electric potential drop through the Nafion across the electrode thickness can yield significant performance loss. Ionomer distributions in the NPMC electrodes with different ionomer loading are extracted from morphological data using nanoscale X-ray computed tomography (nano-XCT) imaging of themore » cathode. Microstructured electrode scaffold (MES) diagnostics are used to measure the electrolyte potential at discrete points across the thickness of the catalyst layer. When using that apparatus, the electrolyte potential drop, the through-thickness reaction distribution, and the proton conductivity are measured and correlated with the corresponding Nafion morphology and cell performance.« less

Process for making a noble metal on tin oxide catalyst

NASA Technical Reports Server (NTRS)

Upchurch, Billy T. (Inventor); Davis, Patricia (Inventor); Miller, Irvin M. (Inventor)

1989-01-01

A quantity of reagent grade tin metal or compound, chloride-free, and high-surface-area silica spheres are placed in deionized water, followed by deaerating the mixture by boiling and adding an oxidizing agent, such as nitric acid. The nitric acid oxidizes the tin to metastannic acid which coats the spheres because the acid is absorbed on the substrate. The metastannic acid becomes tin oxide upon drying and calcining. The tin-oxide coated silica spheres are then placed in water and boiled. A chloride-free precious metal compound in aqueous solution is then added to the mixture containing the spheres, and the precious metal compound is reduced to a precious metal by use of a suitable reducing agent such as formic acid. Very beneficial results were obtained using the precious metal compound tetraammine platinum(II) hydroxide.

Lead poisoning in precious metals refinery assayers: a failure to notify workers at high risk.

PubMed

Kern, D G

1994-05-01

Lead poisoning in a precious metals refinery fire assayer and a routine OSHA inspection prompted an investigation of the index facility, a survey of the industry, and efforts to notify assayers of this previously unrecognized hazard. Air and blood samples were obtained at the index facility. Management personnel from all fire assay laboratories in Rhode Island and southern Massachusetts were interviewed. The industry's trade association, OSHA, NIOSH, trade unions, and the media were asked to assist in a nationwide notification effort. Assayers at the index facility had excessive exposures to lead due to an age-old, lead-based assaying method that remains the industry gold standard. Blood lead levels of the three assayers (mean 61.3 micrograms/dl, range 48-86 micrograms/dl) were considerably higher than those of 16 other refinery workers (mean 27.4 micrograms/dl, range 13-49 micrograms/dl). The industry survey revealed inadequate knowledge of both the lead hazard and the applicability of the OSHA lead standard. Notification efforts failed in large part due to economic obstacles. The notification of workers at high risk of lead exposure and the eradication of occupational lead poisoning will require greater attention to economic forces.

Polymer-Supported Optically Active fac(S)-Tris(thiotato)rhodium(III) Complex for Sulfur-Bridging Reaction With Precious Metal Ions.

PubMed

Aizawa, Sen-Ichi; Tsubosaka, Soshi

2016-01-01

The optically active mixed-ligand fac(S)-tris(thiolato)rhodium(III) complexes, ΔL -fac(S)-[Rh(aet)2 (L-cys-N,S)](-) (aet = 2-aminoethanethiolate, L-cys = L-cysteinate) () and ΔLL -fac(S)-[Rh(aet)(L-cys-N,S)2 ](2-) were newly prepared by the equatorial preference of the carboxyl group in the coordinated L-cys ligand. The amide formation reaction of with 1,10-diaminodecane and polyallylamine gave the diamine-bridged dinuclear Rh(III) complex and the single-chain polymer-supported Rh(III) complex with retention of the ΔL configuration of , respectively. These Rh(III) complexes reacted with Co(III) or Co(II) to give the linear-type trinuclear structure with the S-bridged Co(III) center and the two Δ-Rh(III) terminal moieties. The polymer-supported Rh(III) complex was applied not only to the CD spectropolarimetric detection and determination of a trace of precious metal ions such as Au(III), Pt(II), and Pd(II) but also to concentration and extraction of these metal ions into the solid polymer phase. Chirality 28:85-91, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Bioremediation of trace organic compounds found in precious metals refineries' wastewaters: a review of potential options.

PubMed

Barbosa, V L; Tandlich, R; Burgess, J E

2007-07-01

Platinum group metal (PGM) refining processes produce large quantities of wastewater, which is contaminated with the compounds that make up the solvents/extractants mixtures used in the process. These compounds often include solvesso, beta-hydroxyxime, amines, amides and methyl isobutyl ketone. A process to clean up PGM refinery wastewaters so that they could be re-used in the refining process would greatly contribute to continual water storage problems and to cost reduction for the industry. Based on the concept that organic compounds that are produced biologically can be destroyed biologically, the use of biological processes for the treatment of organic compounds in other types of waste stream has been favoured in recent years, owing to their low cost and environmental acceptability. This review examines the available biotechnologies and their effectiveness for treating compounds likely to be contained in precious metal extraction process wastewaters. The processes examined include: biofilters, fluidized bed reactors, trickle-bed bioreactors, bioscrubbers, two-phase partitioning bioreactors, membrane bioreactors and activated sludge. Although all processes examined showed adequate to excellent removal of organic compounds from various gaseous and fewer liquid waste streams, there was a variation in their effectiveness. Variations in performance of laboratory-scale biological processes are probably due to the inherent change in the microbial population composition due to selection pressure, environmental conditions and the time allowed for adaptation to the organic compounds. However, if these factors are disregarded, it can be established that activated sludge and membrane bioreactors are the most promising processes for use in the treatment of PGM refinery wastewaters.

The Administration of Tibetan Precious Pills

PubMed Central

Czaja, Olaf

2016-01-01

Precious pills represent a special kind of Tibetan drug that once was, and still is, highly sought after by Tibetan, Chinese, and Mongolian patients. Such pills are generally taken as a potent prophylactic remedy, and can be used to cure various diseases. The present study seeks to discuss the dispensation and efficacy of precious pills according to the presentations of historical Tibetan medical scholars. Several treatises dealing with these instructions will be analysed, thereby revealing their underlying concepts, and highlighting their points of both general consensus and disagreement. The analysis of these detailed instructions will reveal the fact that these precious pills were not merely given to a patient but, in order to ensure their full efficacy, involved an elaborate regimen concerning three chronological periods: (1) the time of preparation, (2) the time of dispensation, and (3) the time after dispensation. Thus the present study surveys not only the ritual empowerment of drugs in Tibetan medicine, but also the importance of social relationships between doctors and patients in Tibetan medical history. PMID:27980504

50 CFR 665.260 - Hawaii precious coral fisheries. [Reserved

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Hawaii precious coral fisheries. [Reserved] 665.260 Section 665.260 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Hawaii Fisheries § 665.260 Hawaii precious coral fisheries. [Reserved] ...

50 CFR 665.260 - Hawaii precious coral fisheries. [Reserved

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Hawaii precious coral fisheries. [Reserved] 665.260 Section 665.260 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Hawaii Fisheries § 665.260 Hawaii precious coral fisheries. [Reserved] ...

50 CFR 665.260 - Hawaii precious coral fisheries. [Reserved

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Hawaii precious coral fisheries. [Reserved] 665.260 Section 665.260 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Hawaii Fisheries § 665.260 Hawaii precious coral fisheries. [Reserved] ...

50 CFR 665.260 - Hawaii precious coral fisheries. [Reserved

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Hawaii precious coral fisheries. [Reserved] 665.260 Section 665.260 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Hawaii Fisheries § 665.260 Hawaii precious coral fisheries. [Reserved] ...

50 CFR 665.260 - Hawaii precious coral fisheries. [Reserved

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Hawaii precious coral fisheries. [Reserved] 665.260 Section 665.260 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... Hawaii Fisheries § 665.260 Hawaii precious coral fisheries. [Reserved] ...

Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

NASA Technical Reports Server (NTRS)

Liu, Donhang; Fetter, Lula; Meinhold, Bruce

2015-01-01

A multi-layer ceramic capacitor (MLCC) is a high-temperature (1350C typical) co-fired ceramic monolithic that is composed of many layers of alternately stacked oxide-based dielectric and internal metal electrodes. To make the dielectric layers insulating and the metal electrode layers conducting, only highly oxidation-resistant precious metals, such as platinum, palladium, and silver, can be used for the co-firing of insulating MLCCs in a regular air atmosphere. MLCCs made with precious metals as internal electrodes and terminations are called precious-metal electrode (PME) capacitors. Currently, all military and space-level applications only address the use of PME capacitors.

50 CFR 665.460 - Mariana precious coral fisheries. [Reserved

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Mariana precious coral fisheries. [Reserved] 665.460 Section 665.460 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Mariana Archipelago Fisheries § 665.460 Mariana precious coral fisheries. [Reserved] ...

50 CFR 665.460 - Mariana precious coral fisheries. [Reserved

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Mariana precious coral fisheries. [Reserved] 665.460 Section 665.460 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Mariana Archipelago Fisheries § 665.460 Mariana precious coral fisheries. [Reserved] ...

50 CFR 665.460 - Mariana precious coral fisheries. [Reserved

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Mariana precious coral fisheries. [Reserved] 665.460 Section 665.460 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Mariana Archipelago Fisheries § 665.460 Mariana precious coral fisheries. [Reserved] ...

50 CFR 665.460 - Mariana precious coral fisheries. [Reserved

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Mariana precious coral fisheries. [Reserved] 665.460 Section 665.460 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Mariana Archipelago Fisheries § 665.460 Mariana precious coral fisheries. [Reserved] ...

50 CFR 665.460 - Mariana precious coral fisheries. [Reserved

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Mariana precious coral fisheries. [Reserved] 665.460 Section 665.460 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC Mariana Archipelago Fisheries § 665.460 Mariana precious coral fisheries. [Reserved] ...

76 FR 67793 - Notification of Expanded Pricing Grid for Precious Metals Products Containing Platinum and Gold...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-02

... DEPARTMENT OF THE TREASURY United States Mint Notification of Expanded Pricing Grid for Precious... in the Federal Register on January 6, 2009, outlining the new pricing methodology for numismatic... considerably, and is approaching the upper bracket of the pricing grid. As a result, it is necessary to expand...

50 CFR 665.660 - PRIA precious coral fisheries. [Reserved

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false PRIA precious coral fisheries. [Reserved] 665.660 Section 665.660 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... Pacific Remote Island Area Fisheries § 665.660 PRIA precious coral fisheries. [Reserved] ...

50 CFR 665.660 - PRIA precious coral fisheries. [Reserved

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false PRIA precious coral fisheries. [Reserved] 665.660 Section 665.660 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... Pacific Remote Island Area Fisheries § 665.660 PRIA precious coral fisheries. [Reserved] ...

50 CFR 665.660 - PRIA precious coral fisheries. [Reserved

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false PRIA precious coral fisheries. [Reserved] 665.660 Section 665.660 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... Pacific Remote Island Area Fisheries § 665.660 PRIA precious coral fisheries. [Reserved] ...

50 CFR 665.660 - PRIA precious coral fisheries. [Reserved

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false PRIA precious coral fisheries. [Reserved] 665.660 Section 665.660 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... Pacific Remote Island Area Fisheries § 665.660 PRIA precious coral fisheries. [Reserved] ...

50 CFR 665.660 - PRIA precious coral fisheries. [Reserved

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false PRIA precious coral fisheries. [Reserved] 665.660 Section 665.660 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC... Pacific Remote Island Area Fisheries § 665.660 PRIA precious coral fisheries. [Reserved] ...

Precious metal-bearing epithermal deposits in western Patagonia (NE Lago Fontana region), Argentina

NASA Astrophysics Data System (ADS)

Lanfranchini, Mabel Elena; Etcheverry, Ricardo Oscar; de Barrio, Raúl Ernesto; Recio Hernández, Clemente

2013-04-01

Precious metal-bearing quartz veins occur at the northeastern sector of the Lago Fontana region in southwestern Argentina, within the context of the Andean continental magmatic arc environment. The deposits and their associated alteration zones are spatially related to a Cretaceous calc-alkaline magmatism represented by silicic dikes and hypabyssal intrusions, and hosted by a Late Jurassic to Cretaceous volcano-sedimentary sequence. The veins and related veinlets crop out discontinuously, in general terms in a NW-SE belt. The primary vein mineral assemblage is composed mostly of pyrite ± galena ± chalcopyrite > hematite ± arsenopyrite in silica gangue minerals. Chemical analyses of grab samples from selected quartz veins show as much as 5.7 ppm Au and 224 ppm Ag, as well as elevated Pb, Cu, and Zn. Hydrothermal fluids caused an innermost silicification and adularia-sericite alteration assemblage, and an external propylitic halo. Sulfur isotope values measured for sulfides (δSS from -1.90 to +1.56‰), and oxygen and hydrogen isotopes measured on quartz crystals and extracted primary fluid inclusion waters (δOO = -2.85 to +5.40‰; δDO = -106.0 to -103.4‰) indicate that mineralization probably formed from magmatic fluids, which were mixed with meteoric waters. Also, fluid inclusion data from quartz veins point out that these fluids had low salinity (1.7-4.2 wt% NaCl equiv.), and temperatures of homogenization between 180 and 325 °C. Mineralogical, petrographic and geochemical features for mineralized surface exposures indicate a typical adularia-sericite, low sulfidation epithermal system in the Lago Fontana area that represents a promising target for further exploration programs.

Formation of the metal and energy-carrier price clusters on the world market of nonferrous metals in the postcrisis period

NASA Astrophysics Data System (ADS)

Bogdanov, S. V.; Shevelev, I. M.; Chernyi, S. A.

2016-06-01

The laws of formation of price clusters are revealed upon statistical processing of the data on changing the quotation prices of nonferrous and precious metals, oil, black oil, gasoline, and natural gas in the postcrisis period from January 1, 2009 to November 1, 2013. It is found that the metal prices entering in the price cluster of nonferrous metals most strongly affect the formation of the nonferrous metal price and that the prices of precious metals and energy carriers correct the exchange price of the metal to some extent but do not determine its formation. Equations are derived to calculate the prices. The results of calculation by these equations agree well with the real nonferrous metal prices in the near future.

50 CFR 665.160 - American Samoa precious coral fisheries. [Reserved

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false American Samoa precious coral fisheries. [Reserved] 665.160 Section 665.160 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC American Samoa Fisheries § 665.160 American Samoa precious coral fisheries. [Reserved] ...

50 CFR 665.160 - American Samoa precious coral fisheries. [Reserved

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false American Samoa precious coral fisheries. [Reserved] 665.160 Section 665.160 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC American Samoa Fisheries § 665.160 American Samoa precious coral fisheries. [Reserved] ...

50 CFR 665.160 - American Samoa precious coral fisheries. [Reserved

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false American Samoa precious coral fisheries. [Reserved] 665.160 Section 665.160 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC American Samoa Fisheries § 665.160 American Samoa precious coral fisheries. [Reserved] ...

50 CFR 665.160 - American Samoa precious coral fisheries. [Reserved

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false American Samoa precious coral fisheries. [Reserved] 665.160 Section 665.160 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC American Samoa Fisheries § 665.160 American Samoa precious coral fisheries. [Reserved] ...

50 CFR 665.160 - American Samoa precious coral fisheries. [Reserved

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false American Samoa precious coral fisheries. [Reserved] 665.160 Section 665.160 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... PACIFIC American Samoa Fisheries § 665.160 American Samoa precious coral fisheries. [Reserved] ...

Rare earth and precious elements in the urban sewage sludge and lake surface sediments under anthropogenic influence in the Republic of Benin.

PubMed

Yessoufou, Arouna; Ifon, Binessi Edouard; Suanon, Fidèle; Dimon, Biaou; Sun, Qian; Dedjiho, Comlan Achille; Mama, Daouda; Yu, Chang-Ping

2017-11-09

Nowadays, sewage sludge and water bodies are subjected to heavy pollution due to rapid population growth and urbanization. Heavy metal pollution represents one of the main challenges threatening our environment and the ecosystem. The present work aims to evaluate the contamination state of the sewage sludge and lake sediments in the Republic of Benin. Twenty metallic elements including 15 rare earth elements (Eu, Sb, Cs, Nd, Pr, Gd, La, Ce, Tb, Sm, Dy, Ho, Eu, Yb, and Lu) and five precious elements (Ag, Au, Pd, Pt, and Ru) were investigated using inductive plasma-mass spectrometry. Results showed broad range concentrations of the elements. Ce, La, and Nd were present in both sediments and sewage sludge at concentrations ranging 5.80-41.30 mg/kg dry matter (DM), 3.23-15.60 mg/kg DM, and 2.74-19.26 mg/kg DM, respectively. Pr, Sm, Gd, Tb, Dy, Eu, Er, Yb, Cs, Ho, and Tm concentrations were lower (0.02-5.94 mg/kg DM). Among precious elements, Ag was detected at the highest concentration in all sites (0.43-4.72 mg/kg DM), followed by Pd (0.20-0.57 mg/kg DM) and Au (0.01-0.57 mg/kg DM). Ru and Pt concentrations were < 0.20 mg/kg DM in all samples. Pollution indices and enrichment factor indicated a strong to severe enrichment of the elements, mainly Ce and precious elements in both sediments and sewage sludge. This revealed a growing anthropogenic input which was also implied by principal component analysis. The evaluation of pollution loading index (PLI) indicated a moderate to strong contamination (0.12 ≤ PLI ≤ 0.58; 37 ≤ PLI ≤ 114, respectively, for rare earth elements and precious elements), while the degree of contamination indicated a moderate polymetallic contamination for rare earth elements and significant contamination for precious elements.

Novel Structured Metal Bipolar Plates for Low Cost Manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Conghua

Bipolar plates are an important component in fuel cell stacks and accounts for more than 75% of stack weight and volume, and 20% of the stack cost. The technology development of metal bipolar plates can effectively reduce the fuel cells stack weight and volume over 50%. The challenge is to protect metal plate from corrosion at low cost for the broad commercial applications. While most of today’s PEM fuel cell metallic bipolar plate technologies use some precious metal, the focus of this SBIR project is to develop a low cost, novel nano-structured metal bipolar plate coating technology without using anymore » precious metal. The technology must meet the performance and cost requirements for automobile applications.« less

Effective and selective recovery of gold and palladium ions from metal wastewater using a sulfothermophilic red alga, Galdieria sulphuraria.

PubMed

Ju, Xiaohui; Igarashi, Kensuke; Miyashita, Shin-Ichi; Mitsuhashi, Hiroaki; Inagaki, Kazumi; Fujii, Shin-Ichiro; Sawada, Hitomi; Kuwabara, Tomohiko; Minoda, Ayumi

2016-07-01

The demand for precious metals has increased in recent years. However, low concentrations of precious metals dissolved in wastewater are yet to be recovered because of high operation costs and technical problems. The unicellular red alga, Galdieria sulphuraria, efficiently absorbs precious metals through biosorption. In this study, over 90% of gold and palladium could be selectively recovered from aqua regia-based metal wastewater by using G. sulphuraria. These metals were eluted from the cells into ammonium solutions containing 0.2M ammonium salts without other contaminating metals. The use of G. sulphuraria is an eco-friendly and cost-effective way of recovering low concentrations of gold and palladium discarded in metal wastewater. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Prospecting for Precious Metals in Ultra-Metal-Poor Stars

NASA Astrophysics Data System (ADS)

French, R. S.

2000-05-01

The chemical compositions of the most metal-poor halo stars are living records of the very early nucleosynthetic history of the Galaxy. Only a few prior generations, if not a single one, of element-donating supernovae could have been responsible for the heavy elements observed in ultra-metal-poor (UMP; [Fe/H] < --2.5) stars. Abundances of the heavy neutron-capture elements (Z > 30) can yield direct information about the supernova progenitors to UMP stars, and abundances of unstable thorium and uranium (Z = 90, 92) can potentially provide age estimates for the Galactic halo. Already, many studies have demonstrated that abundances of rare-earth elements (56 <= Z <= 72) in UMP stars are completely consistent with their production in rapid neutron-capture synthesis (r-process) events, usually believed to occur during supernovae explosions. Therefore, mapping the entire abundance pattern of UMP stars is of significant interest. In particular, abundances of the most massive stable elements (Os -> Pb or 76 <= Z <= 82) could provide crucial information about the so-called ``third r-process peak,'' and are critical to the radioactive-dating technique that uses unstable thorium as a chronometer. Until recently, abundance determinations for these elements have been virtually non-existent, as the strongest relevant transitions lay in the vacuum UV, inaccessible to ground-based observation. The availability of high-resolution space-based spectrometers has opened up new regions of spectral coverage, including precisely the range in wavelength needed to make these sensitive measurements. We have undertaken a study of about 10 metal-poor halo giants to determine the abundances of several of the heaviest neutron-capture elements including platinum, osmium, lead, and gold. Preliminary results indicate that the abundance pattern of heavy neutron-capture elements (56 <= Z <= 82) in UMP stars does mimic a scaled solar system r-process. Thus, the ability to estimate the initial

New insights into non-precious metal catalyst layer designs for proton exchange membrane fuel cells: Improving performance and stability

NASA Astrophysics Data System (ADS)

Banham, Dustin; Kishimoto, Takeaki; Sato, Tetsutaro; Kobayashi, Yoshikazu; Narizuka, Kumi; Ozaki, Jun-ichi; Zhou, Yingjie; Marquez, Emil; Bai, Kyoung; Ye, Siyu

2017-03-01

The activity of non-precious metal catalysts (NPMCs) has now reached a stage at which they can be considered as possible alternatives to Pt for some proton exchange membrane fuel cell (PEMFC) applications. However, despite significant efforts over the past 50 years on catalyst development, only limited studies have been performed on NPMC-based cathode catalyst layer (CCL) designs. In this work, an extensive ionomer study is performed to investigate the impact of ionomer equivalent weight on performance, which has uncovered two crucial findings. Firstly, it is demonstrated that beyond a critical CCL conductance, no further improvement in performance is observed. The procedure used to determine this critical conductance can be used by other researchers in this field to aid in their design of high performing NPMC-based CCLs. Secondly, it is shown that the stability of NPMC-based CCLs can be improved through the use of low equivalent weight ionomers. This represents a completely unexplored pathway for further stability improvements, and also provides new insights into the possible degradation mechanisms occurring in NPMC-based CCLs. These findings have broad implications on all future NPMC-based CCL designs.

Supply and demand of some critical metals and present status of their recycling in WEEE.

PubMed

Zhang, Shengen; Ding, Yunji; Liu, Bo; Chang, Chein-Chi

2017-07-01

New development and technological innovations make electrical and electronic equipment (EEE) more functional by using an increasing number of metals, particularly the critical metals (e.g. rare and precious metals) with specialized properties. As millions of people in emerging economies adopt a modern lifestyle, the demand for critical metals is soaring. However, the increasing demand causes the crisis of their supply because of their simple deficiency in the Earth's crust or geopolitical constraints which might create political issues for their supply. This paper focuses on the sustainable supply of typical critical metals (indium, rare earth elements (REEs), lithium, cobalt and precious metals) through recycling waste electrical and electronic equipment (WEEE). To illuminate this issue, the production, consumption, expected future demand, current recycling situation of critical metals, WEEE management and their recycling have been reviewed. We find that the demand of indium, REEs, lithium and cobalt in EEE will continuously increasing, while precious metals are decreasing because of new substitutions with less or even without precious metals. Although the generation of WEEE in 2014 was about 41.9 million tons (Mt), just about 15% (6.5 Mt) was treated environmentally. The inefficient collection of WEEE is the main obstacle to relieving the supply risk of critical metals. Furthermore, due to the widespread use in low concentrations, such as indium, their recycling is not just technological problem, but economic feasibility is. Finally, relevant recommendations are point out to address these issues. Copyright © 2017 Elsevier Ltd. All rights reserved.

High temperature, oxidation resistant noble metal-Al alloy thermocouple

NASA Technical Reports Server (NTRS)

Smialek, James L. (Inventor); Gedwill, Michael G. (Inventor)

1994-01-01

A thermocouple is disclosed. The thermocouple is comprised of an electropositive leg formed of a noble metal-Al alloy and an electronegative leg electrically joined to form a thermocouple junction. The thermocouple provides for accurate and reproducible measurement of high temperatures (600 - 1300 C) in inert, oxidizing or reducing environments, gases, or vacuum. Furthermore, the thermocouple circumvents the need for expensive, strategic precious metals such as rhodium as a constituent component. Selective oxidation of rhodium is also thereby precluded.

Biorefining of precious metals from wastes: an answer to manufacturing of cheap nanocatalysts for fuel cells and power generation via an integrated biorefinery?

PubMed

Yong, Ping; Mikheenko, Iryna P; Deplanche, Kevin; Redwood, Mark D; Macaskie, Lynne E

2010-12-01

Bio-manufacturing of nano-scale palladium was achieved via enzymatically-mediated deposition of Pd from solution using Desulfovibrio desulfuricans, Escherichia coli and Cupriavidus metallidurans. Dried 'Bio-Pd' materials were sintered, applied onto carbon papers and tested as anodes in a proton exchange membrane (PEM) fuel cell for power production. At a Pd(0) loading of 25% by mass the fuel cell power using Bio-Pd( D. desulfuricans ) (positive control) and Bio-Pd( E. coli ) (negative control) was ~140 and ~30 mW respectively. Bio-Pd( C. metallidurans ) was intermediate between these with a power output of ~60 mW. An engineered strain of E. coli (IC007) was previously reported to give a Bio-Pd that was >3-fold more active than Bio-Pd of the parent E. coli MC4100 (i.e. a power output of >110 mW). Using this strain, a mixed metallic catalyst was manufactured from an industrial processing waste. This 'Bio-precious metal' ('Bio-PM') gave ~68% of the power output as commercial Pd(0) and ~50% of that of Bio-Pd( D. desulfuricans ) when used as fuel cell anodic material. The results are discussed in relation to integrated bioprocessing for clean energy.

A hydrometallurgical process for recovering total metal values from waste monolithic ceramic capacitors.

PubMed

Prabaharan, G; Barik, S P; Kumar, B

2016-06-01

A hydrometallurgical process for recovering the total metal values from waste monolithic ceramic capacitors was investigated. The process parameters such as time, temperature, acid concentration, hydrogen peroxide concentration and other reagents (amount of zinc dust and sodium formate) were optimized. Base metals such as Ba, Ti, Sn, Cu and Ni are leached out in two stages using HCl in stage 1 and HCl with H2O2 in stage 2. More than 99% of leaching efficiency for base metals (Cu, Ni, Ba, Ti and Sn) was achieved. Precious metals such as Au and Pd are leached out using aquaregia and nitric acid was used for the leaching of Ag. Base metals (Ba, Ti, Sn, Cu and Ni) are recovered by selective precipitation using H2SO4 and NaOH solution. In case of precious metals, Au and Pd from the leach solution were precipitated out using sodium metabisulphite and sodium formate, respectively. Sodium chloride was used for the precipitation of Ag from leach solution. Overall recovery for base metals and precious metals are 95% and 92%, respectively. Based on the results of the present study, a process flow diagram was proposed for commercial application. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydrometallurgical Recovery of Metals from Large Printed Circuit Board Pieces.

PubMed

Jadhav, U; Hocheng, H

2015-09-29

The recovery of precious metals from waste printed circuit boards (PCBs) is an effective recycling process. This paper presents a promising hydrometallurgical process to recover precious metals from waste PCBs. To simplify the metal leaching process, large pieces of PCBs were used instead of a pulverized sample. The chemical coating present on the PCBs was removed by sodium hydroxide (NaOH) treatment prior to the hydrometallurgical treatment. Among the leaching reagents examined, hydrochloric acid (HCl) showed great potential for the recovery of metals. The HCl-mediated leaching of waste PCBs was investigated over a range of conditions. Increasing the acid concentration decreased the time required for complete metal recovery. The shaking speed showed a pronounced positive effect on metal recovery, but the temperature showed an insignificant effect. The results showed that 1 M HCl recovered all of the metals from 4 cm × 4 cm PCBs at room temperature and 150 rpm shaking speed in 22 h.

Hydrometallurgical Recovery of Metals from Large Printed Circuit Board Pieces

PubMed Central

Jadhav, U.; Hocheng, H.

2015-01-01

The recovery of precious metals from waste printed circuit boards (PCBs) is an effective recycling process. This paper presents a promising hydrometallurgical process to recover precious metals from waste PCBs. To simplify the metal leaching process, large pieces of PCBs were used instead of a pulverized sample. The chemical coating present on the PCBs was removed by sodium hydroxide (NaOH) treatment prior to the hydrometallurgical treatment. Among the leaching reagents examined, hydrochloric acid (HCl) showed great potential for the recovery of metals. The HCl-mediated leaching of waste PCBs was investigated over a range of conditions. Increasing the acid concentration decreased the time required for complete metal recovery. The shaking speed showed a pronounced positive effect on metal recovery, but the temperature showed an insignificant effect. The results showed that 1 M HCl recovered all of the metals from 4 cm × 4 cm PCBs at room temperature and 150 rpm shaking speed in 22 h. PMID:26415827

Chronic beryllium disease in a precious metal refinery. Clinical epidemiologic and immunologic evidence for continuing risk from exposure to low level beryllium fumes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cullen, M.R.; Kominsky, J.R.; Rossman, M.D.

1987-01-01

Five workers at a precious metal refinery developed granulomatous lung disease between 1972 and 1985. The original diagnosis was sarcoidosis, but 4 of the workers were subsequently proved to have hypersensitivity to beryllium by in vitro proliferative responses of lymphocytes obtained by bronchoalveolar lavage. Review of medical records of coworkers and extensive industrial hygiene surveillance of the plant demonstrated that 4 cases occurred in the furnace area where air concentrations of beryllium fume were consistently below the permissible exposure limit of 2 micrograms/M3. A single case has been recognized from parts of the refinery where exposures to cold beryllium dustmore » often exceeded the standard by as much as 20-fold. These data demonstrate that chronic beryllium disease still occurs and confirm the importance of specific immunologic testing in patients suspected of having sarcoidosis but with potential exposure to beryllium. The data raise concern about the adequacy of modern industrial controls, especially in the setting of exposure to highly respirable beryllium fumes.« less

Effect of market factors on the short-time pricing of stock-exchange metals

NASA Astrophysics Data System (ADS)

Bogdanov, S. V.; Shevelev, I. M.; Chernyi, S. A.

2016-12-01

The open trade on the world market is estimated using information of one-day exchange prices of nonferrous and precious metals, oil, reduced crude, and gasoline and the main world stock indices in the time period from January 1, 2009 to December 31, 2015. It is found that the short-term changes in the prices of nonferrous metals are determined by the prices on the metal market. The changes in the prices of energy carriers and the stock trade on the stock market weakly influence the pricing of nonferrous and precious metals. The prices of metals depend on the situation during trade on commodity exchanges, and the stock market indirectly influences the exchange prices of metals through changes in the share prices of the companies that produce copper, aluminum, and zinc.

Cobalt and precious metals in sulphides of peridotite xenoliths and inferences concerning their distribution according to geodynamic environment: A case study from the Scottish lithospheric mantle

NASA Astrophysics Data System (ADS)

Hughes, Hannah S. R.; McDonald, Iain; Faithfull, John W.; Upton, Brian G. J.; Loocke, Matthew

2016-01-01

Abundances of precious metals and cobalt in the lithospheric mantle are typically obtained by bulk geochemical analyses of mantle xenoliths. These elements are strongly chalcophile and the mineralogy, texture and trace element composition of sulphide phases in such samples must be considered. In this study we assess the mineralogy, textures and trace element compositions of sulphides in spinel lherzolites from four Scottish lithospheric terranes, which provide an ideal testing ground to examine the variability of sulphides and their precious metal endowments according to terrane age and geodynamic environment. Specifically we test differences in sulphide composition from Archaean-Palaeoproterozoic cratonic sub-continental lithospheric mantle (SCLM) in northern terranes vs. Palaeozoic lithospheric mantle in southern terranes, as divided by the Great Glen Fault (GGF). Cobalt is consistently elevated in sulphides from Palaeozoic terranes (south of the GGF) with Co concentrations > 2.9 wt.% and Co/Ni ratios > 0.048 (chondrite). In contrast, sulphides from Archaean cratonic terranes (north of the GGF) have low abundances of Co (< 3600 ppm) and low Co/Ni ratios (< 0.030). The causes for Co enrichment remain unclear, but we highlight that globally significant Co mineralisation is associated with ophiolites (e.g., Bou Azzer, Morocco and Outokumpu, Finland) or in oceanic peridotite-floored settings at slow-spreading ridges. Thus we suggest an oceanic affinity for the Co enrichment in the southern terranes of Scotland, likely directly related to the subduction of Co-enriched oceanic crust during the Caledonian Orogeny. Further, we identify a distinction between Pt/Pd ratio across the GGF, such that sulphides in the cratonic SCLM have Pt/Pd ≥ chondrite whilst Palaeozoic sulphides have Pt/Pd < chondrite. We observe that Pt-rich sulphides with discrete Pt-minerals (e.g., PtS) are associated with carbonate and phosphates in two xenolith suites north of the GGF. This three

Molecular metal-Nx centres in porous carbon for electrocatalytic hydrogen evolution

NASA Astrophysics Data System (ADS)

Liang, Hai-Wei; Brüller, Sebastian; Dong, Renhao; Zhang, Jian; Feng, Xinliang; Müllen, Klaus

2015-08-01

Replacement of precious platinum with efficient and low-cost catalysts for electrocatalytic hydrogen evolution at low overpotentials holds tremendous promise for clean energy devices. Here we report a novel type of robust cobalt-nitrogen/carbon catalyst for the hydrogen evolution reaction (HER) that is prepared by the pyrolysis of cobalt-N4 macrocycles or cobalt/o-phenylenediamine composites and using silica colloids as a hard template. We identify the well-dispersed molecular CoNx sites on the carbon support as the active sites responsible for the HER. The CoNx/C catalyst exhibits extremely high turnover frequencies per cobalt site in acids, for example, 0.39 and 6.5 s-1 at an overpotential of 100 and 200 mV, respectively, which are higher than those reported for other scalable non-precious metal HER catalysts. Our results suggest the great promise of developing new families of non-precious metal HER catalysts based on the controlled conversion of homogeneous metal complexes into solid-state carbon catalysts via economically scalable protocols.

Highly porous non-precious bimetallic electrocatalysts for efficient hydrogen evolution

DOE PAGES

Lu, Qi; Hutchings, Gregory S.; Yu, Weiting; ...

2015-03-16

One of the key components of carbon dioxide-free hydrogen production is a robust and efficient non-precious metal catalyst for the hydrogen evolution reaction. We report that a hierarchical nanoporous copper-titanium bimetallic electrocatalyst is able to produce hydrogen from water under a mild overpotential at more than twice the rate of state-of-the- art carbon-supported platinum catalyst. Although both copper and titanium are known to be poor hydrogen evolution catalysts, the combination of these two elements creates unique copper-copper-titanium hollow sites, which have a hydrogen-binding energy very similar to that of platinum, resulting in an exceptional hydrogen evolution activity. Moreover, the hierarchicalmore » porosity of the nanoporous-copper titanium catalyst also contributes to its high hydrogen evolution activity, because it provides a large-surface area for electrocatalytic hydrogen evolution, and improves the mass transport properties. Moreover, the catalyst is self-supported, eliminating the overpotential associated with the catalyst/support interface.« less

Catalyst Architecture for Stable Single Atom Dispersion Enables Site-Specific Spectroscopic and Reactivity Measurements of CO Adsorbed to Pt Atoms, Oxidized Pt Clusters, and Metallic Pt Clusters on TiO2.

PubMed

DeRita, Leo; Dai, Sheng; Lopez-Zepeda, Kimberly; Pham, Nicholas; Graham, George W; Pan, Xiaoqing; Christopher, Phillip

2017-10-11

Oxide-supported precious metal nanoparticles are widely used industrial catalysts. Due to expense and rarity, developing synthetic protocols that reduce precious metal nanoparticle size and stabilize dispersed species is essential. Supported atomically dispersed, single precious metal atoms represent the most efficient metal utilization geometry, although debate regarding the catalytic activity of supported single precious atom species has arisen from difficulty in synthesizing homogeneous and stable single atom dispersions, and a lack of site-specific characterization approaches. We propose a catalyst architecture and characterization approach to overcome these limitations, by depositing ∼1 precious metal atom per support particle and characterizing structures by correlating scanning transmission electron microscopy imaging and CO probe molecule infrared spectroscopy. This is demonstrated for Pt supported on anatase TiO 2 . In these structures, isolated Pt atoms, Pt iso , remain stable through various conditions, and spectroscopic evidence suggests Pt iso species exist in homogeneous local environments. Comparing Pt iso to ∼1 nm preoxidized (Pt ox ) and prereduced (Pt metal ) Pt clusters on TiO 2 , we identify unique spectroscopic signatures of CO bound to each site and find CO adsorption energy is ordered: Pt iso ≪ Pt metal < Pt ox . Pt iso species exhibited a 2-fold greater turnover frequency for CO oxidation than 1 nm Pt metal clusters but share an identical reaction mechanism. We propose the active catalytic sites are cationic interfacial Pt atoms bonded to TiO 2 and that Pt iso exhibits optimal reactivity because every atom is exposed for catalysis and forms an interfacial site with TiO 2 . This approach should be generally useful for studying the behavior of supported precious metal atoms.

An investigation of trends in precious metal and copper content of RAM modules in WEEE: Implications for long term recycling potential.

PubMed

Charles, Rhys Gareth; Douglas, Peter; Hallin, Ingrid Liv; Matthews, Ian; Liversage, Gareth

2017-02-01

Precious metal (PM) and copper content of dynamic-RAM modules placed on the market during 1991-2008 has been analysed by AAS following comminution and acid digestion. Linear regression analysis of compositional data ordered according to sample chronology was used to identify historic temporal trends in module composition resulting from changes in manufacturing practices, and to project future trends for use in more accurate assessment of future recycling potential. DRAM was found to be 'high grade' waste with: stable levels of gold and silver over time; 80% reduction in palladium content during 1991-2008; and 0.23g/module/year increase in copper content with a 75% projected increase from 2008 by 2020. The accuracy of future recycling potential projections for WEEE using current methods based on static compositional data from current devices is questionable due to likely changes in future device composition. The impact on recycling potential projections of waste laptops, smart phones, cell phones and tablets arising in Europe in 2020 resulting from a 75% increase in copper content is considered against existing projections using static compositional data. The results highlight that failing to consider temporal variations in PM content may result in significant discrepancies between projections and future recycling potential. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Leadership and Strategic Management: Keys to Institutional Priorities and Planning

ERIC Educational Resources Information Center

Taylor, James S.; de Lourdes Machado, Maria; Peterson, Marvin W.

2008-01-01

Allocating and managing resources have always been important cornerstones of institutional leadership. Institutional resources include financial, physical and human components. Even in the best of times, it is a challenge to do this effectively. In times of diminished and shrinking resources, distributing these precious commodities across the…

Method for extracting copper, silver and related metals

DOEpatents

Moyer, B.A.; McDowell, W.J.

1987-10-23

A process for selectively extracting precious metals such as silver and gold concurrent with copper extraction from aqueous solutions containing the same. The process utilizes tetrathiamacrocycles and high molecular weight organic acids that exhibit a synergistic relationship when complexing with certain metal ions thereby removing them from ore leach solutions.

Method for extracting copper, silver and related metals

DOEpatents

Moyer, Bruce A.; McDowell, W. J.

1990-01-01

A process for selectively extracting precious metals such as silver and gold concurrent with copper extraction from aqueous solutions containing the same. The process utilizes tetrathiamacrocycles and high molecular weight organic acids that exhibit a synergistic relationship when complexing with certain metal ions thereby removing them from ore leach solutions.

Reduced graphene oxide supported MnS nanotubes hybrid as a novel non-precious metal electrocatalyst for oxygen reduction reaction with high performance

NASA Astrophysics Data System (ADS)

Tang, Yongfu; Chen, Teng; Guo, Wenfeng; Chen, Shunji; Li, Yanshuai; Song, Jianzheng; Chang, Limin; Mu, Shichun; Zhao, Yufeng; Gao, Faming

2017-09-01

Electronic structure of Mn cations, electric conductivity of active materials and three dimensional structure for mass transport play vital roles in the electrocatalytic activity of Mn-based electrocatalysts for oxygen reduction reaction (ORR). To construct efficient and robust Mn-based electrocatalysts, MnS nanotubes anchored on reduced graphene oxide (MnS-NT@rGO) hybrid was synthesized and used as a novel non-precious metal electrocatalyst for ORR. The formation of nano-tubular structure, which offers more active sites and suitable channels for mass transport to enhance the electrocatalytic activity towards ORR, are carefully illustrated based on the core-dissolution/shell-recrystallization type Ostwald ripening effect. Tuned electronic structure of Mn cations, enhanced electric conductivity and suitable nano-tubular structure endow MnS-NT@rGO electrocatalyst comparative catalytic activity to commercial 20 wt % Pt/C in alkaline electrolyte. The MnS-NT@rGO electrocatalyst exhibits higher catalytic activity than rGO supported MnS nanoparticles (MnS-NP@rGO) and MnS nanotubes without rGO substrate (MnS-NT), as well as rGO supported Mn(OH)2 (Mn(OH)2@rGO) and rGO supported MnO (MnO@rGO). Moreover, the MnS-NT@rGO electrocatalyst shows superior durability and methanol tolerance to commercial Pt/C.

Cobalt/copper-decorated carbon nanofibers as novel non-precious electrocatalyst for methanol electrooxidation

PubMed Central

2014-01-01

In this study, Co/Cu-decorated carbon nanofibers are introduced as novel electrocatalyst for methanol oxidation. The introduced nanofibers have been prepared based on graphitization of poly(vinyl alcohol) which has high carbon content compared to many polymer precursors for carbon nanofiber synthesis. Typically, calcination in argon atmosphere of electrospun nanofibers composed of cobalt acetate tetrahydrate, copper acetate monohydrate, and poly(vinyl alcohol) leads to form carbon nanofibers decorated by CoCu nanoparticles. The graphitization of the poly(vinyl alcohol) has been enhanced due to presence of cobalt which acts as effective catalyst. The physicochemical characterization affirmed that the metallic nanoparticles are sheathed by thin crystalline graphite layer. Investigation of the electrocatalytic activity of the introduced nanofibers toward methanol oxidation indicates good performance, as the corresponding onset potential was small compared to many reported materials; 310 mV (vs. Ag/AgCl electrode) and a current density of 12 mA/cm2 was obtained. Moreover, due to the graphite shield, good stability was observed. Overall, the introduced study opens new avenue for cheap and stable transition metals-based nanostructures as non-precious catalysts for fuel cell applications. PMID:24387682

The Administration of Tibetan Precious Pills: Efficacy in Historical and Ritual Contexts.

PubMed

Czaja, Olaf

2015-01-01

Precious pills represent a special kind of Tibetan drug that once was, and still is, highly sought after by Tibetan, Chinese, and Mongolian patients. Such pills are generally taken as a potent prophylactic remedy, and can be used to cure various diseases. The present study seeks to discuss the dispensation and efficacy of precious pills according to the presentations of historical Tibetan medical scholars. Several treatises dealing with these instructions will be analysed, thereby revealing their underlying concepts, and highlighting their points of both general consensus and disagreement. The analysis of these detailed instructions will reveal the fact that these precious pills were not merely given to a patient but, in order to ensure their full efficacy, involved an elaborate regimen concerning three chronological periods: (1) the time of preparation, (2) the time of dispensation, and (3) the time after dispensation. Thus the present study surveys not only the ritual empowerment of drugs in Tibetan medicine, but also the importance of social relationships between doctors and patients in Tibetan medical history.

DOE Award No. DE-FC36-03GO13108 NOVEL NON-PRECIOUS METAL CATALYSTS FOR PEMFC: CATALYST SELECTION THROUGH MOLECULAR MODELING AND DURABILITY STUDIES Final Report (September 2003 – October 2008)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Branko N. Popov

2009-03-03

The objective of this project is to develop novel non-precious metal electrocatalysts for oxygen reduction reaction (ORR), and demonstrate the potential of the catalysts to perform at least as good as conventional Pt catalysts currently in use in polymer electrolyte membrane fuel cell (PEMFC) with a cost at least 50 % less than a target of 0.2 g (Pt loading)/peak kW and with durability > 2,000 h operation with less than 10 % power degradation. A novel nitrogen-modified carbon-based catalyst was obtained by modifying carbon black with nitrogen-containing organic precursor in the absence of transition metal precursor. The catalyst showsmore » the onset potential of approximately 0.76 V (NHE) for ORR and the amount of H2O2 of approximately 3% at 0.5 V (NHE). Furthermore, a carbon composite catalyst was achieved through the high-temperature pyrolysis of the precursors of transition metal (Co and Fe) and nitrogen supported on the nitrogen-modified carbon-based catalyst, followed by chemical post-treatment. This catalyst showed an onset potential for ORR as high as 0.87 V (NHE), and generated less than 1 % of H2O2. The PEM fuel cell exhibited a current density of 2.3 A cm-2 at 0.2 V for a catalyst loading of 6.0 mg cm-2. No significant performance degradation was observed for 480 h continuous operation. The characterization studies indicated that the metal-nitrogen chelate complexes decompose at the temperatures above 800 oC. During the pyrolysis, the transition metals facilitate the incorporation of pyridinic and graphitic nitrogen groups into the carbon matrix, and the carbon surface modified with nitrogen is active for ORR. In order to elucidate the role of transition metal precursor played in the formation of active sites in the non-precious metal catalysts, a novel ruthenium-based chelate (RuNx) catalyst was synthesized by using RuCl3 and propylene diammine as the Ru and N precursors, respectively, followed by high-temperature pyrolysis. This catalyst exhibited

DOE Award No. DE-FC36-03GO13108 NOVEL NON-PRECIOUS METAL CATALYSTS FOR PEMFC: CATALYST SELECTION THROUGH MOLECULAR MODELING AND DURABILITY STUDIES Final Report (September 2003 – October 2008)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Branko N. Popov

2009-02-20

The objective of this project is to develop novel non-precious metal electrocatalysts for oxygen reduction reaction (ORR), and demonstrate the potential of the catalysts to perform at least as good as conventional Pt catalysts currently in use in polymer electrolyte membrane fuel cell (PEMFC) with a cost at least 50 % less than a target of 0.2 g (Pt loading)/peak kW and with durability > 2,000 h operation with less than 10 % power degradation. A novel nitrogen-modified carbon-based catalyst was obtained by modifying carbon black with nitrogen-containing organic precursor in the absence of transition metal precursor. The catalyst showsmore » the onset potential of approximately 0.76 V (NHE) for ORR and the amount of H2O2 of approximately 3% at 0.5 V (NHE). Furthermore, a carbon composite catalyst was achieved through the high-temperature pyrolysis of the precursors of transition metal (Co and Fe) and nitrogen supported on the nitrogen-modified carbon-based catalyst, followed by chemical post-treatment. This catalyst showed an onset potential for ORR as high as 0.87 V (NHE), and generated less than 1 % of H2O2. The PEM fuel cell exhibited a current density of 2.3 A cm-2 at 0.2 V for a catalyst loading of 6.0 mg cm-2. No significant performance degradation was observed for 480 h continuous operation. The characterization studies indicated that the metal-nitrogen chelate complexes decompose at the temperatures above 800 oC. During the pyrolysis, the transition metals facilitate the incorporation of pyridinic and graphitic nitrogen groups into the carbon matrix, and the carbon surface modified with nitrogen is active for ORR. In order to elucidate the role of transition metal precursor played in the formation of active sites in the non-precious metal catalysts, a novel ruthenium-based chelate (RuNx) catalyst was synthesized by using RuCl3 and propylene diammine as the Ru and N precursors, respectively, followed by high-temperature pyrolysis. This catalyst exhibited

Separating and recycling metals from mixed metallic particles of crushed electronic wastes by vacuum metallurgy.

PubMed

Zhan, Lu; Xu, Zhenming

2009-09-15

During the treatment of electronic wastes, a crushing process is usually used to strip metals from various base plates. Several methods have been applied to separate metals from nonmetals. However, mixed metallic particles obtained from these processes are still a mixture of various metals, including some toxic heavy metals such as lead and cadmium. With emphasis on recovering copper and other precious metals, there have hitherto been no satisfactory methods to recover these toxic metals. In this paper, the criterion of separating metals from mixed metallic particles by vacuum metallurgy is built. The results show that the metals with high vapor pressure have been almost recovered completely, leading to a considerable reduction of environmental pollution. In addition, the purity of copper in mixed particles has been improved from about 80 wt % to over 98 wt %.

Cumulative effect of transition metals on nitrogen and fluorine co-doped graphite nanofibers: an efficient and highly durable non-precious metal catalyst for the oxygen reduction reaction.

PubMed

Peera, S Gouse; Arunchander, A; Sahu, A K

2016-08-14

Nitrogen and fluorine co-doped graphite nanofibers (N/F-GNF) and their cumulative effect with Fe and Co have been developed as an alternative non-precious metal catalyst for efficient oxygen reduction reaction (ORR) in acidic media. The synergistic effect between the doped hetero atoms and the co-ordinated Fe and Co towards ORR activity and durability of the catalyst is deeply investigated. A high ORR onset potential comparable with commercial Pt/C catalyst is observed with the Fe-Co/NF-GNF catalyst, which indicates that this catalyst is a potential alternative to Pt/C. A fivefold increase in mass activity is achieved by the Fe-Co/NF-GNF catalyst compared to the simple N/F-GNF catalyst, which endorses the significant role of transition metal atoms in enhancing ORR activity. The advanced Fe-Co/NF-GNF catalyst also exhibits complete tolerance to CH3OH and CO. The Fe-Co/NF-GNF catalyst also exhibits excellent durability towards the ORR with only a 10 mV negative shift in its half wave potential after a 10 000 repeated potential cycling test, whereas in the case of a commercial Pt/C catalyst there was an ∼110 mV negative shift under similar environmental conditions. More stringent corrosive test cycles were also performed by maintaining the cell as high as 1.4 V with a later decrease to 0.6 V vs. RHE for 300 cycles, which showed the excellent durability of the Fe-Co/NF-GNF catalyst in comparison with the Pt/C catalyst. XPS analysis of the Fe-Co/NF-GNF catalyst presents the ORR active chemical states of N (pyridinic-N and graphitic-N) and F (semi-ionic-F) and the co-ordinated sites of Fe and Co species with the dopants. The excellent performance and durability of the Fe-Co/NF-GNF catalyst is due to the synergistic effect between the hetero atoms dopants (N and F) and strong co-ordinating bonds of M-N-C, which protect the graphene layers around the metallic species and greatly mitigates the leaching of Co and Fe during the long term cycling test. The high activity

Metallogeny of precious and base metal mineralization in the Murchison Greenstone Belt, South Africa: indications from U-Pb and Pb-Pb geochronology

NASA Astrophysics Data System (ADS)

Jaguin, J.; Poujol, M.; Boulvais, P.; Robb, L. J.; Paquette, J. L.

2012-10-01

The 3.09 to 2.97 Ga Murchison Greenstone Belt is an important metallotect in the northern Kaapvaal Craton (South Africa), hosting several precious and base metal deposits. Central to the metallotect is the Antimony Line, striking ENE for over 35 km, which hosts a series of structurally controlled Sb-Au deposits. To the north of the Antimony Line, hosted within felsic volcanic rocks, is the Copper-Zinc Line where a series of small, ca. 2.97 Ga Cu-Zn volcanogenic massive sulfide (VMS)-type deposits occur. New data are provided for the Malati Pump gold mine, located at the eastern end of the Antimony Line. Crystallizations of a granodiorite in the Malati Pump Mine and of the Baderoukwe granodiorite are dated at 2,964 ± 7 and 2,970 ± 7 Ma, respectively (zircon U-Pb), while pyrite associated with gold mineralization yielded a Pb-Pb age of 2,967 ± 48 Ma. Therefore, granodiorite emplacement, sulfide mineral deposition and gold mineralization all happened at ca. 2.97 Ga. It is, thus, suggested that the major styles of orogenic Au-Sb and the Cu-Zn VMS mineralization in the Murchison Greenstone Belt are contemporaneous and that the formation of meso- to epithermal Au-Sb mineralization at fairly shallow levels was accompanied by submarine extrusion of felsic volcanic rocks to form associated Cu-Zn VMS mineralization.

16 CFR 23.24 - Misuse of the words “real,” “genuine,” “natural,” “precious,” etc.

Code of Federal Regulations, 2010 CFR

2010-01-01

... the words “real,” “genuine,” “natural,” “precious,” etc. It is unfair or deceptive to use the word “real,” “genuine,” “natural,” “precious,” “semi-precious,” or similar terms to describe any industry...

16 CFR 23.24 - Misuse of the words “real,” “genuine,” “natural,” “precious,” etc.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the words “real,” “genuine,” “natural,” “precious,” etc. It is unfair or deceptive to use the word “real,” “genuine,” “natural,” “precious,” “semi-precious,” or similar terms to describe any industry...

Supported molten-metal catalysts

DOEpatents

Datta, Ravindra; Singh, Ajeet; Halasz, Istvan; Serban, Manuela

2001-01-01

An entirely new class of catalysts called supported molten-metal catalysts, SMMC, which can replace some of the existing precious metal catalysts used in the production of fuels, commodity chemicals, and fine chemicals, as well as in combating pollution. SMMC are based on supporting ultra-thin films or micro-droplets of the relatively low-melting (<600.degree. C.), inexpensive, and abundant metals and semimetals from groups 1, 12, 13, 14, 15 and 16, of the periodic table, or their alloys and intermetallic compounds, on porous refractory supports, much like supported microcrystallites of the traditional solid metal catalysts. It thus provides orders of magnitude higher surface area than is obtainable in conventional reactors containing molten metals in pool form and also avoids corrosion. These have so far been the chief stumbling blocks in the application of molten metal catalysts.

A theoretical study on the mechanism of hydrogen evolution on non-precious partially oxidized nickel-based heterostructures for fuel cells.

PubMed

Pan, Xinju; Zhou, Gang

2018-03-28

It is desirable, yet challenging, to utilize non-precious metals instead of noble-metals as efficient catalysts in the renewable energy manufacturing industry. Using first principles calculations, we study the structural characteristics of partially oxidized nickel-based nanoheterostructures (NiO/Ni NHSs), and the interfacial effects on hydrogen evolution. The origin of the enhanced hydrogen evolution performance is discussed at the microscopic level. This study identifies two types of active sites of the exposed Ni surface available for the hydrogen evolution reaction (HER). One is the hcp-hollow sites near the perimeter boundary that exhibit a more excellent HER performance than platinum (Pt), and the other the second nearest neighbor fcc-hollow sites away from the boundary that exhibit a similar performance to Pt. The interfacial effects result from the competitive charge transfer between NiO and Ni surfaces in NHSs, and enhance the reactivity of NiO/Ni NHSs by shifting the d-states of surface atoms down in energy. The illumination of the mechanism would be helpful for the design of more efficient and cheap transition metal-based catalysts.

Sequestration of precious and pollutant metals in biomass of cultured water hyacinth (Eichhornia crassipes).

PubMed

Newete, Solomon W; Erasmus, Barend F N; Weiersbye, Isabel M; Byrne, Marcus J

2016-10-01

The aim of this study was to investigate the overall root/shoot allocation of metal contaminants, the amount of metal removal by absorption and adsorption within or on the external root surfaces, the dose-response of water hyacinth metal uptake, and phytotoxicity. This was examined in a single-metal tub trial, using arsenic (As), gold (Au), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), uranium (U), and zinc (Zn). Iron and Mn were also used in low-, medium-, and high-concentration treatments to test their dose effect on water hyacinth's metal uptake. Water hyacinth was generally tolerant to metallotoxicity, except for Cu and Hg. Over 80 % of the total amount of metals removed was accumulated in the roots, of which 30-52 % was adsorbed onto the root surfaces. Furthermore, 73-98 % of the total metal assimilation by water hyacinth was located in the roots. The bioconcentration factor (BCF) of Cu, Hg, Au, and Zn exceeded the recommended index of 1000, which is used in selection of phytoremediating plants, but those of U, As, and Mn did not. Nevertheless, the BCF for Mn increased with the increase of Mn concentration in water. This suggests that the use of BCF index alone, without the consideration of plant biomass and metal concentration in water, is inadequate to determine the potential of plants for phytoremediation accurately. Thus, this study confirms that water hyacinth holds potential for a broad spectrum of phytoremediation roles. However, knowing whether these metals are adsorbed on or assimilated within the plant tissues as well as knowing their allocation between roots and shoots will inform decisions how to re-treat biomass for metal recovery, or the mode of biomass reduction for safe disposal after phytoremediation.

Comparative anatomy of epithermal precious- and base-metal districts hosted by volcanic rocks: A talk presented at the GAC/MSC/GGU Joint Annual Meeting, May 11-13, 1983, Victoria, British Columbia

USGS Publications Warehouse

Heald-Wetlaufer, Pamela; Hayba, Daniel O.; Foley, Nora K.; Goss, J.A.

1983-01-01

In order to distinguish dissimilar from similar features of epithermal districts, lithotectonic, mineralogical and geochemical traits are compiled for 15 such districts. The districts occur in structurally complex settings associated with silicic to intermediate volcanics. Affiliation with subduction environments on a continental scale and caldera settings on a regional scale is common but is not demonstrable for all districts. Most deposits formed near the end of major volcanism, but some formed considerably later. Paleodepth to the top of the ore is 300-600m for most districts, although Au-rich districts appear to be shallower. The lateral extent of the ore zone is highly variable and far exceeds the limited vertical range (300-800m). Most ore was deposited from dominantly meteoric fluids ranging in temperature from 220°-290°C. Salinities ranged from 0-13 wt% NaCl equiv., and typical values were 1-3 wt%. Although noted for eight deposits, boiling is clearly associated with precious-metal deposition in only two deposits. Four districts, typified by Goldfield, Nev., are characterized by a highly sulfidized mineral assemblage, advanced argillic alteration, and ore deposition closely following emplacement of the host rock. The remaining eleven districts highlight a second, discrete type of deposit. They contain adularia, exhibit sericitic ± argillic alteration, and were mineralized significantly after emplacement of the host rock. The latter category includes two subgroups: Ag- and base-metal-rich deposits (e.g., Creede, Colo.), and Au-rich, base-metal-poor deposits (e.g., Round Mtn., Nev.).

Non-precious metal catalysts prepared from precursor comprising cyanamide

DOEpatents

Chung, Hoon Taek; Zelenay, Piotr

2015-10-27

Catalyst comprising graphitic carbon and methods of making thereof; said graphitic carbon comprising a metal species, a nitrogen-containing species and a sulfur containing species. A catalyst for oxygen reduction reaction for an alkaline fuel cell was prepared by heating a mixture of cyanamide, carbon black, and a salt selected from an iron sulfate salt and an iron acetate salt at a temperature of from about 700.degree. C. to about 1100.degree. C. under an inert atmosphere. Afterward, the mixture was treated with sulfuric acid at elevated temperature to remove acid soluble components, and the resultant mixture was heated again under an inert atmosphere at the same temperature as the first heat treatment step.

Comparative analysis of textile metal threads from liturgical vestments and folk costumes in Croatia

NASA Astrophysics Data System (ADS)

Šimić, Kristina; Zamboni, Ivana; Fazinić, Stjepko; Mudronja, Domagoj; Sović, Lea; Gouasmia, Sabrina; Soljačić, Ivo

2018-02-01

Textile is essential for everyday life in all societies. It is used in clothes for protection and warmth but also to indicate class and position, show wealth and social status. Threads from precious metals have also been used in combination with fibres for decoration in order to create luxury fabrics for secular and religious elites. We performed elemental analysis of 17th to 20th century metal threads from various textile articles of liturgical vestments and festive folk costumes collected in the museums of northern, southern and central Croatian regions. In order to determine elemental concentrations in threads we performed comparative X-ray Spectroscopy measurements using: (i) Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX) at the Faculty of Textile Technology, (ii) X-ray Fluorescence Spectroscopy (XRF) at the Croatian Conservation Institute and (iii) Particle Induced X-ray Spectroscopy (PIXE) at the Ruđer Bošković Institute Tandem Accelerator Facility using ion micro beam. Rutherford Backscattering Spectroscopy (RBS) was performed as well on selected samples. SEM-EDX investigations of cross-sections along with the surfaces were also performed. In this work we report and discuss the results obtained by the three X-ray methods and RBS for major (gold, silver, copper) and minor elements on different threads like stripes, wires and "srma" (metal thread wrapped around textile yarn).

Efficient hydrogen evolution in transition metal dichalcogenides via a simple one-step hydrazine reaction

PubMed Central

Cummins, Dustin R.; Martinez, Ulises; Sherehiy, Andriy; Kappera, Rajesh; Martinez-Garcia, Alejandro; Schulze, Roland K.; Jasinski, Jacek; Zhang, Jing; Gupta, Ram K.; Lou, Jun; Chhowalla, Manish; Sumanasekera, Gamini; Mohite, Aditya D.; Sunkara, Mahendra K.; Gupta, Gautam

2016-01-01

Hydrogen evolution reaction is catalysed efficiently with precious metals, such as platinum; however, transition metal dichalcogenides have recently emerged as a promising class of materials for electrocatalysis, but these materials still have low activity and durability when compared with precious metals. Here we report a simple one-step scalable approach, where MoOx/MoS2 core-shell nanowires and molybdenum disulfide sheets are exposed to dilute aqueous hydrazine at room temperature, which results in marked improvement in electrocatalytic performance. The nanowires exhibit ∼100 mV improvement in overpotential following exposure to dilute hydrazine, while also showing a 10-fold increase in current density and a significant change in Tafel slope. In situ electrical, gate-dependent measurements and spectroscopic investigations reveal that hydrazine acts as an electron dopant in molybdenum disulfide, increasing its conductivity, while also reducing the MoOx core in the core-shell nanowires, which leads to improved electrocatalytic performance. PMID:27282871

Efficient hydrogen evolution in transition metal dichalcogenides via a simple one-step hydrazine reaction.

PubMed

Cummins, Dustin R; Martinez, Ulises; Sherehiy, Andriy; Kappera, Rajesh; Martinez-Garcia, Alejandro; Schulze, Roland K; Jasinski, Jacek; Zhang, Jing; Gupta, Ram K; Lou, Jun; Chhowalla, Manish; Sumanasekera, Gamini; Mohite, Aditya D; Sunkara, Mahendra K; Gupta, Gautam

2016-06-10

Hydrogen evolution reaction is catalysed efficiently with precious metals, such as platinum; however, transition metal dichalcogenides have recently emerged as a promising class of materials for electrocatalysis, but these materials still have low activity and durability when compared with precious metals. Here we report a simple one-step scalable approach, where MoOx/MoS2 core-shell nanowires and molybdenum disulfide sheets are exposed to dilute aqueous hydrazine at room temperature, which results in marked improvement in electrocatalytic performance. The nanowires exhibit ∼100 mV improvement in overpotential following exposure to dilute hydrazine, while also showing a 10-fold increase in current density and a significant change in Tafel slope. In situ electrical, gate-dependent measurements and spectroscopic investigations reveal that hydrazine acts as an electron dopant in molybdenum disulfide, increasing its conductivity, while also reducing the MoOx core in the core-shell nanowires, which leads to improved electrocatalytic performance.

Efficient hydrogen evolution in transition metal dichalcogenides via a simple one-step hydrazine reaction

DOE PAGES

Cummins, Dustin R.; Martinez, Ulises; Sherehiy, Andriy; ...

2016-06-10

In this study, hydrogen evolution reaction is catalyzed efficiently with precious metals, such as platinum; however, transition metal dichalcogenides have recently emerged as a promising class of materials for electrocatalysis, but these materials still have low activity and durability when compared with precious metals. Here we report a simple one-step scalable approach, where MoO x/MoS 2 core-shell nanowires and molybdenum disulfide sheets are exposed to dilute aqueous hydrazine at room temperature, which results in marked improvement in electrocatalytic performance. The nanowires exhibit ~100 mV improvement in over potential following exposure to dilute hydrazine, while also showing a 10-fold increase inmore » current density and a significant change in Tafel slope. In situ electrical, gate-dependent measurements and spectroscopic investigations reveal that hydrazine acts as an electron dopant in molybdenum disulfide, increasing its conductivity, while also reducing the MoO x core in the core-shell nanowires, which leads to improved electrocatalytic performance.« less

A Cleaner Process for Selective Recovery of Valuable Metals from Electronic Waste of Complex Mixtures of End-of-Life Electronic Products.

PubMed

Sun, Zhi; Xiao, Y; Sietsma, J; Agterhuis, H; Yang, Y

2015-07-07

In recent years, recovery of metals from electronic waste within the European Union has become increasingly important due to potential supply risk of strategic raw material and environmental concerns. Electronic waste, especially a mixture of end-of-life electronic products from a variety of sources, is of inherently high complexity in composition, phase, and physiochemical properties. In this research, a closed-loop hydrometallurgical process was developed to recover valuable metals, i.e., copper and precious metals, from an industrially processed information and communication technology waste. A two-stage leaching design of this process was adopted in order to selectively extract copper and enrich precious metals. It was found that the recovery efficiency and extraction selectivity of copper both reached more than 95% by using ammonia-based leaching solutions. A new electrodeposition process has been proven feasible with 90% current efficiency during copper recovery, and the copper purity can reach 99.8 wt %. The residue from the first-stage leaching was screened into coarse and fine fractions. The coarse fraction was returned to be releached for further copper recovery. The fine fraction was treated in the second-stage leaching using sulfuric acid to further concentrate precious metals, which could achieve a 100% increase in their concentrations in the residue with negligible loss into the leaching solution. By a combination of different leaching steps and proper physical separation of light materials, this process can achieve closed-loop recycling of the waste with significant efficiency.

[An experimental study on the adaptation of three kinds of porcelain fused-to-metal restorations].

PubMed

Pei, Yan-Ping; Chen, Ji-Hua; Chang, Qing; Lin, Song-Shan; Zhang, He

2009-04-01

To compare the adaptation of porcelain fused-to-metal (PFM) restorations made from Ni-Cr alloy, precious alloy and galvanized forming copings after cementation and to provide a theory guidance for their application. Three kinds of crowns (Ni-Cr alloy, precious alloy and galvanized forming) were manufactured and cleaned by ultrasonic vibrate with alcoholic solution for 5 minutes, and cemented on their dies as their order. All the crowns were cemented by polycarboxylate zinc-cement and maintained 10 minutes. After coated in the center of methyl acrylic resins, all the samples were cut vertically along buccolingual direction. The cement thickness of PFM was measured by scanning electron microscope and the data were analyzed by multivariate ANOVA. No significant difference was found between the cement thickness of precious alloy crown and galvanized forming crown (P>0.05), while both of these two kinds of crown had significant differences in cement thickness with Ni-Cr crown (P<0.05). The adaptation of precious alloy crown and galvanized forming crown are superior to Ni-Cr crown.

Rare and Precious Books and Documents Section. Collections and Services Division. Papers.

ERIC Educational Resources Information Center

International Federation of Library Associations, The Hague (Netherlands).

Papers on rare and precious books and documents, which were presented at the 1983 International Federation of Library Associations (IFLA) conference, include: (1) "Report on the State of Work on the Union Catalogue of Incunabula (GW) and Progress in the International Cataloguing of Incunabula" by Ursula Altmann (East Germany); (2)…

Population Genetic Structure of the Deep-Sea Precious Coral Corallium secundum from the Hawaiian Archipelago Based on Microsatellites.

NASA Astrophysics Data System (ADS)

Baco-Taylor, A.

2006-12-01

Deep-sea precious corals (Gerardia sp., Corallium lauuense, and Corallium secundum) on the Islands and seamounts of the Hawaiian Archipelago have supported an extremely profitable fishery, yet little is known about the life history and dispersal of the exploited species. Recent studies indicate significant genetic structure between shallow-water coral populations, including several species capable of long distance dispersal. If significant genetic structure exists in seamount and Island populations of precious corals, this could suggest that the elimination (through overharvesting) of a bed of precious corals would result in loss of overall genetic diversity in the species. Here I discuss results based on microsatellite studies of the precious coral, Corallium secundum, from 11 sites in the Hawaiian Archipelago collected between 1998 and 2004, and compare the population genetic structure and dispersal capabilities of Corallium secundum to the results for Corallium lauuense. Microsatellite studies of Corallium lauuense indicated significant heterozygote deficiency in most populations, suggesting recruitment in most populations is from local sources with only occasional long-distance dispersal events. Also, two populations appear to be significantly isolated from other populations of Corallium lauuense and may be separate stocks. In contrast, Corallium secundum populations have little heterozygote deficiency and separate into 3 distinct regions. In addition to having fisheries management implications for these corals, the results of these studies also have implications for the management and protection of seamount fauna.

Homogeneous deposition-assisted synthesis of iron-nitrogen composites on graphene as highly efficient non-precious metal electrocatalysts for microbial fuel cell power generation

NASA Astrophysics Data System (ADS)

Liu, Yuan; Jin, Xiao-Jun; Dionysiou, Dionysios D.; Liu, Hong; Huang, Yu-Ming

2015-03-01

This work proposed a novel strategy for synthesizing highly efficient non-precious metal oxygen reduction reaction (ORR) electrocatalysts. Fe complexes were homogeneously deposited (HD) on graphene oxide through in situ hydrolysis of urea, followed by two-step pyrolysis under Ar and NH3 atmospheres, resulting in formation of Fe- and N-functionalized graphene (HD-FeN/G). The morphology, crystalline structure and elemental composition of HD-FeN/G were characterized. ORR activity was evaluated by using a rotary disk electrode (RDE) electrochemical system. HD improved the loading and distribution of the Fe-Nx composites on graphene. The ORR activity of the as-prepared HD-FeN/G in neutral medium was comparable to that of the state-of-the-art commercial Pt/C and significantly superior to a FeN/G counterpart produced via traditional approach. The ORR electron transfer number of HD-FeN/G was as high as 3.83 ± 0.08, which suggested that ORR catalysis proceeds through a four-electron pathway. HD-FeN/G was used as a cathodic electrocatalyst in microbial fuel cells (MFCs), and the resultant HD-FeN/G-MFC showed comparable voltage output and maximum power density to those of Pt/C-MFC. The HD-FeN/G-MFC achieved a maximum power density of 885 mW m-2, which was much higher than that of FeN/G-MFC (708 mW m-2). These findings demonstrate that HD-FeN/G produced through the novel synthesis strategy proposed in this work would be a good candidate as cathodic electrocatalyst in MFCs.

Ornamental Stones and Gemstones: The limits of heritage stone designation: The case for and against Australian Precious Opal

NASA Astrophysics Data System (ADS)

Cooper, Barry

2015-04-01

When the international designation of natural stone types was first mooted in 2007, stones that were utilised in building and construction were the primary focus of attention. However following public discussion it soon became apparent that sculptural stones, stone used for utilitarian purposes such as millstones, as well as archaeological materials including stones used by early man could all be positively assessed as a potential Global Heritage Stone Resource (GHSR). Over the past 2 years it has been realised there is also a range of ornamental and semi-precious stones that may also be considered in the same international context. Examples in this respect include Imperial Porphyry sourced from Egypt that was much prized in the ancient world and "Derbyshire Blue John" a variety of fluorspar from central England that was used for vases, chalices, urns, candle sticks, jars, bowls door, jewellery and fire-place surrounds, especially in the 18th and 19th centuries. It is at this point that rock materials, sometimes used as gemstones, impinge on the domain of typical heritage stones. In Australia, the gemstone most identifiable with the country is precious opal formed by sedimentary processes in the Great Artesian Basin. In this paper the question is asked whether "Australian Precious Opal" could be or should be considered as a heritage stone of international significance. Immediately Australian Precious Opal satisfies several GHSR criteria including historic use for more than 50 years and wide-ranging utilisation for prestige jewellery around the world. It is also recognised as a cultural icon including association with national identity in Australia as it is legally defined as Australia's "National Gemstone" as well as being the "Gemstone Emblem" for the State of South Australia. Opal continues to be mined. Designation of Australian Precious Opal as a Global Heritage Stone Resource would likely involve formal international recognition of Australian opal in the

Linking precious metal enrichment and halogen cycling in mafic magmatic systems: insights from the Rum layered intrusion, NW Scotland

NASA Astrophysics Data System (ADS)

Kelly, A. P.; O'Driscoll, B.; Clay, P. L.; Burgess, R.

2017-12-01

Layered intrusions host the world's largest known concentrations of the platinum-group elements (PGE). Emphasis has been attached to the role of halogen-bearing fluids in concentrating the precious metals, but whether this occurs at the magmatic stage, or via subsequent metasomatism, is actively debated. One obstacle to progress has been the analytical difficulty of measuring low abundances of the halogens in the cumulate products of layered intrusions. To elucidate the importance of the halogens in facilitating PGE-mineralisation, as well as fingerprint halogen provenance and assess the importance of halogen cycling in mafic magma systems more generally, a suite of samples encompassing different stages of activity of the Palaeogene Rum layered intrusion was investigated. Halogen abundances were measured by neutron irradiation noble gas mass spectrometric analysis, permitting the detection of relatively low (ppm-ppb) abundances of Cl, Br and I in mg-sized samples. The samples include PGE-enriched chromite seams, various cumulates (e.g., peridotites), picrites (approximating the Rum parental magma), and pegmatites representing volatile-rich melts that circulated the intrusion at a late-stage in its solidification history. The new data reveal that PGE-bearing chromite seams contain relatively low Cl concentrations (2-3 ppm), with high molar ratios of Br/Cl and I/Cl (0.005 and 0.009, respectively). The picrites and cumulates have Br/Cl and I/Cl ratios close to sub-continental lithospheric mantle values of approximately 0.0013 and 0.00002, respectively, and thus likely reflect the Rum magma source region. A positive correlation between Cl and Br signifies comparable partitioning behaviour in all samples. However, I is more variable, displaying a positive correlation with Cl for more primitive samples (e.g. picrite and peridotite), and seemingly decoupling from Br and Cl in chromite seams and pegmatites. The relative enrichment of I over Cl in the chromite seams points

75 FR 81443 - Guides for the Jewelry, Precious Metals, and Pewter Industries

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-28

... consumer survey evidence submitted in response to two Federal Register Notices, the FTC amends the Platinum... consumer survey evidence, the Commission issued a Federal Register Notice in 2008 (``2008 FRN'') soliciting... 2003 marketing survey conducted by Hall & Partners,\\13\\ and two tests evaluating platinum/base metal...

Dedicated Co-deposition System for Metallic Paramagnetic Films

DOE PAGES

Jaeckel, F.; Kotsubo, V.; Hall, J. A.; ...

2012-01-27

Here, we describe a dedicated co-sputtering/ion-mill system developed to study metallic paramagnetic films for use in magnetic microcalorimetry. Small-diameter sputtering guns allow study of several precious-metal-based paramagnetic alloy systems within a reasonable budget. We demonstrated safe operation of a 1" sputtering gun at >5x the rated maximum power, achieving deposition rates up to ~900 Å/min/gun (Cu) in our co-sputtering geometry. Demonstrated co-sputtering deposition ratios up to 100:1 allow accurate tuning of magnetic dopant concentration and eliminate the difficulty of preparing homogeneous alloy targets of extreme dilution.

[Rapid multi-elemental analysis on four precious Tibetan medicines based on LIBS technique].

PubMed

Liu, Xiao-na; Shi, Xin-yuan; Jia, Shuai-yun; Zhao, Na; Wu, Zhi-sheng; Qiao, Yan-jiang

2015-06-01

The laser-induced breakdown spectroscopy (LIBS) was applied to perform a qualitative elementary analysis on four precious Tibetan medicines, i. e. Renqing Mangjue, Renqing Changjue, 25-herb coral pills and 25-herb pearl pills. The specific spectra of the four Tibetan medicines were established. In the experiment, Nd: YAG and 1 064 nm-baseband pulse laser were adopted to collect the spectra. A laser beam focused on the surface of the samples to generate plasma. Its spectral signal was detected by using spectrograph. Based on the National Institute of Standard and Technology (NIST) database, LIBS spectral lines were indentified. The four Tibetan medicines mainly included Ca, Na, K, Mg and other elements and C-N molecular band. Specifically, Fe was detected in Renqing Changjue and 25-herb pearl pills; heavy mental elements Hg and Cu were shown in Renqing Mangjue and Renqing Changjue; Ag was found in Renqing Changjue. The results demonstrated that LIBS is a reliable and rapid multi-element analysis on the four Tibetan medicines. With Real-time, rapid and nondestructive advantages, LIBS has a wide application prospect in the element analysis on ethnic medicines.

76 FR 11985 - Acquisition Regulation: Department of Energy Acquisition Regulation, Government Property

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-04

... to follow procedures set forth in paragraphs (a) through (c). 17. Section 908.7121(b) Precious metals... metals or possessing precious metals excess. 18. Section 908.7121(c) is amended to state that lithium is... redesignated as 945.604-1 Recovering precious metals. The office name and address are updated. Paragraph (d...

A preliminary categorization of end-of-life electrical and electronic equipment as secondary metal resources.

PubMed

Oguchi, Masahiro; Murakami, Shinsuke; Sakanakura, Hirofumi; Kida, Akiko; Kameya, Takashi

2011-01-01

End-of-life electrical and electronic equipment (EEE) has recently received attention as a secondary source of metals. This study examined characteristics of end-of-life EEE as secondary metal resources to consider efficient collection and metal recovery systems according to the specific metals and types of EEE. We constructed an analogy between natural resource development and metal recovery from end-of-life EEE and found that metal content and total annual amount of metal contained in each type of end-of-life EEE should be considered in secondary resource development, as well as the collectability of the end-of-life products. We then categorized 21 EEE types into five groups and discussed their potential as secondary metal resources. Refrigerators, washing machines, air conditioners, and CRT TVs were evaluated as the most important sources of common metals, and personal computers, mobile phones, and video games were evaluated as the most important sources of precious metals. Several types of small digital equipment were also identified as important sources of precious metals; however, mid-size information and communication technology (ICT) equipment (e.g., printers and fax machines) and audio/video equipment were shown to be more important as a source of a variety of less common metals. The physical collectability of each type of EEE was roughly characterized by unit size and number of end-of-life products generated annually. Current collection systems in Japan were examined and potentially appropriate collection methods were suggested for equipment types that currently have no specific collection systems in Japan, particularly for video games, notebook computers, and mid-size ICT and audio/video equipment. Copyright © 2011 Elsevier Ltd. All rights reserved.

Innovative approach for the valorization of useful metals from waste electric and electronic equipment (WEEE)

NASA Astrophysics Data System (ADS)

Soare, V.; Burada, M.; Dumitrescu, D. V.; Constantin, I.; Soare, V.; Popescu, A.-M. J.; Carcea, I.

2016-08-01

Waste electric and electronic equipment are an important secondary source of rare and precious metals and their processing through ecological technologies constitutes a major concern in the European Union and significantly contributes to the reduction of environmental pollution and to the preservation of valuable resources of nonferrous metals. The paper presents an innovative approach for the complex valorization of useful metals contained in WEEE. The method consists in the melting of WEEE in a furnace in a microwave field at temperatures of 1000 ÷1200°C, for the complete separation of the metallic fraction from the organic components. The gases resulting from the melting process were also treated/neutralized in a microwave environment and the obtained metallic bulk (multi-component alloy) was processed through combined hydrometallurgical and electrochemical methods. The major elements in the metallic bulk (Cu, Sn, Zn, Pb) were separated/recovered by anodic dissolution, respectively by leaching in nitric acid followed by cementation using various agents, or by electrodeposition. Depending on the electrochemical parameters, cathodic deposits consisting of Cu, with a purity higher than 99.9%, or of Cu-Sn and Cu-Sn-Zn alloys were obtained. Silver was valorized by leaching/precipitation with NaCl and the gold concentrated in the anodic slime will be recovered by thiourea extraction. The experiments performed demonstrate the possibility of ecological and efficient processing of WEEE in a microwave field and the recovery of nonferrous and precious metals through combined hydrometallurgical and electrochemical methods.

Silicosis prevalence and risk factors in semi-precious stone mining in Brazil.

PubMed

Souza, Tamires P; Watte, Guilherme; Gusso, Alaíde M; Souza, Rafaela; Moreira, José da S; Knorst, Marli M

2017-06-01

Underground mining generates large amounts of dust and exposes workers to silica. This study aims to determine the prevalence and predictor factors for the development of silicosis among semi-precious-stone mineworkers in southern Brazil working in a self-administered cooperative. In a cross-sectional study of 348 current workers and retirees, demographic data, medical, and occupational history were collected through an interview performed by a nurse and medical record review. Risk factor associations were studied by Poisson multivariate regression. The overall prevalence of silicosis was 37%, while in current miners it was 28%. Several risk factors for silicosis were identified in the univariate analysis. Inadequate ventilation in the underground galleries combined with dry drilling, duration of silica exposure, and (inversely) education remained significant in the multivariate analysis (P < 0.05). This study is unusual in studying semi-precious stone mineworkers in a self-administered worker cooperative with limited resources. The prevalence of silicosis was very high. A number of recommendations are made-including technical support for worker cooperatives, surveillance of silica exposure and silicosis, exposure reduction measures, and benefits allowing impaired miners to leave the industry. © 2017 Wiley Periodicals, Inc.

IFLA General Conference, 1986. Collections and Services Division. Section: Rare and Precious Books. Papers.

ERIC Educational Resources Information Center

International Federation of Library Associations and Institutions, The Hague (Netherlands).

Papers on rare and precious books which were presented at the 1986 International Federation of Library Associations (IFLA) conference include: (1) "Compiling of 'The Union Catalogue of Japanese Old Books'--Investigating and Research of Old Books of Japanese Literature and Its Microfilming" (Yasuo Honda, Japan); (2) "The Rare and…

Generation of copper rich metallic phases from waste printed circuit boards.

PubMed

Cayumil, R; Khanna, R; Ikram-Ul-Haq, M; Rajarao, R; Hill, A; Sahajwalla, V

2014-10-01

The rapid consumption and obsolescence of electronics have resulted in e-waste being one of the fastest growing waste streams worldwide. Printed circuit boards (PCBs) are among the most complex e-waste, containing significant quantities of hazardous and toxic materials leading to high levels of pollution if landfilled or processed inappropriately. However, PCBs are also an important resource of metals including copper, tin, lead and precious metals; their recycling is appealing especially as the concentration of these metals in PCBs is considerably higher than in their ores. This article is focused on a novel approach to recover copper rich phases from waste PCBs. Crushed PCBs were heat treated at 1150°C under argon gas flowing at 1L/min into a horizontal tube furnace. Samples were placed into an alumina crucible and positioned in the cold zone of the furnace for 5 min to avoid thermal shock, and then pushed into the hot zone, with specimens exposed to high temperatures for 10 and 20 min. After treatment, residues were pulled back to the cold zone and kept there for 5 min to avoid thermal cracking and re-oxidation. This process resulted in the generation of a metallic phase in the form of droplets and a carbonaceous residue. The metallic phase was formed of copper-rich red droplets and tin-rich white droplets along with the presence of several precious metals. The carbonaceous residue was found to consist of slag and ∼30% carbon. The process conditions led to the segregation of hazardous lead and tin clusters in the metallic phase. The heat treatment temperature was chosen to be above the melting point of copper; molten copper helped to concentrate metallic constituents and their separation from the carbonaceous residue and the slag. Inert atmosphere prevented the re-oxidation of metals and the loss of carbon in the gaseous fraction. Recycling e-waste is expected to lead to enhanced metal recovery, conserving natural resources and providing an environmentally

Metals removal and recovery in bioelectrochemical systems: A review.

PubMed

Nancharaiah, Y V; Venkata Mohan, S; Lens, P N L

2015-11-01

Metal laden wastes and contamination pose a threat to ecosystem well being and human health. Metal containing waste streams are also a valuable resource for recovery of precious and scarce elements. Although biological methods are inexpensive and effective for treating metal wastewaters and in situ bioremediation of metal(loid) contamination, little progress has been made towards metal(loid) recovery. Bioelectrochemical systems are emerging as a new technology platform for removal and recovery of metal ions from metallurgical wastes, process streams and wastewaters. Biodegradation of organic matter by electroactive biofilms at the anode has been successfully coupled to cathodic reduction of metal ions. Until now, leaching of Co(II) from LiCoO2 particles, and removal of metal ions i.e. Co(III/II), Cr(VI), Cu(II), Hg(II), Ag(I), Se(IV), and Cd(II) from aqueous solutions has been demonstrated. This article reviews the state of art research of bioelectrochemical systems for removal and recovery of metal(loid) ions and pertaining removal mechanisms. Copyright © 2015 Elsevier Ltd. All rights reserved.

Properties of low power spark ablation in aqueous solution for dissolution of precious metals and alloys

NASA Astrophysics Data System (ADS)

Goltz, Douglas; Boileau, Michael; Plews, Ian; Charleton, Kimberly; Hinds, Michael W.

2006-07-01

Spark ablation or electric dispersion of metal samples in aqueous solution can be a useful approach for sample preparation. The ablated metal forms a stable suspension that has been described as colloidal, which is easily dissolved with a small amount of concentrated (16 M) HNO 3. In this study, we have examined some of the properties of the spark ablation process for a variety of metals (Rh and Au) and alloys (stainless steel) using a low power spark (100-300 W). Particle size distributions and conductivity measurements were carried out on selected metals to characterize the stable suspensions. A LASER diffraction particle size analyzer was useful for showing that ablated particles varied in size from 1 to 30 μm for both the silver and the nickel alloy, Inconel. In terms of weight percent most of the particles were between 10 and 30 μm. Conductivity of the spark ablation solution was found to increase linearly for approximately 3 min before leveling off at approximately 300 S cm 3. These measurements suggest that a significant portion of the ablated metal is also ionic in nature. Scanning electron microscope measurements revealed that a low power spark is much less damaging to the metal surface than a high power spark. Crater formation of the low power spark was found in a wider area than expected with the highest concentration where the spark was directed. The feasibility of using spark ablation for metal dissolution of a valuable artifact such as gold was also performed. Determinations of Ag (4-12%) and Cu (1-3%) in Bullion Reference Material (BRM) gave results that were in very good agreement with the certified values. The precision was ± 0.27% for Ag at 4.15% (RSD = 6.5%) and ± 0.09% for Cu at 1% (RSD = 9.0%).

A rational repeating template method for synthesis of 2D hexagonally ordered mesoporous precious metals.

PubMed

Takai, Azusa; Doi, Yoji; Yamauchi, Yusuke; Kuroda, Kazuyuki

2011-03-01

A repeating template method is presented for the synthesis of mesoporous metals with 2D hexagonal mesostructures. First, a silica replica (i.e., silica nanorods arranged periodically) is prepared by using 2D hexagonally ordered mesoporous carbon as the template. After that, the obtained silica replica is used as the second template for the preparation of mesoporous ruthenium. After the ruthenium species are introduced into the silica replica, the ruthenium species are then reduced by a vapor-infiltration method by using the reducing agent dimethylamine borane. After the ruthenium deposition, the silica is chemically removed. Analysis by transmission and scanning electron microscopies, a nitrogen-adsorption-desorption isotherm, and small-angle X-ray scattering revealed that the mesoporous ruthenium had a 2D hexagonal mesostructure, although the mesostructural ordering is decreased compared to that of the original mesoporous carbon template. This method is widely applicable to other metal systems. By changing the metal species introduced into the silica replica, several mesoporous metals (palladium and platinum) can be synthesized. Ordered mesoporous ruthenium and palladium, which are not easily attainable by the soft-templating methods, can be prepared. This study has overcome the composition variation limitations of the soft-templating method. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Habitat Evaluation Procedures (HEP) Report; Precious Lands Wildlife Management Area, Technical Report 2000-2003.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozusko, Shana

The Nez Perce Tribe (NPT) currently manages a 15,325 acre parcel of land known as the Precious Lands Wildlife Management Area that was purchased as mitigation for losses incurred by construction of the four lower Snake River dams. The Management Area is located in northern Wallowa County, Oregon and southern Asotin County, Washington (Figure 1). It is divided into three management parcels--the Buford parcel is located on Buford Creek and straddles the WA-OR state line, and the Tamarack and Basin parcels are contiguous to each other and located between the Joseph Creek and Cottonwood Creek drainages in Wallowa County, OR.more » The project was developed under the Pacific Northwest Electric Power Planning and Conservation Act of 1980 (P.L. 96-501), with funding from the Bonneville Power Administration (BPA). The acreage protected under this contract will be credited to BPA as habitat permanently dedicated to wildlife and wildlife mitigation. A modeling strategy known as Habitat Evaluation Procedure (HEP) was developed by the U.S. Fish and Wildlife Service and adopted by BPA as a habitat equivalency accounting system. Nine wildlife species models were used to evaluate distinct cover type features and provide a measure of habitat quality. Models measure a wide range of life requisite variables for each species and monitor overall trends in vegetation community health and diversity. One product of HEP is an evaluation of habitat quality expressed in Habitat Units (HUs). This HU accounting system is used to determine the amount of credit BPA receives for mitigation lands. After construction of the four lower Snake River dams, a HEP loss assessment was conducted to determine how many Habitat Units were inundated behind the dams. Twelve target species were used in that evaluation: Canada goose, mallard, river otter, downy woodpecker, song sparrow, yellow warbler, marsh wren, western meadowlark, chukar, ring-necked pheasant, California quail, and mule deer. The U.S. Army

A preliminary categorization of end-of-life electrical and electronic equipment as secondary metal resources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oguchi, Masahiro, E-mail: oguchi.masahiro@nies.go.jp; Murakami, Shinsuke; Sakanakura, Hirofumi

2011-09-15

Highlights: > End-of-life electrical and electronic equipment (EEE) as secondary metal resources. > The content and the total amount of metals in specific equipment are both important. > We categorized 21 EEE types from contents and total amounts of various metals. > Important equipment types as secondary resources were listed for each metal kind. > Collectability and possible collection systems of various EEE types were discussed. - Abstract: End-of-life electrical and electronic equipment (EEE) has recently received attention as a secondary source of metals. This study examined characteristics of end-of-life EEE as secondary metal resources to consider efficient collection andmore » metal recovery systems according to the specific metals and types of EEE. We constructed an analogy between natural resource development and metal recovery from end-of-life EEE and found that metal content and total annual amount of metal contained in each type of end-of-life EEE should be considered in secondary resource development, as well as the collectability of the end-of-life products. We then categorized 21 EEE types into five groups and discussed their potential as secondary metal resources. Refrigerators, washing machines, air conditioners, and CRT TVs were evaluated as the most important sources of common metals, and personal computers, mobile phones, and video games were evaluated as the most important sources of precious metals. Several types of small digital equipment were also identified as important sources of precious metals; however, mid-size information and communication technology (ICT) equipment (e.g., printers and fax machines) and audio/video equipment were shown to be more important as a source of a variety of less common metals. The physical collectability of each type of EEE was roughly characterized by unit size and number of end-of-life products generated annually. Current collection systems in Japan were examined and potentially appropriate collection

48 CFR 252.208-7000 - Intent to furnish precious metals as Government-furnished material.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Offeror shall cite the type (silver, gold, platinum, palladium, iridium, rhodium, and ruthenium) and... metal* Quantity Deliverable item (NSN and nomenclature)!!rs *If platinum or palladium, specify whether...

48 CFR 252.208-7000 - Intent to furnish precious metals as Government-furnished material.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Offeror shall cite the type (silver, gold, platinum, palladium, iridium, rhodium, and ruthenium) and... metal* Quantity Deliverable item (NSN and nomenclature)!!rs *If platinum or palladium, specify whether...

48 CFR 252.208-7000 - Intent to furnish precious metals as Government-furnished material.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Offeror shall cite the type (silver, gold, platinum, palladium, iridium, rhodium, and ruthenium) and... metal* Quantity Deliverable item (NSN and nomenclature)!!rs *If platinum or palladium, specify whether...

48 CFR 252.208-7000 - Intent to furnish precious metals as Government-furnished material.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Offeror shall cite the type (silver, gold, platinum, palladium, iridium, rhodium, and ruthenium) and... metal* Quantity Deliverable item (NSN and nomenclature)!!rs *If platinum or palladium, specify whether...

Precious Metal Distributions in Direct Nickel Matte Smelting with Low-Cu Mattes

NASA Astrophysics Data System (ADS)

Piskunen, P.; Avarmaa, K.; O'Brien, H.; Klemettinen, L.; Johto, H.; Taskinen, P.

2018-02-01

Base metal (Cu, Fe, and Ni) and trace element (Ag, Au, Co, Pd, and Pt) distributions between low-iron nickel mattes with [Ni]:[Cu] = 4 (w/w) have been studied at 1623 K to 1723 K (1350 °C to 1450 °C). We equilibrated small slag-matte samples with CO-CO2-SO2-Ar atmospheres in pre-selected P_{{{S}2 }} - P_{{{O}2 }} points, maintaining silica saturation by fused silica crucibles. The slags studied contained about 0 to 8.5 wt pct MgO. The matte-slag distribution coefficients L m/s[Me] were obtained from assays by electron probe X-ray microanalysis for the matte and by laser ablation-ICP-mass spectrometry for the slag. The measured L m/s[Me] values were clearly dependent on iron concentration of the matte and on MgO concentration of the slag, with values on the order of 104, 105, and 104 for gold, platinum, and palladium, respectively, in the 5 wt pct iron in matte experiments. The obtained data for silver were scattered, due to volatilization, resulting in depletion of most silver and its escape from matte to gas phase during the 3-hour equilibration period. The matte-to-slag distribution coefficient for silver was estimated to be L m/s[Ag] = 100 to 400. We also measured the distributions of the base metals Cu and Ni in the same conditions as the trace elements.

One-pot synthesis of transition metal ion-chelating ordered mesoporous carbon/carbon nanotube composites for active and durable fuel cell catalysts

NASA Astrophysics Data System (ADS)

Dombrovskis, Johanna K.; Palmqvist, Anders E. C.

2017-07-01

Development of non-precious metal catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells with high activity and durability and with optimal water management properties is of outmost technological importance and highly challenging. Here we study the possibilities offered through judicious selection of small molecular precursors used for the formation of ordered mesoporous carbon-based non-precious metal ORR catalysts. By combining two complementary precursors, we present a one-pot synthesis that leads to a composite material consisting of transition metal ion-chelating ordered mesoporous carbon and multi-walled carbon nanotubes (TM-OMC/CNT). The resulting composite materials show high specific surface areas and a carbon structure that exhibits graphitic signatures. The synthesis procedure allows for tuning of the carbon structure, the surface area, the pore volume and the ratio of the two components of the composite. The TM-OMC/CNT composites were processed into membrane electrode assemblies and evaluated in single cell fuel cell measurements where they showed a combination of good ORR activity and very high durability.

77 FR 41883 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-16

...-0030. Type of Review: Extension without change of a currently approved collection. Title: Anti-Money Laundering Programs for Dealers in Precious Metals, Precious Stones, or Jewels. Abstract: Desires in precious metals, stones, or jewels are required to establish and maintain a written anti-money laundering program...

Challenges to achievement of metal sustainability in our high-tech society

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izatt, Reed M.; Izatt, Steven R.; Bruening, Ronald L.

Achievement of sustainability in metal life cycles from mining of virgin ore to consumer and industrial devices to end-of-life products requires greatly increased recycling and improved processing of metals. Electronic and other high-tech products containing precious, toxic, and specialty metals usually have short lifetimes and low recycling rates. Products containing these metals generally are incinerated, discarded as waste in landfills, or dismantled in informal recycling using crude and environmentally irresponsible procedures. Low metal recycling rates coupled with increasing demand for products containing them necessitate increased mining with attendant environmental, health, energy, water, and carbon-footprint consequences. In this tutorial review, challengesmore » to achieving metal sustainability in present high-tech society are presented; health, environmental, and economic incentives for various stakeholders to improve metal sustainability are discussed; a case for technical improvements in separations technology, especially employing molecular recognition, is given; and global consequences of continuing on the present path are examined.« less

Protecting health from metal exposures in drinking water.

PubMed

Armour, Margaret-Ann

2016-03-01

Drinking water is essential to us as human beings. According to the World Health Organization "The quality of drinking-water is a powerful environmental determinant of health" (http://www.who.int/water_sanitation_health/dwq/en/), but clean drinking water is a precious commodity not always readily available. Surface and ground water are the major sources of drinking water. Both can be contaminated, surface water with bacteria while ground water frequently contains salts of metals that occur naturally or are introduced by human activity. This paper will briefly review the metallic salts found in drinking water in areas around the world, as well as list some of the methods used to reduce or remove them. It will then discuss our research on reducing the risk of pollution of drinking water by removal of metal ions from wastewater.

Occurence of ore metals in some terrestrial geothermal systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Browne, P.

1984-02-01

Drilling programs and the study of active geothermal systems have shown that the reservoir rocks in many fields contain minor quantities of base and precious metals. Commonly, base-metal sulfides occur in the subsurface but, where present, Au, Ag, Hg, As, Tl and Sb rich precipitates deposit near, or at, the surface. Although in some fields (Geysers, Larderello, Tongonan) some of the ore minerals (and others) are relict, there is evidence that they are now depositing in a few systems. Recent work on active hydrothermal systems in New Zealand shows that: (1) Sphalerite, galena, chalcopyrite (forming veins and disseminated discrete crystals)more » plus rare pentlandite, cobaltite and arsenopyrite, occur at Broadlands, NZ. Rare quantities of base-metal sulfides also occur in cores and cuttings from the geothermal fields of Waiotapu, Kawerau, Tauhara, and Ngawha. Further, Kakimoto (1983) has identified cassiterite, native silver, and trace gold in cores from Tauhara, in the south-eastern part of the Wairakei field. Bore temperatures at the depths from which these minerals were recovered are mostly between 220/sup 0/ and 300/sup 0/C, but at Broadlands are locally as low as 120/sup 0/C. The host rocks are Quaternary calc-alkali, silicic lavas and pyroclastic rocks, andesites, dacite and deep Mesozoic greywackes and argillites; however, there is no obvious relationship between mineralization and stratigraphy, permeability or well output. The deposition of amorphous precious metal precipitates (Au, Ag, Hg, As, Sb, Tl) from hot springs and well discharges has taken place at Broadlands, Waiotapu and Rotokawa; it also occurs at Kawerau. Water discharging from Frying Pan Lake, Waimangu, is presently depositing siliceous sinter containing up to 4.1% tungsten.« less

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and... AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Secondary Precious Metals...

Graphenes in the absence of metals as carbocatalysts for selective acetylene hydrogenation and alkene hydrogenation

NASA Astrophysics Data System (ADS)

Primo, Ana; Neatu, Florentina; Florea, Mihaela; Parvulescu, Vasile; Garcia, Hermenegildo

2014-10-01

Catalysis makes possible a chemical reaction by increasing the transformation rate. Hydrogenation of carbon-carbon multiple bonds is one of the most important examples of catalytic reactions. Currently, this type of reaction is carried out in petrochemistry at very large scale, using noble metals such as platinum and palladium or first row transition metals such as nickel. Catalysis is dominated by metals and in many cases by precious ones. Here we report that graphene (a single layer of one-atom-thick carbon atoms) can replace metals for hydrogenation of carbon-carbon multiple bonds. Besides alkene hydrogenation, we have shown that graphenes also exhibit high selectivity for the hydrogenation of acetylene in the presence of a large excess of ethylene.

Our Hidden Past: Precious Metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Ray; Larson, Clarence E.; Banic, George M.

Y-12's calutrons required electrical conductor material, but during the war, copper was in short supply. The U.S. Treasury loaned Y-12 14,700 tons of silver, valued at $600M. All but 67 tons was returned after the war, and those 67 tons remained in Building 9731 until 1970 for use in separating isotopes for medical research.

SEDIMENT-HOSTED PRECIOUS METAL DEPOSITS.

USGS Publications Warehouse

Bagby, W.C.; Pickthorn, W.J.; Goldfarb, R.; Hill, R.A.

1984-01-01

The Dee mine is a sediment-hosted, disseminated gold deposit in the Roberts Mountains allochthon of north central Nevada. Soil samples were collected from the C-horizon in undisturbed areas over the deposit in order to investigate the usefulness of soil geochemistry in identifying this type of deposit. Each sample was sieved to minus 80 mesh and analyzed quantitatively for Au, Ag, As, Sb, Hg, Tl and semi-quantitative data for an additional 31 elements. Rank sum analysis is successful for the Au, Ag, As, Sb, Hg, Tl suite, even though bedrock geology is disregarded. This method involves data transformation into a total element signature by ranking the data in ascending order and summing the element ranks for each sample. The rank sums are then divided into percentile groups and plotted. The rank sum plot for the Dee soils unequivocally identifies three of four known ore zones.

41 CFR 109-27.5106-5 - Assistance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Precious Metals Sales and Recovery operates the precious metals pool. DOE organizations and contractors may... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS SUPPLY AND PROCUREMENT 27...

41 CFR 109-27.5106-5 - Assistance.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Precious Metals Sales and Recovery operates the precious metals pool. DOE organizations and contractors may... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS SUPPLY AND PROCUREMENT 27...

Fabrication of crystals from single metal atoms

PubMed Central

Barry, Nicolas P. E.; Pitto-Barry, Anaïs; Sanchez, Ana M.; Dove, Andrew P.; Procter, Richard J.; Soldevila-Barreda, Joan J.; Kirby, Nigel; Hands-Portman, Ian; Smith, Corinne J.; O’Reilly, Rachel K.; Beanland, Richard; Sadler, Peter J.

2014-01-01

Metal nanocrystals offer new concepts for the design of nanodevices with a range of potential applications. Currently the formation of metal nanocrystals cannot be controlled at the level of individual atoms. Here we describe a new general method for the fabrication of multi-heteroatom-doped graphitic matrices decorated with very small, ångström-sized, three-dimensional (3D)-metal crystals of defined size. We irradiate boron-rich precious-metal-encapsulated self-spreading polymer micelles with electrons and produce, in real time, a doped graphitic support on which individual osmium atoms hop and migrate to form 3D-nanocrystals, as small as 15 Å in diameter, within 1 h. Crystal growth can be observed, quantified and controlled in real time. We also synthesize the first examples of mixed ruthenium–osmium 3D-nanocrystals. This technology not only allows the production of ångström-sized homo- and hetero-crystals, but also provides new experimental insight into the dynamics of nanocrystals and pathways for their assembly from single atoms. PMID:24861089

Bioleaching of metals from WEEE shredding dust.

PubMed

Marra, Alessandra; Cesaro, Alessandra; Rene, Eldon R; Belgiorno, Vincenzo; Lens, Piet N L

2018-03-15

A bioleaching process developed in two separate steps was investigated for the recovery of base metals, precious metals and rare earth elements from dusts generated by Waste Electrical and Electronic Equipment (WEEE) shredding. In the first step, base metals were almost completely leached from the dust in 8 days by Acidithiobacillus thiooxidans (DSM 9463) that lowered the pH of the leaching solution from 3.5 to 1.0. During this step, cerium, europium and neodymium were mobilized at high percentages (>99%), whereas lanthanum and yttrium reached an extraction yield of 80%. In the second step, the cyanide producing Pseudomonas putida WSC361 mobilized 48% of gold within 3 h from the A. thiooxidans leached shredding dust. This work demonstrated the potential application of biohydrometallurgy for resource recovery from WEEE shredding dust, destined to landfill disposal, and its effectiveness in the extraction of valuable substances, including elements at high supply risk as rare earths. Copyright © 2017 Elsevier Ltd. All rights reserved.

Peculiarities of the irisation in precious opals in view of their mosaic-cluster (frustumation) inner fabric

NASA Astrophysics Data System (ADS)

Povarennykh, M. Yu.; Knot'ko, A. V.; Matvienko, E. N.; Plechov, P. Yu.; Burmistrov, A. A.; Luksha, V. L.

2016-04-01

A direct correlation was shown for the first time between mosaic irisation patterns in synthetic and natural precious opals (from Australia, Ethiopia, Honduras, Slovakia, and Russia) and their frustumational (lump or mosaic-cluster) inner structure by means of photoluminescence, X-ray phase analysis, IR and Raman spectroscopy, and scanning electron microscopy.

Secondary precious metal enrichment by steam-heated fluids in the Crofoot-Lewis hot spring gold-silver deposit and relation to paleoclimate

USGS Publications Warehouse

Ebert, S.W.; Rye, R.O.

1997-01-01

controlled largely by basin and range fractures and a high geothermal gradient with H2S for Au complexing derived from organic matter in basin sediments. A wet climate resulted in the formation of a large inland lake which provided abundant recharge water for the hydrothermal system. A fluctuating water table controlled by changing climatic conditions enabled steam-heated acid sulfate fluids to overprint lower grade mineralization resulting in ore-grade precious metal enrichment.

Incorporation of precious metal nanoparticles into various aerogels by different supercritical deposition methods

NASA Astrophysics Data System (ADS)

Saquing, Carl D.

2005-11-01

One major hurdle in nanoparticle fabrication is the difficulty in controlling size, distribution and concentration. Conventional methods in nanoparticle formation require high temperatures which lead to particle agglomeration and size broadening, or involve substantial amount of organic solvents. A clean route to supported-nanoparticles fabrication was investigated using various supercritical (SC) based deposition methods. The SC deposition involves the organometallic precursor (OP) (dimethyl(1,5-cyclooctadiene)platinum(II)[CODPtMe 2] or bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (1,5-cyclooctadiene) ruthenium(II)) dissolution in SC fluid and contacting this solution with a substrate. The OP is adsorbed and subsequent reduction of the OP-impregnated substrate produces metal/substrate composites. The various methods were: (1) thermal reduction at atmospheric pressure in an inert atmosphere; (2) thermal reduction in SC carbon dioxide (scCO2); (3) chemical reduction in scCO2 with H2; and (4) chemical reduction at atmospheric pressure with H2. The synthesis of resorcinol-formaldehyde aerogels (RFAs) and carbon aerogels (CAs) was also studied and used as substrates (along with commercial silica aerogels (SAs)) in the SC deposition. The surface area, pore properties, and density of these aerogels were evaluated and the effects of reactant concentration, pyrolysis and SC deposition on these properties were determined. Using a static method, the adsorption isotherms of CODPtMe2 in scCO2 on two CAs with different pore sizes were measured at 28 MPa and 80°C to determine the maximum metal loading and the effect of pore properties on adsorption and to examine the interactions between the three components. The isotherms could be represented by the Langmuir model and the adsorption data indicated a strong CODPtMe2-CA interaction and that almost all the preexistent micropore area was covered with CODPtMe 2 molecules even at adsorption lower than the maximum capacity. The

[Exposure to metals in dental laboratories].

PubMed

Apostoli, P; Ferioli, A; Crippa, M; Redaelli, P; Braga Marcazzan, G; Alessio, L

1988-11-01

Dental care includes handling of different types of metal alloys usually classified as "noble" and "base" in relation to the presence or absence of either gold or other precious metals. It must be born in mind that exposure to metals in this activities is due not only to those metals present in the alloys but also to those contained in the other materials used during the processes of casting and finishing. The most important metals are the following: Al, Be, Cd, Cr, Co, Cu, Au, In, Hg, Mo, Ni, Pd, Pt, Si, Ag, Sn, Ti, W, Zn. In this paper we investigated the environmental exposure to metals in dental laboratories studying the environmental air concentration of metals in casting and finishing processes estimating the "quality" of the elements present by Particle Induces X-ray Emission (PIXE) and the "quantity" of the elements by electro thermic atomic absorption spectrophotometry (ET-AAS) and the concentration of the main metals in the blood and in the urine of exposed technicians by ET-AAS. These analyses permitted to detect all the metals present in the work environment and to quantify their concentration, which always resulted to be low (except some metals during short time operations). The biological monitoring revealed the existence of moderate absorption of these metals in the exposed workers but it is not possible for us to affirm if this phenomenon represents a real risk for the health of the technicians. Hence further epidemiological and health surveillance investigations are needed to verify morbidity and mortality of the subjects employed in this activity.

Acceptorless dehydrogenation of small molecules through cooperative base metal catalysis

PubMed Central

West, Julian G.; Huang, David; Sorensen, Erik J.

2015-01-01

The dehydrogenation of unactivated alkanes is an important transformation both in industrial and biological systems. Recent efforts towards this reaction have revolved around high temperature, organometallic C–H activation by noble metal catalysts that produce alkenes and hydrogen gas as the sole products. Conversely, natural desaturase systems proceed through stepwise hydrogen atom transfer at physiological temperature; however, these transformations require a terminal oxidant. Here we show combining tetra-n-butylammonium decatungstate (TBADT) and cobaloxime pyridine chloride (COPC) can catalytically dehydrogenate unactivated alkanes and alcohols under near-UV irradiation at room temperature with hydrogen as the sole by-product. This noble metal-free process follows a nature-inspired pathway of high- and low-energy hydrogen atom abstractions. The hydrogen evolution ability of cobaloximes is leveraged to render the system catalytic, with cooperative turnover numbers up to 48 and yields up to 83%. Our results demonstrate how cooperative base metal catalysis can achieve transformations previously restricted to precious metal catalysts. PMID:26656087

High-Performance Direct Methanol Fuel Cells with Precious-Metal-Free Cathode.

PubMed

Li, Qing; Wang, Tanyuan; Havas, Dana; Zhang, Hanguang; Xu, Ping; Han, Jiantao; Cho, Jaephil; Wu, Gang

2016-11-01

Direct methanol fuel cells (DMFCs) hold great promise for applications ranging from portable power for electronics to transportation. However, apart from the high costs, current Pt-based cathodes in DMFCs suffer significantly from performance loss due to severe methanol crossover from anode to cathode. The migrated methanol in cathodes tends to contaminate Pt active sites through yielding a mixed potential region resulting from oxygen reduction reaction and methanol oxidation reaction. Therefore, highly methanol-tolerant cathodes must be developed before DMFC technologies become viable. The newly developed reduced graphene oxide (rGO)-based Fe-N-C cathode exhibits high methanol tolerance and exceeds the performance of current Pt cathodes, as evidenced by both rotating disk electrode and DMFC tests. While the morphology of 2D rGO is largely preserved, the resulting Fe-N-rGO catalyst provides a more unique porous structure. DMFC tests with various methanol concentrations are systematically studied using the best performing Fe-N-rGO catalyst. At feed concentrations greater than 2.0 m, the obtained DMFC performance from the Fe-N-rGO cathode is found to start exceeding that of a Pt/C cathode. This work will open a new avenue to use nonprecious metal cathode for advanced DMFC technologies with increased performance and at significantly reduced cost.

Selective Aerobic Oxidation of Alcohols over Atomically-Dispersed Non-Precious Metal Catalysts

DOE PAGES

Xie, Jiahan; Yin, Kehua; Serov, Alexey; ...

2016-12-15

Catalytic oxidation of alcohols often requires the presence of expensive transition metals. We show that earth-abundant Fe atoms dispersed throughout a nitrogen-containing carbon matrix catalyze the oxidation of benzyl alcohol and 5-hydroxymethylfurfural by O 2 in the aqueous phase. Furthermore, the activity of the catalyst can be regenerated by a mild treatment in H 2. An observed kinetic isotope effect indicates that β-H elimination from the alcohol is the kinetically relevant step in the mechanism, which can be accelerated by substituting Fe with Cu. Dispersed Cr, Co, and Ni also convert alcohols, demonstrating the general utility of metal–nitrogen–carbon materials formore » alcohol oxidation catalysis. Oxidation of aliphatic alcohols is substantially slower than that of aromatic alcohols, but adding 2,2,6,6-tetramethyl-1-piperidinyloxy as a co-catalyst with Fe can significantly improve the reaction rate.« less

Life Is Precious: Views of Adolescents and Their Mothers on Methods to Reduce Suicidal Behavior in Latinas

ERIC Educational Resources Information Center

Humensky, Jennifer L.; Gil, Rosa M.; Mazzula, Silvia; Diaz, Samantha; Lewis-Fernández, Roberto

2017-01-01

Life is Precious (LIP) was developed to help reduce suicidal behavior in Latina adolescents. As part of an external evaluation of the LIP program, we conducted focus groups with adolescent participants and mothers to learn whether participants and families believe that the activities of LIP address risks for suicidal behavior. Four focus groups…

Sustainable metal alkynyl chemistry: 3d metals and polyaza macrocyclic ligands.

PubMed

Ren, Tong

2016-02-25

We describe the chemistry of 3d metal alkynyls based on polyaza macrocyclic ligands, an emerging area of alkynyl chemistry that has previously been dominated by 4d and 5d metals with soft ligands. The abundance of 3d metals and low cost of tetraazacyclotetradecane ligands make these compounds more affordable, sustainable alternatives to metal alkynyls based on precious metals. Taking advantage of the rich variety of starting materials available in the literature, trans-[M(cyclam)(C2R)2]X (cyclam = 1,4,8,11-tetraazacyclotetradecane) compounds have been prepared from the reactions between [M(cyclam)X2]X (M = Cr, Fe and Co; X = Cl or OTf) and LiC2R. With [Co(cyclam)Cl2](+), both the {trans-[Co(cyclam)Cl]2(μ-(C≡C)n)}(2+) and trans-[Co(cyclam)(C2R)Cl](+) compounds have been prepared by a dehydrohalogenation reaction. The latter compounds undergo the second alkynylation reaction to afford dissymmetric trans-[Co(cyclam)(C2R)(C2R')](+) compounds. Similar alkynylation chemistry with complexes of the cyclam derivatives TMC (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) and HMC (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) has been demonstrated in studies of [Ni(TMC)(C2R)](+) and trans-/cis-[Cr(HMC)(C2R)2](+). Me3TACN (1,4,7-N,N',N''-trimethyl-1,4,7-triazacyclononane) is also a supporting ligand that has been observed in transition metal alkynyls. The trans-[M(cyclam)(C2D)(C2A)](+) compounds (D = donor chromophore, A = acceptor chromophore) are excellent candidates for probing photoinduced electron transfer and related photophysical and photochemical processes. 3d Metal ions are often in high-spin ground states, which make these alkynyl compounds promising building blocks for magnetic materials.

Sustainability of Strategic Minerals in Southern Africa and Potential Conflicts and Partnerships

DTIC Science & Technology

2010-01-01

harmful emissions 7 into relatively inert exhaust, and jewelry (in oriental markets ). Iridium is used in petroleum and automobiles. Rhodium...University of Cape Town, interviewed August 20, 2010. 26 Kenneth Beilstein, precious metals marketing expert, Metalur Corporation of Switzerland , email...UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Air Force Academy,Institute for National Security Studies ,USAFA,CO,80840 8

Retrieval of Au, Ag, Cu precious metals coupled with electric energy production via an unconventional coupled redox fuel cell reactor.

PubMed

Zhang, Hui-Min; Fan, Zheng; Xu, Wei; Feng, Xiao; Wu, Zu-Cheng

2017-09-15

The recovery of heavy metals from aqueous solutions or e-wastes is of upmost importance. Retrieval of Au, Ag, and Cu with electricity generation through building an ethanol-metal coupled redox fuel cells (CRFCs) is demonstrated. The cell was uniquely assembled on PdNi/C anode the electro-oxidation of ethanol takes place to give electrons and then go through the external circuit reducing metal ions to metallic on the cathode, metals are recovered. Taking an example of removal of 100mgL -1 gold in 0.5M HAc-NaAc buffer solution as the catholyte, 2.0M ethanol in 1.0M alkaline solution as the anolyte, an open circuit voltage of 1.4V, more than 96% of gold removal efficiency in 20h, and equivalent energy production of 2.0kWhkg -1 of gold can be readily achieved in this system. When gold and copper ions coexist, it was confirmed that metallic Cu is formed on the cathodic electrode later than metallic Au formation by XPS analysis. Thus, this system can achieve step by step electrodeposition of gold and copper while the two metal ions coexisting. This work develops a new approach to retrieve valuable metals from aqueous solution or e-wastes. Copyright © 2017 Elsevier B.V. All rights reserved.

Pt-based Bi-metallic Monolith Catalysts for Partial Upgrading of Microalgae Oil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lawal, Adeniyi; Manganaro, James; Goodall, Brian

Valicor’s proprietary wet extraction process in conjunction with thermochemical pre-treatment was performed on algal biomass from two different algae strains, Nannochloropsis Salina (N.S.) and Chlorella to produce algae oils. Polar lipids such as phospholipids were hydrolyzed, and metals and metalloids, known catalyst poisons, were separated into the aqueous phase, creating an attractive “pre-refined” oil for hydrodeoxygenation (HDO) upgrading by Stevens. Oil content and oil extraction efficiency of approximately 30 and 90% respectively were achieved. At Stevens, we formulated a Pt-based bi-metallic catalyst which was demonstrated to be effective in the hydro-treating of the algae oils to produce ‘green’ diesel. Themore » bi-metallic catalyst was wash-coated on a monolith, and in conjunction with a high throughput high pressure (pilot plant) reactor system, was used in hydrotreating algae oils from N.S. and Chlorella. Mixtures of these algae oils and refinery light atmospheric gas oil (LAGO) supplied by our petroleum refiner partner, Marathon Petroleum Corporation, were co-processed in the pilot plant reactor system using the Pt-based bi-metallic monolith catalyst. A 26 wt% N.S. algae oil/74 wt % LAGO mixture hydrotreated in the reactor system was subjected to the ASTM D975 Diesel Fuel Specification Test and it met all the important requirements, including a cetane index of 50.5. An elemental oxygen analysis performed by an independent and reputable lab reported an oxygen content of trace to none found. The successful co-processing of a mixture of algae oil and LAGO will enable integration of algae oil as a refinery feedstock which is one of the goals of DOE-BETO. We have presented experimental data that show that our precious metal-based catalysts consume less hydrogen than the conventional hydrotreating catalyst NiMo Precious metal catalysts favor the hydrodecarbonylation/hydrodecarboxylation route of HDO over the dehydration route preferred by base

Novel Structured Metal Bipolar Plates for Low Cost Manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Conghua

2013-08-15

Bipolar plates are an important component in fuel cell stacks and accounts for more than 75% of stack weight and volume, and 20% of the stack cost. The technology development of metal bipolar plates can effectively reduce the fuel cells stack weight and volume over 50%. The challenge is to protect metal plate from corrosion at low cost for the broad commercial applications. While most of today’s PEM fuel cell metallic bipolar plate technologies use some precious metal, the focus of this SBIR project is to develop a low cost, novel nano-structured metal bipolar plate technology without using any preciousmore » metal. The technology will meet the performance and cost requirements for automobile applications. Through the Phase I project, TreadStone has identified the corrosion resistant and electrically conductive titanium oxide for the metal bipolar plate surface protection for automotive PEM fuel cell applications. TreadStone has overcome the manufacturing issues to apply the coating on metal substrate surface, and has demonstrated the feasibility of the coated stainless steel plates by ex-situ evaluation tests and the in-situ fuel cell long term durability test. The test results show the feasibility of the proposed nano-structured coating as the low cost metal bipolar plates of PEM fuel cells. The plan for further technology optimization is also outlined for the Phase II project.« less

Recovery of valuable metals from polymetallic mine tailings by natural microbial consortium.

PubMed

Vardanyan, Narine; Sevoyan, Garegin; Navasardyan, Taron; Vardanyan, Arevik

2018-05-28

Possibilities for the recovery of non-ferrous and precious metals from Kapan polymetallic mine tailings (Armenia) were studied. The aim of this paper was to study the possibilities of bioleaching of samples of concentrated tailings by the natural microbial consortium of drainage water. The extent of extraction of metals from the samples of concentrated tailings by natural microbial consortium reached 41-55% and 53-73% for copper and zinc, respectively. Metal leaching efficiencies of pure culture Leptospirillum ferrooxidans Teg were higher, namely 47-93% and 73-81% for copper and zinc, respectively. The content of gold in solid phase of tailings increased about 7-16% and 2-9% after bio-oxidation process by L. ferrooxidans Teg and natural microbial consortium, respectively. It was shown that bioleaching of the samples of tailings could be performed using the natural consortium of drainage water. However, to increase the intensity of the recovery of valuable metals, natural consortium of drainage water combined with iron-oxidizing L. ferrooxidans Teg has been proposed.

75 FR 8682 - Sunshine Act Meetings

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-25

... futures and options in the precious and base metals markets, and to consider Federal position limits in... precious and base metals markets and related hedge exemptions on regulated futures exchanges, derivatives... COMMODITY FUTURES TRADING COMMISSION Sunshine Act Meetings Agency Holding the Meeting: Commodity...

41 CFR 109-45.1002 - Agency responsibilities.

Code of Federal Regulations, 2011 CFR

2011-01-01

... organizations are responsible for establishing a program for the recovery of precious metals. ... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS UTILIZATION AND DISPOSAL 45-SALE, ABANDONMENT, OR DESTRUCTION OF PERSONAL PROPERTY 45.10-Recovery of Precious Metals § 109-45...

41 CFR 109-45.1002 - Agency responsibilities.

Code of Federal Regulations, 2010 CFR

2010-07-01

... organizations are responsible for establishing a program for the recovery of precious metals. ... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS UTILIZATION AND DISPOSAL 45-SALE, ABANDONMENT, OR DESTRUCTION OF PERSONAL PROPERTY 45.10-Recovery of Precious Metals § 109-45...

The Genesis of Precious and Base Metal Mineralization at the Miguel Auza Deposit, Zacatecas, Mexico

NASA Astrophysics Data System (ADS)

Findley, A. A.; Olivo, G. R.; Godin, L.

2009-05-01

The Miguel Auza mine located in Zacatecas State, Mexico, is a vein-type polymetallic epithermal deposit hosted in deformed argillite, siltstone and, greywacke of the Cretaceous Caracol Formation. Silver-rich base metal veins (0.2 m to >1.5 m wide) are spatially associated with the NE-striking, steeply SE- dipping (70-80°) Miguel Auza fault over a strike length of 1.6 km and a depth of 460 m. A 2 km2 monzonitic stock located in the proximity of the mineralized zones, has previously been interpreted as the source of the mineralizing fluids. Four distinct structural stages are correlated with hydrothermal mineral deposition: (I) The Pre-ore stage is characterized by normal faulting, fracturing of host rock, and rotation of bedding planes. This stage consists of quartz, illite, chlorite, +/- pyrite alteration of sedimentary wall rocks. (II) The Pyrite-vein stage is associated with reverse-sense reactivation of early normal faults, dilation of bedding planes/fractures, and deposition of generally barren calcite + pyrite veinlets. (III) The Main-ore stage is related to the development of reverse-fault- hosted massive sulphide veins. During this stage three phases of mineral deposition are recorded: early pyrite and arsenopyrite, intermediate chalcopyrite, pyrite, arsenopyrite, and base metals, and late base metals and Ag-bearing minerals. Associated gangue minerals during the main ore stage are quartz, muscovite, calcite and chlorite. (IV) The Post-ore stage involves late NW-SE striking block faulting, brecciation and calcite veining. Later supergene oxidation of veins led to deposition of Fe-oxides and hydroxides, commonly filling fractures or replacing early-formed sulphide assemblages. The various vein types display classic epithermal textures including open space filling, banding, comb quartz and brecciation. The Ag-bearing minerals comprise pyrargyrite [Ag3(Sb,As)S3], argentotennantite [(Cu,Ag)10(Zn,Fe)2(Sn,As)4S13], polybasite-pearceite [(Ag,Cu)16(Sb,As)2S11], and

41 CFR 109-27.5104-1 - Acquisitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS SUPPLY AND PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-1 Acquisitions. DOE organizations and contractors shall contact the Business Center for Precious Metals Sales and Recovery to determine the...

41 CFR 109-27.5104-1 - Acquisitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS SUPPLY AND PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-1 Acquisitions. DOE organizations and contractors shall contact the Business Center for Precious Metals Sales and Recovery to determine the...

Economic aspects of metals recover

NASA Astrophysics Data System (ADS)

Wieczorek, Daria; Kwaśniewska, Dobrawa

2018-03-01

One of the modern economy models is circular economy in which wastes should be considered as resource and used in an efficient and sustainable way. This also concerns to metals included in scraps. However, the need for metal recovery from waste is not only the result of the latest economic trends but also the result of large and constantly changing demand for metals. Shrinking natural sources of metals, concentrations of ores in small number of countries in the world and resulting from this dependence on import, geopolitical situation, new technologies demands are only a few most important determinants that have been changing the structure of the metal market over years. In this chapter, authors focused on the presentation of economic aspects of metal recovery from various sources. The chapter presents the characteristic of metal market elements (supply, demand and price) and changes that took place over decades, underlining the structure of precious and highly desirable metal market elements. Balance between the demand and supply ensures price stability and rationalizes inflation. However, growing demand on many means that secure supply chains, such as recycling and material recovery, are essential to ensure continuity in the supply chain and guarantee unrestricted technological progress and innovation. The data included in this chapter presents also the concentration of different metals and group of metals in wastes pointing that recycling of waste can become one of the possibilities of acquiring missing and critical metals. Metal-laden wastes include a few groups: waste electrical and electronic equipments, catalysts of different application, introduced on chemical, petrochemical or automotive market, galvanic wastes and wastewaters. The profitability assessment of recycling processes is very complicated. Nevertheless cited data shows that profitability of recovery depends on the metal analyzed and the type of waste. It must be underline that an optimized

Bio‐palladium: from metal recovery to catalytic applications

PubMed Central

De Corte, Simon; Hennebel, Tom; De Gusseme, Bart; Verstraete, Willy; Boon, Nico

2012-01-01

Summary While precious metals are available to a very limited extent, there is an increasing demand to use them as catalyst. This is also true for palladium (Pd) catalysts and their sustainable recycling and production are required. Since Pd catalysts exist nowadays mostly under the form of nanoparticles, these particles need to be produced in an environment‐friendly way. Biological synthesis of Pd nanoparticles (‘bio‐Pd’) is an innovative method for both metal recovery and nanocatalyst synthesis. This review will discuss the different bio‐Pd precipitating microorganisms, the applications of the catalyst (both for environmental purposes and in organic chemistry) and the state of the art of the reactors based on the bio‐Pd concept. In addition, some main challenges are discussed, which need to be overcome in order to create a sustainable nanocatalyst. Finally, some outlooks for bio‐Pd in environmental technology are presented. PMID:21554561

75 FR 60411 - Request for Comment on Options for a Proposed Exemptive Order Relating to the Trading and...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-30

... in the precious metals markets. \\28\\ See http://www.sec.gov/Archives/edgar/data/1459862... efficient exposure to commodity market price movements.\\4\\ These Precious Metal Commodity-Based ETFs have... conditions to the exemption orders) and that novel products may be introduced without undue delay for market...

Selenium, tellurium and precious metal mineralogy in Uchalinsk copper-zinc-pyritic district, the Urals

NASA Astrophysics Data System (ADS)

Vikentev, I.

2016-04-01

During processing the most of Au, Ag, Se, Te, Pb, Bi, Sb, Hg as well as notable part of Cu, Zn and Cd fail for tailings and became heavy metal pollutants. Modes of occurrence of Au, Ag, Te and Se covers two giant VMS deposits: Uchaly (intensively deformed) and Uzelginsk (altered by late hydrothermal processes) as well as middle-sized Molodezn and West Ozern deposits (nondeformed) have been studied. Mineral forms of these elements as well as their presence in disperse mode in common ore minerals (pyrite, chalcopyrite, sphalerite) have been studied using SEM, EPMA, INAA, ICP-MS and LA-ICP-MS.

The Menstruating Womb: A Cross-Cultural Analysis of Body and Gender in Hŏ Chun’s Precious Mirror of Eastern Medicine (1613)

PubMed Central

Wu, Yi-Li

2017-01-01

This paper analyses body and gender in East Asian medicine through a case study of Hŏ Chun’s 許浚 Precious Mirror of Eastern Medicine (Tongŭi pogam 東醫寶鑑, first ed. 1613). While Hŏ Chun’s Chinese sources classified menstrual ailments as a disease of women, Hŏ created a new nosological model that defined menstrual ailments as maladies of the ‘womb’, an internal body part found in men and women alike. I read back and forth between the Precious Mirror and the Chinese sources that Hŏ Chun cites to analyse the textual and intellectual processes by which he constructed his androgynous, menstruating womb. My findings engage with scholarship on the history of East Asian medical exchanges as well as with scholarship on menstruation, sex, and gender in world medicine. PMID:29081728

Biotechnology in the management and resource recovery from metal bearing solid wastes: Recent advances.

PubMed

Sethurajan, Manivannan; van Hullebusch, Eric D; Nancharaiah, Yarlagadda V

2018-04-01

Solid metalliferous wastes (sludges, dusts, residues, slags, red mud and tailing wastes) originating from ferrous and non-ferrous metallurgical industries are a serious environmental threat, when waste management practices are not properly followed. Metalliferous wastes generated by metallurgical industries are promising resources for biotechnological extraction of metals. These wastes still contain significant amounts of valuable non-ferrous metals, sometimes precious metals and also rare earth elements. Elemental composition and mineralogy of the metallurgical wastes is dependent on the nature of mining site and composition of primary ores mined. Most of the metalliferous wastes are oxidized in nature and contain less/no reduced sulfidic minerals (which can be quite well processed by biohydrometallurgy). However, application of biohydrometallurgy is more challenging while extracting metals from metallurgical wastes that contain oxide minerals. In this review, origin, elemental composition and mineralogy of the metallurgical solid wastes are presented. Various bio-hydrometallurgical processes that can be considered for the extraction of non-ferrous metals from metal bearing solid wastes are reviewed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Zinc: A precious trace element for oral health care?

PubMed

Fatima, Tayyaba; Haji Abdul Rahim, Zubaidah Binti; Lin, Chai Wen; Qamar, Zeeshan

2016-08-01

This review will discuss the importance of Zinc in the maintenance of oral health. Zinc (Zn) is a trace element of valuable importance. In the oral cavity, it is naturally present at various sites such as dental plaque, dental hard tissues and saliva. It is proven to be effective against common prevalent oral health problems such as dental caries, gingivitis, periodontitis and malodour. It is being used in various oral health care products to control the formation of dental plaque and inhibiting the formation of dental calculus. It has the potential to sustain and maintain its elevated concentrations for a longer time particularly in the dental plaque and saliva on delivery from the mouth rinses and toothpastes. It has been reported that low concentrations of zinc have the capability to reduce dissolution and promote remineralization under caries simulating conditions. Most importantly low Zn2+ levels in the serum are useful as a tumour marker. Thus taking a note of its potentials, it can be concluded that zinc is a precious element for the maintenance of oral health.

75 FR 69058 - Request for Comment on a Proposal to Exempt, Pursuant to the Authority in Section 4(c) of the...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-10

... categorical Section 4(c) exemption to permit options and futures on shares of all or some precious metal commodity-based ETFs to be traded and cleared as options on securities and security futures, respectively... options and futures on shares of precious metal commodity- based ETFs. The Commission believes that...

41 CFR 109-27.5104-2 - Physical protection and storage.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 41 Public Contracts and Property Management 3 2013-07-01 2013-07-01 false Physical protection and... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-2 Physical protection and storage. Precious metals shall be afforded exceptional physical protection from time of receipt...

41 CFR 109-27.5104-2 - Physical protection and storage.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Physical protection and... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-2 Physical protection and storage. Precious metals shall be afforded exceptional physical protection from time of receipt...

41 CFR 109-27.5104-2 - Physical protection and storage.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 41 Public Contracts and Property Management 3 2014-01-01 2014-01-01 false Physical protection and... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-2 Physical protection and storage. Precious metals shall be afforded exceptional physical protection from time of receipt...

41 CFR 109-27.5104-2 - Physical protection and storage.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Physical protection and... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-2 Physical protection and storage. Precious metals shall be afforded exceptional physical protection from time of receipt...

41 CFR 109-27.5104-2 - Physical protection and storage.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 41 Public Contracts and Property Management 3 2012-01-01 2012-01-01 false Physical protection and... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-2 Physical protection and storage. Precious metals shall be afforded exceptional physical protection from time of receipt...

Egg derived nitrogen-self-doped carbon/carbon nanotube hybrids as noble-metal-free catalysts for oxygen reduction

NASA Astrophysics Data System (ADS)

Zhang, Jian; Wu, Siyu; Chen, Xu; Pan, Mu; Mu, Shichun

2014-12-01

Currently, the development of nitrogen (N) doped carbon based non-precious metal ORR catalysts has become one of the most attractive topics in low temperature fuel cells. Here, we demonstrate a green synthesis route of N-self-doped carbon materials by using eggs as N sources combining with iron sources and multi-walled carbon nanotubes (CE-Fe-MWNT). After carbonized, such hybrid materials possess an outstanding electrocatalytic activity towards ORR comparable to the commercial Pt/C catalyst in alkaline media, and both superior stability and fuel (methanol and CO) tolerance than the commercial Pt/C catalyst, which provide a promising alternative to noble metal catalysts by using abundant natural biological resources.

Very High Output Thermoelectric Devices Based on ITO Nanocomposites

NASA Technical Reports Server (NTRS)

Fralick, Gustave; Gregory, Otto J.

2009-01-01

A material having useful thermoelectric properties was synthesized by combining indium-tin-oxide (ITO) with a NiCoCrAlY alloy/alumina cermet. This material had a very large Seebeck coefficient with electromotive-force-versustemperature behavior that is considered to be excellent with respect to utility in thermocouples and other thermoelectric devices. When deposited in thin-film form, ceramic thermocouples offer advantages over precious-metal (based, variously, on platinum or rhodium) thermocouples that are typically used in gas turbines. Ceramic thermocouples exhibit high melting temperatures, chemical stability at high temperatures, and little or no electromigration. Oxide ceramics also resist oxidation better than metal thermocouples, cost substantially less than precious-metal thermocouples, and, unlike precious-metal thermocouples, do not exert catalytic effects.

Not All That Glitters is Gold: Gold Imitations in History.

PubMed

Karpenko, Vladimír

2007-07-01

When gold became considered as a precious metal for decorative purposes and later for coinage, attempts at producing imitations soon began to appear. There were two motives behind this activity: to make a metal that could pass as gold, and to quite openly imitate this precious metal for people who could not afford true gold. Imitation gold was produced by metallurgists, and later also by alchemists. This paper is about gold imitations that did not contain any precious metal. Gold-like alloys of silver are thus excluded. An attempt is further undertaken to classify into separate groups the various gold imitations that have appeared in different cultures throughout time, with an emphasis on brass as a typical imitation of gold.

40 CFR 421.262 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2010 CFR

2010-07-01

... pollutant property Maximum for any 1 day Maximum for monthly average mg/troy ounce of precious metals... day Maximum for monthly average mg/troy ounce of precious metal in the granulated raw material Copper... monthly average mg/troy ounce of gold produced by cyanide stripping Copper 7.030 3.700 Cyanide (total) 1...

Vapor Phase Hydrogenolysis of Furanics Utilizing Reduced Cobalt Mixed Metal Oxide Catalysts

DOE PAGES

Sulmonetti, Taylor P.; Hu, Bo; Ifkovits, Zachary; ...

2017-03-21

Vapor phase hydrogenolysis of both furfuryl alcohol and furfural were investigated over reduced Co based mixed metal oxides derived from the calcination of a layered double hydroxide precursor. Although a reduced cobalt aluminate sample displays promising selectivity towards 2-methylfuran (2-MF) production, the addition of an Fe dopant into the oxide matrix significantly enhances the activity and selectivity per gram of catalyst. Approximately 82% 2-MF yield is achieved at high conversion when furfuryl alcohol is fed into the reactor at 180 °C over the reduced 3Co-0.25Fe-0.75Al catalyst. Based on structural characterization studies including TPR, XPS, and in-situ XAS it is suggestedmore » that Fe facilitates the reduction of Co, allowing for formation of more metallic species. Altogether, this study demonstrates that non-precious metal catalysts offer promise for the selective conversion of a key biomass oxygenate to a proposed fuel additive.« less

Direct selenylation of mixed Ni/Fe metal-organic frameworks to NiFe-Se/C nanorods for overall water splitting

NASA Astrophysics Data System (ADS)

Xu, Bo; Yang, He; Yuan, Lincheng; Sun, Yiqiang; Chen, Zhiming; Li, Cuncheng

2017-10-01

Development of low-cost, highly active bifunctional catalyst for efficient overall water splitting based on earth-abundant metals is still a great challenging task. In this work, we report a NiFe-Se/C composite nanorod as efficient non-precious-metal electrochemical catalyst derived from direct selenylation of a mixed Ni/Fe metal-organic framework. The as-obtained catalyst requires low overpotential to drive 10 mA cm-2 for HER (160 mV) and OER (240 mV) in 1.0 M KOH, respectively, and its catalytic activity is maintained for at least 20 h. Moreover, water electrolysis using this catalyst achieves high water splitting current density of 10 mA cm-2 at cell voltage of 1.68 V.

Metal recovery by bioleaching of sulfidic mining wastes — Application to a European case study

NASA Astrophysics Data System (ADS)

Guézennec, A. G.; Jacob, J.; Joulian, C.; Dupraz, S.; Menard, Y.; d'Hugues, P.

The non-energy extractive industry (NEEI) of the EU-25 generated a direct turnover of about €40 billion, and provided employment to about 250000 people in 16629 companies in 2004. The use of primary raw materials in the production of other branches of EU industry means they have a central role in guaranteeing industrial and economic sustainability. Nevertheless current demand exceeds production, and so the EU is heavily dependent on minerals and metals imports. In this context of securing access to metals, turning mining wastes into new resources of currently unexploited valuable metals is an important challenge. The mining wastes can contain base and precious metals, but also metalloids and rare earth elements that are nowadays considered as highly critical for the industrial development of the European Union. Nevertheless, the development of alternative routes to conventional processing is still required in order to decrease the cost associated to the treatment of these unconventional resources which are more complex in composition and with lower grades.

40 CFR 421.263 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2010 CFR

2010-07-01

... for any 1 day Maximum for monthly average mg/troy ounce of precious metals, including silver.../troy ounce of precious metals in the granulated raw material Copper 0.819 0.390 Cyanide (total) 0.128 0... Maximum for monthly average mg/troy ounce of gold produced by cyanide stripping Copper 4.736 2.257 Cyanide...

Palladium and gold removal and recovery from precious metal solutions and electronic scrap leachates by Desulfovibrio desulfuricans.

PubMed

Creamer, Neil J; Baxter-Plant, Victoria S; Henderson, John; Potter, M; Macaskie, Lynne E

2006-09-01

Biomass of Desulfovibrio desulfuricans was used to recover Au(III) as Au(0) from test solutions and from waste electronic scrap leachate. Au(0) was precipitated extracellularly by a different mechanism from the biodeposition of Pd(0). The presence of Cu(2+) ( approximately 2000 mg/l) in the leachate inhibited the hydrogenase-mediated removal of Pd(II) but pre-palladisation of the cells in the absence of added Cu(2+) facilitated removal of Pd(II) from the leachate and more than 95% of the Pd(II) was removed autocatalytically from a test solution supplemented with Cu(II) and Pd(II). Metal recovery was demonstrated in a gas-lift electrobioreactor with electrochemically generated hydrogen, followed by precipitation of recovered metal under gravity. A 3-stage bioseparation process for the recovery of Au(III), Pd(II) and Cu(II) is proposed.

48 CFR 208.7302 - Policy.

Code of Federal Regulations, 2010 CFR

2010-10-01

... DEFENSE ACQUISITION PLANNING REQUIRED SOURCES OF SUPPLIES AND SERVICES Use of Government-Owned Precious.... DoD components shall furnish recovered precious metals contained in the DSCP inventory to production...

48 CFR 208.7302 - Policy.

Code of Federal Regulations, 2014 CFR

2014-10-01

... DEFENSE ACQUISITION PLANNING REQUIRED SOURCES OF SUPPLIES AND SERVICES Use of Government-Owned Precious.... DoD components shall furnish recovered precious metals contained in the DSCP inventory to production...

48 CFR 208.7302 - Policy.

Code of Federal Regulations, 2013 CFR

2013-10-01

... DEFENSE ACQUISITION PLANNING REQUIRED SOURCES OF SUPPLIES AND SERVICES Use of Government-Owned Precious.... DoD components shall furnish recovered precious metals contained in the DSCP inventory to production...

48 CFR 208.7302 - Policy.

Code of Federal Regulations, 2011 CFR

2011-10-01

... DEFENSE ACQUISITION PLANNING REQUIRED SOURCES OF SUPPLIES AND SERVICES Use of Government-Owned Precious.... DoD components shall furnish recovered precious metals contained in the DSCP inventory to production...

48 CFR 208.7302 - Policy.

Code of Federal Regulations, 2012 CFR

2012-10-01

... DEFENSE ACQUISITION PLANNING REQUIRED SOURCES OF SUPPLIES AND SERVICES Use of Government-Owned Precious.... DoD components shall furnish recovered precious metals contained in the DSCP inventory to production...

Noble-Metal-Free Molybdenum Disulfide Cocatalyst for Photocatalytic Hydrogen Production.

PubMed

Yuan, Yong-Jun; Lu, Hong-Wei; Yu, Zhen-Tao; Zou, Zhi-Gang

2015-12-21

Photocatalytic water splitting using powered semiconductors as photocatalysts represents a promising strategy for clean, low-cost, and environmentally friendly production of H2 utilizing solar energy. The loading of noble-metal cocatalysts on semiconductors can significantly enhance the solar-to-H2 conversion efficiency. However, the high cost and scarcity of noble metals counter their extensive utilization. Therefore, the use of alternative cocatalysts based on non-precious metal materials is pursued. Nanosized MoS2 cocatalysts have attracted considerable attention in the last decade as a viable alternative to improve solar-to-H2 conversion efficiency because of its superb catalytic activity, excellent stability, low cost, availability, environmental friendliness, and chemical inertness. In this perspective, the design, structures, synthesis, and application of MoS2 -based composite photocatalysts for solar H2 generation are summarized, compared, and discussed. Finally, this Review concludes with a summary and remarks on some challenges and opportunities for the future development of MoS2 -based photocatalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Technique for microswitch manufacture

NASA Technical Reports Server (NTRS)

Kitamura, T.; Kiyoyama, S.

1983-01-01

A five-step technique for microswitch manufacture is described: (1) A clad board is inlaid with a precious metal and the board is pressed. (2) One end of the fixed contact containing a precious metal inlay section is curved, and this edge of the precious metal inlay section becomes a fixed contact. (3) Inserts are formed in the unit body and terminal strips are placed through the top and bottom of the base and held. (4) The unit body is held by the base and the sequential contact strips are cut off. (5) Movable stripes are attached to the support of the terminal strips on the movable side and movable contacts are placed opposite the fixed contacts.

Metallic bionanocatalysts: potential applications as green catalysts and energy materials.

PubMed

Macaskie, Lynne E; Mikheenko, Iryna P; Omajai, Jacob B; Stephen, Alan J; Wood, Joseph

2017-09-01

Microbially generated or supported nanocatalysts have potential applications in green chemistry and environmental application. However, precious (and base) metals biorefined from wastes may be useful for making cheap, low-grade catalysts for clean energy production. The concept of bionanomaterials for energy applications is reviewed with respect to potential fuel cell applications, bio-catalytic upgrading of oils and manufacturing 'drop-in fuel' precursors. Cheap, effective biomaterials would facilitate progress towards dual development goals of sustainable consumption and production patterns and help to ensure access to affordable, reliable, sustainable and modern energy. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Characterization of Printed Circuit Boards for Metal and Energy Recovery after Milling and Mechanical Separation

PubMed Central

Bizzo, Waldir A.; Figueiredo, Renata A.; de Andrade, Valdelis F.

2014-01-01

The proper disposal of electrical and electronic waste is currently a concern of researchers and environmental managers not only because of the large volume of such waste generated, but also because of the heavy metals and toxic substances it contains. This study analyzed printed circuit boards (PCBs) from discarded computers to determine their metal content and characterized them as solid waste and fuel. The analysis showed that PCBs consist of approximately 26% metal, made up mainly of copper, lead, aluminum, iron and tin, as well as other heavy metals such as cadmium and nickel. Comparison with the results of other studies indicated that the concentration of precious metals (gold and silver) has declined over time. Analysis of the leachate revealed high concentrations of cadmium and lead, giving the residue the characteristics of hazardous waste. After milling the PCBs, we found that larger amounts of metal were concentrated in smaller fractions, while the lightest fraction, obtained by density separation, had a gross calorific value of approximately 11 MJ/kg, although with a high ash content. Milling followed by density separation proved potentially useful for recovery of metals and energy-rich fractions. PMID:28788692

Development and application of biotechnologies in the metal mining industry.

PubMed

Johnson, D Barrie

2013-11-01

Metal mining faces a number of significant economic and environmental challenges in the twenty-first century for which established and emerging biotechnologies may, at least in part, provide the answers. Bioprocessing of mineral ores and concentrates is already used in variously engineered formats to extract base (e.g., copper, cobalt, and nickel) and precious (gold and silver) metals in mines throughout the world, though it remains a niche technology. However, current projections of an increasing future need to use low-grade primary metal ores, to reprocess mine wastes, and to develop in situ leaching technologies to extract metals from deep-buried ore bodies, all of which are economically more amenable to bioprocessing than conventional approaches (e.g., pyrometallurgy), would suggest that biomining will become more extensively utilized in the future. Recent research has also shown that bioleaching could be used to process a far wider range of metal ores (e.g., oxidized ores) than has previously been the case. Biotechnologies are also being developed to control mine-related pollution, including securing mine wastes (rocks and tailings) by using "ecological engineering" approaches, and also to remediate and recover metals from waste waters, such as acid mine drainage. This article reviews the current status of biotechnologies within the mining sector and considers how these may be developed and applied in future years.

Metals bioleaching from electronic waste by Chromobacterium violaceum and Pseudomonads sp.

PubMed

Pradhan, Jatindra Kumar; Kumar, Sudhir

2012-11-01

These days, electronic waste needs to be taken into consideration due to its materials content, but due to the heterogeneity of the metals present, reprocessing of electronic waste is quite limited. The bioleaching of metals from electronic waste was investigated by using cyanogenic bacterial strains (Chromobacterium violaceum, Pseudomonas aeruginosa and Pseudomonas fluorescens). A two-step bioleaching process was followed under cyanide-forming conditions for maximum metals mobilization. Both single and mixed cultures of cyanogenic bacteria were able to mobilize metals from electronic waste with different efficiencies. In all the flasks in which high metal mobilizations were observed, the consequent biomass productions were also high. Pseudomonas aeruginosa was applied in the bioleaching process for the first time and this achieved its bioleaching ability of mobilization of metals from electronic waste. Chromobacterium violaceum as a single culture and a mixture of C. violaceum and P. aeruginosa exhibited maximum metal mobilization. Chromobacterium violaceum was capable of leaching more than 79, 69, 46, 9 and 7% of Cu, Au, Zn, Fe and Ag, respectively at an electronic waste concentration of 1% w/v. Moreover, the mixture of C. violaceum and P. aeruginosa exhibited metals leaching of more than 83, 73, 49, 13 and 8% of total Cu, Au, Zn, Fe, and Ag, respectively. Precious metals were mobilized through bioleaching which might be considered as an industrial application for recycling of electronic waste in the near future.

Non-Platinum Group Metal OER/ORR Catalysts for Alkaline Membrane Fuel Cells and Electrolyzers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Danilovic, Nemanja; Ayers, Katherine

Regenerative fuel cells (RFC) are energy storage devices that capture electrical energy in the form of hydrogen, with potential application for backup power and energy storage in remote locations, unmanned missions, and renewable energy capture. A unitized regenerative fuel cell (URFC) combines two separate electrochemical devices (fuel cell and electrolyzer) into one stack. The stack cost is driven by the platinum group metal (PGM) catalysts and the flow field components designed to withstand high potentials in acidic environments. Since the stack is the most expensive subcomponent of both the fuel cell and electrolyzer system, combining the two devices results inmore » substantial reduction in capital cost. However, in the past, combining the two stacks sacrificed device performance (operating cost) largely because the fuel cell had to operate with the thick electrolysis membranes in a URFC configuration, and due to water management issues in switching modes. Recent work in membrane-based electrolysis has resulted in more mechanically robust designs and materials that allow much thinner membranes, and work in flow cell design such as flow batteries has shown improved water transport through channel design and wet-proofing approaches. Therefore, the URFC concept is worth revisiting. At the same time, alkaline exchange membrane (AEM) devices are gathering attention due to the promise of PGM and valve metal elimination from the stack and a resulting strategic and capital cost benefit as compared with proton exchange membrane (PEM) systems. The result is a lower capital cost system that has half the precious metal group (PGM) catalysts, membrane and other stack component materials compared with discrete RFCs, although at the sacrifice of performance (operating cost). Proton has identified innovative AEM based RFC's to fulfill the role of low capital cost energy storage device owing to the use of non-precious metal containing electrodes, that enables certain markets

Metal Resistance and Lithoautotrophy in the Extreme Thermoacidophile Metallosphaera sedula

PubMed Central

Maezato, Yukari; Johnson, Tyler; McCarthy, Samuel; Dana, Karl

2012-01-01

Archaea such as Metallosphaera sedula are thermophilic lithoautotrophs that occupy unusually acidic and metal-rich environments. These traits are thought to underlie their industrial importance for bioleaching of base and precious metals. In this study, a genetic approach was taken to investigate the specific relationship between metal resistance and lithoautotrophy during biotransformation of the primary copper ore, chalcopyrite (CuFeS2). In this study, a genetic system was developed for M. sedula to investigate parameters that limit bioleaching of chalcopyrite. The functional role of the M. sedula copRTA operon was demonstrated by cross-species complementation of a copper-sensitive Sulfolobus solfataricus copR mutant. Inactivation of the gene encoding the M. sedula copper efflux protein, copA, using targeted recombination compromised metal resistance and eliminated chalcopyrite bioleaching. In contrast, a spontaneous M. sedula mutant (CuR1) with elevated metal resistance transformed chalcopyrite at an accelerated rate without affecting chemoheterotrophic growth. Proteomic analysis of CuR1 identified pleiotropic changes, including altered abundance of transport proteins having AAA-ATPase motifs. Addition of the insoluble carbonate mineral witherite (BaCO3) further stimulated chalcopyrite lithotrophy, indicating that carbon was a limiting factor. Since both mineral types were actively colonized, enhanced metal leaching may arise from the cooperative exchange of energy and carbon between surface-adhered populations. Genetic approaches provide a new means of improving the efficiency of metal bioleaching by enhancing the mechanistic understanding of thermophilic lithoautotrophy. PMID:23065978

Vapor phase hydrogenation of furfural over nickel mixed metal oxide catalysts derived from layered double hydroxides

DOE PAGES

Sulmonetti, Taylor P.; Pang, Simon H.; Claure, Micaela Taborga; ...

2016-03-09

The hydrogenation of furfural is investigated over various reduced nickel mixed metal oxides derived from layered double hydroxides (LDHs) containing Ni-Mg-Al and Ni-Co-Al. Upon reduction, relatively large Ni(0) domains develop in the Ni-Mg-Al catalysts, whereas in the Ni-Co-Al catalysts smaller metal particles of Ni(0) and Co(0), potentially as alloys, are formed, as evidenced by XAS, XPS, STEM and EELS. All the reduced Ni catalysts display similar selectivities towards major hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol), though the side products varied with the catalyst composition. The 1.1Ni-0.8Co-Al catalyst showed the greatest activity per titrated site when compared to the othermore » catalysts, with promising activity compared to related catalysts in the literature. In conclusion, the use of base metal catalysts for hydrogenation of furanic compounds may be a promising alternative to the well-studied precious metal catalysts for making biomass-derived chemicals if catalyst selectivity can be improved in future work by alloying or tuning metal-oxide support interactions.« less

Vapor phase hydrogenation of furfural over nickel mixed metal oxide catalysts derived from layered double hydroxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sulmonetti, Taylor P.; Pang, Simon H.; Claure, Micaela Taborga

2016-05-01

The hydrogenation of furfural is investigated over various reduced nickel mixed metal oxides derived from layered double hydroxides (LDHs) containing Ni-Mg-Al and Ni-Co-Al. Upon reduction, relatively large Ni(0) domains develop in the Ni-Mg-Al catalysts, whereas in the Ni-Co-Al catalysts smaller metal particles of Ni(0) and Co(0), potentially as alloys, are formed, as evidenced by XAS, XPS, STEM and EELS. All the reduced Ni catalysts display similar selectivities towards major hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol), though the side products varied with the catalyst composition. The 1.1Ni-0.8Co-Al catalyst showed the greatest activity per titrated site when compared to the othermore » catalysts, with promising activity compared to related catalysts in the literature. The use of base metal catalysts for hydrogenation of furanic compounds may be a promising alternative to the well-studied precious metal catalysts for making biomass-derived chemicals if catalyst selectivity can be improved in future work by alloying or tuning metal-oxide support interactions.« less

Bond and fracture strength of metal-ceramic restorations formed by selective laser sintering

PubMed Central

Bae, Eun-Jeong; Kim, Woong-Chul; Kim, Hae-Young

2014-01-01

PURPOSE The purpose of this study was to compare the fracture strength of the metal and the bond strength in metal-ceramic restorations produced by selective laser sintering (SLS) and by conventional casting (CAST). MATERIALS AND METHODS Non-precious alloy (StarLoy C, DeguDent, Hanau, Germany) was used in CAST group and metal powder (SP2, EOS GmbH, Munich, Germany) in SLS group. Metal specimens in the form of sheets (25.0 × 3.0 × 0.5 mm) were produced in accordance with ISO 9693:1999 standards (n=30). To measure the bond strength, ceramic was fired on a metal specimen and then three-point bending test was performed. In addition, the metal fracture strength was measured by continuing the application of the load. The values were statistically analyzed by performing independent t-tests (α=.05). RESULTS The mean bond strength of the SLS group (50.60 MPa) was higher than that of the CAST group (46.29 MPa), but there was no statistically significant difference. The metal fracture strength of the SLS group (1087.2 MPa) was lower than that of the CAST group (2399.1 MPa), and this difference was statistically significant. CONCLUSION In conclusion the balling phenomenon and the gap formation of the SLS process may increase the metal-ceramic bond strength. PMID:25177469

Efficient selective catalytic reduction of NO by novel carbon-doped metal catalysts made from electroplating sludge.

PubMed

Zhang, Jia; Zhang, Jingyi; Xu, Yunfeng; Su, Huimin; Li, Xiaoman; Zhou, Ji Zhi; Qian, Guangren; Li, Li; Xu, Zhi Ping

2014-10-07

Electroplating sludges, once regarded as industrial wastes, are precious resources of various transition metals. This research has thus investigated the recycling of an electroplating sludge as a novel carbon-doped metal (Fe, Ni, Mg, Cu, and Zn) catalyst, which was different from a traditional carbon-supported metal catalyst, for effective NO selective catalytic reduction (SCR). This catalyst removed >99.7% NO at a temperature as low as 300 °C. It also removed NO steadily (>99%) with a maximum specific accumulative reduced amount (MSARA) of 3.4 mmol/g. Gas species analyses showed that NO removal was accompanied by evolving N2 and CO2. Moreover, in a wide temperature window, the sludge catalyst showed a higher CO2 selectivity (>99%) than an activated carbon-supported metal catalyst. Structure characterizations revealed that carbon-doped metal was transformed to metal oxide in the sludge catalyst after the catalytic test, with most carbon (2.33 wt %) being consumed. These observations suggest that NO removal over the sludge catalyst is a typical SCR where metals/metal oxides act as the catalytic center and carbon as the reducing reagent. Therefore, our report probably provides an opportunity for high value-added utilizations of heavy-metal wastes in mitigating atmospheric pollutions.

A comparative study on the bond strength of porcelain to the millingable Pd-Ag alloy

PubMed Central

Hong, Jun-Tae

2014-01-01

PURPOSE The porcelain fused to gold has been widely used as a restoration both with the natural esthetics of the porcelain and durability and marginal fit of metal casting. However, recently, due to the continuous rise in the price of gold, an interest towards materials to replace gold alloy is getting higher. This study compared the bond strength of porcelain to millingable palladium-silver (Pd-Ag) alloy, with that of 3 conventionally used metal-ceramic alloys. MATERIALS AND METHODS Four types of metal-ceramic alloys, castable nonprecious nickel-chrome alloy, castable precious metal alloys containing 83% and 32% of gold, and millingable Pd-Ag alloy were used to make metal specimens (n=40). And porcelain was applied on the center area of metal specimen. Three-point bending test was performed with universal testing machine. The bond strength data were analyzed with a one-way ANOVA and post hoc Scheffe's tests (α=.05). RESULTS The 3-point bending test showed the strongest (40.42 ± 5.72 MPa) metal-ceramic bond in the nonprecious Ni-Cr alloy, followed by millingable Pd-Ag alloy (37.71 ± 2.46 MPa), precious metal alloy containing 83% of gold (35.89 ± 1.93 MPa), and precious metal alloy containing 32% of gold (34.59 ± 2.63 MPa). Nonprecious Ni-Cr alloy and precious metal alloy containing 32% of gold showed significant difference (P<.05). CONCLUSION The type of metal-ceramic alloys affects the bond strength of porcelain. Every metal-ceramic alloy used in this study showed clinically applicable bond strength with porcelain (25 MPa). PMID:25352959

Examining the evolution of metals utilized in printed circuit boards.

PubMed

Adie, Gilbert Umaye; Sun, Lingyu; Zeng, Xianlai; Zheng, Lixia; Osibanjo, Oladele; Li, Jinhui

2017-07-01

Management of waste electrical and electronic equipment (WEEE) has recently attracted worldwide attention because of high metal concentrations in them. Evolution of toxic and precious metals utilized in WEEE can not only reflect the adventure of eco-design, but can also guide the final recycling option. Pb, As, Cu, Au, Sn and Ag were determined in 10 composite samples of printed circuit boards of cathode ray tube televisions (TV-PCBs) that were produced between 1980 and 2005. The obtained results indicated that average metal concentrations in all TV-PCBs were - Cu: 10.6 ± 4.1%, Sn: 4.21 ± 0.90%, Pb: 3.15 ± 0.54%, Ag: 0.0215 ± 0.0068%, Au: 0.0068 ± 0.0049% and As: 0.0007 ± 0.0004%. No remarkable difference was found in compositions of Pb and Sn over the years, suggesting that there were no major modifications of Sn/Pb solder used in joining the circuitry system. The average composition of Cu fluctuated between 5.10% in 1980 and 12.8% in the mid-1990s and decreased afterwards. The decreases in Ag and Cu compositions could possibly be associated with thinner layers of these metals in newer model products.

Colloidal and physical transport textures exhibited by electrum and naumannite in bonanza epithermal veins from western USA, and their significance

USGS Publications Warehouse

Saunders, James A.; Vikre, Peter G.; Unger, Derick L.; Beasley, Lee

2010-01-01

It is reasonably clear that disequilibrium or “far-from equilibrium” conditions lead to the formation of silica colloids and their deposition in many epithermal deposits. This implies ore-forming solutions had elevated concentrations of dissolved silica, well in excess of amorphous silica saturation. We have previously demonstrated that such colloidal silica particles were deposited in epithermal veins as silica gels and opal, which may later progress along a path to crystallize into more thermodynamically favored (less-soluble) silica phases such as quartz and chalcedony. Also, in some deposits, amorphous silica is co-deposited with precious-metal minerals, such as electrum in the banded super-bonanza ores of the Sleeper deposit (NV). Ore-mineral textures from some western USA bonanza epithermal ores indicate that two precious-metal phases (electrum and naumannite, Ag2Se) form colloidal particles that are transported by ore-forming fluids and are deposited either by aggregation (by sticking to other precious metal-particles) to make dendrites, or are deposited on the “lee” side of protrusion along vein walls (or perhaps by both processes). We can infer by analogy to silica that this also implies that ore-forming solutions contained elevated (supersaturated) dissolved concentrations of both gold and silver that formed colloidal particles under disequilibrium (often chaotic) conditions. Thus physical transport and deposition textures seem to indicate the presence of strongly precious-metal-enriched ore forming fluids, which led to (not surprisingly) the bonanza grades of these remarkable ores. What causes such a precious-metal-rich solution is debatable, but that is the subject of our continued investigations.

Robust Catalysis on 2D Materials Encapsulating Metals: Concept, Application, and Perspective.

PubMed

Deng, Jiao; Deng, Dehui; Bao, Xinhe

2017-11-01

Great endeavors are undertaken to search for low-cost, rich-reserve, and highly efficient alternatives to replace precious-metal catalysts, in order to cut costs and improve the efficiency of catalysts in industry. However, one major problem in metal catalysts, especially nonprecious-metal catalysts, is their poor stability in real catalytic processes. Recently, a novel and promising strategy to construct 2D materials encapsulating nonprecious-metal catalysts has exhibited inimitable advantages toward catalysis, especially under harsh conditions (e.g., strong acidity or alkalinity, high temperature, and high overpotential). The concept, which originates from unique electron penetration through the 2D crystal layer from the encapsulated metals to promote a catalytic reaction on the outermost surface of the 2D crystal, has been widely applied in a variety of reactions under harsh conditions. It has been vividly described as "chainmail for catalyst." Herein, recent progress concerning this chainmail catalyst is reviewed, particularly focusing on the structural design and control with the associated electronic properties of such heterostructure catalysts, and also on their extensive applications in fuel cells, water splitting, CO 2 conversion, solar cells, metal-air batteries, and heterogeneous catalysis. In addition, the current challenges that are faced in fundamental research and industrial application, and future opportunities for these fantastic catalytic materials are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and properties of a novel catalyst for the combustion of methane. Final report, January 1986-December 1989

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hicks, R.F.

1990-10-17

The objective of the research, which was funded by the Physical Sciences Department of the Gas Research Institute, was to understand how to design precious metal catalysts for methane combustion. These catalyst must be stable in the combustion environment and exhibit high rates of oxidation. The authors have found that palladium on alumina does not lose active surface area in air below 900C. Whereas, platinum vaporizes above 600C. The rate of methane oxidation per exposed metal atom depends on the metal used, platinum or palladium, and whether the metal is completely oxidized or covered with adsorbed oxygen during reaction. Themore » percentage of metal oxidized depends on the size, morphology and crystallinity of the metal particles. The relative rates of methane oxidation are: dispersed PtO2: dispersed PdO: crystalline Pt: crystalline Pd = 1:6:16:100.« less

Optimization of the Electrochemical Extraction and Recovery of Metals from Electronic Waste Using Response Surface Methodology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diaz, Luis A.; Clark, Gemma G.; Lister, Tedd E.

The rapid growth of the electronic waste can be viewed both as an environmental threat and as an attractive source of minerals that can reduce the mining of natural resources, and stabilize the market of critical materials, such as rare earths. Here in this article surface response methodology was used to optimize a previously developed electrochemical recovery process for base metals from electronic waste using a mild oxidant (Fe 3+). Through this process an effective extraction of base metals can be achieved enriching the concentration of precious metals and significantly reducing environmental impacts and operational costs associated with the wastemore » generation and chemical consumption. The optimization was performed using a bench-scale system specifically designed for this process. Operational parameters such as flow rate, applied current density and iron concentration were optimized to reduce the specific energy consumption of the electrochemical recovery process to 1.94 kWh per kg of metal recovered at a processing rate of 3.3 g of electronic waste per hour.« less

Optimization of the Electrochemical Extraction and Recovery of Metals from Electronic Waste Using Response Surface Methodology

DOE PAGES

Diaz, Luis A.; Clark, Gemma G.; Lister, Tedd E.

2017-06-08

The rapid growth of the electronic waste can be viewed both as an environmental threat and as an attractive source of minerals that can reduce the mining of natural resources, and stabilize the market of critical materials, such as rare earths. Here in this article surface response methodology was used to optimize a previously developed electrochemical recovery process for base metals from electronic waste using a mild oxidant (Fe 3+). Through this process an effective extraction of base metals can be achieved enriching the concentration of precious metals and significantly reducing environmental impacts and operational costs associated with the wastemore » generation and chemical consumption. The optimization was performed using a bench-scale system specifically designed for this process. Operational parameters such as flow rate, applied current density and iron concentration were optimized to reduce the specific energy consumption of the electrochemical recovery process to 1.94 kWh per kg of metal recovered at a processing rate of 3.3 g of electronic waste per hour.« less

Gold and palladium adsorption from leached electronic scrap using ordered mesoporous carbon nanoscaffolds

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDowell, Rocklan; Dutech, Guy

2014-09-01

Ordered mesoporous carbon (OMC) nanoscaffolds are engineered agglomerates of carbon nanotubes held together by small carbon nanofibers with uniform pore sizes, high pore volume, and high channel permeability. These materials exhibit very high affinity for the adsorption of gold from aqueous acidic mixtures. The efficiency of gold recovery is comparable to those typically accomplished using biopolymer-based adsorbents. The adsorption efficiency for other precious metals such as palladium and platinum is lower. Studies on the precious metal (Au, Pd) adsorption on OMC materials from actual liquors of leached electronics will be presented. Adsorption properties will be compared for several different sorbentsmore » used for the recovery of precious metals. The leach liquor compositions for three different types of electronic scrap materials (personal computer board, cell phone and tv input/output board) will be presented. The sorption efficiencies for Au, Pd, together with a spectrum of competing and non-competing metals, from such leach mixtures will be compared.« less

Effect of metal conditioner on bonding of porcelain to cobalt-chromium alloy

PubMed Central

Kajihara, Yutaro; Takenouchi, Yoshihisa; Tanaka, Takuo; Suzuki, Shiro; Minami, Hiroyuki

2016-01-01

PURPOSE The purpose of this study was to evaluate the efficacy of two different metal conditioners for non-precious metal alloys for the bonding of porcelain to a cobalt-chromium (Co-Cr) alloy. MATERIALS AND METHODS Disk-shaped specimens (2.5×10.0 mm) were cast with Co-Cr alloy and used as adherend materials. The bonding surfaces were polished with a 600-grid silicon carbide paper and airborne-particle abraded using 110 µm alumina particles. Bonding specimens were fabricated by applying and firing either of the metal conditioners on the airborne-particle abraded surface, followed by firing porcelain into 5 mm in diameter and 3 mm in height. Specimens without metal conditioner were also fabricated. Shear bond strength for each group (n=8) were measured and compared (α=.05). Sectional view of bonding interface was observed by SEM. EDS analysis was performed to determine the chemical elements of metal conditioners and to determine the failure modes after shear test. RESULTS There were significant differences among three groups, and two metal conditioner-applied groups showed significantly higher values compared to the non-metal conditioner group. The SEM observation of the sectional view at bonding interface revealed loose contact at porcelain-alloy surface for non-metal conditioner group, however, close contact at both alloy-metal conditioner and metal conditioner-porcelain interfaces for both metal conditioner-applied groups. All the specimens showed mixed failures. EDS analysis showed that one metal conditioner was Si-based material, and another was Ti-based material. Si-based metal conditioner showed higher bond strengths compared to the Ti-based metal conditioner, but exhibited more porous failure surface failure. CONCLUSION Based on the results of this study, it can be stated that the application of metal conditioner is recommended for the bonding of porcelain to cobalt-chromium alloys. PMID:26949481

ZnO@C (core@shell) microspheres derived from spent coffee grounds as applicable non-precious electrode material for DMFCs.

PubMed

Ghouri, Zafar Khan; Al-Meer, Saeed; Barakat, Nasser A M; Kim, Hak Yong

2017-05-11

Although numerous reports have introduced non precious electrocatalysts for methanol oxidation, most of those studies did not consider the corresponding high onset potential which restricts utilization in real fuel cells. In this study, an -90 mV [vs. Ag/AgCl] onset potential non-precious electrocatalyst is introduced as an applicable anode material for the direct methanol fuel cells. Moreover, the proposed material was prepared from a cheap and abundantly existing resource; the spent coffee grounds. Typically, the spent coffee grounds were facilely converted to core@shell (ZnO@C) microspheres through a two-step approach, involving chemical activation and a subsequent calcination at temperature of 700 °C. Activation of the carbon derived from the spent coffee grounds was performed with ZnCl 2 which acts as pore-forming agent as well as a precursor for the ZnO. The structure and morphology were characterized by (XRD), (SEM), and (TEM) analyses while the electrochemical characterizations was evaluated by cyclic voltammetry (CV) technique. Besides the comparatively very low onset potential, the introduced microspheres exhibited relatively high current density; 17 mA/cm 2 . Overall, based on the advantages of the green source of carbon and the good electrocatalytic activity, the spent coffee grounds-derived carbon can be considered a promise anode material for the DMFCs.

Exploring the Utilization of Low-Pressure, Piston-Cylinder Experiments to Determine the Bulk Compositions of Finite, Precious Materials

NASA Technical Reports Server (NTRS)

Vander Kaaden, K. E.; McCubbin, F. M.; Harrington, A. D.

2017-01-01

Determining the bulk composition of precious materials with a finite mass (e.g., meteorite samples) is extremely important in the fields of Earth and Planetary Science. From meteorite studies we are able to place constraints on large scale planetary processes like global differentiation and subsequent volcanism, as well as smaller scale processes like crystallization in a magma chamber or sedimentary compaction at the surface. However, with meteorite samples in particular, far too often we are limited by how precious the sample is as well as its limited mass. In this study, we have utilized aliquots of samples previously studied for toxicological hazards, including both the fresh samples (lunar mare basalt NWA 4734, lunar regolith breccia NWA 7611, martian basalt Tissint, martian regolith breccia NWA 7034, a vestian basalt Berthoud, a vestian regolith breccia NWA 2060, and a terrestrial mid-ocean ridge basalt (MORB)), and those that underwent iron leaching (Tissint, NWA 7034, NWA 4734, MORB). With these small masses of material, we performed low pressure (approx. 0.75 GPa), high temperature (greater than 1600 degrees Celsius) melting experiments. Each sample was analyzed using a JEOL 8530F electron microprobe to determine the bulk composition of the materials that were previously examined. When available, the results of our microprobe data were compared with bulk rock compositions in the literature. The results of this study show that with this technique, only approx. 50 mg of sample is required to accurately determine the bulk composition of the materials of interest.

Characteristics of some silver-, and base metal-bearing, epithermal deposits of Mexico and Peru

USGS Publications Warehouse

Foley, Nora K.

1984-01-01

Although many characteristics of the geology and geochemistry of this type of deposit were considered, the most important criterion for choosing these deposits was that they have substantial quantities of precious- and base-metal mineralization. Additional criteria for selecting the deposits were that they be hosted primarily by calc-alkaline volcanic rocks of intermediate to silicic composition and that they be younger than Tertiary in age. Many deposits in Mexico and Peru and other parts of Central and South America were excluded because the literature describing the districts is not readily available. Furthermore, many districts have not been examined in detail or the information available is of limited geological scope. The four districts that are compiled in this report were chosen because they are described in abundant literature dating from early mining reports on the general geology and mineralogy to very recent data on detailed geochemical and mineralogical studies. They were chosen as being fairly typical, classic examples of near-surface, low-temperature vein deposits as described by Lindgren (1928) in his treatise on ore deposits (Mineral deposits, McGraw-Hill, 1049 p.). These deposits are similar in aspects of their geology and geochemistry to many of the famous, epithermal silver mining districts in Colorado and Nevada including Creede, Colorado, Tonapah, Nevada, and the Sunnyside Mine of the Eureka district, Colorado, and, in the special case of Julcani, to Summitville, Colorado, and Goldfield, Nevada. The characteristics that distinguish them include overall size, production and alteration assemblage. The information documented in each summary will be used in a forthcoming series of papers on the comparative anatomy of precious and base metal deposits in North and South America.

Shape-Controlled Synthesis of Colloidal Metal Nanocrystals by Replicating the Surface Atomic Structure on the Seed.

PubMed

Gilroy, Kyle D; Yang, Xuan; Xie, Shuifen; Zhao, Ming; Qin, Dong; Xia, Younan

2018-06-01

Controlling the surface structure of metal nanocrystals while maximizing the utilization efficiency of the atoms is a subject of great importance. An emerging strategy that has captured the attention of many research groups involves the conformal deposition of one metal as an ultrathin shell (typically 1-6 atomic layers) onto the surface of a seed made of another metal and covered by a set of well-defined facets. This approach forces the deposited metal to faithfully replicate the surface atomic structure of the seed while at the same time serving to minimize the usage of the deposited metal. Here, the recent progress in this area is discussed and analyzed by focusing on the synthetic and mechanistic requisites necessary for achieving surface atomic replication of precious metals. Other related methods are discussed, including the one-pot synthesis, electrochemical deposition, and skin-layer formation through thermal annealing. To close, some of the synergies that arise when the thickness of the deposited shell is decreased controllably down to a few atomic layers are highlighted, along with how the control of thickness can be used to uncover the optimal physicochemical properties necessary for boosting the performance toward a range of catalytic reactions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A case in support of implementing innovative bio-processes in the metal mining industry.

PubMed

Sánchez-Andrea, Irene; Stams, Alfons J M; Weijma, Jan; Gonzalez Contreras, Paula; Dijkman, Henk; Rozendal, Rene A; Johnson, D Barrie

2016-06-01

The metal mining industry faces many large challenges in future years, among which is the increasing need to process low-grade ores as accessible higher grade ores become depleted. This is against a backdrop of increasing global demands for base and precious metals, and rare earth elements. Typically about 99% of solid material hauled to, and ground at, the land surface currently ends up as waste (rock dumps and mineral tailings). Exposure of these to air and water frequently leads to the formation of acidic, metal-contaminated run-off waters, referred to as acid mine drainage, which constitutes a severe threat to the environment. Formation of acid drainage is a natural phenomenon involving various species of lithotrophic (literally 'rock-eating') bacteria and archaea, which oxidize reduced forms of iron and/or sulfur. However, other microorganisms that reduce inorganic sulfur compounds can essentially reverse this process. These microorganisms can be applied on industrial scale to precipitate metals from industrial mineral leachates and acid mine drainage streams, resulting in a net improvement in metal recovery, while minimizing the amounts of leachable metals to the tailings storage dams. Here, we advocate that more extensive exploitation of microorganisms in metal mining operations could be an important way to green up the industry, reducing environmental risks and improving the efficiency and the economy of metal recovery. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Modeling Biogeochemical Cycling of Heavy Metals in Lake Coeur d'Alene Sediments

NASA Astrophysics Data System (ADS)

Sengor, S. S.; Spycher, N.; Belding, E.; Curthoys, K.; Ginn, T. R.

2005-12-01

Mining of precious metals since the late 1800's have left Lake Coeur d'Alene (LCdA) sediments heavily enriched with toxic metals, including Cd, Cu, Pb, and Zn. Indigenous microbes however are capable of catalyzing reactions that detoxify the benthic and aqueous lake environments, and thus constitute an important driving component in the biogeochemical cycles of these metals. Here we report on the development of a quantitative model of transport, fate, exposure and effects of toxic compounds on benthic microbial communities at LCdA. First, chemical data from the LCdA area have been compiled from multiple sources to investigate trends in chemical occurrence, as well as to define model boundary conditions. The model is structured as 1-D diffusive reactive transport model to simulate spatial and temporal distribution of metals through the benthic sediments. Inorganic reaction processes included in the model are aqueous speciation, surface complexation, mineral precipitation/dissolution and abiotic redox reactions. Simulations with and without surface complexation are carried out to evaluate the effect of sorption and the conservative behaviour of metals within the benthic sediments under abiotic and purely diffusive transport. The 1-D inorganic diffusive transport model is then coupled to a biotic reaction network including consortium biodegradation kinetics with multiple electron acceptors, product toxicity, and energy partitioning. Multiyear simulations are performed, with water column chemistry established as a boundary condition from extant data, to explore the role of biogeochemical dynamics on benthic fluxes of metals in the long term.

Geology and geochemistry of epithermal precious metal vein systems in the intra-oceanic arcs of Palau and Yap, western Pacific

USGS Publications Warehouse

Rytuba, J.J.; Miller, W.R.

1990-01-01

The Palau and Yap arcs are part of an intra-oceanic island-arc-trench system which separates the Pacific and Philippine plates in the western Pacific Ocean. The 350-km-long Palau arc consists of over 200 islands while the 400-km-long Yap arc located to the north has only four major islands exposed. Four of the largest islands in Palau are composed primarily of early Eocene to mid-Miocene volcanic rocks and the four islands comprising Yap contain only Miocene volcanic rocks. Basalt and basaltic andesites of the Babelthuap Formation are the oldest volcanic rocks in Palau and are characterized by high MgO, Ni and Cr and low TiO2 and have a boninitic affinity. They form the central and southeastern parts of Babelthuap Island. Oligocene arc tholeiite flows having an age of 34-35.5 Ma comprise most of the three smaller volcanic islands in Palau and the western part of Babelthuap. The youngest volcanic rocks are dacitic intrusions having an age of 22.7-23.2 Ma. The Yap arc is unusual in that metamorphic rocks up to amphibolite grade form most of the islands. These are underlain by a melange composed of igneous and volcanic clasts as well as clasts from a dismembered copper-gold skarn deposit. Miocene volcanic rocks consisting of flows and volcaniclastic deposits overlie the melange and metamorphic complex. An epithermal precious-metal vein system hosted by flows and flow breccias of the Babelthuap Formation occurs in an area 1.5 km by 1 km on the southeast side of Babelthuap Island. Over 50 veins and mineralized breccias ranging up to 2 m in width and having a strike length up to 500 m contain from trace to 13.0 ppm gold. The veins consist of quartz with varying amounts of sulfides and iron oxides after sulfides and the mineralized breccias consist of brecciated country rock cemented by quartz and iron oxides after sulfides. The veins and mineralized breccias generally dip within 15?? of vertical and have two preferred orientations, north-northwest and north

Reduced Cu–Co–Al Mixed Metal Oxides for the Ring-Opening of Furfuryl Alcohol to Produce Renewable Diols

DOE PAGES

Sulmonetti, Taylor P.; Hu, Bo; Lee, Sungsik; ...

2017-08-08

In this study, the ring-opening of furfuryl alcohol to diol products, including 1,2-pentanediol and 1,5- pentanediol, is investigated over reduced Cu-Co-Al mixed metal oxides in a liquid phase batch reactor under H 2 pressure. These catalysts are synthesized through the calcination of layered double hydroxides (LDH) to yield well-dispersed, porous mixed metal oxides, which upon reduction displayed activity towards diols, mainly the valuable monomer 1,5-pentanediol. The addition of Cu facilitated the reduction of Co oxide species at lower temperatures, and under optimized conditions a yield towards 1,5-pentanediol of 44% (total diol yield of 62%) was achieved. Various characterization techniques includingmore » TPR, XPS, and XAS are employed to elucidate the structure of the catalysts, suggesting the formation of both metallic (Co and Cu) and oxide (CoO) species after reduction and passivation. Finally, this study demonstrates the promising characteristics that non-precious multi-metal catalysts have for the conversion of biomass derived platform molecules to plastic precursors« less

Reduced Cu–Co–Al Mixed Metal Oxides for the Ring-Opening of Furfuryl Alcohol to Produce Renewable Diols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sulmonetti, Taylor P.; Hu, Bo; Lee, Sungsik

In this study, the ring-opening of furfuryl alcohol to diol products, including 1,2-pentanediol and 1,5- pentanediol, is investigated over reduced Cu-Co-Al mixed metal oxides in a liquid phase batch reactor under H 2 pressure. These catalysts are synthesized through the calcination of layered double hydroxides (LDH) to yield well-dispersed, porous mixed metal oxides, which upon reduction displayed activity towards diols, mainly the valuable monomer 1,5-pentanediol. The addition of Cu facilitated the reduction of Co oxide species at lower temperatures, and under optimized conditions a yield towards 1,5-pentanediol of 44% (total diol yield of 62%) was achieved. Various characterization techniques includingmore » TPR, XPS, and XAS are employed to elucidate the structure of the catalysts, suggesting the formation of both metallic (Co and Cu) and oxide (CoO) species after reduction and passivation. Finally, this study demonstrates the promising characteristics that non-precious multi-metal catalysts have for the conversion of biomass derived platform molecules to plastic precursors« less

Global mining risk footprint of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum in Japan.

PubMed

Nansai, Keisuke; Nakajima, Kenichi; Kagawa, Shigemi; Kondo, Yasushi; Shigetomi, Yosuke; Suh, Sangwon

2015-02-17

Meeting the 2-degree global warming target requires wide adoption of low-carbon energy technologies. Many such technologies rely on the use of precious metals, however, increasing the dependence of national economies on these resources. Among such metals, those with supply security concerns are referred to as critical metals. Using the Policy Potential Index developed by the Fraser Institute, this study developed a new footprint indicator, the mining risk footprint (MRF), to quantify the mining risk directly and indirectly affecting a national economy through its consumption of critical metals. We formulated the MRF as a product of the material footprint (MF) of the consuming country and the mining risks of the countries where the materials are mined. A case study was conducted for the 2005 Japanese economy to determine the MF and MRF for three critical metals essential for emerging energy technologies: neodymium, cobalt and platinum. The results indicate that in 2005 the MFs generated by Japanese domestic final demand, that is, the consumption-based metal output of Japan, were 1.0 × 10(3) t for neodymium, 9.4 × 10(3) t for cobalt, and 2.1 × 10 t for platinum. Export demand contributes most to the MF, accounting for 3.0 × 10(3) t, 1.3 × 10(5) t, and 3.1 × 10 t, respectively. The MRFs of Japanese total final demand (domestic plus export) were calculated to be 1.7 × 10 points for neodymium, 4.5 × 10(-2) points for cobalt, and 5.6 points for platinum, implying that the Japanese economy is incurring a high mining risk through its use of neodymium. This country's MRFs are all dominated by export demand. The paper concludes by discussing the policy implications and future research directions for measuring the MFs and MRFs of critical metals. For countries poorly endowed with mineral resources, adopting low-carbon energy technologies may imply a shifting of risk from carbon resources to other natural resources, in particular critical metals, and a trade

Public release of optimization of metallization scheme for thin emitter wrap-through solar cells for higher efficiency, reduced precious metal costs, and reduced stress.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruby, Douglas Scott; Murphy, Brian; Meakin, David

2008-08-01

Back-contact crystalline-silicon photovoltaic solar cells and modules offer a number of advantages, including the elimination of grid shadowing losses, reduced cost through use of thinner silicon substrates, simpler module assembly, and improved aesthetics. While the existing edge tab method for interconnecting and stringing edge-connected back contact cells is acceptably straightforward and reliable, there are further gains to be exploited when you have both contact polarities on one side of the cell. In this work, we produce 'busbarless' emitter wrap-through solar cells that use 41% of the gridline silver (Ag) metallization mass compared to the edge tab design. Further, series resistancemore » power losses are reduced by extraction of current from more places on the cell rear, leading to a fill factor improvement of about 6% (relative) on the module level. Series resistance and current-generation losses associated with large rear bondpads and busbars are eliminated. Use of thin silicon (Si) wafers is enabled because of the reduced Ag metallization mass and by interconnection with conductive adhesives leading to reduced bow. The busbarless cell design interconnected with conductive adhesives passes typical International Electrotechnical Commission damp heat and thermal cycling test.« less

Bulk-surface relationship of an electronic structure for high-throughput screening of metal oxide catalysts

NASA Astrophysics Data System (ADS)

Kweun, Joshua Minwoo; Li, Chenzhe; Zheng, Yongping; Cho, Maenghyo; Kim, Yoon Young; Cho, Kyeongjae

2016-05-01

Designing metal-oxides consisting of earth-abundant elements has been a crucial issue to replace precious metal catalysts. To achieve efficient screening of metal-oxide catalysts via bulk descriptors rather than surface descriptors, we investigated the relationship between the electronic structure of bulk and that of the surface for lanthanum-based perovskite oxides, LaMO3 (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu). Through density functional theory calculations, we examined the d-band occupancy of the bulk and surface transition-metal atoms (nBulk and nSurf) and the adsorption energy of an oxygen atom (Eads) on (001), (110), and (111) surfaces. For the (001) surface, we observed strong correlation between the nBulk and nSurf with an R-squared value over 94%, and the result was interpreted in terms of ligand field splitting and antibonding/bonding level splitting. Moreover, the Eads on the surfaces was highly correlated with the nBulk with an R-squared value of more than 94%, and different surface relaxations could be explained by the bulk electronic structure (e.g., LaMnO3 vs. LaTiO3). These results suggest that a bulk-derived descriptor such as nBulk can be used to screen metal-oxide catalysts.

Water Analysis.

ERIC Educational Resources Information Center

MacCarthy, Patrick; And Others

1989-01-01

Analytical methods are reviewed for: alkali and alkaline earth metals; transition metals; precious metals; group 12, 13, 14, and 15 metals, nonmetals; radionuclides; multiple metals; anions; gases; chromatography; mass spectroscopy; photometry; sampling; volatile compounds; surfactants; detergents; pesticides; herbicides; and fungicides. (MVL)

78 FR 40427 - Foreign-Trade Zone (FTZ) 32-Miami, Florida; Notification of Proposed Production Activity; Almod...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-05

... facility is used for the production (restoration and repair) of jewelry comprised of precious metals and..., Florida; Notification of Proposed Production Activity; Almod Diamonds, Ltd. (Jewelry and Precious Stones... of proposed production activity to the FTZ Board on behalf of Almod Diamonds, Ltd. (ADL), located in...

41 CFR 109-27.5104-4 - Physical inventories.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 41 Public Contracts and Property Management 3 2013-07-01 2013-07-01 false Physical inventories... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-4 Physical inventories. (a) Physical inventories shall be conducted annually by custodians, and witnessed by the Precious...

41 CFR 109-27.5104-4 - Physical inventories.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 41 Public Contracts and Property Management 3 2012-01-01 2012-01-01 false Physical inventories... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-4 Physical inventories. (a) Physical inventories shall be conducted annually by custodians, and witnessed by the Precious...

41 CFR 109-27.5104-4 - Physical inventories.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Physical inventories... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-4 Physical inventories. (a) Physical inventories shall be conducted annually by custodians, and witnessed by the Precious...

41 CFR 109-27.5104-4 - Physical inventories.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 41 Public Contracts and Property Management 3 2014-01-01 2014-01-01 false Physical inventories... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-4 Physical inventories. (a) Physical inventories shall be conducted annually by custodians, and witnessed by the Precious...

41 CFR 109-27.5104-4 - Physical inventories.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Physical inventories... PROCUREMENT 27-INVENTORY MANAGEMENT 27.51-Management of Precious Metals § 109-27.5104-4 Physical inventories. (a) Physical inventories shall be conducted annually by custodians, and witnessed by the Precious...

Sandwich-like TiO2@ZnO-based noble metal (Ag, Au, Pt, or Pd) for better photo-oxidation performance: Synergistic effect between noble metal and metal oxide phases

NASA Astrophysics Data System (ADS)

Li, Shunxing; Cai, Jiabai; Wu, Xueqing; Zheng, Fengying

2018-06-01

The performance of different noble metals (NMs) with controllable size (5 nm) as co-catalyst on the photocatalytic oxidation of TiO2@ZnO hollow spheres was tested with benzyl alcohol in the presence of water under ambient conditions. A new type of solar-light-driven TiO2@NMs@ZnO nanocomposite was fabricated by using a template (surface functionalized polystyrene balls), hydrothermal reaction, and calcination. Under simulated sunlight irradiation, the photo-oxidation rate of benzyl alcohol was in the following of TiO2@Ag@ZnO > TiO2@Au@ZnO > TiO2@Pt@ZnO > TiO2@Pd@ZnO > TiO2@ZnO. This result was due to the combination of TiO2 and ZnO, as well as the sandwiched Ag NPs as electron trap site, which can store and shuttle photo-generated electrons, and then enhance photo-generation of active radicals. Electron paramagnetic resonance (EPR) spectroscopy, as well as photo-luminescence (PL), photo-reduction of Cr(VI) and electrochemical measurements were taken to verify this conclusion. Taking into account the multi-functional combination of precious metals and semiconductor materials, this work could provide new insights for the design of high-performance photocatalysts.

Self-assembled nitrogen-doped fullerenes and their catalysis for fuel cell and rechargeable metal-air battery applications.

PubMed

Noh, Seung Hyo; Kwon, Choah; Hwang, Jeemin; Ohsaka, Takeo; Kim, Beom-Jun; Kim, Tae-Young; Yoon, Young-Gi; Chen, Zhongwei; Seo, Min Ho; Han, Byungchan

2017-06-08

In this study, we report self-assembled nitrogen-doped fullerenes (N-fullerene) as non-precious catalysts, which are active for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and thus applicable for energy conversion and storage devices such as fuel cells and metal-air battery systems. We screen the best N-fullerene catalyst at the nitrogen doping level of 10 at%, not at the previously known doping level of 5 or 20 at% for graphene. We identify that the compressive surface strain induced by doped nitrogen plays a key role in the fine-tuning of catalytic activity.

Mineral resource potential of the Middle Santiam Roadless Area, Linn County, Oregon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, G.W.

1984-01-01

This report discusses the results of a mineral survey of the Middle Santiam Roadless Area (06929), Willamette National Forest, Linn County Oregon. Middle Santiam Roadless Area is adjacent on the east of the Quartzville mining district, a district that has yielded small amounts of base- and precious-metal ores. Many rock types and alteration features that characterize the mining district occur only the western part of the roadless area, and analysis of a few samples from this part of the roadless area indicates evidence of weak mineralization. The western part of the roadless area is therefore identified as having a moderatemore » potential for small deposits of base and precious metals and a low potential for large very low-grade precious-metal deposits. The eastern part of the roadless area has a low potential for metalliferous deposits. 7 refs., 4 figs., 1 tab.« less

Economic Assessment for Recycling Critical Metals From Hard Disk Drives Using a Comprehensive Recovery Process

NASA Astrophysics Data System (ADS)

Nguyen, Ruby Thuy; Diaz, Luis A.; Imholte, D. Devin; Lister, Tedd E.

2017-09-01

Since the 2011 price spike of rare earth elements (REEs), research on permanent magnet recycling has blossomed globally in an attempt to reduce future REE criticality. Hard disk drives (HDDs) have emerged as one feasible feedstock for recovering valuable REEs such as praseodymium, neodymium, and dysprosium. Nevertheless, current processes for recycling electronic waste only focus on certain metals as a result of feedstock and metal price uncertainties. In addition, there is a perception that recycling REEs is unprofitable. To shed some light on the economic viability of REE recycling from U.S. HDDs, this article combines techno-economic information of an electro-hydrometallurgical process with end-of-life HDD availability in a simulation model. The results showed that adding REE recovery to an HDD base and precious metal recovery process was profitable given current prices. Recovered REEs from U.S. HDDs could meet up to 5.2% rest-of-world (excluding China) neodymium magnet demand. Feedstock, aluminum, and gold prices are key factors to recycling profitability. REEs contributed 13% to the co-recycling profit.

Non-platinum metal-organic framework based electro-catalyst for promoting oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Das, Dipanwita; Raut, Vrushali; Kireeti, Kota V. M. K.; Jha, Neetu

2018-04-01

We developed two non-precious Metal Organic Framework (MOF) based electrocatalysts, MOF-5 and MOF-i using solvothermal and refluxing methods. The MOFs prepared has been characterized by powder X-ray diffractometer (XRD), Fourier Transform Infra-Red Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) for structural and morphological insights. SEM images reveal cubic shape for solvothermally synthesized MOF-5, whereas refluxing method leads to platelet morphology of MOF-i. The synthesized MOFs has been investigated for Oxygen Reduction Reaction (ORR) studies using Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV), with MOF modified Glassy Carbon (GC) as working electrode. The electrochemical data suggests higher activity of MOF-5 towards ORR compared to MOF-i.

Mineralogical and geochemical controls on the release of trace elements from slag produced by base- and precious-metal smelting at abandoned mine sites

USGS Publications Warehouse

Piatak, N.M.; Seal, R.R.; Hammarstrom, J.M.

2004-01-01

Slag collected from smelter sites associated with historic base-metal mines contains elevated concentrations of trace elements such as Cu, Zn and Pb. Weathering of slag piles, many of which were deposited along stream banks, potentially may release these trace elements into the environment. Slags were sampled from the Ely and Elizabeth mines in the Vermont copper belt, from the copper Basin mining district at Ducktown, Tennessee and from the Clayton silver mine in the Bayhorse mining district, Idaho, in the USA. Primary phases in the slags include: olivine-group minerals, glass, spinels, sulfide minerals and native metals for Vermont samples; glass, sulfide minerals and native metals for the Ducktown sample; and olivine-group minerals, clinopyroxenes, spinels, sulfide minerals, native metals and other unidentified metallic compounds for Clayton slag. Olivine-group minerals and pyroxenes are dominantly fayalitic and hedenbergitic in composition, respectively and contain up to 1.25 wt.% ZnO. Spinel minerals range between magnetite and hercynite in composition and contain Zn (up to 2.07 wt.% ZnO), Ti (up to 4.25 wt.% TiO2) and Cr (up to 1.39 wt.% Cr2O3). Cobalt, Ni, Cu, As, Ag, Sb and Pb occur in the glass phase, sulfides, metallic phases and unidentified metallic compounds. Bulk slag trace-element chemistry shows that the metals of the Vermont and Tennessee slags are dominated by Cu (1900-13,500 mg/kg) and Zn (2310-10,200 mg/kg), whereas the Clayton slag is dominated by Pb (63,000 mg/kg), Zn (19,700 mg/kg), Cu (7550 mg/kg), As (555 mg/kg), Sn (363 mg/kg) and Ag (200 mg/kg). Laboratory-based leach tests indicate metals can be released under simulated natural conditions. Leachates from most slags were found to contain elevated concentrations of Cu and Zn (up to 1800 and 470 ??g/l, respectively), well in excess of the acute toxicity guidelines for aquatic life. For the Idaho slag, the concentration of Pb in the leachate (11,000 ??g/l) is also in excess of the acute

Greener approach for the extraction of copper metal from electronic waste.

PubMed

Jadhao, Prashant; Chauhan, Garima; Pant, K K; Nigam, K D P

2016-11-01

Technology innovations resulted into a major move from agricultural to industrial economy in last few decades. Consequently, generation of waste electronic and electrical equipments (WEEE) has been increased at a significant rate. WEEE contain large amount of precious and heavy metals and therefore, can be considered a potential secondary resource to overcome the scarcity of metals. Also, presence of these metals may affect the ecosystem due to lack of adequate management of WEEE. Building upon our previous experimental investigations for metal extraction from spent catalyst, present study explores the concept of green technology for WEEE management. Efforts have been made to recover base metal from a printed circuit board using eco-friendly chelation technology and results were compared with the conventional acid leaching method. 83.8% recovery of copper metal was achieved using chelation technology whereas only 27% could be recovered using acid leaching method in absence of any oxidant at optimum reaction conditions. Various characterization studies (energy dispersive X-ray analysis, scanning electron microscopy, X-ray diffraction, inductive coupled plasma spectrophotometry) of Printed Circuit Board (PCB) and residues were performed for qualitative and quantitative analysis of samples. Significant metal extraction, more than 96% recovery of chelating agent, recycling of reactant in next chelation cycle and nearly zero discharge to the environment are the major advantages of the proposed green process which articulate the transcendency of chelation technology over other conventional approaches. Kinetic investigation suggests diffusion controlled process as the rate determining step for the chelate assisted recovery of copper from WEEE with activation energy of 22kJ/mol. Copyright © 2015 Elsevier Ltd. All rights reserved.

40 CFR 421.265 - Pretreatment standards for existing sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... day Maximum for monthly average mg/troy ounce of precious metals, including silver, incinerated or... Pollutant or pollutant property Maximum for any 1 day Maximum for monthly average mg/troy ounce of precious... Maximum for any 1 day Maximum for monthly average mg/troy ounce of gold produced by cyanide stripping...

31 CFR 1027.300 - General.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false General. 1027.300 Section 1027.300 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FINANCIAL CRIMES... JEWELS Reports Required To Be Made by Dealers in Precious Metals, Precious Stones, or Jewels § 1027.300...

31 CFR 1027.300 - General.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false General. 1027.300 Section 1027.300 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FINANCIAL CRIMES... JEWELS Reports Required To Be Made by Dealers in Precious Metals, Precious Stones, or Jewels § 1027.300...

40 CFR 438.1 - General applicability.

Code of Federal Regulations, 2013 CFR

2013-07-01

... STANDARDS (CONTINUED) METAL PRODUCTS AND MACHINERY POINT SOURCE CATEGORY § 438.1 General applicability. (a..., or maintenance of metal parts, products, or machines for use in the Metal Product & Machinery (MP&M... Metal Products; Mobile Industrial Equipment; Motor Vehicle; Office Machine; Ordnance; Precious Metals...

40 CFR 438.1 - General applicability.

Code of Federal Regulations, 2014 CFR

2014-07-01

... STANDARDS (CONTINUED) METAL PRODUCTS AND MACHINERY POINT SOURCE CATEGORY § 438.1 General applicability. (a..., or maintenance of metal parts, products, or machines for use in the Metal Product & Machinery (MP&M... Metal Products; Mobile Industrial Equipment; Motor Vehicle; Office Machine; Ordnance; Precious Metals...

40 CFR 438.1 - General applicability.

Code of Federal Regulations, 2012 CFR

2012-07-01

... STANDARDS (CONTINUED) METAL PRODUCTS AND MACHINERY POINT SOURCE CATEGORY § 438.1 General applicability. (a..., or maintenance of metal parts, products, or machines for use in the Metal Product & Machinery (MP&M... Metal Products; Mobile Industrial Equipment; Motor Vehicle; Office Machine; Ordnance; Precious Metals...

One-dimensional manganese-cobalt oxide nanofibres as bi-functional cathode catalysts for rechargeable metal-air batteries

PubMed Central

Jung, Kyu-Nam; Hwang, Soo Min; Park, Min-Sik; Kim, Ki Jae; Kim, Jae-Geun; Dou, Shi Xue; Kim, Jung Ho; Lee, Jong-Won

2015-01-01

Rechargeable metal-air batteries are considered a promising energy storage solution owing to their high theoretical energy density. The major obstacles to realising this technology include the slow kinetics of oxygen reduction and evolution on the cathode (air electrode) upon battery discharging and charging, respectively. Here, we report non-precious metal oxide catalysts based on spinel-type manganese-cobalt oxide nanofibres fabricated by an electrospinning technique. The spinel oxide nanofibres exhibit high catalytic activity towards both oxygen reduction and evolution in an alkaline electrolyte. When incorporated as cathode catalysts in Zn-air batteries, the fibrous spinel oxides considerably reduce the discharge-charge voltage gaps (improve the round-trip efficiency) in comparison to the catalyst-free cathode. Moreover, the nanofibre catalysts remain stable over the course of repeated discharge-charge cycling; however, carbon corrosion in the catalyst/carbon composite cathode degrades the cycling performance of the batteries. PMID:25563733

Reversible Hydrogenation of Carbon Dioxide to Formic Acid and Methanol: Lewis Acid Enhancement of Base Metal Catalysts.

PubMed

Bernskoetter, Wesley H; Hazari, Nilay

2017-04-18

New and sustainable energy vectors are required as a consequence of the environmental issues associated with the continued use of fossil fuels. H 2 is a potential clean energy source, but as a result of problems associated with its storage and transport as a gas, chemical H 2 storage (CHS), which involves the dehydrogenation of small molecules, is an attractive alternative. In principle, formic acid (FA, 4.4 wt % H 2 ) and methanol (MeOH, 12.6 wt % H 2 ) can be obtained renewably and are excellent prospective liquid CHS materials. In addition, MeOH has considerable potential both as a direct replacement for gasoline and as a fuel cell input. The current commercial syntheses of FA and MeOH, however, use nonrenewable feedstocks and will not facilitate the use of these molecules for CHS. An appealing option for the sustainable synthesis of both FA and MeOH, which could be implemented on a large scale, is the direct metal catalyzed hydrogenation of CO 2 . Furthermore, given that CO 2 is a readily available, nontoxic and inexpensive source of carbon, it is expected that there will be economic and environmental benefits from using CO 2 as a feedstock. One strategy to facilitate both the dehydrogenation of FA and MeOH and the hydrogenation of CO 2 and H 2 to FA and MeOH is to utilize a homogeneous transition metal catalyst. In particular, the development of catalysts based on first row transition metals, which are cheaper, and more abundant than their precious metal counterparts, is desirable. In this Account, we describe recent advances in the development of iron and cobalt systems for the hydrogenation of CO 2 to FA and MeOH and the dehydrogenation of FA and MeOH and provide a brief comparison between precious metal and base metal systems. We highlight the different ligands that have been used to stabilize first row transition metal catalysts and discuss the use of additives to promote catalytic activity. In particular, the Account focuses on the crucial role that

40 CFR 421.251 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421.251 Specialized definitions. For the purpose of this subpart the general...

Hybrid input-output approach to metal production and its application to the introduction of lead-free solders.

PubMed

Nakamura, Shinichiro; Murakami, Shinsuke; Nakajima, Kenichi; Nagasaka, Tetsuya

2008-05-15

The production process of metals such as copper, lead, and zinc is characterized by mutual interconnections and interdependence, as well as by the occurrence of a large number of byproducts, which include precious or rare metals, such as gold, silver, bismuth, and indium. On the basis of the framework of waste input-output (WIO), we present a hybrid 10 model that takes full account of the mutual interdependence among the metal production processes and the interdependence between them and all the other production sectors of the economy as well. The combination of a comprehensive representation of the whole national economy and the introduction of process knowledge of metal production allows for a detailed analysis of different materials-use scenarios under the consideration of full supply chain effects. For illustration, a hypothetical case study of the introduction of lead-free solder involving the production of silver as a byproduct of copper and lead smelting processes was developed and implemented using Japanese data. To meet the increased demand for the recovery and recycling of silver resources from end-of-life products, the final destination of metal silver in terms of products and user categories was estimated, and the target components with the highest silver concentration were identified.

Catalytic Formylation of Primary and Secondary Amines with CO2 and H2 Using Abundant-Metal Catalysts.

PubMed

Affan, Mohammad A; Jessop, Philip G

2017-06-19

Catalytic hydrogenation of CO 2 is an efficient and selective way to prepare formic acid derivatives, but most of the highly active catalysts used for this purpose require precious metals. In this study, in situ abundant-metal complexes have been evaluated as potential catalysts for CO 2 hydrogenation to prepare formamides, including N-formylmorpholine, 2-ethylhexylformamide, and dimethylformamide, from the corresponding amines. From these initial screening results, the most active catalysts for these reactions were found to be MX 2 /dmpe in situ catalysts (M = Fe(II), Ni(II); X = Cl - , CH 3 CO 2 - , acac - ; dmpe = 1,2-bis(dimethylphosphino)ethane) in DMSO. The optimal reaction conditions were found to be 100-135 °C and a total pressure of 100 bar. Morpholine was formylated with a TON value of up to 18000, which is the highest TON for the hydrogenation of CO 2 to formamides using any abundant-metal-phosphine complex. With an appropriate selection of catalyst and reaction conditions, >90-98% conversion of amine to formamide could be achieved.

Molecular-Scale Investigation of Heavy Metal Ions at a Charged Langmuir Monolayer

NASA Astrophysics Data System (ADS)

Rock, William; Qiao, Baofu; Uysal, Ahmet; Bu, Wei; Lin, Binhua

Solvent extraction - the surfactant-aided preferential transfer of a species from an aqueous to an organic phase - is an important technique used in heavy and precious metal refining and reprocessing. Solvent extraction requires transfer through an oil/water interface, and interfacial interactions are expected to control transfer kinetics and phase stability, yet these key interactions are poorly understood. Langmuir monolayers with charged headgroups atop concentrated salt solutions containing heavy metal ions act as a model of solvent extraction interfaces; studies of ions at a charged surface are also fundamentally important to many other phenomena including protein solvation, mineral surface chemistry, and electrochemistry. We probe these charged interfaces using a variety of surface-sensitive techniques - vibrational sum frequency generation (VSFG) spectroscopy, x-ray reflectivity (XRR), x-ray fluorescence near total reflection (XFNTR), and grazing incidence diffraction (GID). We integrate experiments with Molecular Dynamics (MD) simulations to uncover the molecular-level interfacial structure. This work is supported by the U.S. DOE, BES, Contract DE-AC02-06CH11357. ChemMatCARS is supported by NSF/CHE-1346572.

Oxygen electrocatalysts in metal-air batteries: from aqueous to nonaqueous electrolytes.

PubMed

Wang, Zhong-Li; Xu, Dan; Xu, Ji-Jing; Zhang, Xin-Bo

2014-11-21

With the development of renewable energy and electrified transportation, electrochemical energy storage will be more important in the future than it has ever been in the past. Although lithium-ion batteries (LIBs) are traditionally considered to be the most likeliest candidate thanks to their relatively long cycle life and high energy efficiency, their limited energy density as well as cost are still causing a bottleneck for their long-term application. Alternatively, metal-air batteries have been proposed as a very promising large-scale electricity storage technology with the replacement of the intercalation reaction mechanism by the catalytic redox reaction of a light weight metal-oxygen couple. Generally, based on the electrolyte, these metal-air batteries can be divided into aqueous and nonaqueous systems, corresponding to two typical batteries of Zn-air and Li-air, respectively. The prominent feature of both batteries are their extremely high theoretical energy density, especially for nonaqueous Li-air batteries, which far exceeds the best that can be achieved with LIBs. In this review, we focus on the major obstacle of sluggish kinetics of the cathode in both batteries, and summarize the fundamentals and recent advances related to the oxygen catalyst materials. According to the electrolyte, the aqueous and nonaqueous electrocatalytic mechanisms of the oxygen reduction and evolution reactions are discussed. Subsequently, seven groups of oxygen catalysts, which have played catalytic roles in both systems, are selectively reviewed, including transition metal oxides (single-metal oxides and mixed-metal oxides), functional carbon materials (nanostructured carbons and doped carbons), metal oxide-nanocarbon hybrid materials, metal-nitrogen complexes (non-pyrolyzed and pyrolyzed), transition metal nitrides, conductive polymers, and precious metals (alloys). Nonaqueous systems have the advantages of energy density and rechargeability over aqueous systems and have

31 CFR 1027.100 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... antiques), that derive 50 percent or more of their value from jewels, precious metals, or precious stones... business in the purchase and sale of covered goods and who, during the prior calendar or tax year: (i... sale of covered goods. (2) For purposes of this section, the term “dealer” does not include: (i) A...

31 CFR 1027.100 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... antiques), that derive 50 percent or more of their value from jewels, precious metals, or precious stones... business in the purchase and sale of covered goods and who, during the prior calendar or tax year: (i... sale of covered goods. (2) For purposes of this section, the term “dealer” does not include: (i) A...

31 CFR 1027.100 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... antiques), that derive 50 percent or more of their value from jewels, precious metals, or precious stones... business in the purchase and sale of covered goods and who, during the prior calendar or tax year: (i... sale of covered goods. (2) For purposes of this section, the term “dealer” does not include: (i) A...

31 CFR 1027.100 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... antiques), that derive 50 percent or more of their value from jewels, precious metals, or precious stones... business in the purchase and sale of covered goods and who, during the prior calendar or tax year: (i... sale of covered goods. (2) For purposes of this section, the term “dealer” does not include: (i) A...

Phillips CO-oxidation catalyts for long-lived CO2 lasers: Activity and initial characterization studies

NASA Technical Reports Server (NTRS)

Kolts, J. H.; Elliott, D. J.; Pennella, F.

1990-01-01

Four different catalysts have been developed specifically for use in sealed carbon dioxide lasers. The catalysts have been designed to be low dusting, stable to shock and vibration, have high activity at low temperatures and have long active lifetimes. Measured global CO oxidation rates range from 1.4 to 2.2 cc CO converted per minute per gram of catalyst at ambient temperature. The catalysts also retain substantial activity at temperatures as low as -35 C. The Phillips laser catalysts are prepared in a variety of different shapes to meet the different pressure drop and gas flow profiles present in the many different styles of lasers. Each catalyst has been tested in sealed TEA lasers and has been shown to substantially increase the sealed life of the laser. Activity measurements made on the precious metal catalysts which were prepared with and without activity promoters showed that the promoter materials increase catalyst CO oxidation activity at least an order of magnitude at ambient temperature. Initial studies using H2 and CO chemisorption, X ray diffraction (XRD) and X ray photoelectron spectroscopy (XPS) have shown that the activity promoters do not significantly affect the precious metal crystallite size or the electronic structure around the precious metal. In addition, the formation or lack of formation of solid solutions between the precious metal and promoters has also been shown not to affect the activity of the promoted catalyst.

The Role of Near-Earth Asteroids in Long-Term Platinum Supply

NASA Astrophysics Data System (ADS)

Blair, B. R.

2000-01-01

High-grade platinum-group metal concentrations have been identified in an abundant class of near-Earth asteroids known as LL Chondrites. The potential existence of a high-value asteroid-derived mineral product is examined from an economic perspective to assess the possible impacts on long-term precious metal supply. It is hypothesized that extraterrestrial sources of platinum group metals will become available in the global marketplace in a 20-year time frame, based on current trends of growth in technology and increasing levels of human activities in near-Earth space. Current and projected trends in platinum supply and demand are cited from the relevant literature to provide an economic context and provide an example for evaluating the economic potential of future asteroid-derived precious and strategic metals.

Addition of platinum and silver nanoparticles to toughen dental porcelain.

PubMed

Fujieda, Tokushi; Uno, Mitsunori; Ishigami, Hajime; Kurachi, Masakazu; Wakamatsu, Nobukazu; Doi, Yutaka

2012-01-01

Several studies have investigated toughening porcelain that is layered over a frame or a core. The introduction of residual compressive stress to the surface of porcelain has been shown to be effective to strengthen it. In the present study, nanoparticles of precious metals of silver and platinum (rather than non-precious metals) were used to evaluate if they could increase the fracture resistance of porcelain. The addition of silver and platinum nanoparticles was found to improve the mechanical properties of porcelain since it increased both the Young's modulus and the fracture toughness of commercial porcelain.

Exploring the Utilization of Low-Pressure, Piston-Cylinder Experiments to Determine the Bulk Compositions of Finite, Precious Materials

NASA Astrophysics Data System (ADS)

Vander Kaaden, K. E.; McCubbin, F. M.; Harrington, A.

2017-12-01

Determining the bulk composition of precious materials with a finite mass (e.g., meteorite samples) is extremely important in the fields of Earth and Planetary Science. From meteorite studies we are able to place constraints on large scale planetary processes like global differentiation and subsequent volcanism, as well as smaller scale processes like crystallization in a magma chamber or sedimentary compaction at the surface. However, with meteorite samples in particular, far too often we are limited by how precious the sample is as well as its limited mass. In this study, we have utilized aliquots of samples previously studied for toxicological hazards [1] including both the fresh samples (lunar mare basalt NWA 4734, lunar regolith breccia NWA 7611, martian basalt Tissint, martian regolith breccia NWA 7034, a vestian basalt Berthoud, a vestian regolith breccia NWA 2060, and a terrestrial mid-ocean ridge basalt (MORB)), and those that underwent iron leaching (Tissint, NWA 7034, NWA 4734, MORB). With these small masses of material, we performed low pressure ( 0.75 GPa), high temperature (>1600°C) melting experiments. Each sample was analyzed using a JEOL 8530F electron microprobe to determine the bulk composition of the materials that were previously examined in [1]. When available, the results of our microprobe data were compared with bulk rock compositions in the literature. The results of this study show that with this technique, only 50 mg of sample is required to accurately determine the bulk composition of the materials of interest. [1] Harrington, A.D., McCubbin, F.M., Kaur, J., Smirnov, A., Galdanes, K., Schoonen, M.A.A., Chen, L.C., Tsirka, S.E., and Gordon, T. (2017) Pulmonary inflammatory responses to acute meteroite dust exposures - Implications for human space exploration. 48th Lunar and Planetary Science Conference, The Woodlands, TX, #2922.

Precious metal enrichment at low-redox in terrestrial native Fe-bearing basalts investigated using laser-ablation ICP-MS

NASA Astrophysics Data System (ADS)

Howarth, Geoffrey H.; Day, James M. D.; Pernet-Fisher, John F.; Goodrich, Cyrena A.; Pearson, D. Graham; Luo, Yan; Ryabov, Viktor V.; Taylor, Lawrence A.

2017-04-01

Primary native Fe is a rare crystallizing phase from terrestrial basaltic magmas, requiring highly reducing conditions (fO2 metal and cohenite) and sulfide, for all three known global occurrences of native Fe bearing basalt. Total HSE abundances in metal grains, obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), are lowest in the Bühl basalt, (∼0.05 ppm), intermediate in the Disko Island basalts (4-8 ppm), and highest the Siberian Khungtukun and Dzhaltul intrusions (10-30 ppm). These differences demonstrate that, while native Fe formation is the result of carbonaceous crustal assimilation, HSE enrichment is not ubiquitous during this process. The Siberian occurrences are characterized by Pt PGE (PPGE: Pt, Pd) enrichment relative to the Ir PGE (IPGE: Rh, Ru, Ir, Os), consistent with models of early stage fractionation of olivine, chromite and metallic IPGE in staging magma reservoirs, prior to the addition of C-rich crustal materials in the shallow crust. Relative to Noril'sk Ni-Cu-PGE sulfide ores

40 CFR 413.21 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... STANDARDS ELECTROPLATING POINT SOURCE CATEGORY Electroplating of Precious Metals Subcategory § 413.21... electroplating process in which a metal is electrodeposited on a basis material and which is followed by a rinse...

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and...

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and...

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and...

40 CFR 421.261 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... apply to this subpart. (b) The term precious metals shall mean gold, platinum, palladium, rhodium, iridium, osmium, and ruthenium. (c) The term Combined Metals, shall mean the total of gold, platinum and...

Biosorptive recovery of platinum from platinum group metal refining wastewaters by immobilised Saccharomyces cerevisiae.

PubMed

Mack, C L; Wilhelmi, B; Duncan, J R; Burgess, J E

2011-01-01

The process of platinum group metal (PGM) refining can be up to 99.99% efficient at best, and although it may seem small, the amount of valuable metal lost to waste streams is appreciable enough to warrant recovery. The method currently used to remove entrained metal ions from refinery wastewaters, chemical precipitation, is not effective for selective recovery of PGMs. The yeast Saccharomyces cerevisiae has been found capable of sorbing numerous precious and base metals, and is a cheap and abundant source of biomass. In this investigation, S. cerevisiae was immobilised using polyethyleneimine and glutaraldehyde to produce a suitable sorbent, capable of high platinum uptake (150-170 mg/g) at low pH (<2). The sorption mechanism was found to be a chemical reaction, which made effective desorption impossible. When applied to PGM refinery wastewater, two key wastewater characteristics limited the success of the sorption process; high inorganic ion content and complex speciation of the platinum ions. The results proved the concept principle of platinum recovery by immobilised yeast biosorption and indicated that a more detailed understanding of the platinum speciation within the wastewater is required before biosorption can be applied. Overall, the sorption of platinum by the S. cerevisiae sorbent was demonstrated to be highly effective in principle, but the complexity of the wastewater requires that pretreatment steps be taken before the successful application of this process to industrial wastewater.

Doped palladium containing oxidation catalysts

DOEpatents

Mohajeri, Nahid

2014-02-18

A supported oxidation catalyst includes a support having a metal oxide or metal salt, and mixed metal particles thereon. The mixed metal particles include first particles including a palladium compound, and second particles including a precious metal group (PMG) metal or PMG metal compound, wherein the PMG metal is not palladium. The oxidation catalyst may also be used as a gas sensor.

Molecular metal–Nx centres in porous carbon for electrocatalytic hydrogen evolution

PubMed Central

Liang, Hai-Wei; Brüller, Sebastian; Dong, Renhao; Zhang, Jian; Feng, Xinliang; Müllen, Klaus

2015-01-01

Replacement of precious platinum with efficient and low-cost catalysts for electrocatalytic hydrogen evolution at low overpotentials holds tremendous promise for clean energy devices. Here we report a novel type of robust cobalt–nitrogen/carbon catalyst for the hydrogen evolution reaction (HER) that is prepared by the pyrolysis of cobalt–N4 macrocycles or cobalt/o-phenylenediamine composites and using silica colloids as a hard template. We identify the well-dispersed molecular CoNx sites on the carbon support as the active sites responsible for the HER. The CoNx/C catalyst exhibits extremely high turnover frequencies per cobalt site in acids, for example, 0.39 and 6.5 s−1 at an overpotential of 100 and 200 mV, respectively, which are higher than those reported for other scalable non-precious metal HER catalysts. Our results suggest the great promise of developing new families of non-precious metal HER catalysts based on the controlled conversion of homogeneous metal complexes into solid-state carbon catalysts via economically scalable protocols. PMID:26250525

How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

NASA Astrophysics Data System (ADS)

Kam, K.; Lemke, K.

2014-12-01

The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with

Characterizing exposures to airborne metals and nanoparticle emissions in a refinery.

PubMed

Miller, Arthur; Drake, Pamela L; Hintz, Patrick; Habjan, Matt

2010-07-01

An air quality survey was conducted at a precious metals refinery in order to evaluate worker exposures to airborne metals and to provide detailed characterization of the aerosols. Two areas within the refinery were characterized: a furnace room and an electro-refining area. In line with standard survey practices, both personal and area air filter samples were collected on 37-mm filters and analyzed for metals by inductively coupled plasma-atomic emission spectroscopy. In addition to the standard sampling, measurements were conducted using other tools, designed to provide enhanced characterization of the workplace aerosols. The number concentration and number-weighted particle size distribution of airborne particles were measured with a fast mobility particle sizer (FMPS). Custom-designed software was used to correlate particle concentration data with spatial location data to generate contour maps of particle number concentrations in the work areas. Short-term samples were collected in areas of localized high concentrations and analyzed using transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) to determine particle morphology and elemental chemistry. Analysis of filter samples indicated that all of the workers were exposed to levels of silver above the Occupational Safety and Health Administration permissible exposure limit of 0.01 mg m(-3) even though the localized ventilation was functioning. Measurements with the FMPS indicated that particle number concentrations near the furnace increased up to 1000-fold above the baseline during the pouring of molten metal. Spatial mapping revealed localized elevated particle concentrations near the furnaces and plumes of particles rising into the stairwells and traveling to the upper work areas. Results of TEM/EDS analyses confirmed the high number of nanoparticles measured by the FMPS and indicated the aerosols were rich in metals including silver, lead, antimony, selenium, and zinc. Results of

Tailor-made Molecular Cobalt Catalyst System for the Selective Transformation of Carbon Dioxide to Dialkoxymethane Ethers.

PubMed

Schieweck, Benjamin G; Klankermayer, Jürgen

2017-08-28

Herein a non-precious transition-metal catalyst system for the selective synthesis of dialkoxymethane ethers from carbon dioxide and molecular hydrogen is presented. The development of a tailored catalyst system based on cobalt salts in combination with selected Triphos ligands and acidic co-catalysts enabled a synthetic pathway, avoiding the oxidation of methanol to attain the formaldehyde level of the central CH 2 unit. This unprecedented productivity based on the molecular cobalt catalyst is the first example of a non-precious transition-metal system for this transformation utilizing renewable carbon dioxide sources. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A density functional theory study of self-regenerating catalysts LaFe(1-x)M(x)O(3-y) (M = Pd, Rh, Pt).

PubMed

Hamada, Ikutaro; Uozumi, Akifumi; Morikawa, Yoshitada; Yanase, Akira; Katayama-Yoshida, Hiroshi

2011-11-23

Periodic density functional theory was used to investigate the stability and electronic structures of precious-metal atoms in the vicinity of LaFe(1-x)M(x)O(3) (M = Pd, Rh, Pt) perovskite catalyst surfaces. It was found that the surface segregation of Pd and Pt is significantly stabilized by the introduction of O vacancies, whereas the solid-solution phase is favorable for Rh, suggesting an important role of O vacancies in the self-regeneration of Pd and Pt. On the basis of the results, we propose a possible scenario for the self-regeneration of the precious metal in the perovskite catalyst.

Mimicking Catalytic Properties of Precious Metals by Using Common Metal Nanostructured Particles

DTIC Science & Technology

2011-12-19

Professor Renzo Rosei Consorzio per la Fisica Department of Physics Strada Costiera 11 Trieste, Italy 34151 EOARD Grant 10-3060...3060 Grant 10-3060 61102F Prof Renzo Rosei Consorzio per la Fisica Department of Physics Strada Costiera 11 Trieste, Italy 34151 N/A European Office...Physics Department, University of Trieste, Trieste, Italy and Consorzio per la Fisica , Trieste, Italy 1. Project motivation and Synopsis of

Gold and platinum in shales with evidence against extraterrestrial sources of metals

USGS Publications Warehouse

Coveney, R.M.; Murowchick, J.B.; Grauch, R.I.; Glascock, M.D.; Denison, J.R.

1992-01-01

Few black shales contain concentrations of precious metals higher than average continental crust (i.e. ???5 ppb Au). Yet Au and Pt alloys have been reported from the Kupferschiefer in Poland. Moreover, thin sulfide beds in certain Chinese and Canadian shales contain several hundred ppb Au, Pd and Pt and average ???4% Mo and ???2.5% Ni in an association that is difficult to explain. Volcanic and non-volcanic exhalations, hydrothermal epigenesis involving either igneous or sedex fluids, biogenic processes and low-temperature secondary enrichment are among the possible factors involved in deriving Ni, PGE and Au for black shales and sulfide beds in black shales. Extraterrestrial sources have been invoked in some cases (e.g., the Cambrian of China). However, available data on abundances of PGE indicate relatively low values for Ir (<0.02-2 ppb) in comparison with amounts for other PGE (up to 700 ppb Pt and 1255 ppb Pd). These data and high contents for Mo are not consistent with extraterrestrial sources of metals for Chinese shales and Ni-Mo-sulfide beds. Data are less complete for the U.S. shales, but nevertheless are suggestive of earthly origins for PGE. ?? 1992.

Cyanobacteria: A Precious Bio-resource in Agriculture, Ecosystem, and Environmental Sustainability

PubMed Central

Singh, Jay Shankar; Kumar, Arun; Rai, Amar N.; Singh, Devendra P.

2016-01-01

Keeping in view, the challenges concerning agro-ecosystem and environment, the recent developments in biotechnology offers a more reliable approach to address the food security for future generations and also resolve the complex environmental problems. Several unique features of cyanobacteria such as oxygenic photosynthesis, high biomass yield, growth on non-arable lands and a wide variety of water sources (contaminated and polluted waters), generation of useful by-products and bio-fuels, enhancing the soil fertility and reducing green house gas emissions, have collectively offered these bio-agents as the precious bio-resource for sustainable development. Cyanobacterial biomass is the effective bio-fertilizer source to improve soil physico-chemical characteristics such as water-holding capacity and mineral nutrient status of the degraded lands. The unique characteristics of cyanobacteria include their ubiquity presence, short generation time and capability to fix the atmospheric N2. Similar to other prokaryotic bacteria, the cyanobacteria are increasingly applied as bio-inoculants for improving soil fertility and environmental quality. Genetically engineered cyanobacteria have been devised with the novel genes for the production of a number of bio-fuels such as bio-diesel, bio-hydrogen, bio-methane, synga, and therefore, open new avenues for the generation of bio-fuels in the economically sustainable manner. This review is an effort to enlist the valuable information about the qualities of cyanobacteria and their potential role in solving the agricultural and environmental problems for the future welfare of the planet. PMID:27148218

Cyanobacteria: A Precious Bio-resource in Agriculture, Ecosystem, and Environmental Sustainability.

PubMed

Singh, Jay Shankar; Kumar, Arun; Rai, Amar N; Singh, Devendra P

2016-01-01

Keeping in view, the challenges concerning agro-ecosystem and environment, the recent developments in biotechnology offers a more reliable approach to address the food security for future generations and also resolve the complex environmental problems. Several unique features of cyanobacteria such as oxygenic photosynthesis, high biomass yield, growth on non-arable lands and a wide variety of water sources (contaminated and polluted waters), generation of useful by-products and bio-fuels, enhancing the soil fertility and reducing green house gas emissions, have collectively offered these bio-agents as the precious bio-resource for sustainable development. Cyanobacterial biomass is the effective bio-fertilizer source to improve soil physico-chemical characteristics such as water-holding capacity and mineral nutrient status of the degraded lands. The unique characteristics of cyanobacteria include their ubiquity presence, short generation time and capability to fix the atmospheric N2. Similar to other prokaryotic bacteria, the cyanobacteria are increasingly applied as bio-inoculants for improving soil fertility and environmental quality. Genetically engineered cyanobacteria have been devised with the novel genes for the production of a number of bio-fuels such as bio-diesel, bio-hydrogen, bio-methane, synga, and therefore, open new avenues for the generation of bio-fuels in the economically sustainable manner. This review is an effort to enlist the valuable information about the qualities of cyanobacteria and their potential role in solving the agricultural and environmental problems for the future welfare of the planet.

Fate of metals contained in waste electrical and electronic equipment in a municipal waste treatment process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oguchi, Masahiro, E-mail: oguchi.masahiro@nies.go.jp; Sakanakura, Hirofumi, E-mail: sakanakura@nies.go.jp; Terazono, Atsushi, E-mail: terazono@nies.go.jp

2012-01-15

Highlights: Black-Right-Pointing-Pointer The fate of 55 metals during shredding and separation of WEEE was investigated. Black-Right-Pointing-Pointer Most metals were mainly distributed to the small-grain fraction. Black-Right-Pointing-Pointer Much of metals in WEEE being treated as municipal waste in Japan end up in landfills. Black-Right-Pointing-Pointer Pre-sorting of small digital products reduces metals to be landfilled at some level. Black-Right-Pointing-Pointer Consideration of metal recovery from other middle-sized WEEE is still important. - Abstract: In Japan, waste electrical and electronic equipment (WEEE) that is not covered by the recycling laws are treated as municipal solid waste. A part of common metals are recovered duringmore » the treatment; however, other metals are rarely recovered and their destinations are not clear. This study investigated the distribution ratios and substance flows of 55 metals contained in WEEE during municipal waste treatment using shredding and separation techniques at a Japanese municipal waste treatment plant. The results revealed that more than half of Cu and most of Al contained in WEEE end up in landfills or dissipate under the current municipal waste treatment system. Among the other metals contained in WEEE, at least 70% of the mass was distributed to the small-grain fraction through the shredding and separation and is to be landfilled. Most kinds of metals were concentrated several fold in the small-grain fraction through the process and therefore the small-grain fraction may be a next target for recovery of metals in terms of both metal content and amount. Separate collection and pre-sorting of small digital products can work as effective way for reducing precious metals and less common metals to be landfilled to some extent; however, much of the total masses of those metals would still end up in landfills and it is also important to consider how to recover and utilize metals contained in other WEEE such as

Evaluation of marginal fit of single implant-supported metal-ceramic crowns prepared by using presintered metal blocks.

PubMed

Pasali, Baris; Sarac, Duygu; Kaleli, Necati; Sarac, Yakup Sinasi

2018-02-01

Recently, presintered metal blocks for nonprecious and precious metal implant-supported restorations have gained popularity in computer-aided design and computer-aided manufacturing (CAD-CAM) systems. However, few studies have evaluated the marginal discrepancy of implant-supported restorations made with these new alloy systems. The purpose of this in vitro study was to compare the milling-sintering method with the lost-wax and milling methods in terms of the marginal fit of implant-supported metal-ceramic restorations. Thirty implant abutments screwed to implant analogs were embedded into acrylic resin to investigate marginal fit and then divided according to fabrication methods into the following 3 groups (n=10): lost-wax (LW; control group), milling (M), and milling-sintering (MS). Porcelain material was applied to all specimens after completion of the fabrication process. Subsequently, all specimens were cemented to implant abutments for the measurement of marginal discrepancies. Twelve marginal discrepancy measurements were recorded on each implant abutment by using a stereomicroscope. The arithmetic mean of these 12 measurements was considered the mean marginal discrepancy value of each abutment. Data were statistically analyzed by using 1-way ANOVA and Tukey honest significant difference tests (α=.05). The lowest mean marginal discrepancy values (81 ±2 μm) were observed in the M group, which was significantly different (P<.001) from the other methods. The highest mean marginal discrepancy values (99 ±2 μm) were observed in the MS group. The results revealed that restorations prepared by the milling-sintering method provided clinically acceptable results (<120 μm); however, this new technique was not found to be as precise as the milling method in terms of marginal fit. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Intermetallic nickel silicide nanocatalyst-A non-noble metal-based general hydrogenation catalyst.

PubMed

Ryabchuk, Pavel; Agostini, Giovanni; Pohl, Marga-Martina; Lund, Henrik; Agapova, Anastasiya; Junge, Henrik; Junge, Kathrin; Beller, Matthias

2018-06-01

Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds including fine chemicals, agrochemicals, and pharmachemicals. On an industrial scale, hydrogenations are typically performed with precious metal catalysts or with base metal catalysts, such as Raney nickel, which requires special handling due to its pyrophoric nature. We report a stable and highly active intermetallic nickel silicide catalyst that can be used for hydrogenations of a wide range of unsaturated compounds. The catalyst is prepared via a straightforward procedure using SiO 2 as the silicon atom source. The process involves thermal reduction of Si-O bonds in the presence of Ni nanoparticles at temperatures below 1000°C. The presence of silicon as a secondary component in the nickel metal lattice plays the key role in its properties and is of crucial importance for improved catalytic activity. This novel catalyst allows for efficient reduction of nitroarenes, carbonyls, nitriles, N-containing heterocycles, and unsaturated carbon-carbon bonds. Moreover, the reported catalyst can be used for oxidation reactions in the presence of molecular oxygen and is capable of promoting acceptorless dehydrogenation of unsaturated N-containing heterocycles, opening avenues for H 2 storage in organic compounds. The generality of the nickel silicide catalyst is demonstrated in the hydrogenation of over a hundred of structurally diverse unsaturated compounds. The wide application scope and high catalytic activity of this novel catalyst make it a nice alternative to known general hydrogenation catalysts, such as Raney nickel and noble metal-based catalysts.

Informal e-waste recycling: environmental risk assessment of heavy metal contamination in Mandoli industrial area, Delhi, India.

PubMed

Pradhan, Jatindra Kumar; Kumar, Sudhir

2014-01-01

Nowadays, e-waste is a major source of environmental problems and opportunities due to presence of hazardous elements and precious metals. This study was aimed to evaluate the pollution risk of heavy metal contamination by informal recycling of e-waste. Environmental risk assessment was determined using multivariate statistical analysis, index of geoaccumulation, enrichment factor, contamination factor, degree of contamination and pollution load index by analysing heavy metals in surface soils, plants and groundwater samples collected from and around informal recycling workshops in Mandoli industrial area, Delhi, India. Concentrations of heavy metals like As (17.08 mg/kg), Cd (1.29 mg/kg), Cu (115.50 mg/kg), Pb (2,645.31 mg/kg), Se (12.67 mg/kg) and Zn (776.84 mg/kg) were higher in surface soils of e-waste recycling areas compared to those in reference site. Level exceeded the values suggested by the US Environmental Protection Agency (EPA). High accumulations of heavy metals were also observed in the native plant samples (Cynodon dactylon) of e-waste recycling areas. The groundwater samples collected form recycling area had high heavy metal concentrations as compared to permissible limit of Indian Standards and maximum allowable limit of WHO guidelines for drinking water. Multivariate analysis and risk assessment studies based on total metal content explains the clear-cut differences among sampling sites and a strong evidence of heavy metal pollution because of informal recycling of e-waste. This study put forward that prolonged informal recycling of e-waste may accumulate high concentration of heavy metals in surface soils, plants and groundwater, which will be a matter of concern for both environmental and occupational hazards. This warrants an immediate need of remedial measures to reduce the heavy metal contamination of e-waste recycling sites.

31 CFR 103.140 - Anti-money laundering programs for dealers in precious metals, precious stones, or jewels.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Anti-money laundering programs for... FOREIGN TRANSACTIONS Anti-Money Laundering Programs Anti-Money Laundering Programs § 103.140 Anti-money...) Anti-money laundering program requirement. (1) Each dealer shall develop and implement a written anti...

Bioassisted Phytomining of Gold

NASA Astrophysics Data System (ADS)

Maluckov, Biljana S.

2015-05-01

Bioassisted phytomining implies targeted use of microorganisms and plants for the selective recovery of the metal. Metals from undissolved compounds are dissolved by applying specially chosen microorganisms and therefore become available to the hyperaccumulating plants. In the article, the selective extraction method of base metals and the precious metal gold by using microorganisms and plants is discussed.

Processing precious metals in a top-blown rotary converter

NASA Astrophysics Data System (ADS)

Whellock, John G.; Matousek, Jan W.

1990-09-01

Copper-nickel/platinum-palladium flotation concentrates produced by the Stillwater Mining Company were smelted and refined in an integrated pilot plant consisting of a submerged-arc electric furnace and top-blown rotary converter. The conversion of high-iron electric furnace mattes was achieved with apparent oxygen efficiencies in excess of 100 percent. Platinum and palladium recoveries averaged 99 percent, and copper and nickel recoveries were 94 percent.

Hydrogen production from bio-fuels using precious metal catalysts

NASA Astrophysics Data System (ADS)

Pasel, Joachim; Wohlrab, Sebastian; Rotov, Mikhail; Löhken, Katrin; Peters, Ralf; Stolten, Detlef

2017-11-01

Fuel cell systems with integrated autothermal reforming unit require active and robust catalysts for H2 production. Thus, an experimental screening of catalysts for autothermal reforming of commercial biodiesel fuel was performed. Catalysts consisted of a monolithic cordierite substrate, an oxide support (γ-Al2O3) and Pt, Ru, Ni, PtRh and PtRu as active phase. Experiments were run by widely varying the O2/C and H2O/C molar ratios at different gas hourly space velocities. Fresh and aged catalysts were characterized by temperature programmed methods and thermogravimetry to find correlations with catalytic activity and stability.

Interactive Hard Rock Mining 2006 Conference CD

EPA Science Inventory

This interactive conference CD provides a forum for the exchange of scientific information on current and future environmental issues which shape the future of the mining industry, including: base metals, precious metals, industrial minerals, and aggregates. The focus of the conf...

GOLD ACRES BIOLOGICAL HEAP DETOXIFICATION

EPA Science Inventory

Many active mine sites, mines in closure stage and some abandoned mines are and have utilized cyanidation to remove and recover precious metals. Discharges from these sites normally contain significant amounts of metal cyanide complexes and concentrations of thiocyanate, soluble...

CYANIDE HEAP BILOGICAL DETOXIFICATION - PHASE II

EPA Science Inventory

Many active mine sites, mines in closure stage and some abandoned mines are and have utilized cyanidation to remove and recover precious metals. Discharges from these sites normally contain significant amounts of metal cyanide complexes and concentrations of thiocyanate, soluble...

CASE STUDY OF AN INTEGRATED PASSIVE BIOLOGICAL ARD TREATMENT SYSTEM

EPA Science Inventory

Many active mine sites, mines in the closure stage and some abandoned mines are and have utilized cyanidation to remove and recover precious metals. Discharges from these sites normally contain significant amounts of metal cyanide complexes and concentrations of thiocyanate, solu...

CYANIDE HEAP BIOLOGICAL DETOXIFICATION - PHASE II

EPA Science Inventory

Many active mine sites, mines in the closure stage and some abandoned mines are and have utilized cyanidation to remove and recover precious metals. Discharges from these sites normally contain significant amounts of metal cyanide complexes and concentrations of thiocyanate, solu...

Challenges of metal recycling and an international covenant as possible instrument of a globally extended producer responsibility.

PubMed

Wilts, Hennning; Bringezu, Stefan; Bleischwitz, Raimund; Lucas, Rainer; Wittmer, Dominic

2011-09-01

As illustrated by the case studies of end-of-life vehicles and waste electric and electronic equipment, the approach of an extended producer responsibility is undermined by the exports of used and waste products. This fact causes severe deficits regarding circular flows, especially of critical raw materials such as platinum group metals. With regard to global recycling there seems to be a responsibility gap which leads somehow to open ends of waste flows and a loss or down-cycling of potential secondary resources. Existing product-orientated extended producer responsibility (EPR) approaches with mass-based recycling quotas do not create adequate incentives to supply waste materials containing precious metals to a high-quality recycling and should be amended by aspects of a material stewardship. The paper analyses incentive effects on EPR for the mentioned product groups and metals, resulting from existing regulations in Germany. It develops a proposal for an international covenant on metal recycling as a policy instrument for a governance-oriented framework to initiate systemic innovations along the complete value chain taking into account product group- and resource group-specific aspects on different spatial levels. It aims at the effective implementation of a central idea of EPR, the transition of a waste regime still focusing on safe disposal towards a sustainable management of resources for the complete lifecycle of products.

An environmentally friendly ball milling process for recovery of valuable metals from e-waste scraps.

PubMed

Zhang, Zhi-Yuan; Zhang, Fu-Shen; Yao, TianQi

2017-10-01

The present study reports a mechanochemical (MC) process for effective recovery of copper (Cu) and precious metals (i.e. Pd and Ag) from e-waste scraps. Results indicated that the mixture of K 2 S 2 O 8 and NaCl (abbreviated as K 2 S 2 O 8 /NaCl hereafter) was the most effective co-milling reagents in terms of high recovery rate. After co-milling with K 2 S 2 O 8 /NaCl, soluble metallic compounds were produced and consequently benefit the subsequent leaching process. 99.9% of Cu and 95.5% of Pd in the e-waste particles could be recovered in 0.5mol/L diluted HCl in 15min. Ag was concentrated in the leaching residue as AgCl and then recovered in 1mol/L NH 3 solution. XRD and XPS analysis indicated that elemental metals in the raw materials were transformed into their corresponding oxidation state during ball milling process at low temperature, implying that solid-solid phase reactions is the reaction mechanism. Based on the results and thermodynamic parameters of the probable reactions, possible reaction pathways during ball milling were proposed. Suggestion on category of e-waste for ball milling process was put forward according to the experiment results. The designed metal recovery process of this study has the advantages of highly recovery rate and quick leaching speed. Thus, this study offers a promising and environmentally friendly method for recovering valuable metals from e-waste. Copyright © 2017 Elsevier Ltd. All rights reserved.

The oxidation of carbon monoxide using tin oxide based catalysts

NASA Technical Reports Server (NTRS)

Sampson, Christopher F.; Jorgensen, Norman

1990-01-01

The preparation conditions for precious metal/tin oxide catalysts were optimized for maximum carbon monoxide/oxygen recombination efficiency. This was achieved by controlling the tin digestion, the peptization to form the sol, the calcination process and the method of adding the precious metals. Extensive studies of the tin oxide structure were carried out over the temperature range 20 to 500 C in air or hydrogen environments using Raman scattering and X ray diffraction. Adsorbed species on tin oxide, generated in an environment containing carbon monoxide, gave rise to a Raman band at about 1600 cm(exp -1) which was assigned to carbonaceous groups, possible carbonate.

Seabed deposits classification at the Precious Stone Mountain hydrothermal field using MultiBeam sonar data

NASA Astrophysics Data System (ADS)

Tao, C.; Zhang, G.; Li, H.; Zhou, J.; Liu, W.; Deng, X.; Chen, S.

2013-12-01

The seabed deposits type and distribution are very complex at the hydrothermal field. In this paper, we provided an approach to study the seabed deposits classification at the Precious Stone Mountain hydrothermal field (PSMHF) using MultiBeam sonar data (Figure 1). The PSMHF was found in the Galapogas microplate at the Leg 3 of the Chinese COMRA 21st Cruise. Using this approach, the seabed deposits at the PSMHF are mainly classified into three types, which are rock, breccia and sediment, respectively. We can find the distribution of the three types of seabed deposits according to the sonar back-scattering data. The rocks are mostly distributed around the hydrothermal vent. The breccia are located at the foot of the vent. Most sediments are distributed at the southwest to the vent due to bottom current. Combining with seabed video, TV-Grab sample and the backscatter data, we draw the map of the seabed deposits distribution at the PSMHF (Figure 2). Figure 1 The flow chart of the seabed deposits classification approach Figure 2 The seabed deposits distribution of the PSMHF

Recovery of Seamount Precious Coral Beds From Heavy Trawling Disturbance

NASA Astrophysics Data System (ADS)

Morgan, N.; Baco-Taylor, A.; Roark, B.

2016-02-01

Resilience and the related concept of recovery provide insights into ecosystem function, connectivity, and succession. Most marine resilience studies have focused on shallow-water ecosystems. However, increasing anthropogenic impacts in the deep sea make studies of resilience and recovery in the deep sea time-critical, with deep-sea hard-substrate habitats and large-scale disturbances having received the least attention. Ironically one of the key anthropogenic impacts to the seafloor, trawling, provides an ideal experimental design to understand processes of recovery from large-scale disturbance in the deep sea. Seamount hard-substrate habitats in particular are thought to have low resilience due to the slow growth rates and recruitment limitations of key structure-forming taxa. The goal of our project is to test the hypothesis of low resilience by examining a series of locations in the far Northwestern Hawaiian Islands and the Emperor Seamount Chain. These sites have had some of the heaviest trawl impacts in the world, from both fish and precious coral fisheries, and include sites that are still trawled as well as ones that have been protected since the establishment of the US Exclusive Economic Zone in 1977. We compare these to untrawled sites as part of a three "treatment" design. During two cruises in 2014 and 2015 we used the AUV Sentry to image nine features (three per treatment). CTD data were also collected. Images were analyzed for all visible megafauna as well as substrate parameters (rugosity, slope, composition, relief). Yuryaku, in the "still trawled" treatment was characterized by extensive areas of bare substrate with abundant trawl scars. This feature also had lower diversity and lower abundance of megafauna compared to the recovering and never trawled locations. Preliminary data suggest recovering and never trawled features have overlapping species, but not in comparable abundances.

40 CFR 421.255 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 28 2010-07-01 2010-07-01 true [Reserved] 421.255 Section 421.255 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

40 CFR 421.257 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 28 2010-07-01 2010-07-01 true [Reserved] 421.257 Section 421.257 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

40 CFR 421.255 - [Reserved

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 29 2014-07-01 2012-07-01 true [Reserved] 421.255 Section 421.255 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

40 CFR 421.255 - [Reserved

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 30 2012-07-01 2012-07-01 false [Reserved] 421.255 Section 421.255 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

40 CFR 421.257 - [Reserved

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 29 2011-07-01 2009-07-01 true [Reserved] 421.257 Section 421.257 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

40 CFR 421.257 - [Reserved

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 30 2013-07-01 2012-07-01 true [Reserved] 421.257 Section 421.257 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

40 CFR 421.255 - [Reserved

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 29 2011-07-01 2009-07-01 true [Reserved] 421.255 Section 421.255 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

40 CFR 421.257 - [Reserved

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 29 2014-07-01 2012-07-01 true [Reserved] 421.257 Section 421.257 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

40 CFR 421.257 - [Reserved

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 30 2012-07-01 2012-07-01 false [Reserved] 421.257 Section 421.257 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

40 CFR 421.255 - [Reserved

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 30 2013-07-01 2012-07-01 true [Reserved] 421.255 Section 421.255 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Precious Metals and Mercury Subcategory § 421...

Bio-oil hydrodeoxygenation catalysts produced using strong electrostatic adsorption

USDA-ARS?s Scientific Manuscript database

We synthesized hydrothermally stable metal catalysts with controlled particle size and distribution, with the goal of determining which catalyst(s) can selectively catalyze the production of aromatics from bio-oil (from pyrolysis of biomass). Both precious and base transition metal catalysts (Ru, Pt...

A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence

NASA Astrophysics Data System (ADS)

Chábera, Pavel; Liu, Yizhu; Prakash, Om; Thyrhaug, Erling; Nahhas, Amal El; Honarfar, Alireza; Essén, Sofia; Fredin, Lisa A.; Harlang, Tobias C. B.; Kjær, Kasper S.; Handrup, Karsten; Ericson, Fredric; Tatsuno, Hideyuki; Morgan, Kelsey; Schnadt, Joachim; Häggström, Lennart; Ericsson, Tore; Sobkowiak, Adam; Lidin, Sven; Huang, Ping; Styring, Stenbjörn; Uhlig, Jens; Bendix, Jesper; Lomoth, Reiner; Sundström, Villy; Persson, Petter; Wärnmark, Kenneth

2017-03-01

Transition-metal complexes are used as photosensitizers, in light-emitting diodes, for biosensing and in photocatalysis. A key feature in these applications is excitation from the ground state to a charge-transfer state; the long charge-transfer-state lifetimes typical for complexes of ruthenium and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron and copper being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs, it remains a formidable scientific challenge to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers. Here we present the iron complex [Fe(btz)3]3+ (where btz is 3,3‧-dimethyl-1,1‧-bis(p-tolyl)-4,4‧-bis(1,2,3-triazol-5-ylidene)), and show that the superior σ-donor and π-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(III) d5 complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer (2LMCT) state that is rarely seen for transition-metal complexes. The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers.

Evidence for photosensitised hydrogen production from water in the absence of precious metals, redox-mediators and co-catalysts.

PubMed

Salzl, S; Ertl, M; Knör, G

2017-03-22

The water-soluble zinc porphyrin complex Zn(TPPS) 4- with TPPS = tetrakis-(4-sulfonatophenyl)porphyrin surprisingly was found to produce significant amounts of hydrogen from aqueous sulfite or amine solutions under visible-light exposure without requiring any other components such as electron relays or additional proton reduction catalysts. Although the production rates and total amounts of chemically stored fuel obtained under these conditions are still much too low to be relevant for practical applications, the background of this unprecedented observation was further studied in its own right. Since the central metal zinc is unlikely to be involved in proton-coupled electron transfer steps upon long-wavelength irradiation and the process does not seem to be much affected by variations of the electron donor added, the mechanism of photocatalytic H 2 release is suggested to involve previously neglected redox features of the in situ generated hydroporphyrin ligand system in aqueous solution.

Body vibrational spectra of metal flute models

NASA Astrophysics Data System (ADS)

Hurtgen, Clare M.; Lawson, Dewey T.

2002-11-01

For years, flutists have argued over the tonal advantages of using different precious metals for their instruments. Occasionally, scientists have entered the fray and attempted to offer an objective point of view based on experimental measurements. However, their research often involved actual instruments and performers, ignoring variations in wall thickness, craftsmanship, and human consistency. These experiments have been conducted using a variety of methods; all have concluded that wall material has no effect on tone. This paper approaches the question using simple tubular models, excited by a wind source through a fipple mouthpiece. The amplitude and phase of the harmonic components of the body vibrational signal were measured with a stereo cartridge. Results demonstrated the existence of complex patterns of wall vibrations in the vicinity of a tone hole lattice, at frequencies that match significant harmonics of the air column. Additionally, the tube wall was found to expand in a nonuniform or ''elliptical'' manner due to the asymmetry of the tone holes. While this method is somewhat removed from direct musical applications, it can provide an objective, quantitative basis for assessing the source of differences among flutes. [Work financed by two Undergraduate Research Support grants from Duke University.

A metal-free organic-inorganic aqueous flow battery.

PubMed

Huskinson, Brian; Marshak, Michael P; Suh, Changwon; Er, Süleyman; Gerhardt, Michael R; Galvin, Cooper J; Chen, Xudong; Aspuru-Guzik, Alán; Gordon, Roy G; Aziz, Michael J

2014-01-09

As the fraction of electricity generation from intermittent renewable sources--such as solar or wind--grows, the ability to store large amounts of electrical energy is of increasing importance. Solid-electrode batteries maintain discharge at peak power for far too short a time to fully regulate wind or solar power output. In contrast, flow batteries can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all of the electro-active species in fluid form. Wide-scale utilization of flow batteries is, however, limited by the abundance and cost of these materials, particularly those using redox-active metals and precious-metal electrocatalysts. Here we describe a class of energy storage materials that exploits the favourable chemical and electrochemical properties of a family of molecules known as quinones. The example we demonstrate is a metal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid (AQDS). AQDS undergoes extremely rapid and reversible two-electron two-proton reduction on a glassy carbon electrode in sulphuric acid. An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br2/Br(-) redox couple, yields a peak galvanic power density exceeding 0.6 W cm(-2) at 1.3 A cm(-2). Cycling of this quinone-bromide flow battery showed >99 per cent storage capacity retention per cycle. The organic anthraquinone species can be synthesized from inexpensive commodity chemicals. This organic approach permits tuning of important properties such as the reduction potential and solubility by adding functional groups: for example, we demonstrate that the addition of two hydroxy groups to AQDS increases the open circuit potential of the cell by 11% and we describe a pathway for further increases in cell voltage. The use of π-aromatic redox-active organic molecules instead of redox-active metals

16 CFR 23.4 - Misrepresentation as to gold content.

Code of Federal Regulations, 2010 CFR

2010-01-01

... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.4 Misrepresentation as to gold content. (a) It is... covered with a base metal (such as nickel), which is covered with a thin wash of gold, unless there is a disclosure that the primary gold coating is covered with a base metal, which is gold washed. (7) Use of the...

16 CFR 23.4 - Misrepresentation as to gold content.

Code of Federal Regulations, 2013 CFR

2013-01-01

... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.4 Misrepresentation as to gold content. (a) It is... covered with a base metal (such as nickel), which is covered with a thin wash of gold, unless there is a disclosure that the primary gold coating is covered with a base metal, which is gold washed. (7) Use of the...

16 CFR 23.4 - Misrepresentation as to gold content.

Code of Federal Regulations, 2012 CFR

2012-01-01

... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.4 Misrepresentation as to gold content. (a) It is... covered with a base metal (such as nickel), which is covered with a thin wash of gold, unless there is a disclosure that the primary gold coating is covered with a base metal, which is gold washed. (7) Use of the...

Catalytic thermal barrier coatings

DOEpatents

Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

2009-06-02

A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

26 CFR 1.897-7T - Treatment of certain partnership interests as entirely U.S. real property interests under...

Code of Federal Regulations, 2010 CFR

2010-04-01

... deposit, money market accounts, commercial paper, U.S. and foreign treasury obligations and bonds, corporate obligations and bonds, precious metals or commodities, and publicly traded instruments. (b...

Compositional variation of glauconites in Upper Cretaceous-Paleogene sedimentary iron-ore deposits in South-eastern Western Siberia

NASA Astrophysics Data System (ADS)

Rudmin, Maxim; Banerjee, Santanu; Mazurov, Aleksey

2017-06-01

Glauconite occurs either as unaltered greenish or as altered brownish variety in Upper Cretaceous-Palaeocene sediments in the southeastern corner of Western Siberia. Studied section within the Bakchar iron-ore deposit includes Ipatovo, Slavgorod, Gan'kino and Lyulinvor formations, which are represented by sandstones, siltstones, claystones and oolitic ironstones of coastal-marine facies. The origin of unaltered glauconite is explained by the ;verdissement theory;. Transgressions during Lower Coniacian, Santonian and Campanian favored the formation of unaltered glauconites in dysoxic to anoxic conditions. Subaerial exposure of glauconite resulted in leaching of potassium, oxidation of iron and formation of iron hydroxides in Upper Coniacian, Maastrichtian and Palaeocene. Glauconite ultimately converts to leptochlorite and hydrogoethite by this alteration. Abundant microscopic gold inclusions, besides sulphides, sulphates, oxides and silicates characterize this glauconite. Mineral inclusions include precious, rare metals and non-ferrous metals. The concentration of gold in glauconite may be as high as 42.9 ppb. Abundant inclusions of various compositions in glauconites indicate enrichment of marine sediments in precious and non-precious metals. While major element composition of glauconites is affected by subaerial exposure, the broadly similar micro-inclusions in both altered and unaltered varieties are possibly related to the comparatively immobile nature of REE and trace elements.

A Metal-Organic Framework Derived Porous Cobalt Manganese Oxide Bifunctional Electrocatalyst for Hybrid Na-Air/Seawater Batteries.

PubMed

Abirami, Mari; Hwang, Soo Min; Yang, Juchan; Senthilkumar, Sirugaloor Thangavel; Kim, Junsoo; Go, Woo-Seok; Senthilkumar, Baskar; Song, Hyun-Kon; Kim, Youngsik

2016-12-07

Spinel-structured transition metal oxides are promising non-precious-metal electrocatalysts for oxygen electrocatalysis in rechargeable metal-air batteries. We applied porous cobalt manganese oxide (CMO) nanocubes as the cathode electrocatalyst in rechargeable seawater batteries, which are a hybrid-type Na-air battery with an open-structured cathode and a seawater catholyte. The porous CMO nanocubes were synthesized by the pyrolysis of a Prussian blue analogue, Mn 3 [Co(CN) 6 ] 2 ·nH 2 O, during air-annealing, which generated numerous pores between the final spinel-type CMO nanoparticles. The porous CMO electrocatalyst improved the redox reactions, such as the oxygen evolution/reduction reactions, at the cathode in the seawater batteries. The battery that used CMO displayed a voltage gap of ∼0.53 V, relatively small compared to that of the batteries employing commercial Pt/C (∼0.64 V) and Ir/C (∼0.73 V) nanoparticles and without any catalyst (∼1.05 V) at the initial cycle. This improved performance was due to the large surface area (catalytically active sites) and the high oxidation states of the randomly distributed Co and Mn cations in the CMO. Using a hard carbon anode, the Na-metal-free seawater battery exhibited a good cycle performance with an average discharge voltage of ∼2.7 V and a discharge capacity of ∼190 mAh g -1 hard carbon during 100 cycles (energy efficiencies of 74-79%).

Stocks, Flows, and Distribution of Critical Metals in Embedded Electronics in Passenger Vehicles.

PubMed

Restrepo, Eliette; Løvik, Amund N; Wäger, Patrick; Widmer, Rolf; Lonka, Radek; Müller, Daniel B

2017-02-07

One of the major applications of critical metals (CMs) is in electrical and electronic equipment (EEE), which is increasingly embedded in other products, notably passenger vehicles. However, recycling strategies for future CM quantities in end-of-life vehicles (ELVs) are poorly understood, mainly due to a limited understating of the complexity of automotive embedded EEE. We introduce a harmonization of the network structure of automotive electronics that enables a comprehensive quantification of CMs in all embedded EEE in a vehicle. This network is combined with a material flow analysis along the vehicle lifecycle in Switzerland to quantify the stocks and flows of Ag, Au, Pd, Ru, Dy, La, Nd, and Co in automotive embedded EEE. In vehicles in use, we calculated 5 -2 +3 t precious metals in controllers embedded in all vehicle types and 220 -60 +90 t rare earth elements (REE); found mainly in five electric motors: alternator, starter, radiator-fan and electronic power steering motor embedded in conventional passenger vehicles and drive motor/generator embedded in hybrid and electric vehicles. Dismantling these devices before ELV shredding, as well as postshredder treatment of automobile shredder residue may increase the recovery of CMs from ELVs. Environmental and economic implications of such recycling strategies must be considered.

Results of studying creep and long-term strength of metals at the Institute of Mechanics at the Lomonosov Moscow State University (To Yu. N. Rabotnov's Anniversary)

NASA Astrophysics Data System (ADS)

Lokoshchenko, A. M.

2014-01-01

Basic results of experimental and theoretical research of creep processes and long-term strength of metals obtained by researchers of the Institute of Mechanics at the Lomonosov Moscow State University are presented. These results further develop and refine the kinetic theory of creep and long-duration strength proposed by Yu. N. Rabotnov. Some problems arising in formulating various types of kinetic equations and describing experimental data for materials that can be considered as statically homogeneous materials (in studying the process of deformation and rupture of such materials, there is no need to study the evolution of individual cracks) are considered. The main specific features of metal creep models at constant and variable stresses, in uniaxial and complex stress states, and with allowance for one or two damage parameters are described. Criterial and kinetic approaches used to determine long-term strength under conditions of a complex stress state are considered. Methods of modeling the metal behavior in an aggressive medium are described. A possibility of using these models for solving engineering problems is demonstrated.

A Bimetallic Nickel-Gallium Complex Catalyzes CO2 Hydrogenation via the Intermediacy of an Anionic d10 Nickel Hydride.

PubMed

Cammarota, Ryan C; Vollmer, Matthew V; Xie, Jing; Ye, Jingyun; Linehan, John C; Burgess, Samantha A; Appel, Aaron M; Gagliardi, Laura; Lu, Connie C

2017-10-11

Large-scale CO 2 hydrogenation could offer a renewable stream of industrially important C 1 chemicals while reducing CO 2 emissions. Critical to this opportunity is the requirement for inexpensive catalysts based on earth-abundant metals instead of precious metals. We report a nickel-gallium complex featuring a Ni(0)→Ga(III) bond that shows remarkable catalytic activity for hydrogenating CO 2 to formate at ambient temperature (3150 turnovers, turnover frequency = 9700 h -1 ), compared with prior homogeneous Ni-centered catalysts. The Lewis acidic Ga(III) ion plays a pivotal role in stabilizing catalytic intermediates, including a rare anionic d 10 Ni hydride. Structural and in situ characterization of this reactive intermediate support a terminal Ni-H moiety, for which the thermodynamic hydride donor strength rivals those of precious metal hydrides. Collectively, our experimental and computational results demonstrate that modulating a transition metal center via a direct interaction with a Lewis acidic support can be a powerful strategy for promoting new reactivity paradigms in base-metal catalysis.

On-Line Control of Metal Processing. Report of the Committee on On-Line Control of Metal Processing

DTIC Science & Technology

1989-02-01

Materials Engineering. His work has concentrated on the electroprocessing of metals in molten salts . He is a member of TMS, AIME, ES, Canadian Institute...continuous ingot casting process with three 32 discrete control loops Figure 4-2 Controller incorporating process model 36 Figure 4-3 Real-time molten ...and others while providing a controlled macrostructure and solidification substructure. In this process, molten metal continuously flows from a

Applications of low temperature CO-oxidation catalysts to breathable gases

NASA Technical Reports Server (NTRS)

Noordally, Ehsan; Richmond, John R.

1990-01-01

Modifications of tin oxide/precious metal catalysts described for use in CO2 lasers have also been developed for use in other applications; namely, as low temperature CO oxidation components in fire escape hoods/masks for mines, aircrafts, hotels, and offices and in sealed environments, such as hyperbaric chambers and submarines. Tin oxide/precious metal catalysts have been prepared on a variety of high surface area cloth substrates for application in fire escape hoods. These show high and stable CO oxidation capability (10 to the 4th power ppm CO reduced to 10 to the 1st power ppm CO) at GHSV of 37,000 h(-1) with water saturated inlet gas at body heat (37 C) and below. Water vapor plays an important role in the surface state/performance of tin oxide catalyst. Water-resistant formulations have been produced by the introduction of transition metal promoters. Tin oxide/precious metal catalysts have also been developed for CO oxidation in the North Sea diving environment. These are currently in use in a variety of hyperbaric chambers and diving vehicles. Ambient temperature operation and resistance to atmospheric water vapor have been demonstrated, and as a result, they offer a viable alternative to hopcalite or heated catalyst systems. A new range of non-tin oxide based low temperature CO oxidation catalysts is described. They are based on reducible metal oxides promoted with previous metals. Preliminary data on selected materials in the form of both cloth artifacts and shaped pellets are presented. They are expected to be applicable both to the breathable gas application area and to CO2 lasers.

Enzyme leaching of surficial geochemical samples for detecting hydromorphic trace-element anomalies associated with precious-metal mineralized bedrock buried beneath glacial overburden in northern Minnesota

USGS Publications Warehouse

Clark, Robert J.; Meier, A.L.; Riddle, G.; ,

1990-01-01

One objective of the International Falls and Roseau, Minnesota, CUSMAP projects was to develop a means of conducting regional-scale geochemical surveys in areas where bedrock is buried beneath complex glacially derived overburden. Partial analysis of B-horizon soils offered hope for detecting subtle hydromorphic trace-element dispersion patterns. An enzyme-based partial leach selectively removes metals from oxide coatings on the surfaces of soil materials without attacking their matrix. Most trace-element concentrations in the resulting solutions are in the part-per-trillion to low part-per-billion range, necessitating determinations by inductively coupled plasma/mass spectrometry. The resulting data show greater contrasts for many trace elements than with other techniques tested. Spatially, many trace metal anomalies are locally discontinuous, but anomalous trends within larger areas are apparent. In many instances, the source for an anomaly seems to be either basal till or bedrock. Ground water flow is probably the most important mechanism for transporting metals toward the surface, although ionic diffusion, electrochemical gradients, and capillary action may play a role in anomaly dispersal. Sample sites near the Rainy Lake-Seine River fault zone, a regional shear zone, often have anomalous concentrations of a variety of metals, commonly including Zn and/or one or more metals which substitute for Zn in sphalerite (Cd, Ge, Ga, and Sn). Shifts in background concentrations of Bi, Sb, and As show a trend across the area indicating a possible regional zoning of lode-Au mineralization. Soil anomalies of Ag, Co, and Tl parallel basement structures, suggesting areas that may have potential for Cobalt/Thunder Baytype silver viens. An area around Baudette, Minnesota, which is underlain by quartz-chlorite-carbonate-altered shear zones, is anomalous in Ag, As, Bi, Co, Mo, Te, Tl, and W. Anomalies of Ag, As, Bi, Te, and W tend to follow the fault zones, suggesting potential

Method of forming supported doped palladium containing oxidation catalysts

DOEpatents

Mohajeri, Nahid

2014-04-22

A method of forming a supported oxidation catalyst includes providing a support comprising a metal oxide or a metal salt, and depositing first palladium compound particles and second precious metal group (PMG) metal particles on the support while in a liquid phase including at least one solvent to form mixed metal comprising particles on the support. The PMG metal is not palladium. The mixed metal particles on the support are separated from the liquid phase to provide the supported oxidation catalyst.

PROCESS DEVELOPMENT FOR THE RECOVERY OF CRITICAL MATERIALS FROM ELECTRONIC WASTE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lister, T. E.; Diaz, L. A.; Clark, G. G.

As electronic technology continues to evolve there is a growing need to develop processes which recover valuable material from antiquated technology. This need follows from the environmental challenges associated with the availability of raw materials and fast growing generation of electronic waste. Although just present in small quantities in electronic devices, the availability of raw materials, such as rare earths and precious metals, becomes critical for the production of high tech electronic devices and the development of green technologies (i.e. wind turbines, electric motors, and solar panels). Therefore, the proper recycling and processing of increasing volumes of electronic waste presentmore » an opportunity to stabilize the market of critical materials, reducing the demand of mined products, and providing a proper disposal and treatment of a hazardous waste stream. This paper will describe development and techno-economic assessment of a comprehensive process for the recovery of value and critical materials from electronic waste. This hydrometallurgical scheme aims to selectively recover different value segments in the materials streams (base metals, precious metals, and rare earths). The economic feasibility for the recovery of rare earths from electronic waste is mostly driven by the efficient recovery of precious metals, such as Au and Pd (ca. 80 % of the total recoverable value). Rare earth elements contained in magnets (speakers, vibrators and hard disk storage) can be recovered as a mixture of rare earths oxides which can later be reduced to the production of new magnets.« less

75 FR 17818 - Self-Regulatory Organizations; NYSE Amex LLC; Order Granting Approval of Proposed Rule Change...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-07

... the Fund under a new name, the Nuveen Diversified Commodity Fund, and with a modified investment plan..., industrial metals, precious metals, livestock, agriculturals, and tropical foods and fibers and may in the... and perfect the mechanism of a free and open market and a national market system, and, in general, to...

76 FR 11243 - Solicitation of Input From Stakeholders To Inform the National Framework for Electronics Stewardship

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-01

... a metal detector, and sign the EPA visitor log. All visitor bags are processed through an X- ray... equipment from solid waste landfills in the United States. EPA does, however, control how cathode ray tube... cell phone and computers/laptops or recover valuable resources, such as precious metals, plastics or...

48 CFR 208.7301 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Precious Metals 208.7301 Definitions. As used in this subpart— Defense Supply Center, Philadelphia (DSCP) means the Defense Logistics Agency field activity located at 700 Robbins Avenue, Philadelphia, PA 19111...

48 CFR 208.7301 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Precious Metals 208.7301 Definitions. As used in this subpart— Defense Supply Center, Philadelphia (DSCP) means the Defense Logistics Agency field activity located at 700 Robbins Avenue, Philadelphia, PA 19111...

48 CFR 208.7301 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Precious Metals 208.7301 Definitions. As used in this subpart— Defense Supply Center, Philadelphia (DSCP) means the Defense Logistics Agency field activity located at 700 Robbins Avenue, Philadelphia, PA 19111...

48 CFR 208.7301 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Precious Metals 208.7301 Definitions. As used in this subpart— Defense Supply Center, Philadelphia (DSCP) means the Defense Logistics Agency field activity located at 700 Robbins Avenue, Philadelphia, PA 19111...

48 CFR 208.7301 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Precious Metals 208.7301 Definitions. As used in this subpart— Defense Supply Center, Philadelphia (DSCP) means the Defense Logistics Agency field activity located at 700 Robbins Avenue, Philadelphia, PA 19111...

Abandoned mines, mountain sports, and climate variability: Implications for the Colorado tourism economy

NASA Astrophysics Data System (ADS)

Todd, Andrew; McKnight, Diane; Wyatt, Lane

Until recently, the allure of the mountains in the American West was primarily extractive, for commodities like timber, water, and precious metals [Baron et. al., 2000]. Now, the effective marketing and management of the regions “white gold” by the ski industry has stimulated significant recreation-related growth and development in the last several decades. Under an uncertain climatic future, however, these burgeoning industries, and the communities that have grown up in relation to them, are facing water quality constraints inherited from historical mining practices, causing mountain water to become a limited resource more valuable than the precious metals of the past. Further, the current lack of proven, in-situ approaches for addressing distributed, mining waste pollution of fresh water complicates potential remediation efforts.

5 CFR 180.105 - Claims not allowed.

Code of Federal Regulations, 2012 CFR

2012-01-01

... articles of gold, silver, other precious metals, paintings, antiques other than bulky furnishings, relics... articles acquired at the request of others and articles for sale. (9) Property used for business. Claims...

5 CFR 180.105 - Claims not allowed.

Code of Federal Regulations, 2013 CFR

2013-01-01

... articles of gold, silver, other precious metals, paintings, antiques other than bulky furnishings, relics... articles acquired at the request of others and articles for sale. (9) Property used for business. Claims...

5 CFR 180.105 - Claims not allowed.

Code of Federal Regulations, 2011 CFR

2011-01-01

... articles of gold, silver, other precious metals, paintings, antiques other than bulky furnishings, relics... articles acquired at the request of others and articles for sale. (9) Property used for business. Claims...

5 CFR 180.105 - Claims not allowed.

Code of Federal Regulations, 2010 CFR

2010-01-01

... articles of gold, silver, other precious metals, paintings, antiques other than bulky furnishings, relics... articles acquired at the request of others and articles for sale. (9) Property used for business. Claims...

5 CFR 180.105 - Claims not allowed.

Code of Federal Regulations, 2014 CFR

2014-01-01

... articles of gold, silver, other precious metals, paintings, antiques other than bulky furnishings, relics... articles acquired at the request of others and articles for sale. (9) Property used for business. Claims...

GOLD NANOPARTICLES: A REVIVAL IN PRECIOUS METAL ADMINISTRATION TO PATIENTS

PubMed Central

Thakor, AS; Jokerst, J; Zaveleta, C; Massoud, TF; Gambhir, SS

2011-01-01

Gold has been used as a therapeutic agent to treat a wide variety of rheumatic diseases including psoriatic arthritis, juvenile arthritis and discoid lupus erythematosus. Although the use of gold has been largely superseded by newer drugs, gold nanoparticles are being used effectively in laboratory based clinical diagnostic methods whilst concurrently showing great promise in vivo either as a diagnostic imaging agent or a therapeutic agent. For these reasons, gold nanoparticles are therefore well placed to enter mainstream clinical practice in the near future. Hence, the present review summarizes the chemistry, pharmacokinetics, bio-distribution, metabolism and toxicity of bulk gold in humans based on decades of clinical observation and experiments in which gold was used to treat patients with rheumatoid arthritis. The beneficial attributes of gold nanoparticles, such as their ease of synthesis, functionalization and shape control are also highlighted demonstrating why gold nanoparticles are an attractive target for further development and optimization. The importance of controlling the size and shape of gold nanoparticles to minimize any potential toxic side effects is also discussed. PMID:21846107

Catalyst for treatment and control of post-combustion emissions

NASA Technical Reports Server (NTRS)

Upchurch, legal representative, Wilhelmina H. (Inventor); Schryer, David R. (Inventor); Upchurch, Billy T. (Inventor)

2008-01-01

The present invention utilizes two precious metals with two to five different metal-oxides in a layered matrix to convert CO, HCs, and NOx to CO.sub.2, and N.sub.2 by oxidation of two components and reduction of the other in a moderately high temperature gaseous environment containing excess oxygen.

Principles and Methods for the Rational Design of Core-Shell Nanoparticle Catalysts with Ultralow Noble Metal Loadings.

PubMed

Hunt, Sean T; Román-Leshkov, Yuriy

2018-05-15

Conspecuts Commercial and emerging renewable energy technologies are underpinned by precious metal catalysts, which enable the transformation of reactants into useful products. However, the noble metals (NMs) comprise the least abundant elements in the lithosphere, making them prohibitively scarce and expensive for future global-scale technologies. As such, intense research efforts have been devoted to eliminating or substantially reducing the loadings of NMs in various catalytic applications. These efforts have resulted in a plethora of heterogeneous NM catalyst morphologies beyond the traditional supported spherical nanoparticle. In many of these new architectures, such as shaped, high index, and bimetallic particles, less than 20% of the loaded NMs are available to perform catalytic turnovers. The majority of NM atoms are subsurface, providing only a secondary catalytic role through geometric and ligand effects with the active surface NM atoms. A handful of architectures can approach 100% NM utilization, but severe drawbacks limit general applicability. For example, in addition to problems with stability and leaching, single atom and ultrasmall cluster catalysts have extreme metal-support interactions, discretized d-bands, and a lack of adjacent NM surface sites. While monolayer thin films do not possess these features, they exhibit such low surface areas that they are not commercially relevant, serving predominantly as model catalysts. This Account champions core-shell nanoparticles (CS NPs) as a vehicle to design highly active, stable, and low-cost materials with high NM utilization for both thermo- and electrocatalysis. The unique benefits of the many emerging NM architectures could be preserved while their fundamental limitations could be overcome through reformulation via a core-shell morphology. However, the commercial realization of CS NPs remains challenging, requiring concerted advances in theory and manufacturing. We begin by formulating seven

ZnSe quantum dots modified with a Ni(cyclam) catalyst for efficient visible-light driven CO2 reduction in water.

PubMed

Kuehnel, Moritz F; Sahm, Constantin D; Neri, Gaia; Lee, Jonathan R; Orchard, Katherine L; Cowan, Alexander J; Reisner, Erwin

2018-03-07

A precious metal and Cd-free photocatalyst system for efficient CO 2 reduction in water is reported. The hybrid assembly consists of ligand-free ZnSe quantum dots (QDs) as a visible-light photosensitiser combined with a phosphonic acid-functionalised Ni(cyclam) catalyst, NiCycP. This precious metal-free photocatalyst system shows a high activity for aqueous CO 2 reduction to CO (Ni-based TON CO > 120), whereas an anchor-free catalyst, Ni(cyclam)Cl 2 , produced three times less CO. Additional ZnSe surface modification with 2-(dimethylamino)ethanethiol (MEDA) partially suppresses H 2 generation and enhances the CO production allowing for a Ni-based TON CO of > 280 and more than 33% selectivity for CO 2 reduction over H 2 evolution, after 20 h visible light irradiation ( λ > 400 nm, AM 1.5G, 1 sun). The external quantum efficiency of 3.4 ± 0.3% at 400 nm is comparable to state-of-the-art precious metal photocatalysts. Transient absorption spectroscopy showed that band-gap excitation of ZnSe QDs is followed by rapid hole scavenging and very fast electron trapping in ZnSe. The trapped electrons transfer to NiCycP on the ps timescale, explaining the high performance for photocatalytic CO 2 reduction. With this work we introduce ZnSe QDs as an inexpensive and efficient visible light-absorber for solar fuel generation.

Adopted children's co-production and use of 'trove' (a digitally enhanced memory box) to better understand their care histories through precious objects.

PubMed

Watson, Debbie; Meineck, Chloe; Lancaster, Beth

2018-05-01

This article presents an innovative project to develop and trial a prototype product called 'trove' to start to address challenges identified regarding current practice of life story work with children who are looked after and adopted. trove is a digitally enhanced memory box that utilises raspberry pi (a small single board computer) and radio-frequency identification (RFID) technologies to enable children to record their memories and to attach these to their precious objects using an electronic tag: providing a safe 'container' for their mementoes and memories. Located in theories of narrative identity and object attachment and drawing on Brodinsky's concept of communicative openness, we describe the children's engagements in the design and report the results of a small trial of 10 troves with adopted children in England.

The characteristics of hydrothermal plumes observed in the Precious Stone Mountain hydrothermal field, the Galapagos spreading center

NASA Astrophysics Data System (ADS)

Chen, S.; Tao, C.; Li, H.; Zhou, J.; Deng, X.; Tao, W.; Zhang, G.; Liu, W.; He, Y.

2014-12-01

The Precious Stone Mountain hydrothermal field (PSMHF) is located on the southern rim of the Galapagos Microplate. It was found at the 3rd leg of the 2009 Chinese DY115-21 expedition on board R/V Dayangyihao. It is efficient to learn the distribution of hydrothermal plumes and locate the hydrothermal vents by detecting the anomalies of turbidity and temperature. Detecting seawater turbidity by MAPR based on deep-tow technology is established and improved during our cruises. We collected data recorded by MAPR and information from geological sampling, yielding the following results: (1)Strong hydrothermal turbidity and temperature anomalies were recorded at 1.23°N, southeast and northwest of PSMHF. According to the CTD data on the mooring system, significant temperature anomalies were observed over PSMHF at the depth of 1,470 m, with anomalies range from 0.2℃ to 0.4℃, which gave another evidence of the existence of hydrothermal plume. (2)At 1.23°N (101.4802°W/1.2305°N), the nose-shaped particle plume was concentrated at a depth interval of 1,400-1,600 m, with 200 m thickness and an east-west diffusion range of 500 m. The maximum turbidity anomaly (0.045 △NTU) was recorded at the depth of 1,500 m, while the background anomaly was about 0.01△NTU. A distinct temperature anomaly was also detected at the seafloor near 1.23°N. Deep-tow camera showed the area was piled up by hydrothermal sulfide sediments. (3) In the southeast (101.49°W/1.21°N), the thickness of hydrothermal plume was 300 m and it was spreading laterally at a depth of 1,500-1,800 m, for a distance about 800 m. The maximum turbidity anomaly of nose-shaped plume is about 0.04 △NTU at the depth of 1,600 m. Distinct temperature anomaly was also detected in the northwest (101.515°W/1.235°N). (4) Terrain and bottom current were the main factors controlling the distribution of hydrothermal plume. Different from the distribution of hydrothermal plumes on the mid-ocean ridges, which was mostly

2014 NEPP Tasks Update for Ceramic and Tantalum Capacitors

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2014-01-01

Presentation describes recent development in research on MnO2, wet, and polymer tantalum capacitors. Low-voltage failures in multilayer ceramic capacitors and techniques to reveal precious metal electrode (PME) and base metal electrode (BME) capacitors with cracks are discussed. A voltage breakdown technique is suggested to select high quality low-voltage BME ceramic capacitors.

Nitrogen–doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Lei; Luo, Langli; Feng, Zhenxing

Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarce resource. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides etc. are their low electronic conductivity and durability. Herein, we report a highly active (360 mV overpotential at 10 mA cm–2GEO) and durable (no degradation after 20000 cycles) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists ofmore » NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron-donation/deviation from Fe and tuned electronic structure of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. We further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.« less

78 FR 20695 - Walk-Through Metal Detectors and Hand-Held Metal Detectors Test Method Validation

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-05

... Detectors and Hand-Held Metal Detectors Test Method Validation AGENCY: National Institute of Justice, DOJ... ensure that the test methods in the standards are properly documented, NIJ is requesting proposals (including price quotes) for test method validation efforts from testing laboratories. NIJ is also seeking...

Heavy metals in soils from Baia Mare mining impacted area (Romania) and their bioavailability

NASA Astrophysics Data System (ADS)

Roba, Carmen; Baciu, Calin; Rosu, Cristina; Pistea, Ioana; Ozunu, Alexandru

2015-04-01

Keywords: heavy metals, soil contamination, bioavailability, Romania The fate of various metals, including chromium, nickel, copper, manganese, mercury, cadmium, and lead, and metalloids, like arsenic, antimony, and selenium, in the natural environment is of great concern, particularly in the vicinity of former mining sites, dumps, tailings piles, and impoundments, but also in urban areas and industrial centres. Most of the studies focused on the heavy metal pollution in mining areas present only the total amounts of metals in soils. The bioavailable concentration of metals in soil may be a better predictor for environmental impact of historical and current dispersion of metals. Assessment of the metal bioavailability and bioaccessibility is critical in understanding the possible effects on soil biota. The bioavailability of metals in soil and their retention in the solid phase of soil is affected by different parameters like pH, metal amount, cation-exchange capacity, content of organic matter, or soil mineralogy. The main objectives of the present study were to determine the total fraction and the bioavailable fraction of Cu, Cd, Pb and Zn from soil in a well-known mining region in Romania, and to evaluate the influence of soil pH on the metal bioavailability in soil. The heavy metal contents and their bioavailability were monitored in a total of 50 soil samples, collected during June and July 2014 from private gardens of the inhabitants from Baia-Mare area. The main mining activities developed in the area consisted of non-ferrous sulphidic ores extraction and processing, aiming to obtain concentrates of lead, copper, zinc and precious metals. After 2006, the metallurgical industry has considerably reduced its activity by closing or diminishing its production capacity. The analysed soil samples proved to have high levels of Pb (50 - 830 mg/kg), Cu (40 - 600 mg/kg), Zn (100 - 700 mg/kg) and Cd (up to 10 mg/kg). The metal abundance in the total fraction is

Modeling Electrochemical Performance of the Hierarchical Morphology of Precious Group Metal-free Cathode for Polymer Electrolyte Fuel Cell

DOE PAGES

Komini Babu, Siddharth; Chung, Hoon Taek; Zelenay, Piotr; ...

2017-08-04

Here, this paper presents a two-dimensional (2D) computational model of a polymer electrolyte fuel cell (PEFC) with a platinum group metal-free (PGM-free) catalyst cathode that can significantly reduce PEFC costs by eliminating the need for expensive platinum catalysts. Due to their comparatively low volumetric activity, PGM-free cathodes are an order of magnitude thicker than their Pt-based counterpart. The resulting need for greater electrode thickness to achieve sufficient power density requires careful attention to the transport losses across the thicker cathodes. The presented model is used to correlate the composition and morphology of the cathode to PEFC performance. The model ismore » a complete cell, continuum model that includes an advanced agglomerate model for a microstructurally consistent representation of the cathode. A unique feature of the approach is the integration of morphology and transport parameter statistics extracted from nano-scale resolution X-ray computed tomography (nano-CT) imaging of PGM-free cathodes. The model was validated with experimental results of PGM-free cathodes with varying Nafion loading. Lastly, our key findings are a need for increased cathode hydrophobicity and increased ionomer conductivity through either reduced tortuosity or increased bulk conductivity. We further use the model to evaluate targets for the volumetric activity and active site density for future catalysts.« less

Modeling Electrochemical Performance of the Hierarchical Morphology of Precious Group Metal-free Cathode for Polymer Electrolyte Fuel Cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komini Babu, Siddharth; Chung, Hoon Taek; Zelenay, Piotr

Here, this paper presents a two-dimensional (2D) computational model of a polymer electrolyte fuel cell (PEFC) with a platinum group metal-free (PGM-free) catalyst cathode that can significantly reduce PEFC costs by eliminating the need for expensive platinum catalysts. Due to their comparatively low volumetric activity, PGM-free cathodes are an order of magnitude thicker than their Pt-based counterpart. The resulting need for greater electrode thickness to achieve sufficient power density requires careful attention to the transport losses across the thicker cathodes. The presented model is used to correlate the composition and morphology of the cathode to PEFC performance. The model ismore » a complete cell, continuum model that includes an advanced agglomerate model for a microstructurally consistent representation of the cathode. A unique feature of the approach is the integration of morphology and transport parameter statistics extracted from nano-scale resolution X-ray computed tomography (nano-CT) imaging of PGM-free cathodes. The model was validated with experimental results of PGM-free cathodes with varying Nafion loading. Lastly, our key findings are a need for increased cathode hydrophobicity and increased ionomer conductivity through either reduced tortuosity or increased bulk conductivity. We further use the model to evaluate targets for the volumetric activity and active site density for future catalysts.« less

Mineralogy of the epithermal precious and base metal deposit Banská Hodruša at the Rozália Mine (Slovakia)

NASA Astrophysics Data System (ADS)

Kubač, Alexander; Chovan, Martin; Koděra, Peter; Kyle, J. Richard; Žitňan, Peter; Lexa, Jaroslav; Vojtko, Rastislav

2018-03-01

The Au-Ag-Pb-Zn-Cu epithermal deposit Banská Hodruša of intermediate-sulphidation type is located in the Middle Miocene Štiavnica stratovolcano on the inner side of the Carpathian arc in Slovakia. This deposit represents an unusual subhorizontal multi-stage vein system, related to processes of underground cauldron subsidence and exhumation of a subvolcanic granodiorite pluton. Veins are developed on a low-angle normal shear zone, possibly representing a detachment zone in andesitic wall rocks that formed during emplacement and exhumation of the granodiorite pluton. The deposit consists of two parts, separated by a thick sill of quartz-diorite porphyry. The eastern part is currently mined, and the western part has already been depleted. The Banská Hodruša mineralization was formed during four stages: (1) low-grade silicified breccia at subhorizontal structures at the base of the deposit; (2) stockwork of steep veins with rhodonite-rhodochrosite, quartz-sulphide-carbonate and quartz-gold assemblages; (3) thin quartz-gold veins with medium dip in tension cracks inside the shear zone and complementary detachment hosted quartz-base metals-gold veins; (4) Post-ore veins. Gold and electrum (920-730) occur as intergrowths with base metal sulphides or hosted in quartz and carbonates, accompanied by Au-Ag tellurides (hessite, petzite). Rare Te-polybasite and Cu-cervelleite result from re-equilibration of early Te-bearing minerals during cooling. Sulphide minerals include low Fe sphalerite ( 1.25 wt%), galena, chalcopyrite, and pyrite. The wall rock alteration is represented mostly by adularia, illite, chlorite, quartz, calcite and pyrite. Precipitation of gold, Au-Ag tellurides, Mn-bearing minerals and adularia resulted from boiling of fluids due to hydraulic fracturing, as well as opening of dilatational structures within the shear zone.

N-doped graphene layers encapsulated NiFe alloy nanoparticles derived from MOFs with superior electrochemical performance for oxygen evolution reaction

NASA Astrophysics Data System (ADS)

Feng, Yi; Yu, Xin-Yao; Paik, Ungyu

2016-09-01

Water splitting, an efficient approach for hydrogen production, is often hindered by unfavorable kinetics of oxygen evolution reaction (OER). In order to reduce the overpotential, noble metal oxides-based electrocatalysts like RuO2 and IrO2 are usually utilized. However, due to their scarcity, the development of cost-effective non-precious OER electrocatalysts with high efficiency and good stability is urgently required. Herein, we report a facile one-step annealing of metal-organic frameworks (MOFs) strategy to synthesize N-doped graphene layers encapsulated NiFe alloy nanoparticles (NiFe@C). Through tuning the nanoparticle size and calcination temperature, NiFe@C with an average size of around 16 nm obtained at 700 °C exhibits superior OER performance with an overpotential of only 281 mV at 10 mA cm-2 and high durability. The facile synthesis method and excellent electrochemical performance show great potential of NiFe@C in replacing the precious metal-based electrocatalysts in the OER.

Publications - IC 47 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

Surveys Comments: Your help is crucial in the compilation of future Alaska Minerals Reports. The quality ; Placer; Platinum; Precious Metals; Red Dog; Sand and Gravel; Silver; Skarn; Soil Chemistry; Stibnite

Silylation of C-H bonds in aromatic heterocycles by an Earth-abundant metal catalyst

NASA Astrophysics Data System (ADS)

Toutov, Anton A.; Liu, Wen-Bo; Betz, Kerry N.; Fedorov, Alexey; Stoltz, Brian M.; Grubbs, Robert H.

2015-02-01

Heteroaromatic compounds containing carbon-silicon (C-Si) bonds are of great interest in the fields of organic electronics and photonics, drug discovery, nuclear medicine and complex molecule synthesis, because these compounds have very useful physicochemical properties. Many of the methods now used to construct heteroaromatic C-Si bonds involve stoichiometric reactions between heteroaryl organometallic species and silicon electrophiles or direct, transition-metal-catalysed intermolecular carbon-hydrogen (C-H) silylation using rhodium or iridium complexes in the presence of excess hydrogen acceptors. Both approaches are useful, but their limitations include functional group incompatibility, narrow scope of application, high cost and low availability of the catalysts, and unproven scalability. For this reason, a new and general catalytic approach to heteroaromatic C-Si bond construction that avoids such limitations is highly desirable. Here we report an example of cross-dehydrogenative heteroaromatic C-H functionalization catalysed by an Earth-abundant alkali metal species. We found that readily available and inexpensive potassium tert-butoxide catalyses the direct silylation of aromatic heterocycles with hydrosilanes, furnishing heteroarylsilanes in a single step. The silylation proceeds under mild conditions, in the absence of hydrogen acceptors, ligands or additives, and is scalable to greater than 100 grams under optionally solvent-free conditions. Substrate classes that are difficult to activate with precious metal catalysts are silylated in good yield and with excellent regioselectivity. The derived heteroarylsilane products readily engage in versatile transformations enabling new synthetic strategies for heteroaromatic elaboration, and are useful in their own right in pharmaceutical and materials science applications.

Mineral resource potential map of the Bighorn Mountains Wilderness Study Area (CDCA-217), San Bernardino County, California

USGS Publications Warehouse

Matti, Jonathan C.; Cox, Brett F.; Rodriguez, Eduardo A.; Obi, Curtis M.; Powell, Robert E.; Hinkle, Margaret E.; Griscom, Andrew; Sabine, Charles; Cwick, Gary J.

1982-01-01

Geological, geochemical, and geophysical evidence, together with a review of historical mining and prospecting activities, suggests that most of the Bighorn Mountains Wilderness Study Area has low potential for the discovery of all types of mineral and energy resources-including precious and base metals, building stone and aggregate, fossil fuels, radioactive-mineral resources, and geothermal resources. Low-grade mineralization has been documented in one small area near Rattlesnake Canyon, and this area has low to moderate potential for future small-scale exploration and development of precious and base metals. Thorium and uranium enrichment have been documented in two small areas in the eastern part of the wilderness study area; these two areas have low to moderate potential for future small-scale exploration and development of radioactive-mineral resources.

40 CFR 421.263 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2014 CFR

2014-07-01

... Ammonia (as N) 599.900 263.700 (b) Raw material granulation. BAT Limitations for the Secondary Precious....051 Zinc 0.653 0.269 Combined metals 0.192 Palladium 0.064 Platinum 0.064 Ammonia (as N) 85.310 37.500... Combined metals 0.300 Ammonia (as N) 133.300 58.600 (d) Spent cyanide stripping solutions. BAT Limitations...

40 CFR 421.263 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2013 CFR

2013-07-01

... Ammonia (as N) 599.900 263.700 (b) Raw material granulation. BAT Limitations for the Secondary Precious....051 Zinc 0.653 0.269 Combined metals 0.192 Palladium 0.064 Platinum 0.064 Ammonia (as N) 85.310 37.500... Combined metals 0.300 Ammonia (as N) 133.300 58.600 (d) Spent cyanide stripping solutions. BAT Limitations...

40 CFR 421.263 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2012 CFR

2012-07-01

... Ammonia (as N) 599.900 263.700 (b) Raw material granulation. BAT Limitations for the Secondary Precious....051 Zinc 0.653 0.269 Combined metals 0.192 Palladium 0.064 Platinum 0.064 Ammonia (as N) 85.310 37.500... Combined metals 0.300 Ammonia (as N) 133.300 58.600 (d) Spent cyanide stripping solutions. BAT Limitations...

40 CFR 421.263 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2011 CFR

2011-07-01

... Ammonia (as N) 599.900 263.700 (b) Raw material granulation. BAT Limitations for the Secondary Precious....051 Zinc 0.653 0.269 Combined metals 0.192 Palladium 0.064 Platinum 0.064 Ammonia (as N) 85.310 37.500... Combined metals 0.300 Ammonia (as N) 133.300 58.600 (d) Spent cyanide stripping solutions. BAT Limitations...

Guanidine Soaps As Vehicles For Coating Ceramic Fibers

NASA Technical Reports Server (NTRS)

Philipp, Warren H.; Veitch, Lisa C.; Jaskowiak, Martha H.

1994-01-01

Soaps made from strong organic base guanidine and organic fatty acids serve as vehicles and binders for coating ceramic fibers, various smooth substrates, and other problematic surfaces with thin precious-metal or metal-oxide films. Films needed to serve as barriers to diffusion in fiber/matrix ceramic composite materials. Guanidine soaps entirely organic and burn off, leaving no residues.

16 CFR 23.18 - Definitions of various pearls.

Code of Federal Regulations, 2010 CFR

2010-01-01

... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.18 Definitions of various pearls. As used in these... material or materials that simulate in appearance a pearl or cultured pearl. (d) Seed pearl: A small pearl...

16 CFR 23.18 - Definitions of various pearls.

Code of Federal Regulations, 2011 CFR

2011-01-01

... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.18 Definitions of various pearls. As used in these... material or materials that simulate in appearance a pearl or cultured pearl. (d) Seed pearl: A small pearl...

Publications - IC 48 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

quality and completeness of the information in these annual reports is dependent on input from all members ; Placer; Platinum; Pogo; Precious Metals; Red Dog; Sand and Gravel; Silver; Skarn; Soil Chemistry

Electro-catalytic activity of multiwall carbon nanotube-metal (Pt or Pd) nanohybrid materials synthesized using microwave-induced reactions and their possible use in fuel cells.

PubMed

V, Lakshman Kumar; Ntim, Susana Addo; Sae-Khow, Ornthida; Janardhana, Chelli; Lakshminarayanan, V; Mitra, Somenath

2012-11-30

Microwave induced reactions for immobilizing platinum and palladium nanoparticles on multiwall carbon nanotubes are presented. The resulting hybrid materials were used as catalysts for direct methanol, ethanol and formic acid oxidation in acidic as well as alkaline media. The electrodes are formed by simply mixing the hybrids with graphite paste, thus using a relatively small quantity of the precious metal. We report Tafel slopes and apparent activation energies at different potentials and temperatures. Ethanol electro-oxidation with the palladium hybrid showed an activation energy of 7.64 kJmol(-1) which is lower than those observed for other systems. This system is economically attractive because Pd is significantly less expensive than Pt and ethanol is fast evolving as a commercial biofuel.

Electro-catalytic activity of multiwall carbon nanotube-metal (Pt or Pd) nanohybrid materials synthesized using microwave-induced reactions and their possible use in fuel cells

PubMed Central

V, Lakshman Kumar; Ntim, Susana Addo; Sae-Khow, Ornthida; Janardhana, Chelli; Lakshminarayanan, V.; Mitra, Somenath

2012-01-01

Microwave induced reactions for immobilizing platinum and palladium nanoparticles on multiwall carbon nanotubes are presented. The resulting hybrid materials were used as catalysts for direct methanol, ethanol and formic acid oxidation in acidic as well as alkaline media. The electrodes are formed by simply mixing the hybrids with graphite paste, thus using a relatively small quantity of the precious metal. We report Tafel slopes and apparent activation energies at different potentials and temperatures. Ethanol electro-oxidation with the palladium hybrid showed an activation energy of 7.64 kJmol−1 which is lower than those observed for other systems. This system is economically attractive because Pd is significantly less expensive than Pt and ethanol is fast evolving as a commercial biofuel. PMID:23118490

An advanced study on the hydrometallurgical processing of waste computer printed circuit boards to extract their valuable content of metals.

PubMed

Birloaga, Ionela; Coman, Vasile; Kopacek, Bernd; Vegliò, Francesco

2014-12-01

This study refers to two chemical leaching systems for the base and precious metals extraction from waste printed circuit boards (WPCBs); sulfuric acid with hydrogen peroxide have been used for the first group of metals, meantime thiourea with the ferric ion in sulfuric acid medium were employed for the second one. The cementation process with zinc, copper and iron metal powders was attempted for solutions purification. The effects of hydrogen peroxide volume in rapport with sulfuric acid concentration and temperature were evaluated for oxidative leaching process. 2M H2SO4 (98% w/v), 5% H2O2, 25 °C, 1/10 S/L ratio and 200 rpm were founded as optimal conditions for Cu extraction. Thiourea acid leaching process, performed on the solid filtrate obtained after three oxidative leaching steps, was carried out with 20 g/L of CS(NH2)2, 6g/L of Fe(3+), 0.5M H2SO4, The cross-leaching method was applied by reusing of thiourea liquid suspension and immersing 5 g/L of this reagent for each other experiment material of leaching. This procedure has lead to the doubling and, respectively, tripling, of gold and silver concentrations into solution. These results reveal a very efficient, promising and environmental friendly method for WPCBs processing. Copyright © 2014 Elsevier Ltd. All rights reserved.

75 FR 47655 - Self-Regulatory Organizations; NYSE Arca, Inc.; Notice of Filing of Proposed Rule Change To List...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-06

... generally occurs at the time of day when trading in the European time zones overlaps with trading in the... precious metals to sites maintained by major newspapers, such as The Wall Street Journal. In addition, the...

Efficient and selective heavy metal sequestration from water by using layered sulfide K 2x Sn 4-x S 8-x (x = 0.65–1; KTS-3)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarma, Debajit; Islam, Saiful M.; Subrahmanyam, K. S.

Heavy metal ions (Cd 2+, Hg 2+, As 3+ and Pb 2+) are an important contributor to the contamination of groundwater and other water bodies in and around industrial areas. Herein, we demonstrate the rapid and efficient capacity of a layered metal sulfide material, K2xSn4-xS8-x (x = 0.65-1, KTS-3) for heavy metal ion removal from water. The effect of concentration, pH, kinetics, and competitive ions such as Na +/Ca 2+ on the heavy metal ion removal capacity of KTS-3 was systematically investigated. X-ray photoelectron spectroscopy (XPS), elemental analyses, and powder X-ray diffraction studies revealed that the heavy metal ion-exchange ofmore » KTS-3 is complete (quantitative replacement of all potassium ions) and topotactic. The heavy metal ion-exchange by using KTS-3 follows the Langmuir-Freundlich model with high exchange capacities, q(m) 205(17) mg g -1 for Cd 2+, 372(21) mg g -1 for Hg 2+ and 391(89) mg g -1 for Pb 2+. KTS-3 retains excellent heavy metal ion-exchange capacity even in very high concentration (1 M) of competing ions (Na +/Ca 2+) and also over a broad pH range (2-12). KTS-3 also exhibits very good ion-exchange capacity for precious Ag + and toxic As 3+ ions. The kinetics of heavy metal ion adsorption by KTS-3 are rapid (absorbs all ions within a few minutes). These properties and the environmentally friendly character of KTS-3 make it a promising candidate for sequestration of heavy metal ions from water.« less

Characterization of Ultra High Temperature Ceramics via Transmission Electron Microscopy. Part 2: UHTCs sintered with addition of TaSi2

DTIC Science & Technology

2010-01-21

substituted by Hf in the TaSi2 phase, indicating that this silicide has a great solubility for the group IV metals . At the triple point junctions Ta5Si3...Mathis Müller for his precious help in TEM specimens’ preparations . FA8655-09-M-4002 40 References 1. L. E. Toth: Transition Metal Carbides and...Transition Metal Disilicides,’ Acta Mater., 44, 3035 (1996). 21. H. Pastor and R. Meyer: An Investigation of the Effect of Additions of Metal Silicides

Potential Applications of Biotechnology to Aerospace Materials.

DTIC Science & Technology

1986-11-01

sulfate:(1) ms + 202 a msO4 where m is a bivalent metal. In the indirect method of bioleach- ing, the metal sulfide is oxidized by ferric ion: ms + 2Fe...possibility exists of using bioleaching or biosorption for recovery of strategic and precious metals such as cobalt, nickel, zinc, arsenic, gallium ...workshop that could be of significant interest to the Materials Laboratory including acetylene compounds , adhesives, structural materials, lubricants, and

Petrologic, tectonic, and metallogenic evolution of the southern segment of the ancestral Cascades magmatic arc, California and Nevada

USGS Publications Warehouse

du Bray, Edward A.; John, David A.; Cousens, Brian L.

2013-01-01

Although rocks in the two arc segments have similar metal abundances, they are metallogenically distinct. Small porphyry copper deposits are characteristic of the northern segment whereas significant epithermal precious metal deposits are most commonly associated with the southern segment. These metallogenic differences are also fundamentally linked to the tectonic settings and crustal regimes within which these two arc segments evolved.

ETV TEST REPORT OF MOBILE SOURCE EMISSIONS CONTROL DEVICES: LUBRIZOL ENGINE CONTROL SYSTEMS PURIFILTER SC17L

EPA Science Inventory

The Environmental Technology Verification report discusses the technology and performance of the Lubrizol Engine Control Systems Purifilter SC17L manufactured by Lubrizol Engine Control Systems. The technology is a precious and base metal, passively regenerated particulate filter...

Development of a brazing process for the production of water- cooled bipolar plates made of chromium-coated metal foils for PEM fuel cells

NASA Astrophysics Data System (ADS)

Mueller, M.; Hoehlich, D.; Scharf, I.; Lampke, T.; Hollaender, U.; Maier, H. J.

2016-03-01

Beside lithium batteries, PEM fuel cells are the most promising strategy as a power source to achieve the targets for introducing and increasing the usage of electric vehicles. Due to limited space and weight problems, water cooled, metallic bipolar plates in a fuel cell metal stack are preferred in motor vehicles. These plates are stamped metal sheets with a complex structure, interconnected media-tight. To meet the multiple tasks and requirements in use, complex and expensive combinations of materials are currently in use (carbon fiber composites, graphite, gold-plated nickel, stainless and acid resistant steel). The production of such plates is expensive as it is connected with considerable effort or the usage of precious metals. As an alternative, metalloid nitrides (CrN, VN, W2N, etc.) show a high chemical resistance, hardness and a good conductivity. So this material category meets the basic requirements of a top layer. However, the standard methods for their production (PVD, CVD) are expensive and have a slow deposition rate and a lower layer thicknesses. Because of these limitations, a full functionality over the life cycle of a bipolar plate is not guaranteed. The contribution shows the development and quantification of an alternative production process for bipolar plates. The expectation is to get significant advantages from the combination of chromium electrodeposition and thermochemical treatment to form chromium nitrides. Both processes are well researched and suitable for series production. The thermochemical treatment of the chromium layer also enables a process-integrated brazing.

Comprehensive process for the recovery of value and critical materials from electronic waste

DOE PAGES

Diaz, Luis A.; Lister, Tedd E.; Parkman, Jacob A.; ...

2016-04-08

The development of technologies that contribute to the proper disposal and treatment of electronic waste is not just an environmental need, but an opportunity for the recovery and recycle of valuable metals and critical materials. Value elements in electronic waste include gold, palladium, silver, copper, nickel, and rare earth elements (RE). Here, we present the development of a process that enables efficient recycling of metals from scrap mobile electronics. An electro recycling (ER) process, based on the regeneration of Fe 3+ as a weak oxidizer, is studied for the selective recovery of base metals while leaving precious metals for separatemore » extraction at reduced chemical demand. A separate process recovers rare earth oxides from magnets in electronics. Furthermore, recovery and extraction efficiencies ca. 90 % were obtained for the extraction of base metals from the non-ferromagnetic fraction in the two different solution matrices tested (H 2SO 4, and HCl). The effect of the pre-extraction of base metals in the increase of precious metals extraction efficiency was verified. On the other hand, the extraction of rare earths from the ferromagnetic fraction, performed by means of anaerobic extraction in acid media, was assessed for the selective recovery of rare earths. We developed a comprehensive flow sheet to process electronic waste to value products.« less

Direct energy conversion using liquid metals

NASA Astrophysics Data System (ADS)

Onea, Alexandru; Diez de los Rios Ramos, Nerea; Hering, Wolfgang; Stieglitz, Robert; Moster, Peter

2014-12-01

Liquid metals have excellent properties to be used as heat transport fluids due to their high thermal conductivity and their wide applicable temperature range. The latter issue can be used to go beyond limitations of existing thermal solar energy systems. Furthermore, the direct energy converter Alkali Metal Thermo Electric Converter (AMTEC) can be used to make intangible areas of energy conversion suitable for a wide range of applications. One objective is to investigate AMTEC as a complementary cycle for the next generation of concentrating solar power (CSP) systems. The experimental research taking place in the Karlsruhe Institute of Technology (KIT) is focused on the construction of a flexible AMTEC test facility, development, test and improvement of liquid-anode and vapor-anode AMTEC devices as well as the coupling of the AMTEC cold side to the heat storage tank proposed for the CSP system. Within this project, the investigations foreseen will focus on the analyses of BASE-metal interface, electrode materials and deposition techniques, corrosion and erosion of materials brought in contact with high temperature sodium. This prototype demonstrator is planned to be integrated in the KArlsruhe SOdium LAboratory (KASOLA), a flexible closed mid-size sodium loop, completely in-house designed, presently under construction at the Institute for Neutron Physics and Reactor Technology (INR) within KIT.

Metal-saturated sulfide assemblages in NWA 2737: Evidence for impact-related sulfur devolatilization in Martian meteorites

NASA Astrophysics Data System (ADS)

Lorand, Jean-Pierre; Barrat, Jean-Alix; Chevrier, Vincent; Sautter, Violaine; Pont, Sylvain

2012-11-01