The Double Solid Reactant Method for modeling the release of trace elements from dissolving solid phases: I. Outline and limitations

2007 ◽  
Vol 55 (8) ◽  
pp. 1627-1635 ◽  
Author(s):  
Marina Accornero ◽  
Luigi Marini
Keyword(s):  
Trace Elements ◽  
Solid Reactant ◽  
Solid Phases ◽  
Double Solid Reactant Method

Coprecipitation of Sr, Ni and U with CaCO3: An Experimental Study

1995 ◽  
Vol 412 ◽  
Author(s):  
Torbjörn Carlsson ◽  
Hannu Aalto
Keyword(s):  
Experimental Study ◽  
Trace Elements ◽  
Nuclear Waste ◽  
Room Temperature ◽  
Nuclear Waste Repository ◽  
Experimental Conditions ◽  
Waste Repository ◽  
Solid Phases ◽  
Titration Vessel ◽  
Made In

AbstractAt the Finnish candidate sites for a nuclear waste repository, calcite (CaCO3) is a common fracture mineral that may participate in coprecipitation processes. The objective of this preliminary work was to study the coprecipitation of the trace elements Sr, Ni, and U with CaCO3 under controlled conditions. The experiments were made in a titration vessel at room temperature under pure N2 or a 0.1 % CO 2/N2 mixture. The water phase contained CaCl2 (0.01M) and NaCl (0.05 M) to which trace amounts of Ni2+, Sr2+ and UO22+ were initially added. CaCO3 was precipitated by the addition of Na2CO3 and the use of CaCO3 seed crystals. When about 10−4 mol of precipitate had formed, the solution and solid phases were analysed with ICPMS. The results seem to indicate that Ni coprecipitated with CaCO3 under the experimental conditions, while U did not. In the case of Sr, further data are needed in order to make any conclusions from the experiments.

scholarly journals The dehydration of crystals of chrome alum

1940 ◽  
Vol 174 (959) ◽  
pp. 487-503 ◽  
Keyword(s):  
Water Vapour ◽  
Copper Sulphate ◽  
Open Space ◽  
Solid Phase ◽  
Lattice Structure ◽  
Solid Product ◽  
Salt Hydrate ◽  
Solid Reactant ◽  
Degree Of Crystallization ◽  
Solid Phases

The loss of water from a salt hydrate can occur with or without changes in the lattice structure. Thus, the water of crystallization of zeolites can be removed without the collapse of the original lattice; whereas in many other hydrates, such as the alums or copper sulphate pentahydrate, the removal of water is associated with changes in the structure of the solid and the production of a new solid phase. In the latter an interface is formed separating the two solid phases, and it is at this interface that the dehydration occurs. The water liberated at the interface passes through a superposed layer of product before it reaches open space. The rate of liberation of water may be dependent on the thickness of the superposed layer of product, as is seen in the case of the dehydration in vacuum of copper sulphate pentahydrate (Garner and Tanner 1930; Smith and Topley 1931). This effect was called “impedance” by Smith and Topley, and they showed that the “impedance” practically vanishes if the dehydration is studied in water-vapour pressures lower than the dis­sociation pressure of the salt hydrate. Since water vapour accelerates the rate of crystallization of the product (Colvin and Hume 1938) it is clear that it is the degree of crystallization of the product that determines whether impedance will occur or not. The two processes, (1) the loss of water from the interface and (2) the subsequent reorganization of the lattice, do not appear to be very closely linked, since the solid product in many examples undergoes considerable shrinkage subsequent to the loss of water (see plate 18 A, for chrome alum). The following model of the dehydration process serves to indicate the possibilities. I represents the solid reactant, and II is a transition layer derived from I by the loss of water either without lattice change or by a collapse of the original lattice. Ill is the product undergoing slow crystallization, and IV is the open space which may be a hard vacuum or may contain water vapour.

Microanalytical Identification of a New Zr-Nb-Fe Phase

1990 ◽  
Vol 48 (2) ◽  
pp. 132-133
Author(s):  
O.T. Woo ◽  
G.J.C. Carpenter
Keyword(s):  
Trace Elements ◽  
Cold Rolling ◽  
Proportionality Factor ◽  
Tube Material ◽  
X Ray ◽  
Metal Foils ◽  
Arc Melting ◽  
Intermetallic Particles ◽  
Intermetallic Precipitates ◽  
Cold Worked

To study the influence of trace elements on the corrosion and hydrogen ingress in Zr-2.5 Nb pressure tube material, buttons of this alloy containing up to 0.83 at% Fe were made by arc-melting. The buttons were then annealed at 973 K for three days, furnace cooled, followed by ≈80% cold-rolling. The microstructure of cold-worked Zr-2.5 at% Nb-0.83 at% Fe (Fig. 1) contained both β-Zr and intermetallic precipitates in the α-Zr grains. The particles were 0.1 to 0.7 μm in size, with shapes ranging from spherical to ellipsoidal and often contained faults. β-Zr appeared either roughly spherical or as irregular elongated patches, often extending to several micrometres.The composition of the intermetallic particles seen in Fig. 1 was determined using Van Cappellen’s extrapolation technique for energy dispersive X-ray analysis of thin metal foils. The method was employed to avoid corrections for absorption and fluorescence via the Cliff-Lorimer equation: CA/CB = kAB · IA/IB, where CA and CB are the concentrations by weight of the elements A and B, and IA and IB are the X-ray intensities; kAB is a proportionality factor.

XRMF applications of a monolithic, polycapillary, focusing x-ray optic

1996 ◽  
Vol 54 ◽  
pp. 240-241
Author(s):  
D. A. Carpenter ◽  
Ning Gao ◽  
G. J. Havrilla
Keyword(s):  
Trace Elements ◽  
Point Source ◽  
Focal Spot ◽  
Fluorescence Analysis ◽  
X Rays ◽  
Focal Distance ◽  
Spot Diameter ◽  
X Ray ◽  
Focal Spot Diameter

A monolithic, polycapillary, x-ray optic was adapted to a laboratory-based x-ray microprobe to evaluate the potential of the optic for x-ray micro fluorescence analysis. The polycapillary was capable of collecting x-rays over a 6 degree angle from a point source and focusing them to a spot approximately 40 µm diameter. The high intensities expected from this capillary should be useful for determining and mapping minor to trace elements in materials. Fig. 1 shows a sketch of the capillary with important dimensions.The microprobe had previously been used with straight and with tapered monocapillaries. Alignment of the monocapillaries with the focal spot was accomplished by electromagnetically scanning the focal spot over the beveled anode. With the polycapillary it was also necessary to manually adjust the distance between the focal spot and the polycapillary.The focal distance and focal spot diameter of the polycapillary were determined from a series of edge scans.

Trace Elements and Iron in Human Metabolism

1979 ◽  
Vol 7 (6) ◽  
pp. 1330-1331
Author(s):  
E. D. WILLS
Keyword(s):  
Trace Elements ◽  
Human Metabolism

Meat and Meat Products Consumption in Italy: Contribution to Trace Elements, Heme Iron and selected B Vitamins supply

2004 ◽  
Vol 74 (4) ◽  
pp. 247-251 ◽  
Author(s):  
Lombardi-Boccia ◽  
Lanzi ◽  
Lucarini ◽  
Di Lullo
Keyword(s):  
Trace Elements ◽  
Daily Intake ◽  
Meat Products ◽  
Heme Iron ◽  
B Vitamins ◽  
Zinc Intake ◽  
Consumption Frequency ◽  
Iron And Zinc ◽  
Iron Heme ◽  
Daily Intakes

This study was undertaken to estimate the contribution of meat and meat products consumption to the daily intakes of trace elements (Fe, Zn, Cu, Se), heme iron, and selected B vitamins (thiamine, riboflavin, niacin) in Italy. Meat and meat products were selected on the basis of their consumption frequency reported by the most recent nationwide dietary individual survey carried out in Italy (INN-CA study). The daily intakes of total iron and heme iron were 1.65 and 1.13 mg/person/day. Zinc intake was 3.65 mg/person/day. Beef made the main contribution to iron, heme iron, and zinc daily intakes. Copper daily intake was 107.3 mug/person/day, with meat products provided the highest contribution (40 mug/person/day). Daily intake of selenium (7.14 mug/person/day) was provided mainly by poultry consumption. Thiamine intake was 228 mug/person/day, and meat products were the main source (110 mug/person/day). Riboflavin intake was 136 mug/person/day, with both beef and meat products as the main contributors (40 mug/person/day). Niacin intake was 7.53 mg/person/day, and poultry was the main source (2.28 mg/person/day). Meat and meat products were a valuable source of micronutrients, supplying 47, 48, and 24% of zinc, niacin, and thiamin daily requirements, respectively, and over 10% of iron, copper, selenium, and riboflavin daily average requirement values of the italian RDAs calculated for the population involved in the survey (INN-CA study).

Pre-concentration of selected trace elements from seawater by co-precipitation on Mg(OH)2

2003 ◽  
Vol 107 ◽  
pp. 945-948 ◽  
Author(s):  
P. M. Nicolaysen ◽  
E. Steinnes ◽  
T. E. Sjobakk
Keyword(s):  
Trace Elements ◽  
Co Precipitation
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