Alkaline Earth Content Research Articles

Kinetics of trace metal complexation: role of alkaline-earth metals

The rate of reaction of inorganic copper with the model ligand ethylenediaminetetraacetic acid (EDTA) is significantly retarded in the presence of calcium at seawater concentrations. The half-life for inorganic copper reacting with EDTA in seawater is /similar to/2 h at 10/sup /minus/7/M EDTA. This kinetic hindrance to the formation of the thermodynamically favored CuEDTA species results from several factors: (1) the preponderance of the calcium complex in the speciation of EDTA, (2) the competition of calcium and copper for reaction with any free EDTA formed by the dissociation of CaEDTA, and (3) the slow kinetics of direct attack of copper on CaEDTA compared to reaction with free or protonated EDTA species. If metal-complexing agents in natural waters behave as discrete ligands, then the reaction of a metal at strong binding sites may also be kinetically hindered at high alkaline-earth concentrations. In contrast with the reaction of EDTA, however, the rate of completion of copper by humic acid is not observably affected by high calcium concentrations.

Refining of steel melts using alkaline earth metals

In secondary refining of steel melts, the use of alkaline earth metals as a slag phase can be of great significance to remove tramp elements of the main groups IV and V. Fundamental data on corresponding refining equilibria and on the solubilities of the alkaline earth metals Mg, Ca, Sr and Ba in iron and iron alloys have been determined by equilibrating the two metal phases, contained in CaO crucibles, under excess argon pressure at 1600°C. The experimental results indicate that tramp elements such as Sn, N, and P are largely transferred from the iron to the alkaline earth metal phase using Ca, Sr or Ba. Equilibrium alkaline earth metal contents are found to be 0.03 % Ca, 0.004 % Sr and 0.0005 % Ba. Solubilities of Ca, Sr and Ba in iron are increased in the presence of Ni and decreased by additions of Cr.In the potential industrial application, reducing conditions must be provided and excessive vaporization must be avoided by adequate techniques of addition of the alkaline earth metals.

Optical Absorption Spectra of Ni<sup>2+</sup> Ions and IR Spectra in (100-<i>x</i>) (PbO⋅GeO<sub>2</sub>)⋅<i>x</i>RO (R=Mg, Ca, Sr, Ba) Glasses

Optical absorption spectra of Ni2+ ion (100-x) (PbO⋅GeO2)⋅xRO⋅0.2wt% NiO glasses are measured, and the results are obtained as follows.The value of 10Dq which represents the intensity of the ligand field shifts toward higher wave number with increasing alkaline earth metal content. The increasing intensity of the ligand field is considered to be the formation of GeO68-, where the glass network was destroyed by alkaline earth metals. In this study, the ν4 peak appears only at 20mol% BaO, which represents a Ni2+ ion with 4-coordination. In other systems the ν4 peak does not appear clearly. It is considered that the Ni2+ ion does not become 4-coordination.According to the measurements of infrared spectra, most of this system consists of Ge6 groups, and the variation of coordination number of Ge with the alkaline earth metal contents hardly appear.

Crystallization behavior of coal gasification ash

Large-scale commercialization of coal gasification would result in large volumes of ash or slag requiring disposal. Burial of ash or slag raises environmental concerns because of the possible leachability of harmful trace elements into groundwater. In this study, Hygas ash was melted as a means of reducing the volume for disposal. The crystallization behavior of melted ash (slag) and other slags modified to lower the melting temperatures was determined. The principal constituents of Hygas ash were Al 2O 3, SiO 2, and Fe 2 O, with low alkali and alkaline earth content and small concentrations of other elements. This material melted at 1400 °C and recrystallized by rejection of iron oxides from a silicate glass. Increasing the Na 2O content to 37 wt% resulted in a totally glassy structure and a lowering of the melting temperature to about 850 °C. Limited leaching tests indicated that the leachability of melted Hygas ash and modified slags increased substantially with increasing Na 2O content.

The influence of the size and concentration of alkaline earth ions on the structural and sorption properties of faujasites

The structural and sorption properties of type X and Y zeolites, ion-exchanged with Mg 2+, Ca 2+, Sr 2+, and Ba 2+ ions have been studied by X rays, IR, and adsorption. The nitrogen sorption in the zeolites was found to decrease with increased alkaline earth content in both X and Y zeolites and followed a general sequence Na + > Mg 2+ > Ca 2+ > Sr 2+ > Ba 2+. A similar trend was shown for the sorption of water, ethanol, and benzene vapors. Equilibrium sorption capacity and diffusion coefficient decreases with increase in cation radius. The sorption behavior of 1:3:5 trimethylbenzene (TMB) was specific: in X-type zeolites the substitution of Ca 2+ or Ba 2+ ions revealed a sharp fall in the sorption of 1:3:5 TMB, which is attributed to a blocking effect caused by Ca 2+ or Ba 2+ cations in the windows (SI site) large cavities.

Taxonomic character of plant species in absorbing and accumulating alkali and alkaline earth metals grown in temperate forest of Japan

Absorption and accumulation of alkali (Li, Na, K, Rb, Cs) and alkaline earth (Mg, Ca, Sr, Ba) metals were investigated as taxonomic characteristics (in 62 plant species). Leaf and soil samples were collected from 9 sites in temperature forest in Japan and the above mentioned elements were analyzed. Considerable differences were found among species in their ability to accumulate alkali and alkaline earth metals. Very high concentrations of Li (45 ppm, D.W.), K (37×103 ppm), Rb (159 ppm) and Cs (8.2 ppm) were detected inLastrea japonica which were about 412, 12, 27 and 6 times higher than those of the species with the lowest concentrations. Na content was high inAcer micranthum (358 ppm) which was 16 times higher than species with the lowest concentration. Other species containing high levels of alkali metals wereHydrangea macrophylla, Struthiopteris niponica, Clethra barbinervis. Mean discrimination ratio (D.R.) for all investigated plant species for Li, Na, Rb, and Cs to K were 1.7, 0.44, 0.9 and 1.8 respectively. High concentrations of alkaline earth metals Ca (36×103 ppm), Sr (345 ppm), and Ba (241 ppm) were found in the leaves ofHydrangea paniculata which were about 31, 84, and 72 times higher than those for the species with the lowest concentration. Mg was very high inStruthiopteris niponica (83×102 ppm). Other species with high concentrations of alkaline earth metals belonged to the genus Viburnum. Mean D.Rs. for Mg, Sr, and Bavs Ca were 1.0, 0.7 and 0.08. Principal component analysis of interrelationships between the mineral content in leaf tissues indicated that these elements could be classified into 2 groups with respect to their accumulation behavior in plants. The alkali metals K, Li, Rb, and Cs behaved similarly in their accumulation in leaves but Na behaved independently. Alkaline earth metals Ca, Mg, Sr, and Ba were also found to behave similarly in their accumulation. Factors scores of 1st and 2nd components revealed three groups of plant species: alkaliphilic, alkaline earthphilic, and neutral (non-accumulators).

Catalytic properties of modified silica gels in oxidative dehydrogenation of ethylbenzene

According to [i], oxides of silicon and alkaline earth metals exhibit low activity in oxidative dehydrogenation of alkylaromatic hydrocarbons. We observed that the activity of catalysts in oxidative dehydrogenation of ethylbenzene increased sharply when small amounts of calcium or strontium oxides were introduced into the composition of macroporous silica gel. A similar effect was also observed when silica gel was modified with magnesium, but in this case the maximum yield of styrene was attained at higher concentrations of magnesium oxide. The obtained results are shown in Fig. I, from which it is evident that the yield of styrene passed through a maximum, depending on the concentration of alkaline-earth metals. With decreasing ionic radius of the cations, the maximums became broader and shifted toward higher concentrations. The decrease of the catalysts' activity when large amounts of the oxides were introduced was probably due to the formation of highly basic centers, which drove the reaction toward exhaustive oxidation and thus lowered the selectivity of the reaction with respect to styrene.

The retention of 226Ra in human soft tissue and bone; implications for the ICRP 20 alkaline earth model.

We have adjusted the ICRP model of alkaline earth metabolism to fit data on the 226Ra content of 87 samples of soft tissue from 17 persons who received radium by injection or ingestion 5 days to 53 yr before measurement. The fitted functions indicate that soft tissue retention rises to 58% of the whole body retention at 18 days after single intake, and then falls steadily reaching 33% at 100 days and 6% at 1000 days. The adjusted model was also found to fit data on bone retention in 5 persons 8–467 days after injection. For both types of tissue, the new functions differ substantially from those originally published. The adjustments improve or do not significantly reduce the model's ability to fit other radium data. The fits to soft tissue and bone data were achieved by changing the quantity B in the ICRP model from its original value for radium {0.06236 (1-RBODY)}−2.410 to {0.1247(1-RBODY)}−2.410 where RBODY is the whole body retention function. This forced new values for five model parameters for radium: beta = 0.6254, omega = 1.436, fC = 5.629, v = 1.521, r = 0.9953. Also changed are the empirical values for the percentages of the body's natural alkaline earth contents which lie in soft tissue: Ca(0.28%), Sr(0.98%), Ba(4.7%), 226Ra(5.5%). For use in dosimetry, effective retention integrals are given for 224,226,228Ra and for 228Th in soft tissue, on bone surfaces, in bone volume, and in the whole body. Integration times of 1 yr, 50 yr and infinity are used. For 226,228Ra, the soft tissue integrals are reduced by factors of 1.5–2.5 below the values originally published; for 224Ra, the reduction factor is about 1.1. The bone volume integrals increase for all isotopes; the percentage increase, about 100%, is greatest for 224Ra. A reanalysis of the autoradiographic data on 226Ra in bone has been carried out using the adjusted functions. The best fit results with dC = 1.5 rather than with the previous value, 10, indicating that the so-called modified version of the ICRP model may be unnecessary. An examination was made of the ability of the ICRP model to predict the outcomes of experiments to which the model functions had not been previously fitted. Results were positive.

Chemical processes affecting alkalis and alkaline earths during continental weathering

The alkali and alkaline earth concentrations in the Toorongo Granodiorite weathering profile are controlled by two competing processes; leaching of cations from primary minerals during their degradation to clays; fixation, by exchange and adsorption, of the same cations onto the secondary clay minerals. Degradation and leaching dominate the early weathering stages whereas during the advanced stages, exchange and adsorption onto clays are of most influence. The alkali and alkaline earth compositional changes in the Toorongo Granodiorite weathering profile are typical of changes occurring during weathering of the continents, consequently the following generalizations apply to continental weathering. Ca, Sr and Na are most rapidly and most strongly removed (as dissolved species) during weathering of fresh continental rocks. Although large quantities of Mg are transported to the marine environment as dissolved species, appreciable amounts remain (fixed in secondary clay minerals) at the weathering site to be removed during mass wasting of continental weathering profiles. Large quantities of Rb, Cs and Ba, fixed in continental weathering profiles by exchange and adsorption onto secondary clays, are transported from the continents only during mass wasting of the continents.

Volcanic Arc Magmas: Implications of a Melting-Mixing Model for Element Recycling in the Crust-Upper Mantle System

A multicomponent melting-mixing model for the origin of volcanic arc basalt magmas implies signifi cant recycling of K, Rb, Ba, and other elements in the crust-upper mantel system. The model accounts for chemical differences in alkali, alkaline earth, and rare earth content between arc basalts and a wide range of oceanic and intraplate basalt types. In essence, the differences are due to modification of mantle peridotite by recycled continental components (derived from sediment and sea water) at convergent plate margins. In a specific model tested by mass balance calculations, residual periodotite (partly depleted in a basalt fraction) in a subducted lithospheric plate thermally equilibrates with the surrounding hotter mantle at depth beneath island arcs, and being less dense, rises as kilometer size diapires. The diapirs are modified by addition of small proportions of melt or saline supercritical fluid from the denser oceanic basalt (eclogite) and sediment. The diapire serves as a source for arc basalts...

Alkali and alkaline earth metal chemistry of marine aerosols generated in the laboratory with natural sea waters

Atmospheric sea salt particles, produced in the laboratory by bubbles bursting at the surface of natural seawater solutions, were examined for their alkali and alkaline earth metal content in several particle size categories. No enrichments of K, Ca and Mg relative to the seawater source were found in these atmospheric particles using 1. (1) Sargasso seawater or Narragansett Bay seawater. 2. (2) filtered seawater or unaltered seawater. 3. (3) two different bubble path lengths. Only with the addition of natural surfactants was any enrichment over the seawater ratio found in these aerosols. In this case, K and Mg may have been enriched on the smallest particles. Calculations, indicate that the organic carbon content of aerosols produced from even highly productive natural seawaters cannot account for apparent enrichments of K observed in the environment. These experiments suggest that enrichment of alkali and alkaline earth metals in sea salt particles produced from most natural seawaters is environmentally insignificant.

Sintered cathode materials for electric vacuum devices

1. A number of Pt, Pd, Ru, Rh, Os, Ir, Ag, W, Mo, Ni, Ni+30% Re, Re, and Re+30% Ni base powder metallurgy alloys containing a beryllate active phase have been developed. Such alloys exhibit, under intense electron bombardment conditions, high and stable coefficients of secondary electron emission and low, controllable levels of thermionic emission. 2. Effective high-temperature thermionic emitters based on tungsten and rhenium with additions of yttrium and gadolinium tetraborides have been formulated. These are distinguished from W+Y2O3 type emitters by simplicity of aging, absence of sparking and breakdowns, and stability of operation. 3. Using the powder metallurgy technique, thin-walled cylindrical tungsten-tantalum alloy cathodes were produced characterized by satisfactory shape stability and long useful life at high temperatures (1700–1900°C) 4. The use of powder metallurgy billets produced from powders containing intermetallic compounds of platinum and palladium with barium reduces by two-thirds labor in the manufacture of platinum-barium and palladium-barium alloy strip. The method lends itself to the manufacture of strip in nickel alloys of increased alkaline-earth metal content.

Chemical characteristics and origin of oceanic ridge volcanic rocks1

Oceanic ridge volcanic rocks alkali metal, alkaline earth, rare earth, nickel and major element content, observing partial melting

Optical and ESR Spectra of Nickel-Containing Alkaline Earth Borate Glasses

The optical and paramagnetic resonance spectra have been obtained for divalent nickel ions in BaO⋅(5.1-1.5)B2O3, SrO⋅(3-1.5)B2O3 and CaO⋅(3-1.5)B2O3 glasses. The coordination about the nickel ion sites is found to be octahedral in all the glasses. Absorption bands due to tetrahedrally coordinated nickel ions are not observed. The crystal field splitting parameter 10 Dq decreases with the amount of alkaline earth contents in these three series of glasses, and also decreases in the sequence of CaO, SrO and BaO containing glasses if these alkaline earth contents are the same in each series of glasses. The value of the Racah parameter B and the spin-orbit coupling coefficient are both less than those values for free nickel ion. This fact is accounted for by introducing weak covalent Ni-O bonds. The covalency is found to become predominant in the order of BaO, SrO and CaO containing glasses.

Further data on the preparation of extremely pure sodium chloride crystals

AbstractThe following methods for purification of sodium chloride were compared in relation to their effectiveness: ion exchange, extraction, crystallization from solution, precipitation and distillation. For the purification of sodium chloride the ion exchange followed by a crystallization from solution in a teflon vessel appeared to be the most effective method giving a sodium chloride with an alkaline earth content about 1 × 10−7mole/mole.

The Hydrothermal Growth of Rare Earth Orthoferrites

Rare earth and yttrium orthoferrites, RFeO3, where R is Y, Yb, Ho, and Tb, have grown under hydrothermal conditions from 20 ml KOH and NaOH solutions at 375°C, ∼8000 psi, and Δt=30° in the 〈110〉 and 〈001〉 directions at rates as great as 6 mil/day. Ease of growth appears to be inversely related to the ionic radius of R3+. TbFeO3 has been deposited on TbAlO3 seeds under similar conditions. The grown orthoferrite has excellent optical properties (much less OH than Y3Fe5O12 grown under similar conditions) and is of good perfection as indicated by Schulz pictures and optical scattering measurements. The proton concentration correlates with the alkali and alkaline earth concentration in the grown crystal and is lower than in garnet because the distribution constants for alkalies and alkaline earths are lower in the orthoferrite lattice. Hydrothermal growth appears to be an advantageous technique for the growth of large orthoferrite crystals for magnetic studies and applications.

The constitution of davidite [discussion

Reply to a paper by J.D. Hayton (GeoScience Abstracts 2-3024). In addition to showing a peculiar and diagnostic lanthanon distribution, davidites are chemically characterized by 1) a relatively high Sr/Ca ratio combined with a low alkaline earth content, 2) a relatively high U/Th ratio combined with a low ThO 2 content.

Untersuchungen über den Einfluß von Keimung und Wachstum der Kartoffel sowie der mineralischen Düngung auf die Eigenschaften von Fruchtsaft und Stärke

ZusammenfassungDas Wachstum der Kartoffel sowie Eigenschaften, Erdalkali‐ und Phosphorsäuregehalt von Kartoffelfruchtsaft und Stärken, wie auch ihre Viskositäten, werden in vier verschiedenen Rodungen in Abhängigkeit von der Jahreszeit und von der Phosphorsäuredüngung, schließlich auch von der Lagerung und Keimung der Kartoffel untersucht. Lagerung und Keimung bewirken Verminderung des Erdalkaligehaltes (Ca und Mg) im Fruchtsaft und Erhöhung des Erdalkaligehaltes in den Stärken, deren Viskosität absinkt; der Phosphorsäuregehalt in Fruchtsaft und Stärke bleibt jedoch konstant (Tabelle 1). Die Phosphorsäuredüngung beschleunigt das Wachstum und erhöht den Ernteertrag der Kartoffel, jedoch nicht ihren Stärkegehalt; der Stärkeertrag wird nur infolge des höheren Ernteertrages an Kartoffeln in entsprechendem Verhältnis um etwa 25% größer (Tabelle 2). Im Gegensatz zur Lagerung und Keimung führt das Wachstum der Kartoffel zu einer Steigerung des Erdalkaligehaltes im Fruchtsaft; es besteht jedoch keine Abhängigkeit von der Phosphorsäuredüngung (Tabelle 3). Das Wachstum der Kartoffelknolle wirkt sich auf die zellreinen und die Nativstärken verschieden aus. Der Erdalkaligehalt der zellreinen Stärke steigt mit dem Wachstum der Kartoffel zunächst an und bleibt dann konstant. Nativ‐Stärken lassen jedoch keine Einflüsse des Wachstums erkennen; bei ihnen besteht auch keine Abhängigkeit des Erdalkaligehaltes von der Phosphorsäuredüngung, während die zellreinen Stärken deutlich geringeren Erdalkaligehalt zeigen. Der Phosphorsäuregehalt beider Stärken ist zwar etwas vom Wachstum, jedoch nicht von der Phosphorsäuredüngung abhängig (Tabelle 4). Die Viskositäten aller Stärken steigen mit dem Wachstum der Kartoffel schnell an und erreichen bei normaler Erntezeit Höchstwerte, die bei Überlagerung der Kartoffel im Boden sehr stark abfallen. Die Phosphorsäuredüngung erhöht unabhängig von der Jahreszeit die Viskosität der zellreinen wie die der Nativ‐Stärken, aber in allen Fällen wird, gleichfalls unabhängig von der Erntezeit das Viskositätsmaximum der zellreinen Stärken früher als das der Nativ‐Stärken erreicht (Abb. 1‐3). Die Viskositätsunterschiede zwischen zellreinen und Nativ‐Stärken, sowie der höhere Phosphorsäuregehalt der Nativ‐Stärken deuten auf Veränderung der Stärken durch fermentative Prozesse des Zellsaftes, die niedrigere Viskosität auf Abbaureaktion, der höhere Phosphorsäuregehalt auf Phosphorylierung der Stärken durch den Kartoffelfruchtsaft.

Chemical Studies on Actin

The content of alkaline earth metals in actin during aging of meats was determined. The content in actin was found to be maximum immediately after slaughter and minimum at two days of aging. The rate of calcium to alkaline earth metals except calcium was high immediately after slaughter, but became low during aging.As the content of alkaline earth metals in actin extracted from the acetone dried actomyosin has been found to be less than that from the same muscle, the result obtained appears to show that in meats actin exists in both, free and bound form, the latter being one constituent of actomyosin, and at the process of aging in which minimum content of alkaline earth metals in actin was observed, actin was more in the form of actomyosin than at other process.

Color Centers in Alkali-Silicate Glasses Containing Alkaline Earth Ions

Samples of alkali metal oxide-silica glasses with various kinds and amounts of alkaline earth oxide calcium oxide and silica were prepared, x-irradiated, and studied by spectrophotometry. Bleaching experiments with visible light were carried out. No effect of alkaline earth content upon the absorption spectra was detected.Room temperature bleaching of a ${\mathrm{K}}_{2}$O-SrO-Si${\mathrm{O}}_{2}$ glass with light of wavelength corresponding to the x-ray induced absorption band at 1.95 ev, decreased absorption generally but failed to create a new absorption band such as the ${Z}_{1}$ band found in KCl, containing Sr${\mathrm{Cl}}_{2}$, that has been irradiated and then bleached.Comparisons are made with alkali-halide systems containing alkaline earth halides. It is suggested that there are inadequacies in the quasi-crystalline model of glass when applied to these glasses.