Total Oxide Content Research Articles

Calculated relationships between activity of alumina and phase assemblages of silica-saturated igneous rocks: Petrogenetic implications of magmatic cordierite, garnet and aluminosilicate

Many peraluminous igneous rocks are characterized by the presence of Al-rich minerals such as cordierite, garnet and aluminosilicate polymorphs. Clearly, one of the important thermodynamic intensive variables controlling the stability of these minerals, relative to Al-poor phases such as ortho- and clinopyroxene, must be the activity of Al 2O 3 ( a Al 2O 3 ) in the melt. Calculated phase relationships of anhydrous mineral assemblages in equilibrium with quartz-saturated liquids show that, at crustal pressures (less than about 10 kbar), garnet, cordierite, and aluminosilicate are only likely to crystallize from melts in which a Al 2O 3 is up to one order of magnitude higher than that required for orthopyroxene+clinopyroxene crystallization. In spite of this, peraluminous granitoid liquids saturated with orthopyroxene+garnet or orthopyroxene+cordierite do not ordinarily contain significantly larger amounts of excess Al (= Al in excess of that required to form feldspars) than peraluminous liquids saturated with orthopyroxene+clinopyroxene. These observations indicate that there must be profound compositional controls on the activity coefficient of Al in silicic melts, and the strongest of such controls appears to be the total alkali content of the melt. The activity coefficient of Al in silicic melts varies directly with total alkali oxide content, so that alkali-poor melts can become markedly peraluminous without ever becoming saturated in aluminous phases, whereas alkali-rich melts of similar normative corundum content can crystallize garnet, cordierite or even aluminosilicate. Because activity of alumina in a silicic melt is not a simple function of excess Al content, classification schemes for silicic igneous rocks based on model mineralogical assemblages, which reflect the value of the thermodynamic effective concentration of Al during crystallization, convey more petrologic information than those based on chemical parameters such as normative corundum content or alumina saturation index.

Control and effects of Cu(I) and Cu(II) ions in BiCaSrCuO glasses

The influence of glass preparation on the Cu(I)/Cu total ratio in BiCaSrCuO glasses has been investigated. It was found that copper ions in the glasses exist mainly in the Cu(I) ionic state. Additionally, the Cu(I)/Cu total ratio increases with the glass melting temperature and changes slightly with copper oxide content. The number of glass network units, [BiO 3] pyramids, decreases in the BiCaSrCuO glasses when the Cu(I)/Cu total ratio and copper oxide content increase. As a consequence of these changes the glass transition temperature, T g, and the glass crystallization temperature, T x, decrease and the glass becomes thermally unstable: the value of ( T x − T g) of the glass decreases. The initial crystalline phase from these glasses in the Bi 2Sr 2CuO y phase. The glasses with the lower Cu(I)/Cu total ratio from larger crystalline.

Relationships between aggregation and iron oxides in Terra Rossa soils from southern Italy

Summary Thirteen samples from six Terra Rossa profiles of southern Italy were studied to determine the influence of Fe oxides in aggregation. Removal of all the Fe oxides by the citrate-bicarbonate-dithionite treatment resulted, in all samples, in a decrease in the proportion of the silt plus sand fraction and an increase in the clay fraction. The change in the particle size distribution (PSD) was highly correlated with the total Fe oxide content and with the hematite content but not so well correlated with the goethite content. When the samples were treated with acid NH4-oxalate to remove the poorly crystalline Fe oxides, there was a decrease in the proportion of the sand fraction and, in general, an increase in the proportion of silt and little or no increase in the proportion of clay; the change in PSD was better correlated with the ratio oxalate-extractable Si/oxalate-extractable Fe than with any other single property. This indicates that silica may contribute to aggregation, probably by forming bridges between Fe oxides and other soil particles.

Solution properties of rare earth elements in silicate melts: Inferences from immiscible liquids

The partitioning behavior of rare earth elements (REE) between immiscible silicate liquids was investigated as a function of temperature and total REE oxide concentration. REE preferentially partition into the end-member liquids that are rich in network-modifying cations, with two-liquid partition coefficients greater than any other cation. The two-liquid partition coefficients of REE in a given experiment are essentially identical to one another. No evidence was seen to suggest that the solution mechanisms of REE in high-silica liquids vary with differences in their ionic radii. “Two-lattice” models of trace element solution behavior fail to remove the compositional dependence of REE two-liquid partition coefficients due to the assumption that all network-forming and network-modifying cations mix ideally with one another. As a result, it is probably incorrect to derive physical interpretations from the results of the application of two-lattice models. The results are applied to the origins of the LREE-enriched phenocryst-matrix partition coefficients seen for some ferromagnesian minerals in high-silica rhyolites. Since liquids with extremely high concentrations of T-O-T linkages do not strongly discriminate between the REE on the basis of their ionic radii, the anomalous REE crystal-matrix partition coefficient patterns are best explained as the result of contamination of these minerals by LREE accessory phases.

The mixed alkali effect in lithium-sodium aluminosilicate glasses

The electrical conductivity of several series of lithium-sodium aluminosilicate glasses has been measured. The results indicate that the mixed alkali effect increases in magnitude with increasing alumina concentration, even though the total alkali oxide content of all glasses considered is identical. These results further indicate that the non-bridging oxygen content of the glass has no significant role in the mechanism responsible for the mixed alkali effect. Results of this study are discussed in terms of current theories proposed to explain this anomalous behavior.

Some metallurgical aspects of steelmaking with sponge iron in electric arc furnaces

Test charges containing sponge iron proportions varying from 38.7–95.4 wt% of the metallic input were melted in a UHP electric arc furnace with a design capacity of 70 tons per heat. After melting started, samples of molten metal and the corresponding slag were taken simultaneously at different time intervals and analysed. The time dependence of the chemical composition of the metal and slag as well as the variation of the temperature of the melt with time are given. Thermodynamic calculations using different methods for finding the activity of ferrous oxide show that there is a linear relationship between a(FeO) and the total ferrous oxide content in the slag. It is also found that the total ferrous oxide content in the slag and the oxygen concentration in the metal vary linearly with the iron proportion from sponge iron in the metallic input. The activity of ferrous oxide decreases with increasing slag basicity due to the formation of calcium ferrites. The relationship between the oxygen concentration and the reciprocal of the carbon content in liquid steel is almost linear. A formula showing the influence of some important factors on the oxygen content in molten steel is given.The effect of sponge iron on the sulphur concentration in the steel is also investigated. The present results indicate that the sulphur content in the steel can be reduced from 0.02 to 0.004 wt% by increasing the iron proportion from sponge iron in the metallic input from 35 to 95 wt %. Using the boundary layer diffusion model, it is found that the rate of decarburization of a steel bath is enhanced by increasing the sponge iron proportion in the metallic input. The activation energy of the decarburization reaction is found to be 56.9 kJ/mol and the mass transfer coefficient of carbon has a value of 0.0161 cm/s at 1 600°C. In a way similar to that used for decarburization, it is also found that the rate of oxidation of manganese dissolved in the bath is enhanced by increasing the sponge iron proportion in the metallic input.

A comparison of Raney copper-zinc and coprecipitated copper-zinc-aluminium oxide methanol syntheses catalysts

A Raney catalyst prepared from an alloy consisting of 43 wt.% copper, 39 wt.% aluminium and 18 wt.% zinc and a commercial copper oxide-zinc oxide-alumina catalyst were tested in methanol synthesis in the temperature range 430–530 K, using a GHSV of 10000 h −1, and constant total pressure of 5000 kPa. Total carbon oxide concentration in the synthesis gas was in the range 15–20 vol.%. It was found that the catalysts had the same activity per unit area of copper and showed almost identical responses to changes in process conditions despite the different morphologies resulting from the methods of catalyst preparation. A Raney copper catalyst, prepared from CuAl 2 and containing less than 1% of residual aluminium, was found to be active in methanol synthesis. The results suggest that the same active species are involved in methanol synthesis in both types of catalyst, and that these active species involve copper metal.

Adsorption of gases at evaporating and condensing water surfaces

Single water droplets 0.23 cm in diameter were suspended and allowed to evaporate partially in a nitrogen stream (velocity, 50 cm s −1) containing various concentrations of SO 2 ((1 — 3) × 10 −3 atm) and water vapor (6.8–16.9 Torr). In a separate series of tests the SO 2 was replaced by oxygen in the 21% – 80% range. The droplets were exposed for fixed time intervals and then removed and analyzed for total sulfur oxide or oxygen content. The temperature of the droplet was monitored during the exposure time. The water vapor concentration in the bulk gas phase as well as the SO 2 or oxygen concentration determined the equilibrium saturation concentration of gas transferred to the water which was always less than at thermal equilibrium. The rate of mass transfer was controlled by heat transfer to the droplets. In the second part of this study, water vapor in various concentrations was passed through a tubular furnace and condensed at various temperatures (0 – 27 °C) to form a cloud in the presence of SO 2 (10 −5 - 10 −2 atm). The sizes of the condensed droplets were in the range 1 – 2 μm. Cloud droplets were separated from the gas stream electrostatically and analyzed for sulfur content. The concentrations of SO 2 in the aqueous phase were supersaturated compared with those at equilibrium, were relatively independent of gas phase SO 2 concentrations of less than 10 −3 atm and were strongly dependent on the amount of water condensed. A mechanism is proposed whereby hydrate formation at the water surface explains the results observed. ft*]|Present address: Corning Glass Works, Wilmington NC 28403, U.S.A.

A spectrophotometric study of the formation of an unidentified monochloramine decomposition product

This paper reports on a study of the formation of an unidentified product(s) of the slow decomposition of monochloramine in organic free aqueous solutions at pH values and Cl/N ratios of importance in the chloramination disinfection of drinking water. Chloramine and total oxidant concentrations determined spectrophotometrically in these solutions became significantly greater with time than those determined by a titrimetric method due to the absorbance of the unidentified product(s). The u.v. spectra of the product(s) was calculated from the difference between measured and predicted spectra and was similar to that obtained in a chloramine free solution resulting from the rapid decomposition of dichloramine at high pH. No spectrophotometric evidence could be found for the formation of significant concentrations of nitrite and/or nitrate. Relative concentration changes of the unidentified product(s) as measured by its calculated absorbance at 243 nm showed that the product(s) accumulates with time and therefore is not likely to be an intermediate in the formation of nitrogen gas. Both increased pH and phosphate buffer increased its formation rate. A formation mechanism involving the decomposition of dichloramine is suggested. Findings suggest that the age/history of chloramine solutions could be an important variable in toxicological studies of chloramines and their reaction products depending on the health effects of the unidentified product(s).

Electrical Conductivity of Lithium Aluminosilicate, Galliosilicate, and Alumino/Galliosilicate Glasses

The density and electrical resistivity of aluminosilicate, galliosilicate, and aluminol galliosilicate glasses containing 15 mol% Li2O were measured as a function of total intermediate oxide content and as a function of the alumina/gallia ratio. Although the density of a given gallia glass is considerably greater than that of the corresponding alumina glass, the molar volumes of the glasses are independent of the identity of the intermediate oxide present. Furthermore, even though the electrical resistivity of a given gallia glass is significantly greater than that of the corresponding alumina glass, the resistivity varies linearly with alumina/gallia ratio for constant intermediate oxide concentration. The results indicate that gallium plays a role identical with that of aluminum in the glass structure.

ChemInform Abstract: VISCOSITY AND THERMAL EXPANSION OF MIXED‐ALKALI SODIUM‐POTASSIUM BORATE GLASSES

AbstractSowohl die Viskosität als auch die thermischen Expansionskoeffizienten ′von Na‐ K‐Boratgläsem sind eine Funktion des Na2O/K2O‐Verhältnisses.

Viscosity and Thermal Expansion of Mixed‐Alkali Sodium‐Potassium Borate Glasses

The transformation‐range viscosity and thermal expansion be‐havior of sodium‐potassium borate glasses were studied. The results indicate that negative deviations from additivity in the viscosity of these glasses are a function of the Na2O to K2O ratio and that the magnitude of these deviations increases with alkali oxide content. The thermal expansion coefficient exhibits a maximum deviation from additivity as a function of the Na2o to K2O ratio. The magnitude of this deviation increases with increasing total alkali oxide content. The results indicate that there is little, if any, interaction between the factors which lead to the mixed‐alkali effect and the changes in the structure of the vitreous network which occur as the alkali oxide content of the glasses increases.

Cholesterol Oxides in Commercial Dry Egg Products: Quantitation

ABSTRACTCholesterol α‐oxide (5α‐cholestan‐5,6α‐epoxy‐3β‐ol), a suspected carcinogen and/or atherogen, and its β‐isomer are found in varying amounts in commercial dried egg products. The level of total cholesterol oxides in dried eggs ranges from undetectable to 311 parts per million of total lipids. The majority of the samples (64%) had total cholesterol oxides content between 6 – 49 ppm. The level of cholesterol α‐oxide ranges from undetectable to 62 ppm. The ratio of α‐oxide to its β‐isomer is found consistantly to be 1 to 4. The formation of cholesterol oxides is greater in samples dried by hot air heated directly with gas burner than those dried by air heated indirectly with steam. Prolonged storage increases cholesterol oxides content in dried egg products.

Behavioural responses of selected marine fishes to chlorinated seawater

Behavioural responses to chlorinated seawater were studied in the laboratory using eight species of fish (topsmelt, Atherinops affinis [Ayres]; pile perch, Rhacochilus vacca [Girard]; señorita, Oxyjulis californica [Günther]; blacksmith, Chromis punctipinnis [Cooper]; northern anchovy, Engraulis mordax [Girard]; opaleye, Girella nigricans [Ayres]; bluebanded goby, Lythrypnus dalli [Gilbert] and mussel blenny, Hypsoblennius jenkinsi Jordan and Evermann) which occur near the Units 7 and 8 discharge of Southern California Edison's Redondo Beach Steam Generating Plant in King Harbor, California, USA. All species except Engraulis demonstrated prolonged avoidance of chlorinated quadrants of the behaviour chamber. The avoidance thresholds were species-specific and species totally avoided estimated total residual oxidant (TRO) concentrations from 0·094 to 0·456 mg/litre. Calculated significant avoidance thresholds averaged 0·066 mg/litre TRO; young Atherinops significantly avoided TRO concentrations as low as 0·028 mg/litre ( p < 0·001). The highest avoidance thresholds were exhibited by sedentary species and were modified by the presence of cover inside the behaviour chamber. The avoidance response protected against mortality in all species except Lythrypnus and Engraulis.

X-ray photoelectron spectroscopic studies of carbon fibre surfaces—II: The effect of electrochemical treatment

Carbon fibres, electrochemically treated using sulphuric acid and ammonium bicarbonate electrolytes, were analysed by X-ray photoelectron spectroscopy. In each case it is observed that polarization of the fibres at successively higher positive potentials causes an increase in the total surface oxide concentration. In addition, the relative proportion of different surface species also varies as a function of fibre potential and can be correlated with the cyclic voltammetric results in the case of sulphuric acid. The O1s spectra can be described simply by two main component signals corresponding to C=O and C-O- type groups, where the former dominate at low potential and the latter dominate at higher potentials. Assignment of curve fitted peaks in the C1s region is not straightforward and cannot be simply correlated with the O1s spectra. Formation of C-N groups on the fibre surface in ammonium bicarbonate shows that the electrolyte can play an important role in the final surface structure. No such interaction was observed in the sulphuric acid case.

Variability and Control of Class C Fly Ash

Abstract Five Class C fly ashes produced in Texas were analyzed for their potential usefulness as a construction material in highways. In order to determine the variability a new test method was devised and termed the calcium oxide heat evolution test, whereby the total calcium oxide content of the Class C fly ashes can be quickly and reliably determined in the field, as a quality control test. By using this test plus the traditional physical and chemical characterizations, the variability of typical fly ashes produced in Texas was ascertained. They were shown to generally conform to the requirements of ASTM for Class C fly ash. In addition to the analysis the potential usefulness of this type of fly ash is discussed, and the test procedures for calcium oxide content are described.

Conditions D'Exploitation De La Méthode à La Diéthyl-P. Phénylénediamine Au Dosage Du Brome Libre Et/Ou Combiné En Milieu Marin

Abstract Free bromine and bromamine analysis by the diethyl-p. phenyl-lene-diamine (DPD) colorimetric method requires some care when chloride and bromide are present at seawater concentration. If no particular problem is encountered in mono and dibromamine determination, on the contrary the analysis of either free bromine or that of a free bromine and tribromamine mixture can induce errors of at least twenty per cent in the total residual oxidant concentration due to halogen loss. In order to prevent that phenomenon, iodide addition into the phosphate buffer and DPD mixture is necessary before the sample introduction. In these conditions the results are in good agreement with those of the phenol red method.

Acute toxicity and behavioral responses of coho salmon ( Oncorhynchus kisutch) and shiner perch ( Cymatogaster aggregata) to chlorine in heated sea-water

The acute toxicity and behavioral response to chlorinated and heated sea-water was determined for coho salmon smolts and 1–3 month old shiner perch. LC 50's were determined for 7.5, 15, 30 and 60 min exposure times; 13, 16 and 20°C ( Δt = 0, 3, 7°C) temperatures and total residual oxidant (TRO) concentrations ranging from 0.077 to 1.035 mg l −1. The mean 60 min LC 50 for shiner perch was significantly reduced ( P ≤ 0.05) from 308 μg l −1 TRO at 13°C to 230 μg l −1 TRO at 20°C. The 60 min LC 50 for coho salmon decreased from 208 μg l −1 TRO at 13°C to 130 μg l −1 at 20°C. The LC 50's for coho salmon in chlorinated sea-water averaged 55% of those for shiner perch. The relationship between TRO concentration, exposure time, and percent survival in chlorinated sea-water at 13°C is presented for both species. A significant ( P ≤ 0.01) avoidance threshold for coho salmon occurred at 2 μg l −1 TRO and was reinforced with increasing temperature. A significant ( P ≤ 0.01) avoidance threshold for shiner perch occurred at 175 μg l −1 TRO, while a significant preference ( P ≤ 0.05 or 0.01) response at 16°C and 20°C occurred at 10, 25, 50 and 100 μg l −1 TRO. The ecological implications of the toxicity tests and the behavioral responses are discussed.

Etude physicochimique de la chloration de l'eau de mer artificielle contenant de l'azote ammoniacal

Chlorine added to ammonia-free sea-water gives rise to a fast and quantitative oxidation of bromide to hypobromite and hypobromous acid. However as ammonia nitrogen levels commonly found in coastal and estuarine sea-water are sufficiently high and thus not negligible compared to the chlorine dose introduced formation of monochloramine to compete with oxidation of bromine leading to bromamines. The relative importance of these two reactional pathways is estimated considering both bromine determination and study of the electron absorption spectra of chlorinated seawater. In order to avoid substitution reactions taking place in the presence of organic compounds, preliminary experiments have been carried out in artificial and u.v. photo-oxidized sea-water. The nature of the species formed depends on the molar ratio added chlorine vs ammonia-nitrogen concentration of seawater. With Cl/N larger than 1.5, only bromide derivatives are obtained: dibromamine, tribromamine and bromine(I) (HBrO + BrO −). Cl/N smaller than 1.5 leads to a mixture of monochloramine, dibromamine and some monobromamine: monochloramine clearly predominates when ammonium concentrations reach higher values. Stoichiometry of ammonia to nitrogen oxidation by chlorine explains this ratio of 1.5 and a strong decrease of the total oxidant concentration is observed under these conditions. Bromamines decompose within the following 30–60 min; only stable compounds remain: either bromine(I) or monochloramine according to Cl/N values. A similar behaviour is observed in natural seawater previously doped with ammonia as to the nature of the products formed for a given Cl/N ratio; however, bromamines decompose more rapidly due to bromination of organic components.

A morphological defect in shiner perch resulting from chronic exposure to chlorinated sea water

1) A morphological defect to one eye was observed in 17 of 20 young shiner perch exposed to chlorinated sea water, and it was absent in the 5 controls. The occurrence of the defect was apparently related to the concentration of total residual oxidants. 2) Behavioral aberrations appeared to be associated with the morphological defect in exposed fish. Fish with severe cases were observed to be unsuccessful at feeding and at avoiding capture by dip-net. 3) Fish which died during the experiment varied in the degree of severity of the observable morphological aspects of the defect.