Carbonate Contamination Research Articles

The role of Ag in the preparation of metal sheathed (Bi,Pb) 2Ca 2Sr 2Cu 3O z tapes

High resolution transmission electron microscopy has been used to examine the Ag-superconductor interface of powder-intube fabricated Bi 1.7 Pb 0.3 Ca 2.05 Sr 2 Cu 3.05 O x . No evidence of any chemical interaction between the Ag and the superconductor could be found. The presence of carbonate contaminants is proposed as the mechanism for the reported lowering of the liquidus temperature of the Ag encapsulated superconductor.

Electrodialytic production of gas-free sodium hydroxide based on Donnan breakdown

An approach to generating high purity NaOH solutions in a continuous flow system by electrodialytic means is described. Sodium hydroxide of ordinary purity flows along one side of a perfluorinated cation exchange membrane; this channel also contains a noble metal anode. Sodium ions from this donor channel are elctrodialyzed across the membrane into a flowing water receptor channel, bounded on the other side by an identical membrane. This membrane is in intimate contact on its far side by a perforated inert plate, beyond which the cathode is located. Water flows through the cathode channel. The restrictor plate causes the accumulation of high concentrations of NaOH on the electrode side of the cathode membrane, resulting in its eventual Donnan breakdown and passage of cathodically generated OH - through it to the central channel. From the purity of the H + -exchanged conductance of the NaOH solution generated, it is estimated that the generated product is at least an order of magnitude purer in terms of carbonate contamination relative to the feed NaOH solution. The pure NaOH generated is directly fed into a high pressure pump and used for anion chromatography.

Zn solubility in low carbonate solutions

While the importance of several metal basic carbonates has been recognized in natural and wastewater systems, the existence of the Zn basic carbonate, hydrozincite, has not been fully appreciated even though solubility data have been available. In the presence of 2 mM total inorganic carbonate, Zn 2+ solutions below pH 8.2 were found to precipitate hydrozincite within 24 h and to contain total dissolved Zn concentrations that were comparable to those predicted from equilibrium with hydrozincite. The identity of the hydrozincite was confirmed by X-ray diffraction and elemental analyses. In the pH range 8.2–10.5, the total dissolved Zn concentrations were less than that expected from equilibrium with hydrozincite by factors of up to 3, while the precipitated solids had C:Zn ratios intermediate between those of hydrozincite and give oxide and exhibited weak hydrozincite X-ray diffraction patterns. At pHs above 10.5, zinc oxides with strong X-ray diffraction patterns were present and total dissolved Zn concentrations approached those expected for equilibrium with zinc oxide. In solutions prepared to exclude carbonate, the total dissolved zinc concentrations in all solutions were similar to those expected for equilibrium with zinc oxide. However, two solids in these “carbonate-free” solutions contained small amounts of inorganic carbonate and exhibited weak hydrozincite X-ray diffraction patterns. The presence of well-defined or poorly-crystalline hydrozincite in all 2 mM inorganic carbon solutions between pH 8–10 and its presence in two solutions prepared to exclude carbonate contamination suggest that hydrozincite is probably a common Zn solid formed in conventional precipitation processes.

Surface characterization of zirconium oxide. I. Surface activation and the development of a strong Lewis acidity

In situ FTIR spectroscopy has been used to investigate the adsorption of carbon monoxide at ambient temperature on two series of Z rO 2 samples, treated in vacua at various temperatures up to 870 K. The first series corresponds to the starting (virgin) material, the second series to the same material that was vacuum cleaned from all surface impurities and then rehydrated. On both specimens CO chemisorbs yielding two σ-coordinated species, which reveal the creation of two families of Lewis acidic centres, whose absolute and relative amounts depend on surface dehydroxylation. Some differences of CO absorptivity, that mainly concern one of the two CO species, are observed between the virgin and the rehydrated samples, and are ascribed to the presence on the former samples of appreciable amounts of surface carbonate contaminants.

ChemInform Abstract: Carbonate and Superoxide Ion‐Radicals as Intermediates in the Chemiluminescence of the Ferricyanide‐Hydrogen Peroxide Redox System.

AbstractThe participation of 1O*2‐dimols in the CL of the Fe(CN)63‐/4‐‐ H2O2 system has been investigated and the role of O2‐·, OH· as well as carbonate contamination has been studied.

Late-Glacial and Early Holocene Vegetational History at the Kolarik Mastodon Site, Northwestern Indiana

Analyses of pollen and plant macrofossils from the Kolarik Mastodon Site provide important refinements of the late-glacial and early Holocene vegetational record for northwestern Indiana. The record spans the period from> 12,000 to 9500 years B.P. Regional vegetation from> 12,000 to at least 11,000 years B.P. consisted of open, spruce-dominated forest or woodland. Both black and white spruce were present locally, along with aspen, fir and tamarack. The mastodon recovered from the site was associated with this vegetation. Vegetation of the region between 11,000 and 9500 years B.P. consisted of pine, spruce and hardwoods (oak, ash, hickory, hornbeam). Macrofossils indicate local presence of jack pine, white pine, tamarack, spruce, fir, alder and birch (probably paper birch). A radiocarbon date from a wood sample indicates that the upper boundary of the spruce-herb pollen zone in the region may be as young as 10,800 years B.P., 1000 years younger than suggested by previous studies in northern Indiana. The age discrepancy may result from carbonate contamination of bulk lake sediments. INTRODUCTION We present results of pollen and macrofossil studies of sediments collected during excavation of mastodon and other vertebrate remains from the Kolarik Site (Ellis, 1981) in Starke Co., Indiana (Fig. 1). These studies provide the basis for reconstructions of vegetation and environment associated with the vertebrate assemblage. In addition, our studies contribute new information on the late-glacial and early Holocene vegetational history of northwestern Indiana and provide chronological and taxonomic refinements of the regional pollen stratigraphy. Bailey (1972) has provided a general outline of postglacial vegetational development in northwestern Indiana. Bailey's studies are based on pollen and radiocarbon stratigraphy of two lakes in LaPorte County, 55 km N of the Kolarik Site (Fig. 1). Because these lakes are in areas of calcareous till, the sediments are susceptible to contamination by dead Paleozoic carbonate, making the radiocarbon dates of bulk lake sediments subject to significant error (Bailey, 1972; Ogden, 1967). The availability of radiocarbon dates based on plant macrofossil samples in clear stratigraphic association with the pollen sequence at the Kolarik Site provides an opportunity to test and refine the regional chronology. In addition, identification of macrofossils from bulk sediments at the Kolarik Site permits identification of palynologically indistinguishable taxa (e.g, species of spruce, pine and birch) and documents the presence of palynologically silent taxa (e.g, aspen, tamarack, herbs, aquatic macrophytes). These identifications form the basis for a more detailed understanding of regional and local vegetational change.2 SITE DESCRIPTION The study site is situated on the property of Andrew Kolarik immediately N of the Starke Co.-Pulaski Co. line in Starke Co. (Bass Lake 7.5' Quadrangle, T32N, R2W, Sec. 36, SE 1/4, SW 1/4, SE 1/4, SW 1/4) (Fig. 1). Elevation of the site is 218 m above mean sea level. 1Present address: Department of Biological Sciences, Idaho State University, Pocatello 83209. 2Vascular plant nomenclature after Fernald (1950).

Evaluating Barite as a Source of Soluble Carbonate and Sulfide Contamination in Drilling Fluids

Summary Even when drilling-grade barites meet all current API specifications, they frequently are contaminated sufficiently with alkaline-soluble carbonate and sulfide minerals to cause serious drilling fluid problems. This paper describes in detail a new supplementary quality paper describes in detail a new supplementary quality control test that can identify many of these problem barites. Widespread use of this new test should facilitate a significant improvement in the quality of barite used in drilling operations. Introduction Barite is the overwhelming, choice as a material to build density in drilling fluids. In 1980, more than 3 million tons of barite were used in the U.S. for this purpose. A single barrel of high-density drilling fluid may contain more than 500 lbm of barite so that even small concentrations of impurities in barite can put significant contamination into the drilling fluid. Pure barite is barium sulfate (BaSO4) and is insoluble throughout the pH range encountered in drilling fluids. Commercial barites meeting current API specifications frequently contain from 10 to 30 wt% of a complex mixture of water-insoluble mineral impurities, but some of these impurities are soluble in alkaline drilling fluids. The cations from these solubilized impurities usually are precipitated as insoluble hydroxides and probably cause precipitated as insoluble hydroxides and probably cause little trouble. The anions, however, usually remain in solution, and when these anions are carbonates or sulfides, they can cause serious drilling fluid problems such as lost circulation, stuck pipe, and even problems such as lost circulation, stuck pipe, and even catastrophic loss of the well. Because of the complex composition of commercial barites, chemical analysis is of limited value in identifying barites that have the potential to cause serious drilling problems. Consequently, a simple screening test has been developed that can identify; those barites that have the potential to generate harmful quantities of soluble carbonate or sulfide ions. It is hoped that this test will be used widely by suppliers to select quality ores and by users to ensure receipt of quality material and to provide early warning of incipient field problems related to carbonate or sulfide ions. Guidelines for interpreting test results in terms of barite quality are highly dependent on specific drilling fluid formulations, and it is beyond the scope of this paper to suggest absolute standards that could be used to qualify a given barite for general use. This paper discusses (1) Exxon Co. U.S.A.'s field experience with carbonate and sulfide contamination from barite, (2) the sensitivity of a barite caustic extraction test to temperature, reaction time, and sodium hydroxide concentration, (3) test precision, and (4) recommended test use. A detailed test procedure is given in the Appendix. Field Experience with Carbonate and Sulfide Contamination From Impure Barite Carbonate Contamination The first clearly documented case of high levels of carbonate ion contamination derived from caustic-soluble materials in a commercial barite meeting current API specifications occurred in 1977 in an Exxon drilling operation at a Laterre well in the Lirette field in southern Louisiana. In addition to the usual rheological, filtration, and chemical tests, the drilling fluid at this well was being monitored by the Garrett Gas Train (GTT) method for carbonates, a new test in 1977. Excessive gel strengths were being encountered on this Laterre well but were not seen on an almost identical offset well. JPT P. 2371

Thermochemical and Theoretical Investigations of the Sodium-Oxygen System. I. The Standard Enthalpy of Formation of Sodium Oxide (Na2O)

Calorimetric measurements of the enthalpy of hydrolysis of pure sodium oxide (Na2O) are described. Based on the enthalpy of reaction, the standard enthalpy of formation at 298.15°K, Δ Hf298o(Na2O), was calculated to be −414.82± 0.28 kJ mole−1 (−99.14± 0.07 kcal mole−1). The enthalpy of reaction reported in the present study is significantly more exothermic than that determined by previous investigators. This discrepancy is attributed to the probable presence of hydroxide, carbonate, or other contaminants in the earlier sodium oxide samples.

The evaluation of14C ages for soil carbonate from the arid zone

The comparison of14C ages determined for pedogenic carbonate and coexisting organic carbon obtained from arid zone calcareous soils and paleosols indicates that the carbonate dates are on average at least 3600 radiocarbon years too old. This is attributed to an initial low14C content of soil carbonate and minimal secondary contamination by environmental14C within the arid zone.

Infrared spectra in the Ag2O-CO2-Ag2CO3 system

The infrared spectrum of silver oxide, Ag2O, has been clarified by comparison with that of silver carbonate. In the region 4000-400 cm-l the spectrum consists of one broad band centred around 530 cm-l, other bands being accounted for in terms of normal, basic, and complex carbonates and surface hydroxyl groups, which are frequently present as contaminants. Conditions for the preparation, storage, and purification of silver oxide to minimize carbonate contamination are defined.

Staining and washing ultrathin sections; a device for handling various materials simultaneously.

To eliminate individual manipulation, as many as 10 grids, each held firmly by a small notched bar of polyethylene plastic, are simultaneously stained, then washed. If the stain used is reactive with atmospheric CO2 it can be forced through a Millipore filter into a small chamber made of glass tubing which contains the grid holder. The stain, cleared of any solid particles, has very little contact with air and remains free of lead carbonate contamination. Washing is carried out by submerging the chamber and removing the grid holder under water (Feldman, D. G., J. Cell Biol., 15: 592-5, 1962). Washing is minimized because there is not the risk of contaminating grids and wash water with stain trapped between the points of forceps. The polyethylene is nonadherent to the wash water, and the grids can therefore be dried quickly on the holder. With this method, the relative stainability of different materials may be observed because each grid within a batch receives identical treatment.

Effects of Foreign Ions on Nickel Hydroxide and Cadmium Electrodes

The behavior of individual positive and negative electrodes of the sintered‐plate nickel‐cadmium battery system in the presence of foreign ions in solutions has been examined. Carbonate choke: The variation of electrochemical capacity as a function of carbonate contamination of the electrolyte, temperature, and current density was measured for both positive and negative electrodes. The effect of carbonate on the negative cadmium electrode is much greater than on the positive. The general mechanism and the role of intermediate complexes are discussed. Nitrate shuttle: Self‐discharge occurs in cells containing nitrate, as a result of reduction of to at the cadmium electrode with subsequent reoxidation to at the nickel hydroxide electrode. Cations on the positive: Addition of Li+, Ag+ Sb+3, Al+3, and As+3 to the electrolyte had effects on capacity and on charge‐retention of well‐formed nickel hydroxide positive electrodes. Lithium promoted the highest average oxidation, particularly at high temperatures (55°C). Arsenic was the best inhibitor of loss of charge. Possible mechanisms are discussed.