Gotowa bibliografia na temat „Cerium chloride”

The effect of nanosized cerium dioxide and a solution of cerium (III) chloride on the state of a post-burn scar was studied in an in vivo experiment via transmission electron microscopy. The intracellular accumulation of cerium compounds with their agglomeration with cytoplasmic and/ or lysosomal localization was observed after 4 injections of nanodispersed cerium dioxide or cerium (III) chloride solution at concentrations of 0.5% and 0.05% in the formed scar area. The application of the cerium preparations both in nanodisperse form (sol) and in solution did not cause inflammatory reactions or cell destruction and had a positive effect on a regenerative process; it contributed to the full-fledged tissue regeneration in a shorter time and changed the scar characteristics for the better. sol, nanodispersed cerium dioxide, cerium (III) chloride solution, electron microscopy, post-burn scar, functional activity of cells

One of the key impediments to aluminum (Al) as an anode in alkaline Al-air batteries is self-corrosion, which limits the battery’s efficiency due to the capacity loss and lifespan reduction. Thus, it is vital to find an efficient electrolyte additive that reduces self-corrosion in Al anodes. In this study, the effect of adding 0.5 to 1.5 wt% of cerium chloride to 4 mol l−1 KOH electrolyte on the self-corrosion of pure Al anode was investigated using electrochemical experiments. The results show that the addition of cerium chloride to the electrolyte reduces self-corrosion of the Al anode with a negligible effect on the anode activity. Cerium chloride forms cerium hydroxide (Ce (OH)3) in the alkaline electrolyte, which is adsorbed on the Al surface. Therefore, the corrosion potential increased, and self-corrosion current density decreased. As the cerium chloride concentration increased, the Al anode efficiency increased from 43.8% to 76.1%, and the capacity density increased from 1294 to 2244 mAh g−1. Furthermore, increasing the immersion time of the Al anode in the electrolyte containing cerium chloride increased the self-corrosion resistance and provided the self-healing properties for the anode.

The effect of the addition of benzotriazole (BTA) or cerium chloride separately and in combination on the anticorrosion performance of Cu-Se-Te alloy in 3.5 wt% NaCl solution has been investigated. The results show that the addition of either BTA or cerium chloride significantly reduces the corrosion rate of Cu-0.25Se-0.25Te, but BTA exhibits a better inhibition effect. Meanwhile, scanning electron microscope analysis displays that the separate addition of BTA or cerium chloride makes the depth of corrosion pit of the sample decrease and the corroded surface smooth. With the combination of BTA and cerium chloride rising, the surface of the sample becomes much flatter and no obvious corrosion pit is found. Energy dispersive spectrum and x-ray photoelectron spectroscopy analyses suggest that when BTA and cerium chloride are added together, CeO2, Ce(OH)3, or complex formed by Ce and BTA might deposit on the surface of copper alloy, which induces the passivation film on the surface of the alloy to become denser and enhances the binding strength of the interface between the surface film and the matrix, thus improving the corrosion inhibition performance of the complex system.

The present study aims to shed light directly towards the extraction of (IV) cerium ions using "liquid surfactant membrane" technology, "LSM" developed in the presence of synergistic cationic and nonionic materials. The effect of various factors such as Ce (IV) transport, synergistic surfactants, curing ratio, stir speed, temperature, and mixing time between the carrier and the cerium ion on the extraction rate was studied by LSM taking into account surfactant agents. The positive effect of benzethonium chloride "Hy-1622" on the extraction of cerium ion was demonstrated by LSMs technique. Experiments confirmed the efficiency of Hy-1622 chloride synergistically with Span 80/85 to extract cerium ions with LSMs technology for emulsions in the oil phase is critical as it determines the stability, viscosity and mass transfer resistance of the resulting emulsion. Besides, Hy-1622 chloride was found as a new cationic surfactant that appeared in FTIR characterization and surfactant was found to speed up the permeability process and accelerate the extraction rate due to electrostatic interaction with the carrier.

The effects of reaction temperature (150–300 °C), chemical composition of the starting cerium salt (cerium nitrate and cerium chloride), and doping with trivalent cations (Sc3+ and Y3+) on the coarsening of CeO2 particles in dilute suspensions under hydrothermal conditions were investigated. The particle size was measured by x-ray line broadening and by transmission electron microscopy. The particle coarsening kinetics followed a parabolic law, indicating that the interfacial reaction (dissolution) was the rate-controlling step. Furthermore, the particle size distribution data can be well-described by the Lifshitz–Slyozov–Wagner theory of Ostwald ripening controlled by the interfacial reaction. Doping with 6 at.% Y3+ produced a significant reduction in the coarsening rate but almost no change in the activation energy. At the same concentration, Sc3+ was more effective than Y3+ in reducing the coarsening rate. Particles synthesized from a starting solution of cerium(III) chloride coarsened at a markedly slower rate than that for particles synthesized from cerium(III) nitrate. The mechanisms controlling the coarsening of the particles are discussed.

[Truncated abstract] Corrosion of steel structures caused by sulphide is a common engineering problem encountered by many industries, such as the petroleum, chemical processing, mining and mineral processing industries. The control of sulphide corrosion is still a controversial topic among corrosion engineers. There is an absence of guideline for a reliable acceptable limit of sulphide level in service and each processing industry has its own empirical values. Selection of inhibitors in the sulphide environment depends on laboratory testing before its actual application in pipelines and reaction vessels. Many investigators have postulated the corrosion mechanisms due to sulphide based on operating envelopes such as pH, chloride, manganese, hydrogen sulphide, sulphate reducing bacteria levels and inhibitor concentration. It is recommended in the literature that the batch dosing of inhibitor and biocide needs to be evaluated in regards to sulphide reducing bacteria (SRB) level, which may produce sulphide concentrations up to 2000 ppm. Although sulphide scale formation may protect the base metal by providing a physical barrier, the detrimental effects of sulphide are often inevitable, such as stress corrosion cracking, hydrogen embrittlement, etc. Currently, there are many chemicals that are used as inhibitors to prevent corrosion by scavenging the sulphide from the environment. Cerium, a rare-earth element, is not used as inhibitor in the sulphide environment. Also, there are no previous research findings on the effects of compounds of rare-earth metals, such as cerium chloride (CeCl3), in sulphide environment. This research examines the corrosion behaviour of 0.4Mo-0.8Cr steel, a High Strength Low Alloy (HSLA) steel, in sulphide-polluted artificial seawater with the addition of CeCl3 and glutaraldehyde. ... It is postulated that the moderate inhibiting effect of CeCl3 is due to the scavenging effect thereby forming Ce2S3 complex. Further reaction of sulphide with steel resulted in ferrous sulphide, leading to an increased corrosion rate. It is also concluded that the CeCl3 interferes with both anodic and cathodic reactions in deaerated conditions. Addition of glutaraldehyde in the sulphide-polluted seawater was found to decrease the corrosion rate. According to the electrochemical measurements conducted, the concurrent addition of glutaraldehyde and CeCl3 appeared to have an added effect on reducing the corrosion of the steel, as evidenced by the increase of the open circuit potential during the short-term testing. From the weight loss measurements after 60 days, sulphide pollution in deaerated seawater was found to increase corrosion rate. This is attributed to the increase of sulphide activity whereby continual dissolution of steel was encountered. From the weight loss tests, it was found that the addition of CeCl3 and glutaraldehyde reduced the corrosion rate of the steel in the solutions containing 0-10 ppm sulphide. There is no noticeable corrosion rate decrease for the solution containing 100 ppm sulphide. The added effect of CeCl3 and glutaraldehyde to the SRB medium has resulted in lower corrosion rates. Further detailed experimentation is required to elucidate the corrosion reduction mechanism in glutaraldehyde-containing environments.

Etude thermodynamique et cinétique de la réduction électrolytique de terres rares cériques, réalisée au sein de l'eutectique fondu LICL-KCL. Comportement singulier du néodyme étudié dans l'eutectique BACL::(2)-KCL jusqu'à 1300k; on montre que la stabilité de ND(II) croit avec la température. Etude des alliages entre les métaux des terres rares et les métaux de transition de composition générale LNM::(X), dont les propriétés thermodynamiques ont été déterminées par mesure de la F. E. M. De la pile LN/LNCL::(3), LICL+KCL/LNM::(X); application aux alliages LA-NI ET ND-FE entre 700 et 800K.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Ce manuscrit décrit la synthèse et la conception de 3 nouvelles familles de molécules, les [alpha],[alpha]-diméthylamines, les 6-nitroaminopyridines et les benzimidazoles substitués. L’étude des [alpha],[alpha]-diméthylamines nous a amené à développer une voie de synthèse originale en utilisant les propriétés chimiques du chlorure de cérium, qui, lorsqu’il est complexé avec un organolithien permet d’alkyler deux fois une fonction nitrile. Une étude exhaustive des propriétés chimiques du cérium et du chlorure de cérium en synthèse organique a également été menée. La synthèse totale de la 6-nitro-2-aminopyridine nous a amené à développer une voie de synthèse générale permettant de conduire aux différents isomères de position de ce composé. Cette voie a également été optimisée et transposée à une unité de synthèse de 50L. Les différentes conditions réactionnelles de cyclisation de diamines fonctionnalisées nous ont permis de synthétiser des séries de 5 benzimidazoles fonctionnalisés : les benzimidazoles, les 2-méthylbenzimidazoles, les benzimidazolones, les 2-chlorobenzimidazoles et les 2-mercaptobenzimidazoles. Une revue exhaustive des différentes méthodes de préparation de ces benzimidazoles est également détaillée et ont servi de base à ce travail de synthèse
The present report describes the design and the synthesis of 3 new family of molecules, the [alpha],[alpha]-dimethylamines, the 6-nitroaminopyridines and substituted benzimidazoles. The study of [alpha],[alpha]-dimethylamines devellop an original synthetic route using the chemical properties of cerium chloride, witch can alkyl two times a nitril fonction when it is complexed with organolithium reagent. Also, an exhaustive study was carried on chemical properties of cerium and cerium chloride in organic synthesis. The total synthesis of 6-nitro-2-aminopyridine bring us to devellop a general synthetic route leading to different position isomeres of this compound. Also, this route was optimized and transposed to a 50L synthesis unity. The different conditions of cyclisation of substituted diamines allowed us to synthetise 5 series of fonctionnalized benzimidazoles : the benzimidazoles, the 2-methylbenzimidazoles, the benzimidazolones, the 2-chlorobenzimidazoles and the 2-mercaptobenzimidazoles. An exhaustive review of the different methods for preparing benzimidazoles was carried and was the basis for this synthetic work

Ce manuscrit décrit la synthèse et la conception de 3 nouvelles familles de molécules, les [alpha],[alpha]-diméthylamines, les 6-nitroaminopyridines et les benzimidazoles substitués. L’étude des [alpha],[alpha]-diméthylamines nous a amené à développer une voie de synthèse originale en utilisant les propriétés chimiques du chlorure de cérium, qui, lorsqu’il est complexé avec un organolithien permet d’alkyler deux fois une fonction nitrile. Une étude exhaustive des propriétés chimiques du cérium et du chlorure de cérium en synthèse organique a également été menée. La synthèse totale de la 6-nitro-2-aminopyridine nous a amené à développer une voie de synthèse générale permettant de conduire aux différents isomères de position de ce composé. Cette voie a également été optimisée et transposée à une unité de synthèse de 50L. Les différentes conditions réactionnelles de cyclisation de diamines fonctionnalisées nous ont permis de synthétiser des séries de 5 benzimidazoles fonctionnalisés : les benzimidazoles, les 2-méthylbenzimidazoles, les benzimidazolones, les 2-chlorobenzimidazoles et les 2-mercaptobenzimidazoles. Une revue exhaustive des différentes méthodes de préparation de ces benzimidazoles est également détaillée et ont servi de base à ce travail de synthèse
The present report describes the design and the synthesis of 3 new family of molecules, the [alpha],[alpha]-dimethylamines, the 6-nitroaminopyridines and substituted benzimidazoles. The study of [alpha],[alpha]-dimethylamines devellop an original synthetic route using the chemical properties of cerium chloride, witch can alkyl two times a nitril fonction when it is complexed with organolithium reagent. Also, an exhaustive study was carried on chemical properties of cerium and cerium chloride in organic synthesis. The total synthesis of 6-nitro-2-aminopyridine bring us to devellop a general synthetic route leading to different position isomeres of this compound. Also, this route was optimized and transposed to a 50L synthesis unity. The different conditions of cyclisation of substituted diamines allowed us to synthetise 5 series of fonctionnalized benzimidazoles : the benzimidazoles, the 2-methylbenzimidazoles, the benzimidazolones, the 2-chlorobenzimidazoles and the 2-mercaptobenzimidazoles. An exhaustive review of the different methods for preparing benzimidazoles was carried and was the basis for this synthetic work

The Ceratium species occurring in the Vaal River since 2000, was identified as Ceratium hirundinella (O.F. Müller) Dujardin as proposed by Van Ginkel et al (2001). Ceratium hirundinella is known to cause problems in drinking water purification and has been penetrating into the final drinking water of Rand Water since 2006. Ceratium hirundinella is associated with many other water purification problems such as disrupting of the coagulation and flocculation processes, blocking of sand filters and algal penetration into the drinking water. Ceratium hirundinella also produce fishy taste and odorous compounds and causes discolouration of the water. The aims of this study were to determine the main environmental factors which are associated with the bloom formation of C. hirundinella in the source water and to investigate the influence of C. hirundinella on the production of potable water. In order to optimise treatment processes and resolve problems associated with high C. hirundinella concentrations during the production of potable water, jar testing and chlorine exposure experiments were performed. Multivariate statistical analyses were performed to determine the main environmental variables behind C. hirundinella blooms. Ten years data (2000 - 2009) from the sampling point C–VRB5T in the Vaal River, (5 km upstream from the Barrage weir) were used for this investigation, because C. hirundinella occurred there frequently during the ten year period. In this study, it was found that C. hirundinella was favoured by high pH, Chemical Oxygen Demand (COD), orthophoshapte (PO4), and silica concentrations, as well as low turbidity and low dissolved inorganic nitrogen (DIN) concentrations. No correlation was found between C. hirundinella and temperature, suggesting that this alga does not occur during periods of extreme warm or extreme cold conditions, but most probably during autumn and spring. The results of the multivariate statistical analysis performed with historical data from Vaalkop dam, indicate that the dinoflagellate C. hirundinella seems to be favoured by low temperature and turbidity, and high DIN, Fe, Methyl–orange alkalinity, Cd, PO4, Conductivity, pH, hardness and SO4 concentrations. In order to optimise treatment processes such as coagulation, flocculation and sedimentation, jar testing experiments were performed to investigate different coagulant chemicals namely: cationic poly–electrolyte only, cationic poly–electrolyte in combination with slaked lime (CaO) and CaO in combination with activated silica. Water from four different sampling localities were chosen to perform the different jar testing experiments: 1) sampling point M–FOREBAY (in the Forebay, connecting the canal to the Zuikerbosch Purification plant) near Vereeniging due to its proximity to the Zuikerbosch treatment plant, 2) M–CANAL_VD (upstream from the inflow of the recovered water from Panfontein) to determine the influence of (if any) the recovered water from Panfontein on Forebay source water, 3) source water from Vaalkop Dam (M–RAW_VAALKOP) and 4) source water from Rietvlei Dam (water from both Vaalkop and Rietvlei Dams contained high concentrations of C. hirundinella at that time of sampling) to determine which coagulant chemical is the most effective in removing high concentrations of C. hirundinella cells during the production of drinking water. The jar testing experiments with Vaalkop Dam and Rietvlei Dam source water (rich with C. hirundinella) indicated that using cationic poly–electrolyte alone did not remove high concentrations of C. hirundinella efficiently. However, when CaO (in combination with cationic poly–electrolyte or activated silica) were dosed to Vaalkop Dam source water a significant decrease of C. hirundinella concentration was observed. This indicates that the C. hirundinella cells were “shocked or stressed” when exposed to the high pH of the CaO, rendering it immobile and thereby enhancing the coagulation and flocculation process. However, when 10 mg/L CaO in combination with poly–electrolyte was dosed to Rietvlei Dam source water the turbidity and chlorophyll–665 results indicated that this coagulant chemical procedure was ineffective in removing algal material from the source water. The jar testing experiments using the cationic poly–electrolyte alone or cationic poly–electrolyte in combination with CaO on M–FOREBAY and M–CANAL_VD source water, showed a decrease in turbidity, chlorophyll–665 concentration, and total algal biomass, with an increase of coagulant chemical. When CaO in combination with activated silica was dosed, the inherent turbidity of the lime increased the turbidity of the Vaalkop Dam, M–FOREBAY and M–CANAL_VD source water to such an extent that it affected coagulation negatively, resulting in high turbidity values in the supernatant. Regardless of the turbidity values, the chlorophyll–665 concentration and total algal biomass (C. hirundinella specifically in Vaalkop Dam source water) decreased significantly when CaO was dosed in combination with activated silica. Therefore it was concluded that a cationic poly–electrolyte alone is a good coagulant chemical for the removal of turbidity, but when high algal biomass occur in the source water it is essential to add CaO to “stress” or “shock” the algae for the effective removal thereof. However, when CaO in combination with activated silica was dosed to Rietvlei Dam source water a decrease in turbidity and chlorophyll–665 concentration was found with an increasing coagulant chemical concentration. These results confirm the fact that coagulant chemicals may perform differently during different periods of the year when water chemistry changes and that certain coagulant chemicals may never be suitable to use for certain source waters. For the effective removal of algae during water purification, it is recommended that cationic poly–electrolyte in combination with CaO are used as coagulant chemical at the Zuikerbosch Water Purification Plant. Turbidity is not a good indication of algal removal efficiency during jar testing experiments. If problems with high algal concentrations in the source water are experienced it is advisable to also determine the chlorophyll–665 concentrations of the supernatant water during the regular jar testing experiments, since it will give a better indication of algal removal. Chlorine exposure experiments were performed on water from Vaalkop Dam (M–RAW_VAALKOP) and Rietvlei Dam source water, to determine the possibility of implementing pre– or intermediate chlorination with the aim to render the cells immobile for more effective coagulation. The chlorine exposure experiments with Vaalkop Dam and Rietvlei Dam source water showed similar results. The chlorine concentration to be dosed as part of pre– or intermediate chlorination will differ for each type of source water as the chemical and biological composition of each water body are unique. When the effect of chlorine on the freshwater dinoflagellate C. hirundinella was investigated, it was found that the effective chlorine concentration where 50 % of Ceratium cells were rendered immobile (EC50) was approximately 1.16 mg/L for Vaalkop Dam source water. For the source water sampled from Rietvlei Dam, it was found that the EC50 was at approximately 0.87 mg/L. Results of analyses to determine the organic compounds in the water after chlorination revealed that an increase in chlorine concentration resulted in increase in total organic carbon concentration (TOC), as well as a slight increase in MIB and trihalomethanes (CHCl3). Pre– or intermediate chlorination seem to be an effective treatment option for the dinoflagellate C. hirundinella to be rendered immobile and thereby assisting in its coagulation process. The use of pre– or intermediate chlorination to effectively treat source waters containing high concentrations of C. hirundinella is a viable option to consider. However, the organic compounds in the water should be monitored and the EC50 value for each source water composition should be determined carefully as to restrict cell lysis and subsequent release of organic compounds into the water.
Thesis (M.Sc. (Environmental Science))--North-West University, Potchefstroom Campus, 2012.

The aim of this work was to get a detailed insight into the ion’s interactions along with the structure-making/structure-breaking tendency that has been retrieved through the perusal of calculated parameters from volumetric measurements for aqueous solutions of three newly synthesized ionic liquids: 1-butyl-3-methylimidazolium chlorite, 1-butyl-3-methylimidazolium chlorate and 1-butyl-3-methylimidazolium perchlorate. Further, the antimicrobial activity of synthesized and commercial (1-butyl-3-methylimidazolium chloride) ionic liquids on certain strains of bacteria and fungi was obtained. Antimicrobial tests were performed using the in vitro microdilution method against isolated strains of Escherichia coli, Staphylococcus aureus, Bacillus cereus bacteria, and the fungus Candida guilliermondii. This method is a rapid, quantitative method for the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using small amounts of samples (µl) and test compound. Based on the obtained results, the influence of the homologous series of chloride oxyanions on hydration and antimicrobial properties of imidazole-based ionic liquids will be discussed.

In this paper, I discuss and present the advanced experiments methods for thermochemical properties of plutonium in liquid gallium at 1073 k, application to plutonium cerium separation and the theoretical studies on Pu isotope transmutation. Electrochemical investigations on plutonium diluted in liquid gallium using molten chlorides showed that gallium can be used as solvent metal for pyrochemical processes involving plutonium at 1073 k. In particular, a selective extraction of plutonium from gallium by anodic oxidation is thermodynamically possible. The deposition of plutonium on a liquid gallium cathode is also possible with CaCl 2 as molten salt with a careful control of cathode potential.

In this study, bio-self-healing concrete was manufactured using a natural phenomenon called microbial-induced calcium carbonate precipitation (MICP). The bacillus cereus bacteria isolated from Qatari soil was used for this purpose. These bacteria have endured the harsh weather of high temperatures, humidity, and alkaline soil conditions. Hence, are a potential candidate for long-term self-healing in concrete structures that are subjected to the climate of the Middle Eastern region. The bacteria were encapsulated in sodium alginate beads then the beads were added to the cement-sand mortar. The nutrients for bacteria such as urea, calcium nitrate, yeast extract, and calcium chloride were mixed in mortar as dry constituents. After curing for 28 days, cracks were artificially induced in the prismatic samples, which were reinforced with steel rebars at the tensile side. Samples were placed in water to instigate self-healing. It was observed that the bacteria healed the cracks up to 0.70 mm. It is concluded that the used bacteria are viable in the alkaline concrete matrix and capable of producing calcium carbonate.

Environmental impacts associated with the mining of carbonatite deposits are an emerging concern due to the demand for critical metals. This study investigates the chemistry of tailings seepage at the former Saint Lawrence Columbium mine near Oka, Québec, Canada, which produced pyrochlore concentrate and ferroniobium from a carbonatite-hosted Nb-REE deposit. Its objectives are to characterize the mineralogy of the tailings and their pore water and effluent chemistries. Geochemical mass balance modeling, constrained by aqueous speciation modeling and mineralogy, is then used to identify reactions controlling the chemical evolution of pore water along its flow path through the tailings impoundment. The tailings are composed mainly of REE-enriched calcite (82 wt. %), biotite (12 wt. %) and fluorapatite (4 wt. %). Minor minerals include chlorite, pyrite, sphalerite, molybdenite and unrecovered pyrochlore. Secondary minerals include gypsum, barite and strontianite. Within the unsaturated zone, pore water chemistry is controlled by sulfide oxidation and calcite dissolution with acid neutralization. With increasing depth below the water table, pore water composition reflects gypsum dissolution followed by sulfate reduction and FeS precipitation driven by the oxidation of organic carbon in the tailings. Concomitantly, incongruent dissolution of biotite and chlorite releases K, Mg, Fe, Mn, Ba and F, forming kaolinite and Ca-smectite. Cation exchange reactions further remove Ca from solution, increasing concentrations of Na and K. Fluoride concentrations reach 23 mg/L and 8 mg/L in tailings pore water and effluent, respectively. At a pH of 8.3, Mo is highly mobile and reaches an average concentration of 83 µg/L in tailings effluent. Although U also forms mobile complexes, concentrations do not exceed 16 µg/L due to the low solubility of its pyrochlore host. Adsorption and the low solubility of pyrochlore limit concentrations of Nb to less than 49 µg/L. Cerium, from calcite dissolution, is strongly adsorbed although it reaches concentrations (unfiltered) in excess of 1 mg/L and 100 µg/L in pore water and effluent, respectively. Mine tailings from carbonatite deposits are enriched in a variety of incompatible elements with mineral hosts of varying reactivity. Some of these elements, such as F and Mo, may represent contaminants of concern because of their mobility in alkaline tailings waters.