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Letteratura scientifica selezionata sul tema "Alkaline-Earth metal cations"

Autore: Grafiati

Pubblicato: 15 febbraio 2025

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Articoli di riviste sul tema "Alkaline-Earth metal cations"

Ustimova, M. A., A. Yu Lebedeva, Yu V. Fedorov, D. V. Berdnikova e O. A. Fedorova. "FRET-based metal ion sensing by a crown-containing bisstyryl dye". New Journal of Chemistry 42, n. 10 (2018): 7908–13. http://dx.doi.org/10.1039/c8nj00205c.

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Tsuzuki, Seiji, Toshihiko Mandai, Soma Suzuki, Wataru Shinoda, Takenobu Nakamura, Tetsuya Morishita, Kazuhide Ueno et al. "Effect of the cation on the stability of cation–glyme complexes and their interactions with the [TFSA]− anion". Physical Chemistry Chemical Physics 19, n. 28 (2017): 18262–72. http://dx.doi.org/10.1039/c7cp02779f.

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Novikov, G. V., N. V. Lobus, N. A. Shulga e O. Yu Bogdanova. "Adsorption of Rare Earth Metal Cations by Base Metal Sulfides in the Broken Spur and TAG Hydrothermal Fields, Atlantic Ocean". Литология и полезные ископаемые, n. 1 (1 gennaio 2023): 38–49. http://dx.doi.org/10.31857/s0024497x23010068.

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The article presents the results of sorption of rare earth metal cations on samples of deepsea polymetallic sulfides of the hydrothermal fields of the Broken Spur and TAG of the Mid-Atlantic Ridge. The main minerals of these samples were respectively marcasite, pyrrhotine, pyrite, sphalerite and chalcopyrite, pyrite, and marcasite. It has been established that these sulfide minerals of iron, copper and zinc are natural adsorbents. The exchange capacity of sulfide minerals for rare earth metal cations is in the range of 0.006‒0.061 mg-eq/g. The exchange complex of sulfide minerals consists of cations of alkaline, alkaline-earth metals and basic cations of metals of the crystal lattice – Fe, Zn, Cu (in very limited quantities). The mechanism of absorption of rare earth metal cations is ion-exchange, equivalent to the exchange cations of sulfide minerals. It was found that in the composition of sulfide minerals, rare earth metal cations are almost completely in sorbed form (more than 90% of the total amount); The chemically bound form can be, apparently, only for Lu and Dy cations. The mineral composition of sulfide deposits is preserved in the products of exchange reactions, new phases do not appear.

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Usenik, Andrea, Matija Modrušan, Katarina Leko, Jakov Borovec, Sven Marinac, Lucija Hok, Nikola Cindro et al. "A Combined Thermodynamic and Computational Study of Alkaline Earth Metal Cations Complexation by a Fluorescent Calix[4]arene Receptor". International Journal of Molecular Sciences 26, n. 3 (31 gennaio 2025): 1264. https://doi.org/10.3390/ijms26031264.

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Complexation of alkaline earth metal cations with fluorescent tertiary-amide lower-rim calix[4]arene derivative bearing two phenanthridine moieties was studied experimentally (UV spectrophotometry, fluorimetry, isothermal microcalorimetry, NMR spectroscopy) and computationally (classical molecular dynamics and DFT calculations) at 25 °C. The complexation reactions were studied in acetonitrile, methanol, and ethanol, whereby the solvent effect on cation-binding processes was particularly addressed. The complex stability constants and standard reaction thermodynamic quantities (Gibbs energies, enthalpies, and entropies) were determined. The receptor exhibited particularly high affinity towards alkaline earth metal cations in acetonitrile, with peak affinity for Ca2+. The stability of all complexes was significantly lower in ethanol and methanol, where the most stable complex was formed with Sr2+. The decrease in cation-binding abilities was a consequence of the differences in solvation of the reactants and products of the complexation reactions (involving inclusion of the solvent molecule in the calixarene cone), cation charge density, as well as the cation–ligand binding site compatibility. The reactions were enthalpically controlled in acetonitrile, whereas in methanol and ethanol, the binding processes were endothermic and thus entropy driven. The results of 1H NMR measurements, MD simulations, and DFT calculations provided an insight into the structure of the complexes and the corresponding adducts with solvent molecules, as well as the structural aspects behind the differences in complexation thermodynamics. Due to the significant increase in its fluorescence upon cation binding, the studied calixarene derivative was proven to be a promising luminescent sensor for alkaline earth metal cations.

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Vetrova, Daria A., e Sergey A. Kuznetsov. "Study of alkaline earth metals cations influence on the electrochemical behaviour of the Ti (IV) / Ti (III) redox couple in the CsCl — CsF melt". Transactions of the Kоla Science Centre of RAS. Series: Engineering Sciences 13, n. 1/2022 (27 dicembre 2022): 51–57. http://dx.doi.org/10.37614/2949-1215.2022.13.1.008.

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The influence of the alkaline earth metal cations (Mg2+, Ca2+, Sr2+ и Ва2+) on the charge transfer kinetics of the Ti (IV) / Ti (III) redox couple in melts of alkali metal halides was studied by cyclic voltammetry method. Standard rate constants of charge transfer have been determined by the Nicholson method. The activation energies of the charge transfer process in the CsCl — CsF (10 wt. %) — K2TiF6 melt with the addition of alkaline earth metal cations were calculated.

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Sviben, Igor, Nives Galić, Vladislav Tomišić e Leo Frkanec. "Extraction and complexation of alkali and alkaline earth metal cations by lower-rim calix[4]arene diethylene glycol amide derivatives". New Journal of Chemistry 39, n. 8 (2015): 6099–107. http://dx.doi.org/10.1039/c5nj00805k.

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The metal-ion extraction abilities of calix[4]arene derivatives1and2are largely dependent on the type of the amide group forming the cation-binding site. Tertiary-amide derivative2was shown to be an excellent extractant for most alkali and alkaline earth cations.

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Zhu, Ming, Hongfang Ma, Mingjing Wang, Zhihua Wang e Adel Sharif. "Effects of Cations on Corrosion of Inconel 625 in Molten Chloride Salts". High Temperature Materials and Processes 35, n. 4 (1 aprile 2016): 337–45. http://dx.doi.org/10.1515/htmp-2014-0225.

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AbstractHot corrosion of Inconel 625 in sodium chloride, potassium chloride, magnesium chloride, calcium chloride and their mixtures with different compositions is conducted at 900°C to investigate the effects of cations in chloride salts on corrosion behavior of the alloy. XRD, SEM/EDS were used to analyze the compositions, phases, and morphologies of the corrosion products. The results showed that Inconel 625 suffers more severe corrosion in alkaline earth metal chloride molten salts than alkaline metal chloride molten salts. For corrosion in mixture salts, the corrosion rate increased with increasing alkaline earth metal chloride salt content in the mixture. Cations in the chloride molten salts mainly affect the thermal and chemical properties of the salts such as vapor pressure and hydroscopicities, which can affect the basicity of the molten salt. Corrosion of Inconel 625 in alkaline earth metal chloride salts is accelerated with increasing basicity.

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Fransen, John R., e Philip J. Dutton. "Cation binding and conformation of octafunctionalized calix[4]resorcinarenes". Canadian Journal of Chemistry 73, n. 12 (1 dicembre 1995): 2217–23. http://dx.doi.org/10.1139/v95-275.

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The preparations of four calix[4]resorcinarene esters and two calix[4]resorcinarene amides are reported. The logarithms of association constants have been determined by the picrate extraction method for a variety of metal cations, including alkali metal, alkaline earth, lanthanum, and silver cations. Strong binding toward silver ion, and selectivity amongst the alkaline earth cations, was observed for the octa-α-(diethyl acetamide) 3c. Flattened cone conformations have been established for both C-undecylcalix[4]resorcinarene octa-α-(methyl acetate), 3a, and octa-α-(diethyl acetamide), 3c, in chloroform solutions at 200 K. Dynamic nuclear magnetic resonance was used to identify rapid conformational interconversions of both 3a and 3c corresponding to pseudorotation between flattened cone conformations. The silver complex of 3c also exhibits pseudorotation; however, the activation barrier was observed to increase from 42 kJ mol−1 in the free ligand to 49 kJ mol−1 in the complex. The NMR data indicate that the metal cation binding occurs in a symmetrical fashion using two pairs of binding sites that are disposed across the macrocyclic ring from one another. Considering these data it is concluded that four carbonyl functions are involved in the binding of a metal cation in a 1:1 complex with the ligand. Key words: resorcinarene, picrate, association constant, dynamic NMR, pseudorotation.

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Bortun, Anatoly I., Lyudmila Bortun, Abraham Clearfield, Enrique Jaimez, María A. Villa-García, José R. García e Julio Rodríguez. "Synthesis and Characterization of the Inorganic Ion Exchanger Based on Titanium 2-carboxyethylphosphonate". Journal of Materials Research 12, n. 4 (aprile 1997): 1122–30. http://dx.doi.org/10.1557/jmr.1997.0155.

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An inorganic ion exchanger based on titanium 2-carboxyethylphosphonate (TiPC) has been synthesized by reaction between solutions of TiCl3 and 2-carboxyethylphosphonic acid at elevated temperature. The solid was characterized by chemical analysis, 31P MAS NMR, x-ray powder diffraction, IR spectroscopy, and TG analysis. It was found that TiPC is a highly crystalline layered solid with the interlayer distance 13.1 Å, and exhibits a high thermal stability. The intercalation of n-alkylamines and the ion exchange properties of TiPC toward alkali, alkaline earth, and some transition metal cations have been studied. The exchanger shows high affinity to alkaline earth metal cations and some di- and trivalent cations.

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GUAN, QING-MEI, YAN HAN e ZHONG-ZHI YANG. "MOLECULAR DYNAMICS STUDIES ON Fe2+, Co2+, AND Ni2+ AQUEOUS SOLUTIONS BASED ON ABEEM/MM FLUCTUATING CHARGE MODEL". Journal of Theoretical and Computational Chemistry 07, n. 06 (dicembre 2008): 1187–201. http://dx.doi.org/10.1142/s0219633608004519.

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Based on atom-bond electronegativity equalization method fused into molecular mechanics (ABEEM/MM), the intermolecular potential for transition metal ion Fe 2+, Co 2+, and Ni 2+ cations in water has been derived. Parameters for the effective interaction between a cation and a water molecule were determined by reproducing the ab initio results. Many structural and dynamic properties of Fe 2+(aq.), Co 2+(aq.), and Ni 2+(aq.) were studied using these potential parameters. Strong influences of the twofold charged cations on the structures of the hydration shells and some other properties of aqueous ionic solutions are discussed and compared with the results of a previous study of alkali metal and alkaline-earth metal cations in water. At the same time, comparative study of the hydration properties of each cation is also discussed. This work demonstrates that ABEEM/MM provides a useful tool in the exploration of the hydration of transition metal cations in water.

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Più fonti

Tesi sul tema "Alkaline-Earth metal cations"

Magisson, Aymeric. "Synthèse de nanοzeοlithes à petits pοres sélectifs". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMC253.

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L'objectif principal de cette thèse de doctorat est le développement de zéolithes à petits poresde taille nanométriques, ciblant une sélectivité d'adsorption élevée pour le CO2. Les deuxpremiers chapitres présentent l'état de l'art actuel sur diverses caractéristiques et propriétés deszéolithes, leurs voies de synthèse et applications. Les procédures de synthèse réalisées dans cetravail de thèse et les techniques de caractérisation utilisées sont également présentées. Letroisième chapitre décrit le comportement d'adsorption du CO2 à faible pression partielle dansle réseau poreux de la chabazite nanométrique (CHA) synthétisée en présence de cationscalcium et baryum utilisés comme agents structurants. Le quatrième chapitre détaille lacristallisation des phases pures et échantillons imbriqués de chabazite (CHA)/phillipsite (PHI).Les performances des zéolithes obtenues sont évaluées en adsorption de dioxyde de carbone etd'azote. Enfin, le cinquième chapitre présente le développement d'une procédure de synthèseautonome pour des zéolithes nanométriques, et détaille les étapes suivies afin d’optimiser sesconditions opératoires. Cette synthèse réalisée par un robot se situe à l'interface entre la synthèseà grande échelle et l'expérimentation par criblage, offrant les moyens de reproduire facilementdes synthèses exigeantes
The main objective of this PhD thesis is the development of small-pore nanosized zeolitestargeting a high adsorption selectivity towards CO2. The first two chapters present the currentstate of the art on various features and properties of zeolites, their synthesis routes, andapplications. The syntheses procedures carried out in this work and the characterisationtechniques used are presented. The third chapter describes the low partial pressure adsorptionbehaviour of CO2 in the porous network of nanometric Chabazite (CHA) synthesised in thepresence of calcium and barium cations used as structure-directing agents. The fourth chapterdetails the crystallisation of pure phases and intergrown chabazite (CHA)/Phillipsite (PHI)zeolite samples. The performance of the obtained zeolites is evaluated in adsorption of carbondioxide and nitrogen. Finally, the fifth chapter presents the development of an autonomoussynthesis procedure for nanosized zeolites and details the steps involved in optimising itsoperating conditions. This synthesis carried out by robot stands at the interface between largescalesynthesis and screening experimentation, providing the means to easily reproducechallenging syntheses

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Cheng, Wei-Sheng, e 鄭瑋昇. "Alkaline-earth Metal Cations and Transition Metal Cations Doped Metal-organic Framworks(MOFs) Effects on Hydrogen Adsorption". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/31630771863244993641.

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Capitoli di libri sul tema "Alkaline-Earth metal cations"

Läubli, Markus W. "Simultaneous determination of alkali and alkaline earth metal ions with isocratic ion chromatography using the SUPER-SEP cation column (according to Schomburg)". In Recent Developments in Ion Exchange, 31–39. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0777-5_4.

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Yu, T. R., e H. Y. Sun. "Specific Adsorption of Cations". In Chemistry of Variable Charge Soils. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195097450.003.0008.

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In the adsorption of cations by soils, except for the electrostatic force discussed in Chapter 3, specific forces between the surface of soil particles and the cations may sometimes be involved. The adsorption caused by these specific forces is called specific adsorption. Apparently, this adsorption would be related to both the nature of the cations and the surface properties of the soil. Generally speaking, various oxides are the principal materials responsible for specific adsorption of cations in soils. Variable charge soils contain large amounts of iron and aluminum oxides. At the same time, their negative surface charge sites that can attract cations electrostatically are small in quantity. It can be expected that, compared to constant charge soils, their specific adsorption for cations would have more significance. Most of the cation species that can be adsorbed specifically by soils, such as copper, zinc, cobalt, and cadmium, belong to heavy metals. A large part of these heavy metals are transition elements in the periodic table. Alkali metal and alkaline earth metal ions can also be adsorbed specifically to some extent by soils under certain circumstances. However, this kind of adsorption is of less importance when compared to electrostatic adsorption, and the mechanism involved may be different from that for heavy metals. Among heavy metals, zinc occupies a special position in soil science because it is one important nutrient element for plants. In this chapter, after treatment on the principles of specific adsorption of heavy metal ions, detailed discussions will be presented for both the relative importance of specific adsorption and electrostatic adsorption of these ions and the consequences of specific adsorption, using the adsorption of zinc ions as an example. The cause of the difference in properties between the transition metal ions and the alkali metal and alkaline earth metal ions with respect to adsorption lies primarily in the difference in their atomic structure. Alkali metal and alkaline earth metal ions are characterized by a small amount of electric charge in the atomic nucleus, large ionic size, and weak polarizability. Therefore, the atom is difficult to deform.

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Puchta, Ralph, Ewa Pasgreta e Rudi van Eldik. "Ligand exchange processes on the smallest solvated alkali and alkaline earth metal cations: An experimental and theoretical approach". In Advances in Inorganic Chemistry, 523–71. Elsevier, 2009. http://dx.doi.org/10.1016/s0898-8838(09)00209-8.

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Wang, J. H. "Lime Potential". In Chemistry of Variable Charge Soils. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195097450.003.0015.

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The properties of hydrogen and aluminum ions have been examined in Chapters 10 and 11. These two ion species are ions that directly induce the acid reaction in soils. In soils devoid of soluble salts, the content of cations is constant and the negative surface charges are saturated by, besides hydrogen and aluminum ions, alkali metal and alkaline earth metal ions. These ions are called base ions. The acidity of a soil is determined chiefly by the ratio of the quantity of hydrogen and aluminum ions to that of base ions. Among these base ions, calcium ions occupy the most important position, because they generally account for 65-80% of the total amount of base ions in variable charge soils. Therefore, calcium is an ion species closely related to the acidity of soils. In addition to the parameter pH that directly reflects the concentration of hydrogen ions, one other desirable way is to find a parameter that can reflect the ratio of the hydrogen ions to the calcium ions. This parameter is the lime potential. Since the introduction of the concept of lime potential 40 years ago, little practical application has been made in soil science, although some further theoretical considerations were advanced in the 1950s and the 1960s. Actually, as shall be seen in this chapter, for strongly acid soils, such as variable charge soils, because the quantity of hydrogen ions is too high and at the same time the quantity of calcium ions is too low, lime potential that can reflect the relative ratio of these two ion species is of significance not only in theory but also in practice. The mathematical expression of lime potential is pH-0.5pCa. Lime potential is a simple function of the chemical potential of calcium hydroxide, lime. Hence it may be called lime potential. The physical meaning of pH-0.5pCa can be derived as follows.

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Atti di convegni sul tema "Alkaline-Earth metal cations"

Mosses, R. W., J. P. R. Wells, T. P. J. Han, H. G. Gallagher e M. Yamaga. "Spectroscopy of Rare-Earth Doped Perovskite Phase Strontium Lanthanum Aluminate". In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cthh47.

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Strontium lanthanum aluminate (SrLaAlO4) belongs to a wide family of compounds with the general formula ABCO4 (where A denotes an alkaline earth cation: B denotes Y. Sc or a trivalent rare earth element and C denotes Al, Ga or a transition metal ion). This material crystallises in the perovskite phase, with tetragonal K2NiF4 structure having space group 14/mmm. The structure is composed of CO6 layers in the ab plane. The C cations are surrounded by six oxygens and sit in slightly distorted octahedral sites. Between these layers, the A cations and trivalent B cations are randomly distributed in nine co-ordinated sites of C4v symmetry. The random distribution of Sr2+ and La3+ ions leads to a structural disorder that causes inhomogeneous broadening of the spectral lines of rare-earth ions doped into these crystals.

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Kohlin, Lee, Hayden Pritchard, Behrooz Heidari DehKordi, Adam C. Gladen e Dilpreet Bajwa. "Investigation on the Catalytic Ability of Alkaline Earth Metal Cations and Nitrite Anions on Low Temperature Molten Salt Torrefaction". In ASME 2024 18th International Conference on Energy Sustainability collocated with the ASME 2024 Heat Transfer Summer Conference and the ASME 2024 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/es2024-131470.

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Abstract The present study investigates the catalytic ability of alkaline earth metal nitrates (calcium and magnesium nitrate), of nitrite (NO2) anions, and of low lithium nitrate-containing salt blends on low temperature molten salt torrefaction of ponderosa pine and cave-in-rock switchgrass. Severity of torrefaction is characterized by analyzing mass yields, higher heating values (HHV), chemical composition, and pH of the torrefied biomass. Results show that torrefaction with magnesium nitrate produces a solid, non-water-soluble byproduct and results in low torrefied biomass mass yields. However, Mg appears to be more catalytic than Ca, wherein Mg decomposes cellulose and hemicellulose to a greater degree than Ca from torrefaction at the same temperature. Based on mass yields and chemical composition at 240°C, Ca is slightly more catalytic than K. Additionally, at 240°C, blends containing Ca are shown to have simultaneously higher mass yields and HHV compared to inert gas torrefaction, effectively increasing energy yields. The reactivity of nitrite anions increases sensitivity to temperature and provides severe decomposition of pine. For example, the HHV of pine torrefied in nitrites at 190°C is 0.31MJ/kg higher than pine torrefied in inert gas at 240°C. For salts containing a small amount of lithium nitrate, changes in the lithium content impacts the torrefaction severity. Increasing lithium content from 3wt% to 5wt%, results in more than a 4% increase in HHV for both feedstocks and a large decrease in mass yield of pine (12%) and switchgrass (23%).

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Amamoto, Ippei, Naoki Mitamura, Tatsuya Tsuzuki, Yasushi Takasaki, Atsushi Shibayama, Tetsuji Yano, Masami Nakada e Yoshihiro Okamoto. "Removal of Fission Products in the Spent Electrolyte Using Iron Phosphate Glass as a Sorbent". In ASME 2010 13th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2010. http://dx.doi.org/10.1115/icem2010-40272.

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This study is carried out to make the pyroprocessing hold a competitive advantage from the viewpoint of environmental load reduction and economical improvement. As one of the measures to reduce the volume of the high-level radioactive waste (HLW), the phosphate conversion method is applied for removal of fission products (FP) from the melt, referring to the spent electrolyte in this paper. Among the removing target chlorides in the spent electrolyte i.e., alkali metals, alkaline earth metals and rare earth elements, only the rare earth elements and lithium form the precipitates as insoluble phosphates by reaction with Li3PO4. The sand filtration method was applied to separate FP precipitates from the spent electrolyte. The iron phosphate glass (IPG) powder, which is a compatible material for the immobilization of FP, was used as a filter medium. After filtration experiment, it was proven that insoluble FP could almost be completely removed from the spent electrolyte. Subsequently, we attempted to separate the dissolved FP from the spent electrolyte. The IPG was being used once again but this time as a sorbent instead. This is possible because the IPG has some unique characteristics, e.g., changing the valence of iron, which is one of its network modifiers due to its manufacturing temperature. Therefore, it would be likely to sorb some FP when the chemical condition of IPG is unstable. We produced three kinds of IPG under different manufacturing temperature and confirmed that those glasses could sorb FP as anticipated. According to the experimental result, its sorption efficiency of metal cations was attained at around 20–40%.

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Ge, Xiaojing, Ghith Biheri, Abdulmohsin Imqam, Baojun Bai e Yuwei Zhang. "Experimental Study: Investigating the Anions and Cations’ Effects on the Elasticity of the Anionic and Cationic High Viscosity Friction Reducers". In SPE Western Regional Meeting. SPE, 2023. http://dx.doi.org/10.2118/213048-ms.

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Abstract High viscosity friction reducers (HVFRs) are widely used as friction-reducing agents and proppant carriers during hydraulic fracturing. The reuse of produced water has gained popularity due to environmental and economic benefits. Currently, the field’s most commonly used friction reducers are anionic and cationic HVFRs. Anionic HVFRs are typically pumped with freshwater, while cationic HVFRs are used with high Total Dissolved Solids (TDS) produced water. Cationic friction reducers are believed to have better TDS tolerance, friction reduction performance, and proppant transport capabilities compared to anionic friction reducers under high TDS conditions due to their superior viscoelastic properties. In addition, the impact of different anions and cations on the viscosity of HVFRs has been thoroughly studied, and viscosity reduction mechanisms include charge shielding, increasing the degree of hydrolysis, and forming coordination complexes. However, anions and cations’ effects on the elasticity of HVFRs still remain to be investigated. Besides, most previous experimental studies either do not specify experimental procedures or control the experimental variables well. Therefore, the ultimate objective of this experimental study is to analyze various cations and anions’ effects on the elasticity of anionic and cationic HVFRs comparably and precisely with experimental variables well controlled. Two hypotheses based on anions and cations’ effects on the viscosity of HVFRs are proposed and will be tested in this study. First, the elasticity reduction of anionic HVFRs is mainly due to cations, whereas the elasticity reduction of cationic HVFRs is mainly due to anions. Second, the salts’ effects on the elasticity reduction of HVFRs should follow the same trend as the salts’ effects on the viscosity reduction of HVFRs. For anionic HVFRs, monovalent Alkali metals should have a similar effect; divalent Alkaline earth metals should have a similar effect; transition metals should have the most severe effect. For cationic HVFRs, SO42- should have more pronounced effects than Cl-. To demonstrate both hypotheses, an anionic and a cationic HVFR at 4 gallons per thousand gallons (GPT) were selected and analyzed. The elasticity measurements of both anionic and cationic HVFRs were conducted with deionized (DI) water and various salts respectively. Fe3+ and H+ (or pH) effects were specifically investigated. The results showed both hypotheses were accepted.

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Weber, Marvin J., J. Wong, R. B. Greegor, F. W. Lytle e D. R. Sandstrom. "Optically detected x-ray absorption spectroscopy of luminescent materials". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.mgg2.

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X-ray absorption near edge and extended fine structure (EXAFS/XANES) has been observed from luminescence excitation spectra of crystals and glasses using synchrotron radiation. The luminescence may either be intrinsic (recombination radiation from alkaki halides, alkaline earth fluorides, oxides) or from activator ions (rare earths, transition metals, organic dyes) excited directly or indirectly. Core electron excitations of cations and anions in luminescent materials have been investigated in the energy range from the VUV to hard x-rays. Absorption features may appear as an increase or decrease in the luminescence intensity depending on the sample thickness with respect to the x-ray absorption length, observation geometry, and intermediate relaxation processes. For materials with multiple sites, conventional x-ray absorption spectroscopy measures some average of different site populations. Since luminescence spectra vary with the local environment, using optical detection measurements can be both atom specific via the characteristic x-ray absorption edge energy and site and valence specific via the optical wavelength.

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