Temat: dissolution - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Determination of leaching parameters for the recovery of platinum group metals from secondary materials
Autorzy:: Lillkung, K.
Aromaa, J.
Forsen, O.
Tematy:: platinum dissolution
palladium dissolution
rhodium dissolution
chloride concentration; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/109368.pdf Link otwiera się w nowym oknie
Opis:: The leaching parameters for the recovery of platinum group metals were investigated with potentiostatic measurements using wire electrodes. The dissolution rates of Pt, Pd and Rh were measured in concentrated NaCl solution. The parameters inspected were the temperature, redox potential and chloride content. Measurements were done at temperatures 25–94 °C using four different NaCl concentrations, 62.5–250 g/l. Measurements were done at potentials of 950–1250 mV vs. SCE for Pt and Rh and 380–470 mV vs. SCE for Pd. Although higher temperature, potential and chloride content generally increased the dissolution rate, the effect was found to be nonlinear and slightly different for different metals. Based on the results, strongly oxidizing conditions are needed for the leaching process in order to achieve reasonable dissolution rates.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Mercury-free dissolution of aluminum-based nuclear material: from basic science to the plant
Autorzy:: Crooks III, W.
Crown, J.
Dunn, K.
Mickalonis, J.
Murray, A.
Navratil, J.
Tematy:: aluminum dissolution
plutonium oxide dissolution
stainless steel corrosion
mercury-free; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/148380.pdf Link otwiera się w nowym oknie
Opis:: Conditions were optimized for the first plant-scale dissolution of an aluminum-containing nuclear material without using mercury as a catalyst. This nuclear material was a homogeneous mixture of plutonium oxide and aluminum metal that had been compounded for use as the core matrix in Mark 42 nuclear fuel. B ecause this material had later failed plutonium distribution specifications, it was rejected for use in the fabrication of Mark 42 fuel tubes, and was stored at the Savannah River Site (SRS) awaiting disposition. This powder-like material was composed of a mixture of ~80% aluminum and 11% plutonium. Historically, aluminum-clad spent nuclear fuels have been dissolved using a mercuric nitrate catalyst in a nitric acid (HNO3) solution to facilitate the dissolution of the bulk aluminum cladding. Developmental work at SRS indicated that the plutonium oxide/aluminum compounded matrix could be dissolved using boric acid-hydrofluoric acid-nitric acid as a substitute for mercury. Various mercury-free conditions were studied to evaluate the rate of dissolution of the Mark 42 compact material and to assess the corrosion rate to the stainless steel dissolver. The elimination of mercury from the dissolution process fit with waste minimization and industrial hygiene goals to reduce the use of mercury in the United States. The mercury-free dissolution technology was optimized for Mark 42 compact material in laboratory-scale tests, and successfully implemented at the plant.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: The Cistercians in the times of the monasteries dissolution : the case of Jędrzejów and Szczyrzyc : the monastery economy in Szczyrzyc in the first half of the 19th century
Cystersi w dobie kasat : przypadek Jędrzejowa i Szczyrzyca : gospodarka klasztoru w Szczyrzycu w pierwszej połowie XIX wieku
Autorzy:: Kargol, Tomasz
Wydawca:: Towarzystwo Wydawnicze "Historia Iagellonica"
na zlecenie Jędrzejowskiego Towarzystwa Kulturalno-Naukowego
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 4.

Tytuł:: Dissolution kinetics of secondary covellite resulted fromdigenitedissolutionin ferric/acid/chloride media
Autorzy:: Aracena, Alvaro
Espinoza, Camila
Jerez, Oscar
Carvajal, Danilo
Jaques, Aldonza
Tematy:: dissolution kinetics
digenite
covellite
diffusion; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/110306.pdf Link otwiera się w nowym oknie
Opis:: Dissolution kinetics of digenite (Cu₉S₅) was studied in Fe³+-H₂SO₄-NaCl media. The temperature range for the study was between 297 and 373 K (24 and 100°C), with a ferric concentration between 0.0100 and 0.0806 mol/dm³, a sulfuric acid concentration of 0.05 to 1.5 mol/dm3 and a NaCl concentration of 1.5 to 5 mol/dm3. Agitation speed and particle size were also studied. Results indicate that the dissolution mechanisms of digenite occurs in two stages: i) generation of covellite (CuS) with the formation of cupric ion (Cu²⁺) and ii) dissolution of covellite (CuS) with copper production in the system, as well as amorphous sulfur (S°). The second stage occurred very slowly compared to the first stage, the above variables studied directly affected the second stage. Temperature, Fe^{3+^{and H₂SO₄ concentration positively affected dissolution of covellite formed (second stage), while the presence of NaCl did not increase dissolution of Cu₉S₅ or CuS. Results showed that stirring speed had an important role in the dissolution rate of CuS. Dissolution kinetics was analyzed using the model of diffusion through the porous layer. Covellite dissolution reaction order was 2.3 and 0.2 with respect to the concentration of ferric and sulfuric acid, respectively, and the rate was inversely proportional to particle size. The calculated activation energy was 36.1 kJ/mol, which is a typical value for a reaction controlled by diffusion in the porous layer at temperature between 297 and 373 K (24 and 100°C).}}
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: The study of physicochemical properties of solid dispersions of ibuprofen in the presence of chitosan
Autorzy:: Grimling, Bożena
Meler, Jan
Szcześniak, Maria
Pluta, Janusz
Górniak, Agata
Tematy:: chitosan
dissolution
ibuprofen
solid dispersion; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Powiązania:: https://bibliotekanauki.pl/articles/1034797.pdf Link otwiera się w nowym oknie
Opis:: The aim of the present study was to increase the solubility of ibuprofen. Among the methods to increase the solubility selected solid dispersions of the drug with the polymer. Chitosan was used as the polymer. Solid dispersion obtained. Ibuprofen was incorporated into the chitosan type 652 with molar masse chitosan Mη = 429 kDa. Solid dispersions were prepared by using different ratios of ibuprofen and chitosan (1:9. 3:7 and 5:5). Formulations were tested dissolution rate of the ibuprofen. The highest dissolution of ibuprofen, amounting to 12.59%, was observed after 60 minutes from solid dispersion prepared by the evaporation method and 12.18% from physical mixtures with drug-polymer weight ratio 1:9 in the presence chitosan. The solubility of the drug improved more than 60-fold. XRPD analysis indicates the presence of the ibuprofen in amorphous form in the solid dispersion obtained by the modified solvent evaporation.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Investigation of fenofibrate solubility in the presence of chitosan
Autorzy:: Grimling, Bożena
Meler, Jan
Pluta, Janusz
Tematy:: chitosan
dissolution
fenofibrate
solid state; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Powiązania:: https://bibliotekanauki.pl/articles/1035391.pdf Link otwiera się w nowym oknie
Opis:: Fenofibrate is an active substance which is well absorbed from the gastrointestinal tract, but it is characterized by limited solubility. Due to a wide spectrum of its pharmacological activity, it would be beneficial to improve its solubility, and thus increase the drug absorption capability. The aim of the study was to investigate the effect of chitosan on the solubility of fenofibrate incorporated into this polymer carrier. The study investigated fenofibrate in solid dispersions at the drug to polymer ratio of 3:7,5:5,7:3. The solubility investigation was performed by means of a dynamic method in a dissolution apparatus; mean amount of dissolved fenofibrate and the drug to polymer quantitative ratio in which the solid dispersion possessed the most beneficial properties improving the drug solubility were calculated. The study revealed a multi-fold increase (from 33 to 50 times) in fenofibrat solubility in the presence of chitosan, which increased with duration of the study and with increasing percentage of the polymer in formulations. The obtained results may help develop new technologies for fenofibrate preparations with chitosan, with better solubility characteristics, and thus increased bioavailability of the drug.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Corrosion of carbonate speleothems by an allogenic river inferred from petrography and a weight loss experiment : a case study from the Demänová Cave System, Slovakia
Autorzy:: Sala, Przemysław
Bella, Paweł
Tematy:: Karst
carbonates
hiatus
dissolution
palaeoenvironment; Pokaż więcej
Wydawca:: Polskie Towarzystwo Geologiczne
Powiązania:: https://bibliotekanauki.pl/articles/27311293.pdf Link otwiera się w nowym oknie
Opis:: The crystallization of speleothems can be interrupted by the invasion of allogenic water into cave passages. These interruptions were studied, both in speleothems currently submerged in an underground river and in speleothem sections, which were found at the lowermost fluvially active passage level of the Demänová Cave System. The interaction between speleothems and allogenic water, undersaturated with respect to calcite, is manifested in the presence of siliciclastic material and the corrosion of calcite crystals. The progressive development of corrosion features depends on the duration of the interaction of calcite crystals with allogenic water. Moreover, the movement of the water and siliciclastic deposition over the speleothems can influence the corrosion process. The estimated rate of corrosion, caused by the underground Demänovka River and measured by the weight loss of experimental tablets, is up to 0.029 mm/y. U-series dating indicated that the interaction of speleothems with allogenic water occurred during the Vistulian (Weichselian). The identification of corrosion episodes, caused by allogenic water, is a step towards understanding the origin of hiatuses and establishing criteria for recognition of them.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: IMPACT OF EXCIPIENTS ON PHARMACEUTICAL AVAILABILITY OF FOLIC ACID FROM TABLETS
Autorzy:: Ostróżka-Cieślik, Aneta
Dolińska, Barbara
Ryszka, Florian
Tematy:: folic acid
dietary supplements
dissolution testing; Pokaż więcej
Wydawca:: Polskie Towarzystwo Farmaceutyczne
Powiązania:: https://bibliotekanauki.pl/articles/895567.pdf Link otwiera się w nowym oknie
Opis:: The impact of excipients contained in individual formulations on the pharmaceutical availability of folic acid was investigated. The release rate of the active substance and the disintegration time of the tablets were analysed. It has been found that in the presence of sorbitol, glucose and starch, 100% of folic acid is released within 60 minutes, and in the presence of lactose and starch - 95%, and the release rates for them are 0.0717 min-1 and 0.0555 min-1 respectively.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Dissolution kinetics of hemimorphite in methane sulfonic acid
Autorzy:: Zhang, Qian
Wen, Shuming
Feng, Qicheng
Nie, Wenlin
Wu, Dandan
Tematy:: hemimorphite
methane sulfonic acid
dissolution
kinetics; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/110482.pdf Link otwiera się w nowym oknie
Opis:: Hemimorphite has a large content of zinc, but its recovery using flotation alone is low. Nowadays, hydrometallurgical and pyrometallurgical methods are used to treat zinc ores. In this work, the leaching and dissolution kinetics of hemimorphite by using methane sulfonic acid (MSA) as an alternative leaching reagent was investigated. The effects of several experimental parameters including reaction temperature, MSA concentration, particle size, and stirring speed were also analyzed. Results showed that zinc leaching increased with increased reaction temperature, MSA concentration, and stirring speed, as well as decreased particle size. The mechanism of hemimorphite dissolution in MSA solutions may be a new variant of the shrinking-core model. Based on experimental data and kinetics, the apparent activation energy was determined to be 49.50 kJ/mol. The rate of reaction equation was also obtained to describe the process and found that the MSA concentration largely influenced the leaching of hemimorphite.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Synthesis and solubility of hopeite Zn₃(PO₄)₂·4H₂O
Autorzy:: Bajda, Tomasz
Rogowska, Melania
Pawłowska, Agnieszka
Tematy:: zinc
phosphate
apatite
dissolution
solubility product; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mineralogiczne
Powiązania:: https://bibliotekanauki.pl/articles/46220160.pdf Link otwiera się w nowym oknie
Opis:: Minerals from the phosphate groups are used in environmental engineering as thermodynamically stable vehicles for heavy metals such as zinc. The hopeite Zn₃(PO₄)₂·4H₂O was synthesized and characterized by X-ray diffraction and scanning electron microscopy. The solubility of the hopeite was measured at 25°C. The average solubility product, log K_sp, for the reaction Zn₃(PO₄)₂·4H₂O ⇔ 3Zn²⁺ + 2PO₄ ³⁻ + 4H₂O at 25°C is –35.72 ± 0.03. The free energy of formation, ΔG°f ,298, calculated from this measured solubility product is –3597.4 ± 1.0 kJ mol−1. The immobilization of zinc in the hopeite structure offers the possibility of developing an effective method for removing Zn from wastewater, water and soils.
Dostawca treści:: Biblioteka Nauki

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