Studies on electrochemical dissolution of sintered molybdenum discs as a potential method for targets dissolution in 99mTc production

Electrochemical dissolution of pressed into discs and sintered metallic molybdenum powder with the mass of 712 ± 10 mg (n = 15) in potassium hydroxide solution was studied in detail. The technique was considered to apply for dissolution of irradiated 100Mo target in the 99mTc production. The effect of various parameters, e.g., the concentration of the electrolyte solution, temperature, current density, and surface area of the platinum cathode, was investigated. The shortest time for total dissolution of molybdenum target was 70 min. This result was achieved using an electrolyte solution of 5 M KOH, temperature 55 °C and the current density of 365 mA/cm2.

Peningkatan Perolehan Uranium, Torium, dan Logam Tanah Jarang dalam Residu Pelarutan Parsial pada Pengolahan Monasit

ABSTRAK. Monasit merupakan mineral hasil samping pengolahan timah yang mengandung fosfat, logam tanah jarang, dan unsur radioaktif berupa uranium dan torium. Unsur-unsur tersebut dapat dimanfaatkan secara optimal jika terpisah satu dengan yang lainnya melalui proses pengolahan. Pengolahan monasit meliputi proses dekomposisi, pelarutan parsial, dan pengendapan. Pemisahan unsur logam tanah jarang dari unsur radioaktif dalam monasit dilakukan melalui proses pelarutan parsial, akan tetapi pemisahan tersebut belum optimal sehingga diperlukan proses lebih lanjut untuk meningkatkan perolehan unsur-unsur tersebut. Pada penelitian ini, proses tersebut dilakukan melalui dua metode yaitu pelarutan total dengan asam klorida (HCl) yang bertujuan untuk melarutkan semua unsur dalam endapan dan pengendapan dengan ammonium hidroksida (NH4OH) yang bertujuan untuk memisahkan unsur radioaktif dan unsur logam tanah jarang. Kedua metode tersebut dilakukan pada kondisi optimum proses dengan berbagai variasi pH, suhu, dan waktu. Berdasarkan hasil pengamatan diperoleh bahwa kelarutan optimum masing-masing unsur sebesar 67,6% uranium, 15,3% torium, dan 50,8% LTJ pada kondisi proses pelarutan pH 1, pada suhu 80°C selama 2 jam. Sedangkan pada proses pengendapan diperoleh recovery pengendapan masing-masing unsur sebesar 57% uranium, 75,7% torium, 4,8% logam tanah jarang pada kondisi pH 6. Berdasarkan data tersebut disimpulkan bahwa uranium, torium, dan logam tanah jarang dapat larut pada kondisi proses pelarutan pH 1, suhu 80°C selama 2 jam, dan dapat dipisahkan pada kondisi pH pengendapan 6.ABSTRACT. Monazite is a by-product of tin processing containing phosphate, rare earth elements, and radioactive elements such as uranium and thorium. These elements can be utilized optimally if separated from one another through processing. Monazite processing includes decomposition, partial dissolution, and precipitation processes. The separation of rare earth elements from radioactive elements in monazite is carried out through a partial dissolution process, but the separation is not optimal so that further processes are needed to increase the recovery of these elements. In this study, the process was carried out using two methods, namely total dissolution with hydrochloric acid (HCl) which aims to dissolve all elements in the precipitate and precipitation with ammonium hydroxide (NH4OH) which aims to separate radioactive elements and rare earth elements. Both methods were carried out under optimum process conditions with various variations in pH, temperature, and time. Based on observations, it was found that the optimum solubility of each element was 67.6% uranium, 15.3% thorium and 50.8% LTJ under the dissolving process conditions of pH 1, at 80°C for 2 hours. While in the deposition process, the precipitation recovery of each element is 57% uranium, 75.7% thorium, 4.8% rare earth metals at pH 6 conditions. Based on these data, it can be concluded that uranium, thorium, and rare earth elements can be dissolved at pH 1, at 80°C for 2 hours, and can be separated at pH 6 precipitation conditions.

ANTHROPOGENIC IMPACTS ON THE WESTERN SECTOR OF SEPETIBA BAY (SE DO BRAZIL) ACCESSED BY THE PB ISOTOPE COMPOSITION OF SURFACE SEDIMENTS

This work analyses lead concentrations and isotope ratios 204Pb,206Pb,207Pb,208Pb, determined by leaching and total dissolution techniques from surface bottom sediment samples collected in the western sector of Sepetiba Bay, Rio de Janeiro (SE Brazil). The main aim of this work was to identify possible sources of Pb, particularly those related to anthropogenic activities for the study area located in the external region of this bay. Isotope ratios of 206Pb, 207Pb ranged from 1.160 to 1.259 for the total dissolution technique and from 1.175 to 1.188 for the leaching technique. The Pb isotope signature of the surface sediments of the western sector of Sepetiba Bay were compared with that obtained in other studies performed in Sepetiba Bay, including records of pre- and pos-industrial activity, and in other Brazilian regions. The isotope signature of the analyzed sediments in the western sector of Sepetiba Bay is similar to that obtained in previous works realized in the eastern and northeastern internal region of this bay which is under strong urbanization and industrial pressure. The results of Pb isotope signature obtained by the integrated use of total dissolution and leaching techniques allowed to trace the presence of sediments dredged from highly contaminated areas located in the eastern and north-eastern internal region of Sepetiba Bay probably as a consequence of dredging activities and natural processes of sediment dispersion. IMPACTOS ANTROPOGÊNICOS NO SETOR OESTE DA BAÍA DE SEPETIBA (SE DO BRASIL) ACESSADOS PELA COMPOSIÇÃO ISOTÓPICA DE PB DE SEDIMENTOS SUPERFÍCIAIS ResumoEste trabalho analisa as concentrações de chumbo (Pb) e isótopos de Pb (204Pb, 206Pb, 207Pb, 208Pb) determinados por técnicas de lixiviação e dissolução total de amostras de sedimentos de fundo, coletadas no setor oeste (região externa) da Baía de Sepetiba, no Rio de Janeiro (SE Brasil). O principal objetivo deste trabalho foi identificar possíveis fontes de Pb, principalmente aquelas relacionadas a atividades antropogênicas na área de estudo. A assinatura do isótopo Pb dos sedimentos analisados foi comparada com os dados obtidos em outros estudos realizados na Baía de Sepetiba e em outras regiões brasileiras, incluindo registros de atividade pré e pós-industrial. Na região externa da Baía de Sepetiba, os valores de 206Pb/207Pb variaram de 1.160 a 1.259 para a técnica de dissolução total e de 1.175 a 1.188 para a técnica de lixiviação. A assinatura isotópica dos sedimentos analisados é semelhante à obtida em trabalhos anteriores realizados na região interna leste e nordeste desta baía, que está sob forte influência da urbanização e pressão industrial. Os resultados da assinatura dos isótopos de Pb obtidos pelo uso integrado das técnicas de dissolução total e lixiviação permitiram rastrear, no setor oeste (região externa) da Baía de Sepetiba, a presença de sedimentos provinientes de áreas altamente contaminadas localizadas na região interna leste e nordeste da baía de Sepetiba, provavelmente como conseqüência das atividades de dragagem e processos naturais de dispersão de sedimentos. Palavras-chave: Isótopos de Pb. Geoquímica. Atividades antropogênicas. Fonte de sedimentos. Impacto de dragagem. Litoral.

Fotografía y post-realidad

Resumen: La ya eterna crisis de los principales valores tradicionales de la fotografía sigue cuestionando su esencia y su papel en nuestra sociedad postmoderna. La abundancia de imágenes que invaden las pantallas de nuestros teléfonos inteligentes ha terminado por conformar una nueva realidad virtual que se superpone a nuestro mundo real y físico hasta prácticamente su total disolución, en lo que vendría a ser un nuevo estado de conciencia, que podríamos definir como post-realidad. El advenimiento de nuevos dispositivos de realidad aumentada ampliaría estos límites para crear un nuevo tipo de imágenes capaces de retratar distintos ámbitos, ya alejados del puro consumo de identidades ficticias surgidos a raíz del uso de redes sociales como Instagram. Palabras clave: Fotografía, post-realidad, Instagram, Realidad Aumentada Resumen en inglés: The already eternal crisis of the main traditional values of photography continues to question its essence and its role in our postmodern society. The abundance of images that invade the screens of our smartphones has ended up shaping a new virtual reality that overlaps our real and physical world until practically its total dissolution, in what would become a new state of consciousness, which we could define as post-reality. The advent of new augmented reality devices would expand these limits to create a new type of images capable of portraying different areas, already removed from the pure consumption of fictitious identities arising from the use of social networks like Instagram. Key words: Photography, post-reality, Instagram, Augmented Reality

Scandium and Titanium Recovery from Bauxite Residue by Direct Leaching with a Brønsted Acidic Ionic Liquid

In this study, bauxite residue was directly leached using the Brønsted acidic ionic liquid 1-ethyl-3-methylimidazolium hydrogensulfate. Stirring rate, retention time, temperature, and pulp density have been studied in detail as the parameters that affect the leaching process. Their optimized combination has shown high recovery yields of Sc, nearly 80%, and Ti (90%), almost total dissolution of Fe, while Al and Na were partially extracted in the range of 30–40%. Si and rare earth element (REEs) dissolutions were found to be negligible, whereas Ca was dissolved and reprecipitated as CaSO4. The solid residue after leaching was fully characterized, providing explanations for the destiny of REEs that remain undissolved during the leaching process. The solid residue produced after dissolution can be further treated to extract REEs, while the leachate can be subjected to metal recovery processes (i.e., liquid–liquid extraction) to extract metals and regenerate ionic liquid.

Dissolution and Solubility Product of Cd-Fluorapatite [Cd5(PO4)3F] at pH of 2–9 and 25–45°C

Dissolution of the synthetic cadmium fluorapatite [Cd5(PO4)3F] at 25°C, 35°C, and 45°C was experimentally examined in HNO3 solution, pure water, and NaOH solution. The characterization results confirmed that the cadmium fluorapatite nanorods used in the experiments showed no obvious variation after dissolution. During the dissolution of Cd5(PO4)3F in HNO3 solution (pH = 2) at 25°C, the fluoride, phosphate, and cadmium ions were rapidly released from solid to solution, and their aqueous concentrations had reached the highest values after dissolution for <1 h, 1440 h, and 2880 h, respectively. After that, the total dissolution rates declined slowly though the solution Cd/P molar ratios increased incessantly from 1.55∼1.67 to 3.18∼3.22. The solubility product for Cd5(PO4)3F (Ksp) was determined to be 10−60.03 (10−59.74∼10−60.46) at 25°C, 10−60.38 (10−60.32∼10−60.48) at 35°C, and 10−60.45 (10−60.33∼10−60.63) at 45°C. Based on the log Ksp values obtained at an initial pH of 2 and 25°C, the Gibbs free energy of formation for Cd5(PO4)3F (ΔGf0) was calculated to be −4065.76 kJ/mol (−4064.11∼−4068.23 kJ/mol). The thermodynamic parameters for the dissolution process were computed to be 342515.78 J/K·mol, −85088.80 J/mol, −1434.91 J/K·mol, and 2339.50 J/K·mol for ΔG0, ΔH0, ΔS0, and ΔCp0, correspondingly.

Effective management of bone fractures with the IlluminOss® photodynamic bone stabilization system: initial clinical experience from the European Union registry

The IlluminOss^® system (IS) uses a light-curable polymer contained within an inflatable balloon catheter, forming a patient customized intramedullary implant. A registry was established in Germany and The Netherlands to prospectively collect technical and clinical outcomes in patients treated with IS for fractures of the phalange, metacarpal, radius, ulna, distal radius, fibula, clavicle and/or olecranon. Humeral, femoral, tibial and pelvic fractures were included under compassionate use. Procedural success included successful placement of the device at the target fracture site and achievement of fracture stabilization. Clinical and radiographic assessments were made postoperatively through 12 months. One hundred thirty two patients (149 fractures) were enrolled with most fractures (85%) resulting from low-energy trauma. Simple fractures predominated (47%) followed by complex (23%) and wedge (16%) fractures. Procedural success was achieved in all patients and no implants required removal or revision. Normal range of motion was realized in 87% of fractures. Radiographically, there was substantial cortical bridging, total dissolution of the fracture line, and complete fracture healing. Across a variety of fracture types, the IS provides a safe and effective approach for rapid healing and functional recovery.

Homogenization Experiments of Crystal-Rich Inclusions in Spodumene from Jiajika Lithium Deposit, China, under Elevated External Pressures in a Hydrothermal Diamond-Anvil Cell

Extensive studies of the crystal-rich inclusions (CIs) hosted in minerals in pegmatite have resulted in substantially different models for the formation mechanism of the pegmatite. In order to evaluate these previously proposed formation mechanisms, the total homogenization processes of CIs hosted in spodumene from the Jiajika pegmatite deposit in Sichuan, China, were observed in situ under external H2O pressures in a new type of hydrothermal diamond-anvil cell (HDAC). The CIs in a spodumene chip were loaded in the sample chamber of HDAC with water, such that the CIs were under preset external H2O pressures during heating to avoid possible decrepitation. Our in situ observations showed that the crystals within the CIs were dissolved in carbonic-rich aqueous fluid during heating and that cristobalite was usually the first mineral being dissolved, followed by zabuyelite and silicate minerals until their total dissolution at temperatures between 500 and 720°C. These observations indicated that the minerals within the CIs were daughter minerals crystallized from an entrapped carbonate- and silica-rich aqueous solution and therefore provided useful information for evaluating the formation models of granitic pegmatites.

Design and Application of Removable Plugging Slurry for Fractured Carbonate Reservoir

To meet the requirements of leakage stopping and reservoir protection at the same time in fractured formation, the removable plugging slurries with high temperature tolerance were designed, evaluated and applied in the field successfully. Analysis shows that the fibre materials can deposit onto crack surface, bridge and seal fractures quickly and the selected particles can bridge in throat near wellbore. The comprehensive grading of filling particles was determined from the point of view of gradient filling. The designed plugging slurries KJD155 and KJD200 with higher total dissolution rates sealed 1 mm, 2 mm, 3 mm, and 4 mm crack blocks effectively at room temperature and high temperature (KJD155 at 155 °C; KJD200 at 200 °C) respectively. Their pressure bearing ability of them was up to 5 MPa under bottom hole conditions, which was beneficial to the next operation. Field application of the designed plugging slurries was carried out successfully and showed that they were removable and did smaller damage to reservoir.