Journal articles: 'Sulfuros de cobre'

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Orozco Santander, Ivana Marcela, Vanesa Lucia Bazan, Andrea Alejandra Diaz, and Rodolfo Francisco Lara. "Tostación de sulfuros por reducción carbotérmica." DYNA 83, no. 198 (September 1, 2016): 228. http://dx.doi.org/10.15446/dyna.v83n198.50769.

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El proceso de reducción carbotérmica es una reducción directa de sulfuros. Permite realizar una tostación en donde se obtienen concentraciones mayores de metales como molibdeno, empleando un agente reductor (en este caso, el carbón C) y un captador de azufre como el CaO, evitando la contaminación del aire con gases tóxicos como el SO2. En este trabajo se analizan concentrados sulfurados ricos en cobre, hierro y molibdeno, obtenidos por flotación rougher y flotaciones diferenciales, dando origen a diferentes leyes. Los concentrados se sometieron al proceso de reducción carbotérmica en donde se estudiaron los parámetros de trabajo. Se ajustaron los valores del agente captador y reductor, para retener las mayores concentraciones de azufre. Analizando los resultados obtenidos se fijó la temperatura, el tiempo óptimo de trabajo y optimas relación molar del CaO y C para los cuales se alcanzó la mayor recuperación de metales como el molibdeno.

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Huarachi-Olivera, Ronald, Alex Dueñas-Gonza, Ursulo Yapo, Moisés Almanza, Dennys Manuel, Antonio Lazarte-Rivera, Gelbert Mogrovejo-Medina, Homar Taco-Cervantes, and Mario Esparza. "Biolixiviación de mineral cuarzo por Acidithiobacillus ferrooxidans en reactor de columna por gravedad." Revista de Metalurgia 53, no. 2 (June 7, 2017): 096. http://dx.doi.org/10.3989/revmetalm.096.

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La biolixiviación es el proceso mediante el cual se extrae cobre de minerales sulfuros de baja ley usando microorganismos. La lixiviación química se aplica preferentemente para extraer cobre de minerales oxidados o mixtos, pero no existe información de aplicación de microorganismos en esta operación. En tal sentido, en la presente investigación se trabajó con reactores en columna por gravedad para procesos de lixiviación química, con cultivos bacterianos de Acidithiobacillus ferrooxidans en medio 9K y mineral de cuarzo que contenía cuprita y pirita, con diferentes tamaños de partícula. Se encontró que después de 24 días de lixiviación química se recuperó el 86% de cobre cuando se incluyeron bacterias, mientras que sin ellas sólo se recuperó el 54%. La mayor recuperación de cobre en ambos procesos se obtuvo en el siguiente orden de acuerdo al tamaño de partícula: 9,5 mm > 12,5 mm > 19,05 mm. Así, la aplicación de células bacterianas a procesos lixiviación química con minerales oxidados de cobre que incluyen cuarzo y células de A. ferrooxidans, aumenta la recuperación de cobre cuanto menor sea el tamaño de partícula del mineral. Esta tecnología puede ser utilizada por empresas mineras que aún siguen realizando lixiviación química convencional y se puede incluir en la operación la adición de microorganismos para aumentar la recuperación de cobre de minerales sulfurados incluyendo cuarzo.

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Arias Arce, Vladimir Alejandro, Daniel Florencio Lovera Dávila, Abad Flores Paucarima, and Tito Libio Sánchez Rojas. "Correlación del potencial óxido reducción y la población bacteriana durante el estudio de biolixiviación de sulfuros de cobre." Revista del Instituto de investigación de la Facultad de minas, metalurgia y ciencias geográficas 24, no. 47 (June 18, 2021): 19–28. http://dx.doi.org/10.15381/iigeo.v24i47.20639.

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Se estudio la correlación de las variables población bacteriana y potencial de óxido reducción (ORP) en la biolixiviación de minerales sulfurados mediante cepa bacteriana de Acidithiobacilus Ferrooxidans aisladas a partir de efluente ácido de mina, buscando la solubilización del cobre y la liberación del oro presente en un mineral con sulfuros superior a 80%. Las variables de experimentación fueron: La densidad de pulpa a 1, 2 y 6 % (W/V), concentración de sulfato ferroso como parte del medio 9k de 0, 3, 6, 9 y 15 gr/L; manteniendo constante la temperatura, agitación del medio y el pH. Los ensayos se realizaron en tres etapas consecutivas, iniciándose con inoculo conteniendo 7.05x107 Cel/mL y luego, la obtenida en cada etapa previa, observándose la variación en los periodos de adaptación y crecimiento. En la primera etapa la máxima población bacteriana alcanzada fue de 4.75x107 Cel/mL en 24 días con 6 g/L de sulfato ferroso. En la segunda etapa se obtuvo una máxima densidad de 6.30x107 Cel/mL sin la adición de sulfato ferroso. En la tercera etapa la densidad bacteriana alcanzada fue de 4.51x107 Cel/mL., con inicios de crecimiento exponencial aproximadamente a los 13, 8 y 3 días, respectivamente. Las cepas bacterianas fueron adaptadas satisfactoriamente en distintos medios conteniendo cantidades variadas de hierro y minerales sulfurados, dando mejores resultados sin la adición de sulfato ferroso.

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Reinoso Mena, Milton, Ricardo Andrade Terán, Washington Lomas Zumba, Marcos Gallardo Inga, and Franco Pinzón Rivas. "PROSPECTO MINERO LA ESPERANZA, NUEVOS INDICIOS DE UN PÓRFIDO DE Cu-Mo-Au, SIGCHOS – COTOPAXI." FIGEMPA: Investigación y Desarrollo 1, no. 2 (December 31, 2020): 16–23. http://dx.doi.org/10.29166/revfig.v1i2.2209.

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La investigación presenta datos relacionados a un nuevo pórfido localizado en la parte centro-norte de la cordillera Occidental, al norte de Ecuador, sector La Cocha de San Isidro, cantón Sigchos. La geología del área corresponde a rocas volcano-sedimentarias, lavas andesíticas de corteza oceánica atribuidas a la Formación Macuchi del Eoceno. Presenta intrusiones terciarias tipo: tonalitas, dioritas y granodioritas que están relacionadas con la mineralización. Para la identificación de este prospecto, se realizó una reinterpretación y tratamiento estadístico de datos geoquímicos de sedimentos fluviales históricos y muestras de roca de afloramientos en drenajes de primero y segundo orden; identificando anomalías de cobre, molibdeno, oro y plata. En el área de estudio se han identificado tres zonas similares de interés mineral denominadas San Isidro, San Miguelito y La Chala, relacionadas a intrusivos dioríticos, cuarzo-dioríticos y tonalíticos, que presenta una fuerte silicificación, alteración propilítica y alteración potásica local relacionada al núcleo del sistema, asociadas a fases de stockwork de Qz + sulfuros. Se reportan valores importantes en cobre de hasta 0,43%; en molibdeno 0,04%, y en oro hasta 0,86 g/t. Con base en los datos geológicos y en los resultados de laboratorio de las muestras, se puede interpretar que estas zonas corresponden a un depósito tipo pórfido cobre-molibdeno- oro.

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Teja-Ruiz, A. M. Teja-Ruiz, J. C. J.C. Juárez-Tapia, K. K. Flores-Castro, J. I. Martínez- Soto, M. Pérez-Labra, J. E. Cruz-Peláez Cruz-Peláez, V. E. Reyes-Cruz, and M. Reyes- Pérez. "Identificación de sulfuros de arsénico complejos contenidos en una muestra mineral de Fresnillo, Zacatecas y propuesta de disolución de semimetales." Tópicos de Investigación en Ciencias de la Tierra y Materiales 6, no. 6 (October 5, 2019): 23–32. http://dx.doi.org/10.29057/aactm.v6i6.4991.

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En la industria minera, los concentrados de cobre, plomo y zinc son comúnmente castigados de manera comercial por su alto contenido de arsénico. En busca de combatir esta problemática, se caracterizó un mineral proveniente de Fresnillo, Zacatecas, con importantes concentraciones de este metal tóxico a fin de someterlo a un baño alcalino y lograr la separación del arsénico del resto del mineral. El análisis químico realizado a la muestra del mineral mediante la técnica de Espectroscopia de Emisión de Plasma Acoplada por Inducción (ICP) y Fluorescencia de Rayos X (FRX) identificó un alto contenido de Fe (17.94 % w/w) y As (12.95 % w/w), los cuales forman parte del sulfuro complejo identificado como arsenopirita (FeAsS) [96-900-0110]. Además, la presencia de estos elementos fue corroborada mediante las técnicas de DRX, MEB-EDS y MOP. Estas ténicas tambien revelaron la presencia de sulfuros de metales base como ZnS y PbS, así como especies de ganga como SiO2 y algunos elementos minoritarios como: Sb, Ag, Cu, Zn y Pb. La construcción de diagramas de Pourbaix utilizando el sistema Fe-As-S-NaOH-H2O a 25 °C, permitió determinar que las especies AsO4 3- y FeO*OH predominan bajo las condiciones experimentales a las que se llevaron a cabo las pruebas preliminares ([Mineral]= 8 g L-1, [NaOH]= 2 mol L-1, 25 °C, RPM= 800 min-1 y 720 min), logrando la disolución de 47 % del semimetal.

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López Badilla, Gustavo, Rosa Angélica Arreola Álvarez, Lluvia S. Martínez Valdez, Yuliana Mendieta Rodríguez, Mariela García Rodríguez, María del Carmen Pérez Marmolejo, and José L. Rocha Crespo. "La corrosión de los dispositivos electrónicos de la industria electrónica de Mexicali, B. C. México influenciado por la contaminación del H2S." Nova Scientia 5, no. 9 (October 28, 2014): 29. http://dx.doi.org/10.21640/ns.v5i9.155.

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El sulfuro de hidrógeno (H2S) es un ácido débil que se dispersa en el aire, por el viento cuando se emite a partir de fuentes naturales y antropogénicas, principalmente de las plantas industriales. Es un contaminante con un alto nivel de toxicidad que afecta a la calidad del medio ambiente. Es un contaminante atmosférico agresivo que ataca los metales utilizados en la industria electrónica como acero al carbono, cobre y aleaciones de plata, y formación de películas delgadas como productos de corrosión y dendritas, siendo los sulfuros los más comunes que dañan las superficies metálicas, promoviendo la corrosión metálica. Este gas ingresa a los interiores de las plantas industriales, por los sistemas de aire acondicionado, agujeros, techos, en cualquier período del año. En las temporadas de otoño, invierno y primavera, el personal en las empresas deja algunas puertas abiertas en ciertas áreas de las empresas, por no tener sistemas de aire acondicionado, con el conocimiento del efecto negativo del H2S en los componentes metálicos de componentes electrónicos, y este ácido corrosivo penetra fácilmente. Por esta razón, se realizó un estudio en el interior de dos plantas de la industria electrónica en Mexicali expuestos a bajas concentraciones de H2S, para determinar el daño causado a estos dispositivos electrónicos. Se aplicó la técnica de Microscopía Electrónica de Barrido (MBE) para determinar los tipo de tipos de corrosión formados: uniforme o picaduras principalmente, y conocer con mayor exactitud los agentes químicos que reaccionan con las superficies metálicas de los componentes electrónicos. La técnica MBE muestra las microfotografías y la información de los productos de corrosión presentados en este estudio, en correlación con la humedad relativa (HR) y los niveles de temperatura.

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López Badilla, Gustavo, Hugo Tiznado Vázquez, Gerardo Soto Herrera, Benjamín Valdez Salas, Miguel Schorr Wiener, and Roumen Zlatev. "Corrosión de dispositivos electrónicos por contaminantes atmosféricos en interiores de plantas industriales de ambientes áridos y marinos." Nova Scientia 3, no. 5 (November 3, 2014): 11. http://dx.doi.org/10.21640/ns.v3i5.197.

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La industria electrónica ha crecido en los últimos cincuenta años, sobre todo en los países desarrollados, contribuyendo a su progreso económico. Particularmente en el Estado de Baja California ubicada en el noroeste de México, estas empresas han prosperado en los parques industriales de Mexicali considerada como una zona árida y Ensenada, un puerto y ciudad en el Océano Pacífico, que es una región marina. En ambos ambientes, durante el invierno y el verano los principales factores climáticos en ambientes de interiores son la humedad y temperatura, que aunados a los contaminantes del aire generan corrosión en dispositivos y equipos electrónicos, disminuyendo su rendimiento operativo. El cambio de clima en interiores de plantas industriales se debe a la variación de humedad, temperatura, radiación solar, así como a la concentración de contaminantes atmosféricos como el CO, SO2, H2S, NOX, O3 y partículas sólidas PM2.5 y PM10 provenientes de exteriores de la industria electrónica. Los gases y partículas contaminantes del aire son detectados por Estaciones de Monitoreo Ambiental (EMA) en Mexicali, mientras, que el SOX y Cl- se determinaron en Ensenada por la técnica de platos de sulfatación (TPS) y el método de la vela húmeda (MVH). Las probetas metálicas en ambas ciudades fueron analizadas por microscopia de barrido por electrones (MBE) y espectroscopia de electrones Auger (EEA) para determinar los productos de corrosión. Los equipos electrónicos instalados en las plantas están constituidos por componentes de cobre, siendo un metal muy utilizado por su buena conductividad eléctrica y térmica. Debido a que están expuestos a una amplia gama de ambientes agresivos, se origina deterioro del cobre, generando fallas en los equipos y con ello pérdidas económicas. Los materiales metálicos utilizados en los dispositivos electrónicos son susceptibles a la corrosión en interiores de plantas industriales por la variaciones de humedad y temperatura que generan el tiempo de humectación (TH), originando formación de una película delgada de agua sobre la superficie metálica, además de la exposición principalmente de sulfuros en Mexicali y cloruros en Ensenada, generan el proceso de corrosión.

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Gonzalez-Partida, E., and V. Torres-Rodriguez. "EVOLUCION TECTONICA DE LA PORCION CENTRO-OCCIDENTAL DE MEXICO Y SU RELACION CON LOS YACIMIENTOS MINERALES ASOCIADOS." Geofísica Internacional 27, no. 4 (October 1, 1988): 543–81. http://dx.doi.org/10.22201/igeof.00167169p.1988.27.4.810.

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Se demuestra la existencia de provincias o franjas metálicas en la porción centro-occidental de México cuya distribución y origen obedecen a los procesos tectónicos siguientes: Formación de un arco volcánico submarino con alto contenido de pelíticos en la zona de post-arco. La mineralización es sinsedimentaria de cobre-pirrotita en el arco y polimetálica en el post-arco. Estas rocas están afectadas por un metamorfismo epizonal de la facies de esquistos verdes. Se propone el nombre de "Secuencia Volcanosedimentaria Metamorfizada" para estas rocas cuya edad es Permo-Triásica.Magmatismo intrusivo calcoalcalino de margen continental y edad Jurásica que forma el batolito de Puerto Vallarta y algunas rocas intrusivas de Baja California. No se conocen mineralizaciones asociadas a estas rocas.Levantamiento, erosión y formación de deltas progradantes y desarrollo de yacimiento de origen químico asociados a sedimentos terrígenos con mineralizaciones de Pb, Zn, Ag.Formación de un arco de islas con cuenca marginal, creada a partir de una tectónica distensiva en la zona de post-arco. La edad del arco es Cretácico Temprano. Este marco geológico contiene los sulfuros masivos polimetálicos más importantes de México. Se propone el nombre de "Secuencia Volcanosedimentaria no Metamórfica" para este conjunto litológico.Migraciones laterales del magmatismo continental ocurridas entre el Cretácico Tardío y el Terciario Medio, quedando definidas las provincias metálicas del centro-occidente de México. Las asociaciones más importantes son: Fe (Ti, Cu, Sn); Cu, Au; Pb, Zn, Ag (Au, Cu); Au, Ag (Pb, Zn, Cu); Sn; CaF2; Mn y Hg, Sb (Mn). La distribución de estas franjas es semiparalela a la actual línea de costa y en varias de ellas se observan traslapes debidos a procesos heterocronos.En el Reciente se están desarrollando depósitos de placer en litorales y plataforma continental con mineralización de magnetita, hematita, rutilo y zircón.

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Morales, A., J. F. Hevia, and G. Cifuentes. "Lixiviación amoniacal de polvos de fundición de cobre y precipitación como sulfuro de cobre." Revista de Metalurgia 45, no. 6 (December 30, 2009): 406–14. http://dx.doi.org/10.3989/revmetalm.0822.

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Brem, J. J., H. E. Trulls, M. Sánchez Negrette, and M. L. Ortíz. "Alteraciones estructurales del tejido óseo en ratas tratadas con tetratiomolibdato de amonio." Revista Veterinaria 20, no. 1 (January 1, 2009): 25. http://dx.doi.org/10.30972/vet.2011878.

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El tetratiomolibdato (TTMo) se sintetiza en los pre–estómagos de los rumiantes por reacción del molibdeno con los sulfuros producidos por reducción bacteriana de los elementos azufrados de la dieta. TTMo sería el responsable tanto del bloqueo de la absorción del cobre como de su posterior utilización tisular, provocando una deficiencia secundaria del mismo. El objetivo del trabajo fue verificar el efecto del TTMo de amonio sobre la histología de huesos largos en este modelo experimental con el fin de aportar información acerca de la fragilidad ósea que presentan los rumiantes con molibdenosis. Se utilizaron 30 ratas Wistar de sexo macho, de 80 a 90 días de edad, agrupadas en forma aleatoria en lotes testigos y tratados, conformados con 15 animales cada uno. Estos últimos recibieron 54 mg/l de TTMo con el agua de bebida durante 100 días y, teniendo en cuenta el contenido de Cu y Mo de la dieta y la cantidad de agua y alimento consumido, el lote tratado fue sometido a un desafío de 40 ppm de Mo. Los animales mostraron sintomatología clínica claramente compatible con una deficiencia secundaria de Cu por molibdenosis. Las lesiones más importantes observadas en el tejido óseo de los animales tratados consistieron en engrosamiento del cartílago de crecimiento, con masas de condrocitos hipertróficos y falta de distribución ordenada de células en forma columnar. El tejido subperióstico mostró un incremento de espesor y hemorragias en toda la extensión de diáfisis y metáfisis. También se observó falta de reemplazo del cartílago y hueso inmaduro por tejido óseo maduro, acompañado por abundante producción de tejido fibroso, alterándose así la estructura ósea normal. Tales lesiones pudieron ser provocadas por reacciones tisulares de expansión transversal metafisiaria por una mayor deformabilidad ósea frente al desafío de cargas que el hueso debió soportar.

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Palais, J. M. "Particle Morphology, Composition and Associated Ice Chemistry of Tephra Layers in the Byrd Ice Core: Evidence for Hydrovolcanic Eruptions." Annals of Glaciology 7 (1985): 42–48. http://dx.doi.org/10.1017/s0260305500005887.

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In 1968 an ice core 2164 m long was recovered from Byrd station in West Antarctica. About 2000 tephra layers were observed in the core and have been differentiated into ash and dust bands according to the grain size and concentration of particles in the layers. Mount Takahe, a local volcano in Marie Byrd Land, Antarctica is the probable source. Detailed examinations of the particle morphology, composition and ice chemistry associated with some of the tephra layers have led to the conclusion that the eruptions which produced the layers were probably hydrovolcanic. Melted glacier ice is considered the most likely source of the water involved in the eruptions. Processes associated with hydrovolcanism such as particle aggregation (causing premature deposition of fine particles), rapid conversion of sulfur dioxide to sulfuric acid (in the presence of abundant moisture) and scavenging of acid droplets by the fine dust particles are inferred to have taken place. Such processes would greatly reduce the atmospheric residence time of the eruptive products and thus their atmospheric and climatic impact.

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Palais, J. M. "Particle Morphology, Composition and Associated Ice Chemistry of Tephra Layers in the Byrd Ice Core: Evidence for Hydrovolcanic Eruptions." Annals of Glaciology 7 (1985): 42–48. http://dx.doi.org/10.3189/s0260305500005887.

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In 1968 an ice core 2164 m long was recovered from Byrd station in West Antarctica. About 2000 tephra layers were observed in the core and have been differentiated into ash and dust bands according to the grain size and concentration of particles in the layers. Mount Takahe, a local volcano in Marie Byrd Land, Antarctica is the probable source.Detailed examinations of the particle morphology, composition and ice chemistry associated with some of the tephra layers have led to the conclusion that the eruptions which produced the layers were probably hydrovolcanic. Melted glacier ice is considered the most likely source of the water involved in the eruptions.Processes associated with hydrovolcanism such as particle aggregation (causing premature deposition of fine particles), rapid conversion of sulfur dioxide to sulfuric acid (in the presence of abundant moisture) and scavenging of acid droplets by the fine dust particles are inferred to have taken place. Such processes would greatly reduce the atmospheric residence time of the eruptive products and thus their atmospheric and climatic impact.

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Olazo Quispe, Renzo, and Adolfo La Rosa-Toro Gómez. "MICROPARTÍCULAS DE Ag/Ag S TIPO CORE-SHELL COMO 2 SENSOR POTENCIOMÉTRICO PARA LA DETECCIÓN DE CIANURO." Revista de la Sociedad Química del Perú 80, no. 1 (March 31, 2014): 51–64. http://dx.doi.org/10.37761/rsqp.v80i1.221.

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La síntesis de micropartículas de plata con película superficial de sulfuro de plata mezcladas con grafito en polvo ha permitido obtener un sensor electroquímico capaz de detectar cianuro con buena sensibilidad. Se caracterizó las micropartículas de plata y sulfuro de plata mediante voltametría cíclica (VC), Difracción de Rayos X (DRX), Fluorescencia de Rayos X (XRF), Microscopía de Barrido Electrónico(SEM) y Espectrometría de Energía Dispersiva de Rayos X (EDX). Se realizó ensayos potenciométricos para determinar el coeficiente de selectividad del sensor

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Suslick, Kenneth S., Hangxun Xu, and David J. Flannigan. "Evidence for a plasma core during acoustic cavitation in sulfuric acid." Journal of the Acoustical Society of America 129, no. 4 (April 2011): 2585. http://dx.doi.org/10.1121/1.3588549.

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Eddingsaas, Nathan C., and Kenneth S. Suslick. "Evidence for a Plasma Core during Multibubble Sonoluminescence in Sulfuric Acid." Journal of the American Chemical Society 129, no. 13 (April 2007): 3838–39. http://dx.doi.org/10.1021/ja070192z.

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Wu, Yiping, Jianjun Wang, Qing Wang, Haowu Li, Ningning Zhang, and Yufeng Xiao. "Geochemical features and genetic mechanism of deep-water source rocks in the Senegal basin, West Africa." Thermal Science 23, no. 5 Part A (2019): 2641–49. http://dx.doi.org/10.2298/tsci181130153w.

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This paper discusses the maturity of source rocks of the Senegal basin through basin simulation, so as to get a better understanding of oil-source correlation. Based on the analysis of pyrolysis chromatography and total organic carbon (TOC) data of core samples taken from 11 wells, the model of Cenomanian-Turonian marine sediment-organic facies was established, and the genetic mechanism of high-quality source rocks was clarified. The results show that source rocks in the Senegal Basin may occur in the Aptian-Albian of Lower Cretaceous and Cenomanian-Turonian of Upper Cretaceous. One is hybrid organic facies in the shallow carbonate platforms in the shelf area and is characterized by moderate to high TOC (<3%) and hidrogen index ? HI, (100-400 mg HC/g). The other is well-preserved marine facies in continental slope to abyssal sea, with high TOC (>3%) and high HI (max 900 mg HC/g TOC). Molecular fossils originating from aryl carotene are the indicator of the existence of euphotic zone in the ancient ocean. The compounds of aryl isoprenes and sulfurous aryl isoprenes are detected in the black shale samples of well DSDP 367. They rooted in photosynthetic green sulfur bacteria and the carbon isotope value of these compounds is higher 10?~15? than those of fossil molecules of algae and cyanobacteria. Two packages of oil-prone source rocks separately occurr in the Aptian-Albian of Lower Cretaceous and Cenomanian-Turonian of Upper Cretaceous. High-graded marine source rocks of the Senegal Basin may occur in a sulfurous, anoxic deep-water environment with sufficient carbon sequestration.

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Chung, Sheng-Heng, Chi-Hao Chang, and Arumugam Manthiram. "A core–shell electrode for dynamically and statically stable Li–S battery chemistry." Energy & Environmental Science 9, no. 10 (2016): 3188–200. http://dx.doi.org/10.1039/c6ee01280a.

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Boonmee, Sarum, and Nupol Mai-Ngam. "Effect of Sulfur on the Formation of the Graphite Degradation in Ductile Iron." Materials Science Forum 895 (March 2017): 89–93. http://dx.doi.org/10.4028/www.scientific.net/msf.895.89.

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The objective of this study is to evaluate the effect of sulfur in core sand on the formation of the graphite degradation in ductile iron. The graphite degradation is caused by the depletion of Mg in liquid iron resulting in low nodularity zone underneath the casting surface. The content of sulfur in molding materials has been known as an important factor of the occurrence of the graphite degradation. It was found that the greater content of sulfur in the core sand promoted the formation of the graphite degradation. The graphite degradation with the thickness ranged from 113 to 1116 μm was observed for the sulfur content from 0.24 to 1.68 wt%S.

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Chang, Zhi, Hui Dou, Bing Ding, Jie Wang, Ya Wang, Guiyin Xu, and Cheng Li. "Interconnected core–shell pyrolyzed polyacrylonitrile@sulfur/carbon nanocomposites for rechargeable lithium–sulfur batteries." New Journal of Chemistry 40, no. 9 (2016): 7680–86. http://dx.doi.org/10.1039/c6nj00325g.

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Interconnected core–shell pyrolyzed polyacrylonitrile@sulfur/carbon nanocomposites have been prepared and adopted as cathode materials to prevent the irreversible deposition of insoluble discharge products, leading to improved cyclic stability for lithium–sulfur batteries.

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Khorshidi, Alireza, and Shahab Shariati. "Sulfuric acid functionalized MCM-41 coated on magnetite nanoparticles as a recyclable core–shell solid acid catalyst for three-component condensation of indoles, aldehydes and thiols." RSC Adv. 4, no. 78 (2014): 41469–75. http://dx.doi.org/10.1039/c4ra05550k.

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21

Yeşilot, Serkan, Sedat Küçükköylü, Emrah Demir, and Rezan Demir-Cakan. "Phosphazene based star-branched polymeric cathode materials via inverse vulcanization of sulfur for lithium–sulfur batteries." Polymer Chemistry 11, no. 25 (2020): 4124–32. http://dx.doi.org/10.1039/d0py00490a.

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Novel insoluble star-shaped hexa-branched polymeric materials based on cyclotriphosphazene core are prepared by the inverse vulcanization of sulfur with hexakis(styreneoxy)cyclotriphosphazene and tested as cathode for lithium–sulfur (Li–S) batteries.

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22

Salvarezza, Roberto Carlos, and Pilar Carro. "Exploring the core level shift origin of sulfur and thiolates on Pd(111) surfaces." Physical Chemistry Chemical Physics 17, no. 37 (2015): 24349–55. http://dx.doi.org/10.1039/c5cp04180e.

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DFT calculations show that the core level shift (CLS) of the S 2p binding energy of thiol and sulfur atoms on different thiol–Pd(111) surfaces strongly depends on the adsorbed or subsurface state of sulfur atoms.

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23

Gao, Shan, Linxia Wang, Hui Li, Zunfeng Liu, Guoliang Shi, Jianfei Peng, Bin Wang, Weichao Wang, and Kyeongjae Cho. "Core–shell PdAu nanocluster catalysts to suppress sulfur poisoning." Physical Chemistry Chemical Physics 23, no. 28 (2021): 15010–19. http://dx.doi.org/10.1039/d1cp01274f.

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24

Cháidez, Josué, José Parga, Jesús Valenzuela, Raúl Carrillo, and Isaías Almaguer. "Leaching Chalcopyrite Concentrate with Oxygen and Sulfuric Acid Using a Low-Pressure Reactor." Metals 9, no. 2 (February 6, 2019): 189. http://dx.doi.org/10.3390/met9020189.

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This article presents a copper leaching process from chalcopyrite concentrates using a low-pressure reactor. The experiments were carried out in a 30 L batch reactor at an oxygen pressure of 1 kg/cm2 and solid concentration of 100 g/L. The temperature, particle size and initial acid concentration were varied based on a Taguchi L9 experimental design. The initial and final samples of the study were characterized by chemical analysis, X-ray diffraction and particle size distribution. The mass balance showed that 98% of copper was extracted from the chalcopyrite concentrate in 3 h under the following experimental conditions: 130 g/L of initial sulfuric acid concentration, temperature of 100 °C, oxygen pressure of 1 kg/cm2, solid concentration of 100 g/L and particle size of −105 + 75 μm. The ANOVA demonstrated that temperature had the greatest influence on copper extraction. The activation energy was 61.93 kJ/mol. The best fit to a linear correlation was the chemical reaction equation that controls the kinetics for the leaching copper from chalcopyrite. The images obtained by SEM showed evidence of shrinking in the core model with the formation of a porous elemental sulfur product layer.

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Xu, Hong Sheng, Chang Wei, Cun Xiong Li, Yan Song, Zhi Gan Deng, and Gang Fan. "Kinetics of Pressure Acid Leaching of Zinc from Zinc Silicate Ore." Advanced Materials Research 402 (November 2011): 266–71. http://dx.doi.org/10.4028/www.scientific.net/amr.402.266.

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The present work is concerned with the kinetic study of pressure leaching of zinc silicate ore in sulfuric acid solutions. The effects of leaching temperature, particle size, sulfuric acid concentration and agitation speed on the zinc extraction were evaluated. The results obtained show that the zinc extraction increases with increasing sulfuric acid concentration and leaching temperature. The leaching kinetics was analyzed by using a shrinking core model with diffusion control given by: 1-2/3x-(1-x)2/3=Kt, which represented well the experimental data. The apparent activation energy was determined to be 44.56kJ/mol at temperatures ranging between 80 and 140°C.

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Zapata, Dioni Mabel, M. A. Márquez, and D. M. H. Ossa. "Sulfur Product Layer in Sphalerite Biooxidation: Evidences for a Mechanism of Formation." Advanced Materials Research 20-21 (July 2007): 134–38. http://dx.doi.org/10.4028/www.scientific.net/amr.20-21.134.

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The sphalerite-pyrite oxidation by Acidithiobacillus ferrooxidans was studied to analyze how the formation of the elemental sulfur layers occurs around sphalerite grains. Two possible mechanisms of formation have been raised. One mechanism corresponds to the formation of sulfur pseudomorphs where, both, iron and zinc have been leached of the sphalerite, whereas compound sulfur is oxidized, in situ, to elemental sulfur, leaving an unreacted core of sphalerite that remains in the center. Another mechanism consists in the dissolution of iron, zinc and sulfur presents. When the attack by Fe3+ as by H+ broken the S-metal bonds, sulfur is then oxidized to a series of sulfur intermediate compounds. These compounds in solution then are oxidized to elemental sulfur, which precipitates on sphalerite grains.

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27

Sizemore, Steven T., and John V. Paietta. "Cloning and Characterization of scon-3+, a New Member of the Neurospora crassa Sulfur Regulatory System." Eukaryotic Cell 1, no. 6 (December 2002): 875–83. http://dx.doi.org/10.1128/ec.1.6.875-883.2002.

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ABSTRACT The sulfur regulatory system of Neurospora crassa consists of a group of sulfur-regulated structural genes (e.g., arylsulfatase) that are under coordinate control of the CYS3 positive regulator and sulfur controller (SCON) negative regulators. Here we report on the cloning of scon-3+ , which encodes a polypeptide of 171 amino acids and is a Skp1 family homolog. Repeat-induced point mutation of scon-3+ resulted in a phenotype of constitutive expression of arylsulfatase, a phenotype consistent with other sulfur controller mutants. Northern analysis indicated that, unlike other members of the sulfur regulatory system, expression of scon-3+ is not under the direct control of the CYS3 transcriptional activator. In particular, scon-3+ mRNA was detectable under sulfur repressing or derepressing conditions in a Δcys-3 mutant. In yeast, Skp1p and an F-box protein binding partner are core constituents of a class of E3 ubiquitin ligases known as SCF complexes. The N. crassa negative regulator SCON2 contains an F-box motif essential for the operation of the sulfur regulatory system and suggests a role for an SCF complex in the N. crassa sulfur regulatory system. A crucial set of experiments, by using a yeast two-hybrid approach with confirming coimmunoprecipitation assays, demonstrated that SCON3 interacts with SCON2 in a manner dependent upon the F-box motif of SCON2. The protein-protein interaction detected between SCON2 and SCON3 represents the initial demonstration in a filamentous fungus of functional interaction between putative core components of a SCF complex.

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Judiawan, William, Yanni Sudiyani, and Elda Nurnasari. "Conversion of hemicellulose from kenaf core fiber to xylose through dilute sulfuric acid hydrolysis." Jurnal Kimia Terapan Indonesia 21, no. 1 (June 27, 2019): 14–22. http://dx.doi.org/10.14203/jkti.v21i1.412.

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Kenaf (Hibiscus cannabinus) is a lignocellulosic plant that is usually utilized as a fiber source for sack production. The core from kenaf fiber has not been utilized yet in Indonesia, therefore it is still considered as a waste. Hemicellulose from kenaf core can be hydrolyzed to xylose through dilute sulfuric acid hydrolysis in high temperature. Hydrolysis in this study was done by using autoclave at 121℃ and 10% (m/v) biomass: acid ratio for 15 and 45 minutes with a variation on acid concentration (2%, 4%, and 6% v/v). Xylose concentration in the hydrolyzate tends to increase with higher acid concentration and longer heating time. 6% (v/v) sulfuric acid concentration and 45 minutes of heating time produce the highest xylose concentration (20.53 gr/L) and yield (86.50%)

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29

Frontera, Patrizia, Pier Luigi Antonucci, and Anastasia Macario. "Focus on Materials for Sulfur-Resistant Catalysts in the Reforming of Biofuels." Catalysts 11, no. 9 (August 26, 2021): 1029. http://dx.doi.org/10.3390/catal11091029.

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The reforming of biofuels represents a promising technology for low carbon and renewable hydrogen production today. The core of the process is an active and stable catalyst, which can help to improve this technology and its efficiency. With this review, we aim to survey the more relevant literature on heterogeneous catalysts for the reforming of biofuels with improved sulfur tolerance. The review is structured into four main sections. Following the introduction, the fundamental aspects of sulfur poisoning are discussed. In the third section, the basic principles of the reforming of biofuels are reported, and finally, in the fourth section—the core of the review—recent progresses in the development of sulfur resistant catalysts are discussed, distinguishing the role of the metal (noble and non-noble) from that of the support.

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30

Hrbek, Jan, Jose A. Rodriguez, Joseph Dvorak, and Tomas Jirsak. "Sulfur Adsorption and Reaction with a TiO2(110) Surface: O↔S Exchange and Sulfide Formation." Collection of Czechoslovak Chemical Communications 66, no. 8 (2001): 1149–63. http://dx.doi.org/10.1135/cccc20011149.

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Upon sulfur adsorption on TiO2(110) at 600 K, all surface oxygen is replaced by sulfur. High-resolution photoemission data show a complete loss of oxygen from the surface layer, a large binding energy shift and attenuation of Ti core levels, and the presence of three different S species. The bonding of sulfur is examined using first-principles density-functional calculations and the periodic supercell approach. At saturation the top layer of the oxide surface is converted to sulfide, with the majority of sulfur buckled above the Ti lattice plane and the remaining sulfur bonded in bridging sites. A mechanism for this self-limiting thermodynamically unlikely surface reaction is proposed.

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31

Wang, Hongjun, Yali Feng, Haoran Li, Xiangyi Deng, and Jinxing Kang. "The kinetics of vanadium extraction from spent hydroprocessing catalyst by leaching with sulfuric acid at atmospheric pressure." Metallurgical Research & Technology 116, no. 2 (2019): 214. http://dx.doi.org/10.1051/metal/2018073.

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The dissolution kinetics of vanadium from spent hydroprocessing catalyst was investigated by leaching with sulfuric acid at atmospheric pressure. The effects of stirring speed (400–800 rpm), initial sulfuric acid concentration (0.60–1.20 mol/l) and reaction temperature (373–423 K) on the vanadium dissolution were studied. The results showed that the vanadium dissolution ratio was practically independent of stirring speed at the investigated range, while increasing with the increases of sulfuric acid concentration and reaction temperature. The experimental data agreed quite well with the shrinking core model, with solid membrane diffusion as the rate controlling step. The apparent activation energy was calculated as 11.44 kJ/mol, and the reaction order with respect to sulfuric acid concentrations was determined to be 1.51. The kinetics equation of the leaching process was established as: 1 − 2x/3 − (1 − x)2/3 = 0.067[H2SO4]1.51exp[ − 11563/RT ]t.

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32

Liang, Yuanling, Peter M. A. Sherwood, and Dilip K. Paul. "Valence and core photoemission of the films formed electrochemically on nickel in sulfuric acid." Journal of the Chemical Society, Faraday Transactions 90, no. 9 (1994): 1271. http://dx.doi.org/10.1039/ft9949001271.

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33

Pirjola, L., M. Karl, T. Rönkkö, and F. Arnold. "Model studies of volatile diesel exhaust particle formation: are organic vapours involved in nucleation and growth?" Atmospheric Chemistry and Physics 15, no. 18 (September 23, 2015): 10435–52. http://dx.doi.org/10.5194/acp-15-10435-2015.

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Abstract. A high concentration of volatile nucleation mode particles (NUP) formed in the atmosphere when the exhaust cools and dilutes has hazardous health effects and it impairs the visibility in urban areas. Nucleation mechanisms in diesel exhaust are only poorly understood. We performed model studies using two sectional aerosol dynamics process models AEROFOR and MAFOR on the formation of particles in the exhaust of a diesel engine, equipped with an oxidative after-treatment system and running with low fuel sulfur content (FSC) fuel, under laboratory sampling conditions where the dilution system mimics real-world conditions. Different nucleation mechanisms were tested. Based on the measured gaseous sulfuric acid (GSA) and non-volatile core and soot particle number concentrations of the raw exhaust, the model simulations showed that the best agreement between model predictions and measurements in terms of particle number size distribution was obtained by barrier-free heteromolecular homogeneous nucleation between the GSA and a semi-volatile organic vapour combined with the homogeneous nucleation of GSA alone. Major growth of the particles was predicted to occur due to the similar organic vapour at concentrations of (1−2) × 1012 cm−3. The pre-existing core and soot mode concentrations had an opposite trend on the NUP formation, and the maximum NUP formation was predicted if a diesel particle filter (DPF) was used. On the other hand, the model predicted that the NUP formation ceased if the GSA concentration in the raw exhaust was less than 1010 cm−3, which was the case when biofuel was used.

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34

Yang, Ji, Fuqiang Cheng, Zuogang Zhu, Jinsheng Feng, Min Xue, Zihui Meng, and Lili Qiu. "An enhanced gas sensor based on SiO2@mesoporous MCM-41 core–shell nanocomposites for SO2 visual detection." Analyst 145, no. 12 (2020): 4352–57. http://dx.doi.org/10.1039/d0an00621a.

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35

Huang, Ling, Jianli Cheng, Xiaodong Li, Demao Yuan, Wei Ni, Guoxing Qu, Qun Guan, Yun Zhang, and Bin Wang. "Sulfur quantum dots wrapped by conductive polymer shell with internal void spaces for high-performance lithium–sulfur batteries." Journal of Materials Chemistry A 3, no. 7 (2015): 4049–57. http://dx.doi.org/10.1039/c4ta06609j.

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36

Dell’Era, Alessandro, Francesca A. Scaramuzzo, Marco Stoller, Carla Lupi, Marco Rossi, Daniele Passeri, and Mauro Pasquali. "Spinning Disk Reactor Technique for the Synthesis of Nanometric Sulfur TiO2Core–Shell Powder for Lithium Batteries." Applied Sciences 9, no. 9 (May 9, 2019): 1913. http://dx.doi.org/10.3390/app9091913.

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Sulfur/lithium battery performances are strictly related to the morphology and nanostructure of sulfur particles. In this work, a comparison of the morphological characteristics and electrochemical properties of electrodes based on colloidal sulfur (CS) obtained by means of traditional chemical precipitation from aqueous solution and via spinning disk reactor (SDR) has been performed. In particular, through the SDR technique and by using different fluid dynamic conditions, it was possible to obtain monodisperse and nanometricsulfurparticles with higher electrochemical performances when used as the cathodic active material in lithium batteries. Moreover, a method to produce core–shell nanoparticles with sulfur and titanium dioxide, starting from a colloidal sulfur (S8) solution and produced by SDR, has been performed, obtaining good electrochemical results. In particular, the nanometric sulfur powder produced by the SDR technique showed a capacity higher than CS after 100 cycles, even if the capacity decreased rapidly in both cases. Instead, considering the core–shell S–TiO2 material, the nanostructured electrode allowed a wide use of active material and a reduced capacity decay during cycling. Specifically, the material showed an initial capacity of 1395 mAh/g, i.e., representing 83% of the theoretical value, which decreased during operation up to 450 mAh/g after about 30 cycles. Then, the material capacity remained unchanged and no substantial loss of capacity was recorded up to 100th cycle.

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37

Jiang, Peng, Rong Wang, and Zilin Chen. "Thiol-based non-injection synthesis of near-infrared Ag2S/ZnS core/shell quantum dots." RSC Advances 5, no. 70 (2015): 56789–93. http://dx.doi.org/10.1039/c5ra08008h.

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A novel non-injection method for near-infrared Ag₂S/ZnS core/shell QDs using alkanethiols as both ligand and sulfur source has been developed. The quantum yield was significantly increased after coating a ZnS shell on the Ag₂S core.

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38

Zhang, Kailong, Yanhua Xu, Yue Lu, Yongchun Zhu, Yuying Qian, Danfeng Wang, Jianbin Zhou, Ning Lin, and Yitai Qian. "A graphene oxide-wrapped bipyramidal sulfur@polyaniline core–shell structure as a cathode for Li–S batteries with enhanced electrochemical performance." Journal of Materials Chemistry A 4, no. 17 (2016): 6404–10. http://dx.doi.org/10.1039/c6ta01118g.

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39

Fu, Ying Kun, Zhi Ping Li, Feng Peng Lai, Bao Song Yang, and Chao Meng. "An Experimental Study on Fracture Conductivity Influenced by Sulfur Deposition." Applied Mechanics and Materials 423-426 (September 2013): 644–48. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.644.

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Deposition of solid elemental sulfur may arouse severe damage to the formation and significantly affect the gas deliverability in sour gas reservoirs. As one main measure of stimulation, hydraulic fracturing always ceases to work due to the sulfur deposition in the fractures. To have a better understanding of the failure of fracture conductivity caused by sulfur deposition and learn the degree of fracture conductivity improved by acidification, an experimental was implemented and studied. In this paper, both the sulfur powder and an artificial fractured core were employed to simulate the process of sulfur deposition in the fractures. A further step was made to inject some hydrochloric acid into the blocked fracture caused by sulfur powder. The result showed that the fracture conductivity could be greatly reduced by the sulfur deposition. The fracture conductivity can be decreased by 17%~47% due to sulfur deposition. However, to some degree, acid-fracturing can improve the conductivity of fracture by eroding the surface of fracture. This means the failure of fracture blocked by sulfur deposition can be improved by acidification.

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40

Mahmoud, M. A. A. "Effect of Elemental-Sulfur Deposition on the Rock Petrophysical Properties in Sour-Gas Reservoirs." SPE Journal 19, no. 04 (December 31, 2013): 703–15. http://dx.doi.org/10.2118/164440-pa.

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Summary The deposition of elemental sulfur as a solid phase results in plugging the pore space available for gas flow and reduces the reservoir productivity. Elemental sulfur also can be deposited as a liquid phase if the reservoir temperature is greater than 115°C. The liquid sulfur restricts the inflow of gas because of the big density difference between liquid sulfur and gas, which could be 20 times or more. For isothermal conditions in the reservoir, the reduction in reservoir pressure to lower than a critical value causes the elemental sulfur to deposit in the formation, and in turn the gas-well productivity is affected. Accurate prediction of sulfur deposition will help better manage sour-gas reservoirs with potential sulfur-deposition problems. In this paper, a new analytical model was developed to predict the effect of sulfur deposition on the damage of the near-wellbore region. The damage was quantified through the investigation of the effect of sulfur deposition on rock porosity, relative permeability of the gas phase, and the change in rock wettability. The main objective of this model is to investigate the effect of radial distance on formation damage. Different rock- and fluid-property correlations were used in the model. Previous studies did not consider the change in gas properties with pressure, and numerically modeled the sulfur deposition as a condensate in a gas/condensate reservoir. This paper will consider sulfur adsorption, and the actual physical properties of the sulfur will be used in the developed model. The optimum gas-flow velocity that will maximize the sulfur solubility in the gas will be determined. A coreflood experiment was performed to determine the effect of sulfur deposition on the carbonate-rock permeability, porosity, and wettability. The experiment was used to determine the effect of sulfur adsorption on the rock petrophysical properties. The contact angle was measured for a carbonate core saturated with sulfur by use of a pendant-drop tensiometer. Analytical and numerical solutions showed that the deposition of sulfur was affected by the radial distance from the wellbore and sulfur-solubility changes as a function of the pressure drop. Sulfur deposition was found to have a great effect on the rock wettability, and in turn the gas production will be affected. The model can be used to predict the critical flow velocity that the gas can flow without precipitating sulfur. The optimum gas-flow velocity was estimated to be a range that maximizes the sulfur solubility in the gas. It was confirmed experimentally that the sulfur deposition reduced the carbonate-core porosity and permeability, and changed the contact angle (rock wettability). The contact angle increased, which means sulfur adsorption on the rock surfaces changed the rock toward more-gas-wet rock.

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Wang, Wei Jing, Tian Yan Xue, Dong Wang, and Tao Qi. "Kinetic Study on Sulfuric Acid Dissolution of Na_xH_2-xTiO₃ from Sodium Hydroxide Molten Method." Advanced Materials Research 881-883 (January 2014): 1545–48. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1545.

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The dissolution kinetic of NaxH2-xTiO3(resulting from high titanium slag treatment by NaOH) by diluted sulfuric acid (38~51 wt. %) was carried out in temperature range of 10 to 50°C with an initial acid/NaxH2-xTiO3(wt.) ratio of 1:1. The effects of the sulfuric acid concentration and temperature on titanium dissolution percent were reported, and both of them significantly affected the dissolution rate. The experimental data indicate that the shrinking core model controlled by diffusion in product layer is most applicable for the titanium dissolution process, and the apparent activation energy has been estimated to be 28.69 kJ/mol.

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42

Wu, Jingyi, Xiongwei Li, Hongxia Zeng, Yang Xue, Fangyan Chen, Zhigang Xue, Yunsheng Ye, and Xiaolin Xie. "Fast electrochemical kinetics and strong polysulfide adsorption by a highly oriented MoS2 nanosheet@N-doped carbon interlayer for lithium–sulfur batteries." Journal of Materials Chemistry A 7, no. 13 (2019): 7897–906. http://dx.doi.org/10.1039/c9ta00458k.

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43

Dunya, Hamza, Maziar Ashuri, Dana Alramahi, Zheng Yue, Kamil Kucuk, Carlo U. Segre, and Braja K. Mandal. "MnO2-Coated Dual Core–Shell Spindle-Like Nanorods for Improved Capacity Retention of Lithium–Sulfur Batteries." ChemEngineering 4, no. 2 (June 19, 2020): 42. http://dx.doi.org/10.3390/chemengineering4020042.

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The emerging need for high-performance lithium–sulfur batteries has motivated many researchers to investigate different designs. However, the polysulfide shuttle effect, which is the result of dissolution of many intermediate polysulfides in electrolyte, has still remained unsolved. In this study, we have designed a sulfur-filled dual core–shell spindle-like nanorod structure coated with manganese oxide (S@HCNR@MnO2) to achieve a high-performance cathode for lithium–sulfur batteries. The cathode showed an initial discharge capacity of 1661 mA h g−1 with 80% retention of capacity over 70 cycles at a 0.2C rate. Furthermore, compared with the nanorods without any coating (S@HCNR), the MnO2-coated material displayed superior rate capability, cycling stability, and Coulombic efficiency. The synergistic effects of the nitrogen-doped hollow carbon host and the MnO2 second shell are responsible for the improved electrochemical performance of this nanostructure.

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44

Wang, Ping, Jie Zhang, Haili He, Xiaolong Xu, and Yongdong Jin. "Efficient visible light-driven H2 production in water by CdS/CdSe core/shell nanocrystals and an ordinary nickel–sulfur complex." Nanoscale 6, no. 22 (2014): 13470–75. http://dx.doi.org/10.1039/c4nr04600e.

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45

Banoub, Joseph H., and Howard J. Hodder. "Structural investigation of the lipopolysaccharide core isolated from a virulent strain of Vibrio ordalii." Canadian Journal of Biochemistry and Cell Biology 63, no. 12 (December 1, 1985): 1199–205. http://dx.doi.org/10.1139/o85-150.

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The structure of the core oligosaccharide of Vibrio ordalii has been investigated. The studies involved the use of nuclear magnetic resonance, methylation analysis, partial hydrolysis with hydrochloric acid, nitrous acid deamination, partial hydrolysis with sulfuric acid, Smith degradation, and oxidation with chromium trioxide. As a result of these studies the following structure is proposed.[Formula: see text]

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46

Won, Jong Sung, Ha Ram Lee, Min Jun Lee, Min Hong Jeon, Seung Goo Lee, and Yong Lak Joo. "Fabrication of Activated Carbon Fibers with Sheath-Core, Hollow, or Porous Structures via Conjugated Melt Spinning of Polyethylene Precursor." Polymers 12, no. 12 (December 3, 2020): 2895. http://dx.doi.org/10.3390/polym12122895.

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Using polyethylene as carbon precursor, we have fabricated cost-effective carbon fibers with a sheath-core structure via conjugate melt spinning. Low-density polyethylene (LDPE) and high-density polyethylene (HDPE) were used as the sheath and core of the fiber, respectively, while sulfonation with sulfuric acid was conducted to enable the crosslinking of polyethylene. We demonstrated that carbonization and activation of the sheath-core-structured polyethylene fiber can result in a well-developed microporous structure in the sheath layer, and due to the core-sheath structure, the resulting activated carbon fibers exhibit a high tensile strength of ~455 MPa, initial modulus of ~14.4 GPa, and Brunauer-Emmett-Teller (BET) surface area of ~1224 m2/g. Finally, activated carbon fibers with a hollow, sheath-core, and porous were successfully fabricated by controlling the degree of crosslinking of the LDPE/HDPE sheath-core fiber.

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47

del Real, I., J. F. H. Thompson, A. C. Simon, and M. Reich. "Geochemical and Isotopic Signature of Pyrite as a Proxy for Fluid Source and Evolution in the Candelaria-Punta del Cobre Iron Oxide Copper-Gold District, Chile." Economic Geology 115, no. 7 (November 1, 2020): 1493–518. http://dx.doi.org/10.5382/econgeo.4765.

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Abstract Pyrite is ubiquitous in the world-class iron oxide copper-gold (IOCG) deposits of the Candelaria-Punta del Cobre district, documented from early to late stages of mineralization and observed in deep and shallow levels of mineralized bodies. Despite its abundance, the chemical and isotopic signature of pyrite from the Candelaria-Punta del Cobre district, and most IOCG deposits worldwide, remains poorly understood. We evaluated in situ chemical and isotopic variations at the grain scale in a set of pyrite-bearing samples collected throughout the district in order to characterize and further understand the nature of mineralization in this IOCG system. Our multianalytical approach integrated synchrotron micro-X-ray fluorescence (μ-XRF) mapping of pyrite grains with electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry data, and sulfur isotope determinations using secondary ion mass spectrometry (SIMS) complemented with bulk sulfur isotope analyses of coeval pyrite, chalcopyrite, and anhydrite. Synchrotron μ-XRF elemental concentration maps of individual pyrite grains reveal a strong zonation of Co, Ni, As, and Se. The observed relationships between Ni and Se are interpreted to reflect changes in temperature and redox conditions during ore formation and provide constraints on fluid evolution. Co and Ni concentrations and ratios suggest contributions from magmas of mafic-intermediate composition. Pyrite chemical concentrations reflect potential stratigraphic controls, where the sample from the upper part of the stratigraphy diverges from trends formed by the rest of the sample set from lower stratigraphic levels. The SIMS δ34S values of pyrite (and chalcopyrite) range between –2 up to 10‰, and bulk δ34S values of pyrite range between 4 up to 12‰. The majority of the δ34S analyses, falling between –1 and 2‰, indicate a magmatic source for sulfur and, by inference, for the hydrothermal ore fluid(s). Variation in the δ34S signature can be explained by changes in the redox conditions, fluid sources, and/or the temperature of the hydrothermal fluid. The Se/S ratio combined with δ34S values in pyrite is consistent with mixing between a magmatic-hydrothermal fluid and a fluid with a probable basinal signature. The results of this study are consistent with the hydrothermal fluids responsible for mineralization in the Candelaria-Punta del Cobre district being predominantly of magmatic origin, plausibly from mafic-intermediate magmas based on the Ni-Co content in pyrite. External fluid incursion, potentially from a basinal sedimentary source, occurred late in the evolution of the system, adding additional reduced sulfur as pyrite. There is no evidence to suggest that the late fluid added significant Cu-Au mineralization, but this cannot be ruled out. Finally, the data reveal that trace element ratios coupled with spatially resolved sulfur isotope data in pyrite are powerful proxies to track the magmatic-hydrothermal evolution of IOCG systems and help constrain the source of their contained metals.

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Zhao, Shuo, Yue Xu, Xiaochao Xian, Na Liu, and Wenjing Li. "Fabrication of Porous Si@C Composites with Core-Shell Structure and Their Electrochemical Performance for Li-ion Batteries." Batteries 5, no. 1 (February 27, 2019): 27. http://dx.doi.org/10.3390/batteries5010027.

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The pores in silicon particles can accommodate the volume expansion of silicon during the charging–discharging process. However, pores in silicon particles are easily occupied by carbon during the preparation of silicon/carbon composites. In this paper, sulfur was adsorbed in the pores of porous silicon particles before polyaniline (PANI) coating by in-situ polymerization, so that the pores were preserved in porous silicon@carbon (p-Si/@C) composites after the sublimation of sulfur during carbonization. The microstructure and the electrochemical performances of the obtained p-Si/@C composites were investigated. The results indicate that p-Si/@C composites prepared with a sulfur-melting process show a better high-rate performance than those without a sulfur-melting process. Remarkably, the former show a better capacity retention when returning to a low current density. The reversible capacities of the former were 1178 mAh·g−1, 1055 mAh·g−1, 944 mAh·g−1, and 751 mAh·g−1 at 0.2 A·g−1, 0.3 A·g−1, 0.5 A·g−1, and 1.0 A·g−1, respectively. Moreover, the reversible capacities could return to 870 mAh·g−1, 996 mAh·g−1, and 1027 mAh·g−1 when current densities returned to 0.5, 0.3, and 0.2 A·g−1, respectively.

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Wei, Wenli, Pengcheng Du, Dong Liu, Qi Wang, and Peng Liu. "Facile one-pot synthesis of well-defined coaxial sulfur/polypyrrole tubular nanocomposites as cathodes for long-cycling lithium–sulfur batteries." Nanoscale 10, no. 27 (2018): 13037–44. http://dx.doi.org/10.1039/c8nr01530a.

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Varas, Lautaro R., Felipe Fantuzzi, Lúcia Helena Coutinho, Rafael B. Bernini, Marco Antonio Chaer Nascimento, and G. G. B. de Souza. "Are disulfide bonds resilient to double ionization? Insights from coincidence spectroscopy and ab initio calculations." RSC Advances 10, no. 58 (2020): 35039–48. http://dx.doi.org/10.1039/d0ra05979j.

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Journal articles on the topic 'Sulfuros de cobre'

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