Impact of oxy-fuel combustion gases on mercury retention in activated carbons from a macroalgae waste: Effect of water

The aim of this study is to understand the different sorption behaviors of mercury species on activated carbons in the oxy-fuel combustion of coal and the effect of high quantities of water vapor on the retention process. The work evaluates the interactions between the mercury species and a series of activated carbons prepared from a macroalgae waste (algae meal) from the agar–agar industry in oxy-combustion atmospheres, focussing on the role that the high concentration of water in the flue gases plays in mercury retention. Two novel aspects are considered in this work (i) the impact of oxy-combustion gases on the retention of mercury by activated carbons and (ii) the performance of activated carbons prepared from biomass algae wastes for this application. The results obtained at laboratory scale indicate that the effect of the chemical and textural characteristics of the activated carbons on mercury capture is not as important as that of reactive gases, such as the SOx and water vapor present in the flue gas. Mercury retention was found to be much lower in the oxy-combustion atmosphere than in the O2 + N2 (12.6% O2) atmosphere. However, the oxidation of elemental mercury (Hg0) to form oxidized mercury (Hg2+) amounted to 60%, resulting in an enhancement of mercury retention in the flue gas desulfurization units and a reduction in the amalgamation of Hg0 in the CO2 compression unit. This result is of considerable importance for the development of technologies based on activated carbon sorbents for mercury control in oxy-combustion processes.The authors acknowledge the financial support provided by the National Research Program under the project CTM2011–22921 and the Program FEDER of the Principado de Asturias 2007–2013 under the Project PC10-40.Peer reviewe

Optical Response of CVD-Grown ML-WS2 Flakes on an Ultra-Dense Au NP Plasmonic Array

The combination of metallic nanostructures with two-dimensional transition metal dichalcogenides is an efficient way to make the optical properties of the latter more appealing for opto-electronic applications. In this work, we investigate the optical properties of monolayer WS2 flakes grown by chemical vapour deposition and transferred onto a densely-packed array of plasmonic Au nanoparticles (NPs). The optical response was measured as a function of the thickness of a dielectric spacer intercalated between the two materials and of the system temperature, in the 75–350 K range. We show that a weak interaction is established between WS2 and Au NPs, leading to temperature- and spacer-thickness-dependent coupling between the localized surface plasmon resonance of Au NPs and the WS2 exciton. We suggest that the closely-packed morphology of the plasmonic array promotes a high confinement of the electromagnetic field in regions inaccessible by the WS2 deposited on top. This allows the achievement of direct contact between WS2 and Au while preserving a strong connotation of the properties of the two materials also in the hybrid system

Paper pulp-based adsorbents for the removal of pharmaceuticals from wastewater: A novel approach towards diversification

In this work, two pulps, bleached (BP) and raw pulp (RP), derived from the paper production process, were used as precursors of non-activated and activated carbons (ACs). In the case of non-ACs, the production involved either pyrolysis or pyrolysis followed by acid washing. For ACs production, the pulps were impregnated with K2CO3 or H3PO4, and then pyrolysed and acid washed. After production, the materials were physically and chemically characterized. Then, batch adsorption tests on the removal of two pharmaceuticals (the anti-epileptic carbamazepine (CBZ) and the antibiotic sulfamethoxazole (SMX)) from ultra-pure water and from Waste Water Treatment Plant (WWTP) effluents were performed. In ultra-pure water, non-ACs were not able to adsorb CBZ or SMX while ACs showed good adsorption capacities. In WWTP effluents, although ACs satisfactorily adsorbed CBZ and SMX, they showed lower adsorption capacities for the latter. Tests with WWTP effluents revealed that the best adsorption capacities were achieved by carbons produced from BP and activated with H3PO4: 92±19mgg-1 for CBZ and 13.0±0.6mgg-1 for SMX. These results indicate the potential of paper pulps as precursors for ACs that can be applied in wastewater treatment.publishe

Comprehensive use of the macroalgae industrial waste from the Agar-Agar Industry. Energy and environmental applications

Tesis doctoral presentada en el Departamento de Energía de la Universidad de Oviedo, mayo de 2014[EN] The present memory is aimed at a comprehensive use of macroalgae waste, Algae meal, from the Agar-Agar industry as a source of energy for the pyrolysis process and as to preparare of activated carbons from algae meal and its carbonized products. The work was provided by the operating programme FEDER of the Principado de Asturias 2007–2013. The Algae meal was pyrolysed using two different heating methods: pyrolysis in an electrical furnace and pyrolysis in a microwave furnace. In both cases three fractions were obtained for use in industrial applications: 1) a solid fraction , char, which can be used as precursor of activated carbons or as a fuel, having the best chemical properties the one that is obtained by conventional pyrolysis; 2) a liquid fraction , bio- oils, which can be applied as fuel after a pretreatment for the removal of nitrogen compounds; and 3) a gaseous fraction , biogas , which can also be used as fuel or as a raw material in chemical synthesis due to its high syngas content, especially in the case of microwave pyrolysis. As regards to the preparation of activated carbons, the chemical activation conditions were optimized, to obtain adsorbents that can be applied for the retention of gaseous pollutant. Two types of precursors were used, Algae meal and its char obtained by pyrolysis, using two different heating methods : conventional activation and microwave activation. In addition, the influence of the activation temperature and the activating agent/precursor ratio were studied. In general, the activated carbons obtained had very good chemical and textural properties: they were mainly microporous and had specific surface areas of up to 2118 m2/g. The best adsorbent materials were those obtained by conventional activation, using Algae meal as precursor, at temperatures between 750-900 °C and activation agent/precursor ratios of 0.5:1 and 1:1. Once prepared and characterized, some of the activated carbons were used to capture CO2, CH4 and H2 at high pressures. It was found that all of them had a high selectivity towards CO2 and a low selectivity towards CH4 and H2, and they could be used in PSA processes or for the separation of mixtures of CO2/H2 or CO2/CH4. On the other hand, some of them were applied for the retention of gaseous mercury in two different atmospheres: air and oxy-combustion. In general, most of them showed a good retention capacity for gaseous mercury in air atmosphere, comparable to that of a commercial activated carbon specifically designed for the retention of mercury. However, they displayed a worse mercury retention under capacity an oxy-combustion atmosphere.[ES] La presente memoria tiene como objetivo el aprovechamiento integral de un residuo de macroalga, Harina de Algas, procedente de la industria del Agar- Agar, mediante dos vías bien diferenciadas: por un lado la valorización energética de este residuo mediante un proceso de pirólisis y por otro lado la preparación de carbones activados a partir de la Harina de algas y de su carbonizado obtenido en dicho proceso de pirólisis. Todo ello se encuentra financiado dentro del programa operativo FEDER del Principado de Asturias (2007-2013). En lo referente a la pirólisis de la Harina de algas, se han abordado dos metodologías de calentamiento diferentes: la pirólisis en horno eléctrico convencional y la pirólisis en horno microondas. En ambos casos se han obtenido tres fracciones que pueden tener una aplicación industrial: 1) una sólida, carbonizado o char, que puede ser utilizada como precursor de carbones activados o como combustible, teniendo mejores propiedades químicas la fracción obtenida mediante pirolisis convencional; 2) una líquida, conocida como bio-aceites, que podría ser aplicada como combustible si se realiza un pre-tratamiento de eliminación de compuestos nitrogenados y 3) una fracción gaseosa, bio-gas, que podría también ser usada como combustible o en la síntesis de productos químicos dado su alto contenido en gas de síntesis, sobre todo en el caso del bio-gas obtenido mediante pirólisis en microondas. Con respecto a la preparación de carbones activados se han optimizado las condiciones de activación química para la obtención de materiales adsorbentes que pudieran ser aplicados a la retención de contaminantes gaseosos. Se han utilizado dos tipos de precursores, Harina de algas y su carbonizado, y dos metodologías de calentamiento diferentes: activación convencional y activación microondas. Además, se ha estudiado la influencia de la temperatura de activación y la relación de agente activante/precursor. En general, se obtuvieron carbones activados con muy buenas propiedades químicas y texturales, siendo éstos principalmente microporosos con áreas superficiales de hasta 2118 m2/g. Las mejores características las presentaban los obtenidos utilizando la harina de algas como precursor mediante activación convencional, con temperaturas comprendidas entre 750-900 ºC y relaciones de agente/activante precursor de 0,5:1 y 1:1. Una vez preparados y caracterizados dichos carbones activados, parte de estos materiales fueron utilizados para la captura de CO2, CH4 y H2 a altas presiones. Se encontró que todos los carbones activados evaluados poseen alta selectividad hacia el CO2 y baja selectividad hacia el CH4 y H2, pudiendo ser utilizados en procesos PSA (Pressure Swing Adsorption) o en separación de mezclas CO2/H2 o CO2/CH4. Por otro lado, algunos de ellos fueron aplicados a la retención de mercurio gaseoso bajo dos atmósferas diferentes: aire y oxicombustión. En general, la mayoría de los carbones activados presentaron buenas retenciones de mercurio gaseoso en atmósfera de aire, comparables con las del carbón activado comercial específico para la retención de mercurio. Sin embargo, presentaron peor retención de mercurio en atmósfera de oxi-combustión.Peer reviewe

Effects of large river dam regulation on bacterioplankton community structure

16 pages, 5 figures, 3 tablesLarge rivers are commonly regulated by damming, yet the effects of such disruption on prokaryotic communities have seldom been studied. We describe the effects of the three large reservoirs of the Ebro River (NE Iberian Peninsula) on bacterioplankton assemblages by comparing several sites located before and after the impoundments on three occasions. We monitored the abundances of several bacterial phylotypes identified by rRNA gene probing, and those of two functional groups (picocyanobacteria and aerobic anoxygenic phototrophic bacteria-AAPs). Much greater numbers of particles colonized by bacteria were found in upstream waters than downstream sites. Picocyanobacteria were found in negligible numbers at most sites, whereas AAPs constituted up to 14% of total prokaryotes, but there was no clear effect of reservoirs on the spatial dynamics of these two groups. Instead, damming caused a pronounced decline in Betaproteobacteria, Gammaproteobacteria and Bacteroidetes from upstream to downstream sites, whereas Alphaproteobacteria and Actinobacteria significantly increased after the reservoirs. Redundancy analysis revealed that conductivity, temperature and dissolved inorganic nitrogen were the environmental predictors that best explained the observed variability in bacterial community composition. Our data show that impoundments exerted significant impacts on bacterial riverine assemblages and call attention to the unforeseen ecological consequences of river regulationThis study was funded by the Confederaci on Hidrogr afica del Ebro. Additional funds were provided by the project SCARCE (Consolider-Ingenio 2010, CSD2009-00065). We acknowledge the support of Concha Duran throughout the study, and the help from Elisabet Tornes and Carmen Guti errez in the field and laboratoryPeer reviewe

Conventional and microwave pyrolysis of a macroalgae waste from the Agar–Agar industry. Prospects for bio-fuel production

[EN] A comparative study of the pyrolysis of a macroalgae industrial solid waste (algae meal) in an electrical conventional furnace and in a microwave furnace has been carried out. It was found that the chars obtained from both pyrolyses are similar and show good properties for performing as a solid bio-fuel and as a precursor of activated carbon. Bio-oils from conventional pyrolysis have a greater number of phenolic, pyrrole and alkane compounds whereas benzene and pyridine compounds are more predominant in microwave pyrolysis with a major presence of light compounds. The bio-gas fraction from microwave pyrolysis presents a much higher syngas content (H2 + CO), and a lower CO2 and CH4 proportion than that obtained by conventional pyrolysis. Yields are similar for both treatments with a slightly higher gas yield in the case of microwave pyrolysis due to the fact that microwave heating favors heterogeneous reactions between the gases and the char.The financial support for this work was provided by the operating program FEDER of Principado de Asturias 2007–2013 under the Project PC10-40. The authors thank the industry for providing the macroalgae industrial residue used in this work.Peer reviewe

New process for producing methanol from coke oven gas by means of CO2 reforming. Comparison with conventional process

[EN] A novel method of producing methanol from coke oven gas (COG), involving the CO2 reforming of COG to obtain an appropriate syngas for the synthesis of methanol is proposed. This method is compared with a conventional process of methanol synthesis from natural gas, in terms of energy consumption, CO2 emissions, raw material exploitation and methanol purity. Whereas this new process requires the consumption of less energy, the conventional process allows a higher energy recovery. CO2 emissions are considerably lower with the new process, but the geographic situation of the plant plays a determinant role. From the point of view of raw material exploitation and methanol purity, the process proposed yields better results. These results suggest that methanol production from coke oven gas would be a more attractive alternative to conventional processes.JMB acknowledges the support received from the CSIC JAE Program. Financial support from the PCTI Asturias (Projects PEST08-03 and PEST08-21) is also acknowledged. The authors would also like to express their gratitude to Professor José R. Alvarez, of the Department of Chemical and Environmental Engineering at the University of Oviedo, for his help in setting up the Fortran program used in the membrane gas separation unit within Aspen Plus.Peer reviewe

Pneumonia associada a influenza A (H1N1)

OBJETIVO: Descrever as características dos pacientes com pneumonia associada a influenza A (H1N1) tratados em dois hospitais na região da Ligúria, Itália, e descrever seu tratamento e desfechos. MÉTODOS: Estudo prospectivo observacional que incluiu todos os pacientes com mais de 16 anos de idade e com diagnóstico confirmado de influenza A (H1N1) admitidos no Hospital Villa Scassi, em Gênova, ou no Hospital Geral de Sestri Levante, em Sestri Levante, Itália, entre setembro de 2009 e janeiro de 2010. O desfecho primário foi mortalidade em até 60 dias do diagnóstico, e os desfechos secundários foram necessidade de ventilação mecânica e tempo de hospitalização. RESULTADOS: Durante o período do estudo, dos 40 pacientes com diagnóstico confirmado de influenza A (H1N1), 27 apresentaram pneumonia. A média de idade dos 27 pacientes foi de 42,8 ± 14,8 anos, e o tempo médio de hospitalização foi de 11,6 ± 8,2 dias. Dos 27 pacientes, 20 tiveram insuficiência respiratória, 4 necessitaram de ventilação mecânica invasiva e 5, de ventilação mecânica não invasiva. Somente 1 paciente com várias comorbidades teve falência múltipla de órgãos e faleceu. CONCLUSÕES: Embora a influenza A (H1N1) tenha sido mais branda e com menor incidência de mortalidade na Itália do que em outros países, 9 de nossos pacientes (33%) tiveram evolução rápida para falência respiratória e necessitaram de ventilação mecânica