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Neutron Activation Analysis: A Primary (Ratio) Method to Determine SI-Traceable Values of Element Content in Complex Samples

BODE, Peter; GREENBERG, Robert R.; FERNANDESC, Elisabete A. De Nadai
Fonte: SWISS CHEMICAL SOC Publicador: SWISS CHEMICAL SOC
Tipo: Artigo de Revista Científica
ENG
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The metrological principles of neutron activation analysis are discussed. It has been demonstrated that this method can provide elemental amount of substance with values fully traceable to the SI. The method has been used by several laboratories worldwide in a number of CCQM key comparisons - interlaboratory comparison tests at the highest metrological level - supplying results equivalent to values from other methods for elemental or isotopic analysis in complex samples without the need to perform chemical destruction and dissolution of these samples. The CCOM accepted therefore in April 2007 the claim that neutron activation analysis should have the similar status as the methods originally listed by the CCOM as `primary methods of measurement`. Analytical characteristics and scope of application are given.

Production, characterization and application of activated carbon from brewer`s spent grain lignin

MUSSATTO, Solange I.; FERNANDES, Marcela; ROCHA, George J. M.; ORFAO, Jose J. M.; TEIXEIRA, Jose A.; ROBERTO, Ines C.
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
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459.9504%
Different types of activated carbon were prepared by chemical activation of brewer`s spent grain (BSG) lignin using H(3)PO(4) at various acid/lignin ratios (1, 2, or 3 g/g) and carbonization temperatures (300, 450, or 600 degrees C), according to a 2(2) full-factorial design. The resulting materials were characterized with regard to their surface area, pore volume, and pore size distribution, and used for detoxification of BSG hemicellulosic hydrolysate (a mixture of sugars, phenolic compounds, metallic ions, among other compounds). BSG carbons presented BET surface areas between 33 and 692 m(2)/g, and micro- and mesopores with volumes between 0.058 and 0.453 cm(3)/g. The carbons showed high capacity for adsorption of metallic ions, mainly nickel, iron, chromium, and silicon. The concentration of phenolic compounds and color were also reduced by these sorbents. These results suggest that activated carbons with characteristics similar to those commercially found and high adsorption capacity can be produced from BSG lignin. (C) 2009 Elsevier Ltd. All rights reserved.; CAPES; FAPESP; CNPq (Brazil)

Time Evolution of the Activation Energy in a Batch Chemical Oscillator

NOGUEIRA, Paulo A.; OLIVEIRA, Hyria C. L.; VARELA, Hamilton
Fonte: AMER CHEMICAL SOC Publicador: AMER CHEMICAL SOC
Tipo: Artigo de Revista Científica
ENG
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459.9504%
The batch-operated bromate/phosphate/acetone/dual catalyst system was studied at four temperatures between 5 and 35 degrees C. The dynamics was simultaneously followed by potential measurements with platinum and bromide selective electrodes, and spectroscopically at two different wavelengths. By simultaneously recording these four time series it was possible to characterize the dynamics of the sequential oscillations that evolve in time. The existence of three sequential oscillatory patterns at each temperature allowed estimating the activation energies in each case. Along with the activation energy of the induction period, it was possible to trace the time evolution of the overall activation energy at four different stages as the reaction proceeds. The study was carried out for two different sets of initial concentrations and it was observed that the overall activation energy increases as reactants turn into products. This finding was propounded as a result of the decrease in the driving force, or the system`s affinity, of the catalytic oxidative bromination of acetone with acidic bromate, as the closed system evolves toward the thermodynamic equilibrium.; Conselho Nacional de Desenvolviniento Cientifico e Tecnologico (CNPq)[142727/2006-7]; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Conselho Nacional de Desenvolviniento Cientifico e Tecnologico (CNPq)[302698/2007-8]; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[04/04528-0]

Activated carbon production from brewer’s spent grain lignin

Mussatto, Solange I.; Fernandes, Marcela; Rocha, George J. M.; Orfão, J. J. M.; Teixeira, J. A.; Roberto, Inês Conceição
Fonte: BioMicroWorld 2009 Publicador: BioMicroWorld 2009
Tipo: Conferência ou Objeto de Conferência
Publicado em //2009 ENG
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Activated carbons are adsorbents that are industrially used in multiple processes for product separation and purification, and for the treatment of liquid and gaseous effluents. Despite its frequent use in the water and waste industries, activated carbons remain an expensive material. In view of the high cost and the tedious procedures for the preparation and regeneration of activated carbons, there is a continuing search for low-cost potential adsorbents. The preparation of activated carbons from lignin is an attractive way of giving added value to this material, which is mainly used as in-house fuel for the recovery of both energy and residual inorganic matter. Over the past few decades, some works have been done on the activation of agricultural lignocellulosic waste materials to carbons, due to their low cost and high availability. Nevertheless, there is not any literature report about the activated carbon production from brewer’s spent grain (BSG) lignin. Use of BSG lignin as starting material for activated carbon production is interesting because BSG (the main brewery by-product) is produced in large amounts during all year, and is a lignin-rich material. Lignin can be converted in activated carbon by physical or chemical activation...

Adsorption of fluoxetine onto waste-based activated carbon; Adsorção de fluoxetina a carvões de bio-resíduos ativados

Jaria, Guilaine Marques
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Dissertação de Mestrado
ENG
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454.8729%
Activated carbons are one of the most promising techniques for the removal of organic and inorganic compounds from waters. In this work three activated carbons were produced using as precursor primary paper mill sludge. Chemical activation was performed using three different activation agents, KOH, NaOH and ZnCl2, and the same pyrolysis conditions were applied. The characterization of the obtained materials was made by means of total organic carbon analysis (TOC), Fourier infrared spectroscopy with attenuated total reflectance (FTIR-ATR), proximate and ultimate analysis, scanning electron microscopy (SEM), Hg porosimetry, BET isotherms and point of zero charge (PZC) determination. Adsorption studies were made, beginning with adsorption kinetic and then adsorption equilibrium (isotherms of adsorption), all performed in batch experiments. Generally, the carbons presented an equilibrium time of around six hours. Equilibrium studies allowed test the adsorption capacity of the produced carbons for fluoxetine-HCl. These two studies were also performed to the primary sludge pyrolysed under the same conditions without activation and also to a commercial activated carbon as reference. Among the produced materials, the carbon activated with ZnCl2 has the higher BET surface area and percentage of carbon. The maximum adsorption capacity (mg g-1) was of 96.2 ± 1.0 for PBFG4; 120.4 ± 2.5 for PS800-10; 191.6 ± 4.8 for PS800-10KOH; 136.6 ± 9.6 for PS800-10NaOH; and 28.4 ± 0.3 for PS800-10ZnCl2. The isotherms obtained point for different mechanism of adsorption between the carbons...

Textural Development of Activated Carbon Prepared from Recycled PET With Different Chemical Activation Agents

Cansado, Isabel; Ribeiro Carrott, Manuela; Carrott, Peter; Mourão, Paulo
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Aula Formato: 38813 bytes; application/pdf
ENG
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In this work a series of microporous activated carbons, with different burn offs, was prepared from recycled PET provided by Selenis (Portalegre-Portugal). These AC were prepared by chemical activation with KOH, NaOH and H3PO4, and carbonised under a N2 flow of 85cm3min-1 between 873 and 1273K. The carbonised samples were then cooled and successively washed until the washable solutions achieved a pH around 7.0, afterwards these were dried at 110ºC. All adsorbents were characterised by the adsorption of N2 at 77K and the pHpcz and the elemental analyse were determined. First, with all activation agents when the carbonization temperature increased up to 723K, the carbonization yield increased. With NaOH, the carbonization yield varied from 8 to 31% and the optimal ratio of NaOH/PET was less than with KOH. The pore size was in all cases larger (between 1.15 and 2.4 nm) when compared with the AC obtained with the other activating agents. On the other hand, the AC prepared with H3PO4 present the narrowest pore size (between 0.76 and 0.83 nm) and the highest micropore volume (0.34 cm3 g-1) was obtained with a ratio of H3PO4/PET =0.75. All samples prepared with H3PO4 present an acidic point of zero charge, between 2.3 and 4.2. AC prepared by chemical activation with KOH...

Comparison of the Dubinin-Radushkevich and Quenched Solid Density Functional Theory Approaches for the Characterisation of Narrow Microporosity in Activated Carbons Obtained by Chemical Activation with KOH or NaOH of Kraft and Hydrolytic Lignins

P.J.M. Carrott; M.M.L. Ribeiro Carrott; Suhas
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
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The classical DR method and the Quenched Solid Density Functional Theory (QSDFT) approach have been used to analyse N2 at 77 K isotherms determined on activated carbons prepared by alkaline chemical activation of different lignins. The QSDFT pore size distributions are bimodal with a narrow peak below 1 nm and a broad peak from 1 to 2.5–3.5 nm. Deconvolution allows estimation of the volumes and widths of the narrow micropores. These are lower than estimated by the DR analysis as this does not separate micropore and non-micropore adsorption. On the basis of the QSDFT analysis, the optimum conditions for obtaining materials with a high volume of narrow micropores were activation temperatures of 550–650 C, hydroxide/lignin ratio of 1 and dwell time at the maximum activation temperature of 30 min. KOH was preferable to NaOH as it requires lower temperatures and results in materials with higher narrow micropore volumes. The ‘‘best’’ material obtained, prepared with KOH at 550 C, had mean micropore width of 0.7 nm and micropore volume of 0.37 cm3 g 1 which compares very favourably with molecular sieve carbons prepared from synthetic polymers. Furthermore, this material was obtained with an activation yield of 32.9%, which is quite high for alkaline chemical activation.

Preparação e caracterização de carvão ativado quimicamente a partir da casca de arroz

Schettino Jr.,Miguel A.; Freitas,Jair C. C.; Cunha,Alfredo G.; Emmerich,Francisco G.; Soares,Ana B.; Silva,Paulo R. N.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 PT
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This work consists in a study about the chemical activation of charred rice hulls using NaOH as the activation agent. The influence of the naturally-occurring silica was particularly evidenced. X-ray diffraction patterns showed the formation of sodium carbonate and silicates in the activated samples, whereas thermogravimetric curves revealed a strong reduction in the ash content of these samples after washing with water. Nitrogen adsorption data indicated a microporosity development only in the washed samples, with BET surface area values of 450 and 1380 m²/g achieved for the samples activated at 800 °C starting from the precursor with or without silica, respectively.

Production and characterization of granular activated carbon from activated sludge

Al-Qodah,Z.; Shawabkah,R.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2009 EN
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In this study, activated sludge was used as a precursor to prepare activated carbon using sulfuric acid as a chemical activation agent. The effect of preparation conditions on the produced activated carbon characteristics as an adsorbent was investigated. The results indicate that the produced activated carbon has a highly porous structure and a specific surface area of 580 m²/g. The FT-IR analysis depicts the presence of a variety of functional groups which explain its improved adsorption behavior against pesticides. The XRD analysis reveals that the produced activated carbon has low content of inorganic constituents compared with the precursor. The adsorption isotherm data were fitted to three adsorption isotherm models and found to closely fit the BET model with R² equal 0.948 at pH 3, indicating a multilayer of pesticide adsorption. The maximum loading capacity of the produced activated carbon was 110 mg pesticides/g adsorbent and was obtained at this pH value. This maximum loading was found experimentally to steeply decrease as the solution pH increases. The obtained results show that activated sludge is a promising low cost precursor for the production of activated carbon.

Analysis of signal transduction networking using activation ratios

Femenia, Francisco J
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 157 leaves; 2398662 bytes; 3470768 bytes; application/pdf; application/pdf
ENG
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The molecular processes by which information is incorporated and distributed within a cell are termed signal transduction. These pathways allow cells to interact with each other and with their environments and are critical to the proper cellular function in a variety of contexts. Previously developed methods for analyzing signaling networks have been largely ignored, most likely due to their mathematical complexity and difficulty in application. A novel analysis framework was developed to assist in the examination of signaling networks, both to facilitate the reconstruction of previously undetermined pathways as well as to quantitatively characterize interactions between components. This approach, termed activation ratio analysis, involves the ratio between active and inactive forms of signaling intermediates at steady state. The activation ratio of an intermediate is shown to depend linearly upon the concentration of the activating enzyme. The slope of the line is defined as the activation factor, and is determined by the kinetic parameters of activation and inactivation. The mathematical functionality of the activation ratio changes for other signaling network arrangements. It is therefore possible to extract the original network structure from a set of measured activation ratios...

Avaliação do desempenho de adsorventes obtidos a partir de resíduos da indústria de curtumes na adsorção de poluentes

Loureiro, Joana Filipa Fonseca Sargaço
Fonte: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto Publicador: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto
Tipo: Dissertação de Mestrado
Publicado em //2012 POR
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Na procura por uma solução de valorização dos resíduos gerados pela indústria de curtumes, o presente trabalho tem como principais objectivos a preparação de adsorventes a partir de resíduos desta actividade e a avaliação do seu desempenho na adsorção de poluentes. Para atingir este objectivo, inicialmente procedeu-se à carbonização das aparas de couro wet-white à temperatura de 800 ºC. Seguidamente, os carbonizados foram activados por activação química, tendo sido o hidróxido de potássio o agente activante escolhido. As razões mássicas hidróxido de potássio:precursor usadas na impregnação, foram iguais a 0,5:1 e 1:1. Para a razão 0,5:1, as temperaturas de activação escolhidas foram 700 e 800 ºC. Para a razão de impregnação 1:1, as temperaturas de activação usadas foram 700, 800 e 900 ºC. Para uma avaliação preliminar da capacidade de adsorção dos carvões activados produzidos, efectuou-se a determinação do número de azul de metileno. Este teste provou serem as amostras activadas a 900 ºC as que apresentaram melhores resultados (número de azul de metileno: 24g/100g) e as amostras activadas a 700 ºC, as que apresentaram menor capacidade de adsorção (1g/100g, para a razão de 0,5:1 e 7g/100g...

Produção de carvão activado a partir de resíduos da indústria de curtumes

Magalhães, Maria João Rodrigues
Fonte: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto Publicador: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto
Tipo: Dissertação de Mestrado
Publicado em //2010 POR
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As aparas de wet-blue e de wet-white constituem um resíduo sólido da indústria de curtumes com um elevado teor em carbono, tornando relevante a sua utilização na preparação de materiais de interesse tecnológico. Este trabalho teve como objectivo a preparação de carvões activados a partir de resíduos da indústria de curtumes. Os métodos de activação utilizados para a preparação dos carvões activados foram a activação física com dióxido de carbono e activação química com hidróxido de potássio. A carbonização dos resíduos foi estudada na gama de temperaturas de 500 ºC a 800 ºC, verificando-se que a sua carbonização se pode considerar completa para a temperatura de 800 ºC. Na activação física os precursores foram previamente carbonizados sob uma atmosfera inerte a 800 ºC e posteriormente activados a 940 ºC usando o CO2 como agente activante. Na etapa de activação variou-se o tempo de activação (20, 40 e 60 minutos) de modo a estudar a influência do grau de queima nas propriedades texturais dos carvões activados. O carvão activado obtido pelo método de activação física com maior área superficial específica foi o carvão preparado a partir do resíduo de wet-blue para um tempo de activação de 40 minutos e grau de queima de 23 % (SBET = 152 m2/g). Para a activação química...

Preparação de materiais de carbono para a adsorção de compostos orgânicos voláteis (COV).

Campos, Marisa Soares da Costa
Fonte: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto Publicador: Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto
Tipo: Dissertação de Mestrado
Publicado em //2012 POR
Relevância na Pesquisa
456.28734%
A presente dissertação estudou a produção de carvão ativado a partir de resíduo de wet-blue, proveniente da indústria de curtumes, para a adsorção de compostos orgânicos voláteis, nomeadamente o acetato de etilo. Este estudo teve como principais objetivos: a otimização das condições de preparação de carvões ativados a partir deste tipo de resíduo; a avaliação do seu desempenho na adsorção do acetato de etilo e a correlação das propriedades texturais dos adsorventes com o seu desempenho na adsorção do COV. O método de ativação para a preparação dos carvões ativados foi a ativação química com hidróxido de potássio. Nesta etapa foi estudado o efeito da temperatura de ativação e da razão de impregnação KOH:precursor nas propriedades texturais. Nestes ensaios observou-se uma diminuição do rendimento de carbonizado com o aumento da temperatura de ativação e da razão KOH:precursor. Para a caracterização dos carvões ativados foram determinados os seus parâmetros texturais a partir das isotérmicas de adsorção/dessorção de N2 a 77 K. O carvão ativado com melhores propriedades texturais foi o ativado a 900ºC e com razão de impregnação de 3:1, m ca_900 3:1, com área superficial específica de 1902 m2/g...

The influence of chemical activation on hardness of dual-curing resin cements

Fonseca,Renata Garcia; Cruz,Carlos Alberto dos Santos; Adabo,Gelson Luis
Fonte: Sociedade Brasileira de Pesquisa Odontológica - SBPqO Publicador: Sociedade Brasileira de Pesquisa Odontológica - SBPqO
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2004 EN
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During the cementation of metallic restorations, the polymerization of dual-curing resin cements depends exclusively on chemical activation. This study evaluated the influence of chemical activation compared with dual-curing (chemical and light activation), on the hardness of four dual-curing resin cements. In a darkened environment, equal weight proportions of base and catalyst pastes of the cements Scotchbond Resin Cement, Variolink II, Enforce and Panavia F were mixed and inserted into moulds with cavities of 4 mm in diameter and 2 mm in height. Subsequently, the cements were: 1) not exposed to light (chemical activation = self-cured groups) or 2) photoactivated (dual-curing = dual-cured groups). The Vickers hardness number was measured at 1 hour, 24 hours and 7 days after the start time of cements' spatulation. For all the cements, the hardness values of self-cured groups were lower than those of the respective dual-cured groups at 1 hour and 24 hours. At 7 days, this behavior continued for Variolink II and Panavia F, whilst for Scotchbond Resin Cement and Enforce there was no statistical difference between the two activation modes. All cements showed a significant increase in their hardness values from 1 hour to 7 days for both activation modes. Of the self-cured groups...

Tailoring the textural properties of activated carbon xerogels by chemical activation with KOH

Zubizarreta, Leire; Arenillas de la Puente, Ana; Pirard, Jean-Paul; Pis Martínez, José Juan; Job, Nathalie
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 9211995 bytes; application/pdf
ENG
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660.79016%
11 pages, 10 figures, 3 tables.-- Printed version published Nov 1, 2008.; Resorcinol–formaldehyde xerogels synthesised with different resorcinol/sodium carbonate molar ratios were chemically activated either after drying or after drying and pyrolysis, using potassium hydroxide. It was found that organic (i.e. dried) and carbon (i.e. pyrolysed) xerogels behave differently when subjected to chemical activation. In the case of carbon xerogels, the increase in the microporosity takes place without any significant modification to the meso/macroporosity formed during the synthesis step, leading to micro–mesoporous or micro–macroporous materials with a larger micropore volume. Furthermore, control of the microporosity is possible because its development depends on the amount of KOH used. However, when organic xerogels are activated, mainly microporous materials with BET specific surface areas of up to 2000 m2 g−1 are obtained, there hardly remaining any of the meso/macroporosity formed during the gel synthesis. Thus, the combination of different synthesis conditions and chemical activation with potassium hydroxide allows the textural properties of carbon xerogels to be tailored at both micropore and meso/macropore levels.; L.Z. acknowledges the support received from the CSIC I3P Programme cofinanced by the European Social Fund. N.J. is grateful to the F.R.S.-F.N.R.S. (Belgium) for a postdoctoral fellowship. The Belgian authors thank the Fonds de Bay...

Preparation of carbon dioxide adsorbents from the chemical activation of urea–formaldehyde and melamine–formaldehyde resins

Drage, Trevor C.; Arenillas de la Puente, Ana; Smith, Karl M.; Pevida García, Covadonga; Piippo, S.; Snape, Colin E.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 22195 bytes; application/pdf
ENG
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10 pages, 4 figures, 3 tables.-- Available online Aug 14, 2006.; Adsorption is considered to be one of the more promising technologies for the capture of CO2 from flue gases. In general, nitrogen enrichment is reported to be effective in enhancing the specific adsorbent–adsorbate interaction for CO2. Nitrogen enriched carbons were produced from urea–formaldehyde and melamine–formaldehyde resins polymerised in the presence of K2CO3 as a chemical activation agent, with activation undertaken over a range of temperatures. CO2 adsorption capacity was determined to be dependent upon both textural properties and more importantly nitrogen functionality. Adsorbents capable of capturing above 8 wt.% CO2 at 25°C were produced from the chemical activation of urea–formaldehyde resin at 500°C. Chemical activation seems to produce more effective adsorbents than CO2 activation.; The authors are grateful for support for this work provided by the Research Fund for Coal and Steel (RFC-CR-03008) and for CP a grant from Plan I + D + I Gobierno del Principado de Asturias.; Peer reviewed

Activation of carbon nanofibres for hydrogen storage

Blackman, James M.; Patrick, John W.; Arenillas de la Puente, Ana; Shi, Wei; Snape, Colin E.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 918459 bytes; application/pdf
ENG
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10 pages, 10 figures, 6 tables.-- Printed version published Jul 2006.; The present study was aimed to investigate different methods of activation of carbon nanofibres, CNF, in order to determine the beneficial effect on the hydrogen sorption capacities of increasing the surface area. Two activation systems were used: physical activation with CO2 and chemical activation with KOH. A range of potential adsorbents were thus prepared by varying the temperature and time of activation. The structure of the CNF proved more suitable to activation by KOH than by CO2, with the former yielding higher surface area carbons (up to 1000 m2 g−1). The increased surface area, however, did not correspond directly with a proportional increase in hydrogen adsorption capacity. Although high surface areas are important for hydrogen storage by adsorption on solids, it would appear that it is essential that not only the physical, but also the chemical, properties of the adsorbents have to be considered in the quest for carbon based materials, with high hydrogen storage capacities.; The financial support of the EPSRC (Engineering and Physical Sciences Research Council) and Air Products and Chemicals, Inc. is gratefully acknowledged.; Peer reviewed

Alkaline chemical activation of urban glass wastes to produce cementituous materials

Torres, Trinidad José de; Palacios, M.; Hellouin, M.; Puertas, F.
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Comunicación de congreso Formato: 878931 bytes; application/pdf
ENG
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560.9719%
En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.-- 4 pages, 4 figures, 2 tables.; This is a preliminary work for evaluate the promising direction to reuse the recycled vitreous material by the alkaline activation than help to produce an alternative material with cementitious characteristic. NaOH and NaOH/Na2CO3 solutions were used like activation agents during the alkaline chemical activation of glass waste/blast furnace slag mixtures. The particle size of glass waste and nature of alkaline solution were analyzed to identify their influence on the mechanical properties. The NaOH/Na2CO3 solutions showed better performance to activate the blast furnace slag. The mechano-chemical process is an option for dissolve the glass waste in an alkaline solution. The alkaline solution formed with the glass waste will be use like alkaline activation agent for the blast furnace slag.; The authors wish to thank to CSIC for funding this research through project Z2008RU0038. J.J. Torres worked under a postdoctoral fellowship awarded by the CONACYT-Mexico.; Peer reviewed

Use of an activated carbon from antibiotic waste for the removal of Hg(II) from aqueous solution

Budinova, Temenuzhka; Petrov, Nartzislav; Parra Soto, José Bernardo; Baloutzov, Venelin
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 22195 bytes; application/pdf
ENG
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8 pages, 6 figures, 4 tables.-- PMID: 17428604 [PubMed].-- Available online Apr 10, 2007.; Porous carbon has been prepared from waste antibiotic material by a chemical activation method using K2CO3 as an activating reagent. Carbon was studied systematically by the adsorption of nitrogen and iodine. It was found that the process parameters such as activation temperature and activation time are crucial for preparing high-quality activated carbon. The proper choice of the preparation conditions allows to produce microporous activated carbon with a micropore volume up to 0.492 cm3/g and a BET surface area of 1260 m2/g. Adsorption of mercury(II) from an aqueous solution on antibiotic carbon was investigated under the varying conditions of agitation time, metal ion concentration and pH. The adsorption capacity of the carbon is 129 mg/g.; Financial support from The Ministry of Education and Science (project CC-1401) is gratefully acknowledged.; Peer reviewed

Production, Characterization and Application of Activated Carbon Obtained from the Corncob: The Search for the Reuse of an Agroindustrial Waste; Produção, Caracterização e Aplicação do Carvão Ativado Obtido a partir do Sabugo de Milho: A Busca pelo Reaproveitamento de um Resíduo Agroindustrial

Priscila F. de Sales; Universidade Federal de Lavras; Alexandre C. Bertoli; Universidade Federal de Lavras; Felipe M. Pinto; Universidade Estadual de Campinas; Zuy Maria Magriotis
Fonte: Revista Virtual de Química Publicador: Revista Virtual de Química
Tipo: ; Formato: binary/octet-stream
Publicado em 08/07/2015 PT
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The production, characterization and application of activated carbon obtained from corncobs as an adsorbent was studied.  Fresh material was submitted to thermal analysis (TG-DTA), and the carbon obtained from chemical activation was characterized by specific surface area (SBET), distribution of pore size (DFT), Scanning Electron Microscopy (SEM) and Infrared spectroscopy with Fourier transform (FT-IR). The adsorption of orange dye (OG) and methylene blue (MB) proved that data from isothermal adsorption were better adjusted to the Sips model.  The maximum quantities, 86 mg g-1 and 124 mg g-1, were obtained respectively for the adsorption of the dyes Orange G (OG) and Methylene Blue (MB). The results allow to conclude that the chemical activation of corncobs was responsible for the production of material, which is adequate to be applied as an adsorbent, enabling reuse of this agroindustrial residue. DOI: 10.5935/1984-6835.20150066; Foi estudada a produção, caracterização e aplicação do carvão ativado obtido a partir de sabugo de milho como adsorvente. Enquanto o material “in natura” foi submetido à análise térmica (TG-DTA), o carvão obtido da ativação química foi caracterizado pelas análises de área superficial específica (SBET)...