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01724 Preparation and characterization of spherical activated carbons from oil agglomerated bituminous coals for removing organic impurities from water
05 Nuclear fuels (scientific, technical) 03/01724 Preparation and characterization of spherical activated carbons from oil agglomerated bituminous coals for removing organic impurities from water Gryglewicz, G. et al. Carbon, 2002, 40, (13), 2403-2411. A new and simple method of producing of spherical activated carbons (SACS) from different bituminous coals, i.e. gas coal, gas-coking coal and orthocoking coal, is presented. Coal agglomerates of spherical shape obtained by oil agglomeration using rapeseed oil and linseed oil, were subjected to carbonization and activation with steam at 850°C. The SACS prepared from gas-coking coal (hvAb) agglomerates were characterized by the best developed porous structure with surface area Sam of about 800 m*/g and pore volume of 0.40 cm’/g. The adsorption capacity of the produced SACS was determined in terms of substituted phenolic compounds. The adsorption of 2-chlorophenol (OCP), 4chlorophenol (PCP) and 4-nitrophenol (PNP) from aqueous solutions was studied under a static conditions on the SAC prepared from gascoking coal agglomerated using rapeseed oil. At high concentrations of the solute the adsorption behavior of OCP was found to be different in comparison to PCP and PNP. The adsorption of the two last phenolic compounds on the selected SAC is very well described by Langmuir adsorption model. For OCP a two-stepped adsorption isotherm was obtained. The Langmuir isotherm equation fits very well only for the first stage of the OCP adsorption.
03/01725 Primary carbonization of an anisotropic ‘mesophase’ pitch compared to conventional isotropic
in aqueous
solution
by
Rio, S. and Delebarre, A. Fuel, 2003, 82, (2), 153.-159. Coal combustion in power plant produces fly ash. Fly ash may be used in water treatment to remove mercury (Hg”) from water or to immobilize mercury mobile forms in silts and soils. Experiments were carried out on two kinds of fly ashes produced by two circulating fluidized bed plants with different chemical composition: silicoaluminous fly ashes and sulfo-calcic fly ashes. For the two kinds of fly ashes, adsorption equilibrium were reached in 3 days. Furthermore, removal of mercury was increased with increasing pH. Sulfa-calcic fly ashes allow us to remove mercury more efficiently and more steady. The chemical analysis of fly ash surface was carried out by electron spectroscopy. The results show that mercury is bound to ash surface thanks to several chemical reactions between mercury and various oxides (silicon, aluminium and calcium silicate) of the surface of the ashes.
03/01727 Structural modification during mild oxidation-relevance
optical texture. The enhanced is discussed in terms of structural and possibie oxidative polymerization
propensity of QI to peculiarities of the reactions.
03/01726 Unconverted chars obtained during biomass gasification on a pilot-scale gasifler as a source of activated carbon production Garcia-Garcia, A. et al. Bioresource Technology, 2003, 88, (I), 27-32. Biomass gasification was used to produce activated carbon on a pilotscale fluidized-bed gasifier. The feedstock included both biomass alone and biomass mixed with coal and coal/granulated plastic wastes. This paper reports the results obtained from four different runs undertaken under various conditions of fuel supply, different ratios of steam/air for the gasification and temperature. These conditions were selected because they led to a significant amount of unconverted chars produced during gasification (from 0.72 to 1.4 kg) which then served as raw material for the production of activated carbon whilst the amount of gas obtained was also high enough for its potential use for different end-use applications. From the analysis of the results obtained, it can be concluded that a reasonable porosity development (mainly in the area of narrow micropores) was obtained by gasifying unblended pine wastes with steam for 4 h, producing about 1.4 kg of good-quality activated carbon (micropore volume of 0.263 cm3/g). In other runs, chars with a reduced microporosity development (i.e. 0.180 cm3/g) were obtained, however, they could be used as a proper starting material for the chemically activated carbon production.
pitch
Oshida, K. and Bonnamy, S. Carbon, 2002, 40, (14), 2699-2711. The evolution during carbonization treatments of a 100% anisotropic pitch (pitch C) was compared to that of Ashland 240 (100% y resins). The anisotropic pitch C results from a gas-sparge preparation leading to a composition of 93% fl resins (QS-TI) and 7% y resins (QS). It is made of a major component (QS-TI), in which droplets (100-300 nm in size) partially toluene soluble are distributed. The physicochemical, textural and microtextural evolutions of the two pitches were studied. During pitch C primary carbonization, anisotropic droplets grow by coalescence, then decompose into Brooks and Taylor mesophase spheres suspended in isotropic drops. These drops develop at the expense of the anisotropic matrix by a continuous regeneration of the small anisotropic droplets which feed the isotropic drops by diffusion process. Then inside these drops, mesophase spheres grow then coalesce and the behaviour of a conventional pitch is restored. These various molecular associations are due to absence of chemical events below 450°C leading to the global mass spectrum being constant. At 500°C the material is homogeneously anisotropic though plastic, the metastable system is destroyed and the evolution of conventional pitches is recovered, i.e. above 550°C macropores develop up to solidification at 600°C (semi-coke stage).
03/01726 Removal of mercury fluidized bed plant fly ash
homogeneous aggregation parent pitch
of coal-tar pitch fractions to carbonization behavior
Machnikowski, J. et al. Carbon, 2002, 40, (1 l), 1937-1947. Modified pitches with softening points of about 175°C were prepared by air-blowing at 300°C of coal-tar pitches from different commercial coke-oven tars. The modifications induced by the mild oxidation were monitored using solvent and extrographic fractionation, elemental analysis, ‘H NMR and HPLC. Optical microscopy was used to follow the effect of air-blowing on carbonization behaviour. Low molecular weight cata-condensed PAHs and those with basic nitrogen and hydroxylic functionalities present in extrographic fractions F2 and F4, respectively, are preferentially polymerized pitch constituents. In contrast, peri-condensed PAHs in extrographic fractions F2 and F3, are practically unreactive under the oxidation conditions used. The mild oxidation enhances the tendency of quinoline insoluble (QI) particles to form aggregates in an early stage of thermal treatment, modifying the mode of mesophase development and leading to a non-
05 NUCLEAR FUELS Scientific, technical 03/01729 Derivation of variance-to-mean periodic and pulsed neutron source
formula
for
Kitamura, Y. et al. Annuls of Nuclear Energy, 2003, 30, (S), 897-909. Derivation of a variance-to-mean formula was performed to obtain the prompt neutron decay constant a of the subcritical reactor system that is driven by the periodic and pulsed neutron source. The formula was derived for an experimental technique where the Y value is measured by choosing an injection of pulsed neutrons as the origin of the counting gate. By using the derived formula, it was indicated that the o value can be easily determined. From this fact, it was concluded that the present formula was useful to measure the o value for future experiments with the accelerator driven system.
03/01730 Theoretical calculations for the production OgMo using natural uranium in Iran
of
Sayareh, R. et al. Annals of Nuclear Energy, 2003, 30, (8), 883-895. In the field of medical diagnostics, 99mTc with a half life of 6 h is widely used for medical purposes and produced from the decay of 99mMo (1, ,r = 66 h). The need for this isotope in the Iranian medical centres is about 20 Ci/week and is currently being imported. In this paper, the theoretical calculations related to the production of 99mMo, using natural UOz and irradiating it within the Tehran Research Reactor are presented. The calculations are carried out by the use of the MCNP-4A and ORIGEN-2 codes. It is expected that following chemical separations, approximately 20 Ci/week of 99mMo may be obtained by irradiating 100 g of natural UO1 for a period of 7 days inside the reactor. This amount. may be produced every other week due to the limitations on the reactor operation. Detailed calculations have been presented to the proper regulatory bodies for approval. Once authorized, the production is expected to begin in the first half of 2003.
03/01731 Validation of axial pin power distributions 10x10 BWR assembly across an enrichment boundary full-density water moderation conditions
in a under
Jatuff, F. et al. Annals of Nuclear Energy, 2003, 30, (8), 91 l-930. Critical experiments involving fuel pin gamma-scans have been performed to characterize total fission reaction rate axial distributions in a Westinghouse SVEA-96+ assembly under full-density water moderation [these investigations are part of the co-operation between PSI and Unterausschuss Kernenergie (UAK) or association of the Swiss nuclear operators, viz. Kernkraftwerk Leibstadt AG, Kernkraftwerk Gbsgen-Daniken AG, BKW FMB Energie AG and Nordostschweizerische Kraftwerke AG]. The measurements have covered an 80-cm long region of the SVEA-96 + assembly involving two important axial heterogeneities: (a) the enrichment boundary separating the lower axial Fuel
and
Energy
Abstracts
September
2003
299
03/01725 Primary carbonization of an anisotropic ‘mesophase’ pitch compared to conventional isotropic
in aqueous
solution
by
Rio, S. and Delebarre, A. Fuel, 2003, 82, (2), 153.-159. Coal combustion in power plant produces fly ash. Fly ash may be used in water treatment to remove mercury (Hg”) from water or to immobilize mercury mobile forms in silts and soils. Experiments were carried out on two kinds of fly ashes produced by two circulating fluidized bed plants with different chemical composition: silicoaluminous fly ashes and sulfo-calcic fly ashes. For the two kinds of fly ashes, adsorption equilibrium were reached in 3 days. Furthermore, removal of mercury was increased with increasing pH. Sulfa-calcic fly ashes allow us to remove mercury more efficiently and more steady. The chemical analysis of fly ash surface was carried out by electron spectroscopy. The results show that mercury is bound to ash surface thanks to several chemical reactions between mercury and various oxides (silicon, aluminium and calcium silicate) of the surface of the ashes.
03/01727 Structural modification during mild oxidation-relevance
optical texture. The enhanced is discussed in terms of structural and possibie oxidative polymerization
propensity of QI to peculiarities of the reactions.
03/01726 Unconverted chars obtained during biomass gasification on a pilot-scale gasifler as a source of activated carbon production Garcia-Garcia, A. et al. Bioresource Technology, 2003, 88, (I), 27-32. Biomass gasification was used to produce activated carbon on a pilotscale fluidized-bed gasifier. The feedstock included both biomass alone and biomass mixed with coal and coal/granulated plastic wastes. This paper reports the results obtained from four different runs undertaken under various conditions of fuel supply, different ratios of steam/air for the gasification and temperature. These conditions were selected because they led to a significant amount of unconverted chars produced during gasification (from 0.72 to 1.4 kg) which then served as raw material for the production of activated carbon whilst the amount of gas obtained was also high enough for its potential use for different end-use applications. From the analysis of the results obtained, it can be concluded that a reasonable porosity development (mainly in the area of narrow micropores) was obtained by gasifying unblended pine wastes with steam for 4 h, producing about 1.4 kg of good-quality activated carbon (micropore volume of 0.263 cm3/g). In other runs, chars with a reduced microporosity development (i.e. 0.180 cm3/g) were obtained, however, they could be used as a proper starting material for the chemically activated carbon production.
pitch
Oshida, K. and Bonnamy, S. Carbon, 2002, 40, (14), 2699-2711. The evolution during carbonization treatments of a 100% anisotropic pitch (pitch C) was compared to that of Ashland 240 (100% y resins). The anisotropic pitch C results from a gas-sparge preparation leading to a composition of 93% fl resins (QS-TI) and 7% y resins (QS). It is made of a major component (QS-TI), in which droplets (100-300 nm in size) partially toluene soluble are distributed. The physicochemical, textural and microtextural evolutions of the two pitches were studied. During pitch C primary carbonization, anisotropic droplets grow by coalescence, then decompose into Brooks and Taylor mesophase spheres suspended in isotropic drops. These drops develop at the expense of the anisotropic matrix by a continuous regeneration of the small anisotropic droplets which feed the isotropic drops by diffusion process. Then inside these drops, mesophase spheres grow then coalesce and the behaviour of a conventional pitch is restored. These various molecular associations are due to absence of chemical events below 450°C leading to the global mass spectrum being constant. At 500°C the material is homogeneously anisotropic though plastic, the metastable system is destroyed and the evolution of conventional pitches is recovered, i.e. above 550°C macropores develop up to solidification at 600°C (semi-coke stage).
03/01726 Removal of mercury fluidized bed plant fly ash
homogeneous aggregation parent pitch
of coal-tar pitch fractions to carbonization behavior
Machnikowski, J. et al. Carbon, 2002, 40, (1 l), 1937-1947. Modified pitches with softening points of about 175°C were prepared by air-blowing at 300°C of coal-tar pitches from different commercial coke-oven tars. The modifications induced by the mild oxidation were monitored using solvent and extrographic fractionation, elemental analysis, ‘H NMR and HPLC. Optical microscopy was used to follow the effect of air-blowing on carbonization behaviour. Low molecular weight cata-condensed PAHs and those with basic nitrogen and hydroxylic functionalities present in extrographic fractions F2 and F4, respectively, are preferentially polymerized pitch constituents. In contrast, peri-condensed PAHs in extrographic fractions F2 and F3, are practically unreactive under the oxidation conditions used. The mild oxidation enhances the tendency of quinoline insoluble (QI) particles to form aggregates in an early stage of thermal treatment, modifying the mode of mesophase development and leading to a non-
05 NUCLEAR FUELS Scientific, technical 03/01729 Derivation of variance-to-mean periodic and pulsed neutron source
formula
for
Kitamura, Y. et al. Annuls of Nuclear Energy, 2003, 30, (S), 897-909. Derivation of a variance-to-mean formula was performed to obtain the prompt neutron decay constant a of the subcritical reactor system that is driven by the periodic and pulsed neutron source. The formula was derived for an experimental technique where the Y value is measured by choosing an injection of pulsed neutrons as the origin of the counting gate. By using the derived formula, it was indicated that the o value can be easily determined. From this fact, it was concluded that the present formula was useful to measure the o value for future experiments with the accelerator driven system.
03/01730 Theoretical calculations for the production OgMo using natural uranium in Iran
of
Sayareh, R. et al. Annals of Nuclear Energy, 2003, 30, (8), 883-895. In the field of medical diagnostics, 99mTc with a half life of 6 h is widely used for medical purposes and produced from the decay of 99mMo (1, ,r = 66 h). The need for this isotope in the Iranian medical centres is about 20 Ci/week and is currently being imported. In this paper, the theoretical calculations related to the production of 99mMo, using natural UOz and irradiating it within the Tehran Research Reactor are presented. The calculations are carried out by the use of the MCNP-4A and ORIGEN-2 codes. It is expected that following chemical separations, approximately 20 Ci/week of 99mMo may be obtained by irradiating 100 g of natural UO1 for a period of 7 days inside the reactor. This amount. may be produced every other week due to the limitations on the reactor operation. Detailed calculations have been presented to the proper regulatory bodies for approval. Once authorized, the production is expected to begin in the first half of 2003.
03/01731 Validation of axial pin power distributions 10x10 BWR assembly across an enrichment boundary full-density water moderation conditions
in a under
Jatuff, F. et al. Annals of Nuclear Energy, 2003, 30, (8), 91 l-930. Critical experiments involving fuel pin gamma-scans have been performed to characterize total fission reaction rate axial distributions in a Westinghouse SVEA-96+ assembly under full-density water moderation [these investigations are part of the co-operation between PSI and Unterausschuss Kernenergie (UAK) or association of the Swiss nuclear operators, viz. Kernkraftwerk Leibstadt AG, Kernkraftwerk Gbsgen-Daniken AG, BKW FMB Energie AG and Nordostschweizerische Kraftwerke AG]. The measurements have covered an 80-cm long region of the SVEA-96 + assembly involving two important axial heterogeneities: (a) the enrichment boundary separating the lower axial Fuel
and
Energy
Abstracts
September
2003
299