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00601 Capacitance limits of high surface area activated carbons for double layer capacitors
04 By-products related to fuels a surfactant, sodium oleate. It has been characterized by B E T m e a s u r e m e n t and BJH m e t h o d for its surface area and pore-size distribution, and by constant-current charge discharge technique, cyclic v o l t a m m e t r y and electrochemical i m p e d a n c e spectrum (EIS) for its specific capacitance, equivalent series resistance and power capability. It was found that, after the surface modification, the wettability of the organic electrolyte based on non-polar organic solvent (i.e. propylene carbonate) to the activated carbon aerogel was improved greatly, which resulted in a lower internal resistance and a higher usable surface area. As results, a higher specific capacitance, energy density and power capability were achieved for the capacitor using the modified activated carbon aerogel electrodes than those w i t h o u t the surface modification. The effects from the surface modification b e c a m e more significant at higher charge discharge rates, at which the wettability of the electrolyte to the electrode material usually becomes more i m p o r t a n t and critical.
06/00599 Activated-carbon electric-double-layer capacitors: electrochemical characterization and adaptive algorithm implementation Verbrugge, M. W. et al. Journal o f Power Sources, 2005, 141, (2), 369 385. A n activated-carbon electric-double-layer capacitor is characterized and an adaptive algorithm is derived and i m p l e m e n t e d that is c o m m e n s u r a t e with p o t e n t i a l traction applications of these energy storage devices. The electrochemical characterization relies on a simplified equivalent circuit interpretation extracted from a morecomplete m a t h e m a t i c a l r e p r e s e n t a t i o n of the capacitor system. In addition to the high power capability and potentially low costs of this class of capacitors, we clarify the substantial invariance of the device performance with respect to temperature, a distinct advantage over battery systems. The robustness of the equivalent circuit in terms of capturing the salient features of the e x p e r i m e n t a l data over the t e m p e r a t u r e and voltage range of interest enables the formulation of a model-reference adaptive algorithm. The algorithm developed and i m p l e m e n t e d in this work is fully recursive in that the only variables required for on-line regression are those of the previous time step and the current time step. Successful comparisons of the algorithm's a d a p t e d state of charge and power predictions provide an initial validation of the algorithm.
06•00600 Application of zeolitised coal fly ashes to the depuration of liquid wastes Otal, E. et al. Fuel, 2005, 84, (11), 1440 1446. In this study, the application of some zeolitized fly ashes and synthetic zeolites to the d e c o n t a m i n a t i o n of the leachate produced in a municipal solid waste (MSW) t r e a t m e n t plant and to the liquid waste from a pig farm was analysed. Thus, the reduction of organic matter ( B O D and COD), a m m o n i u m and total nitrogen, phosphorus and metals contents after a zeolite t r e a t m e n t was evaluated. Several synthetic zeolites were tested: some commercial zeolites and other synthetic zeolites and zeolitized ashes obtained after a coal fly ash alkaline h y d r o t h e r m a l process. Two forms of contact between the zeolitic m a t e r i a l and the liquid waste were tested: in a stirred tank and in a column. In addition, other variables d e t e r m i n e d were the a m o u n t of zeolite and the residence time. The results showed that zeolites, especially zeolitized fly ash, clearly produced a strong reduction in the leachate nitrogen and p h o s p h o r u s content.
06/00601 Capacitance limits of high surface area activated carbons for double layer capacitors Barbieri, O. et al. Carbon, 2005, 43, (6), 1303 1310. A large specific surface area (SSA) of carbon materials used for electrochemical double layer capacitors ( E D L C ) is the most i m p o r t a n t p a r a m e t e r leading to a large gravimetric capacitance (Cg). However, for a SSA determined with the differential functional theory (DFT) model above a value of 1200 m2/g the plot of Cg versus SDFT exhibits a plateau. We suggest that this limitation of Cg can be ascribed to a space constriction for charge a c c o m m o d a t i o n inside the pore walls. As a consequence, the use of extremely high surface area carbons for E D L C s may be unprofitable.
06/00602 resins
Carbon adsorbents from waste ion-exchange
Gun'ko, V. M. et al. Carbon, 2005, 43, (6), 1143 1150. A series of activated carbons was p r e p a r e d from different waste commercial ion-exchange resins and studied by means of adsorption, S E M and I R methods. Samples were additionally w a s h e d or washed/ frozen. This resulted in increases in micro- and mesoporosity in comparison with initial activated carbons. For some samples, the latter t r e a t m e n t gives e n h a n c e m e n t of mesoporosity but reduction of microporosity and vice versa comparing with only w a s h e d carbons due to different localization of water droplets in m e s o p o r e s or micropores. Changes in the m o r p h o l o g y of chars and activated samples d e p e n d e d on resin composition and history. Relatively high values of
porosity (f2p ~ 0.4 cm3/g) and specific surface area (SBET ~ 600 m2/g) show that activated carbons prepared from waste ion-exchange resins can be utilized for different purposes, especially afier a d d i t i o n a l treatment (such as washing, i m p r e g n a t i o n by certain c o m p o u n d s and subsequent thermal activation).
06/00603
CFBC ash hydration studies
Anthony, E. J. et al. Fuel, 2005, 84, (11), 1393 1397. H y d r a t i o n studies on C F B C ashes have shown that the acetone technique to prevent hydration in stored samples is relatively effective, only allowing some slight degree of hydration over days in the presence of excess water. In the presence of large excesses of water sufficient to control t e m p e r a t u r e increases, the degree of b u l k mixing has no effect on the degree of hydration, which is shown to be relatively slow at a m b i e n t conditions, taking hours to complete. Finally, the effect of salt addition on hydration has been shown to be negligible at the low levels typical of wastewater, but there may be effects at ion concentrations typical of seawater. This work suggests that experience gained from lime hydration should be applied with caution to studies on hydration of C F B C ashes.
06/00604 ashes
Economic utilisation of activated fiuidized fly
Sykurski, H. G. IG1rbo, 2005, L, (3), 175. A review of methods was discussed of fluidised fly ashes (FFA) mechanically activated by an E M D C method. The activation by E M D C m e t h o d is a waste-free process at which 100%, of raw material mass is being changed into a final product. The application of F F A was described in power sector for production of binders, as an additive to construction and road building concretes in engineering building and in hydro technique.
06/00605 Effect of pre-oxidation on the porosity development in a heavy oil fly ash by CO2 activation Seggiani, M. et al. Fuel, 2005, 84, (12 13), 1593 1596. The effect of pre-oxidation on the porosity evolution in heavy oil fly ash subjected to activation with CO2 has been investigated. After preliminary acid leaching, used to reduce the m i n e r a l m a t t e r content, the leached fly ash has been oxidized in air at 250:C for 36 h. Pyrolysis was conducted on the un-oxidized and oxidized leached fly ash at 900:C for 2 h and the resultant chars were activated with CO2 at 900:C for different times. The activated samples have been characterized as regards the surface area and the pore volume. The pre-oxidation enhances the porosity d e v e l o p m e n t mainly in terms of mesoporosity leading to obtain activated products with higher surface area (about 270 m-/g at a 40%, burn-off).
06/00606 Fly ash - a potential source of soil amendment and a component of integrated plant nutrient supply system Mittra, B. N. et al. Fuel, 2005, 84, (11), 1447 1451. In sub-tropical climate the high rainfall and high t e m p e r a t u r e is responsible for low soil productivity due to losses of bases and low organic matter content in soil. In acid lateritic soil low availability of P and high content of A1 and Fe posses nutritional imbalance which is generally corrected by lime materials. Alkaline fly ash can be used in such problematic soil as an a m e n d e d m a t e r i a l and also it acts as source of plant nutrition for crop production. A n a t t e m p t was m a d e to develop an integrated plant n u t r i e n t supply system utilizing the fly ash along with other organic wastes like p a p e r factory sludge, farm yard manure, crop residue and chemical fertilizers for rice p e a n u t cropping system. Direct and residual effects of fly ash were assessed based on crop yield, n u t r i e n t uptake and changes in soil characteristics. The application 10 t ha 1 of fly ash in combination with organic sources and chemical fertilizer increased the grain yield and n u t r i e n t uptake of rice, and pod yield of p e a n u t c o m p a r e d to chemical fertilizers alone. The heavy metal contents in plant and soil system was analysed and found to r e m a i n below the permissible level. The results indicated that fly ash could be applied safely to tropical agro eco-systems for retaining productivity of acid lateritic soil.
06/00607
Ge extraction from gasification fly ash
Font, O. et al. Fuel, 2005, 84, (11), 1384 1392. W a t e r - s o l u b l e g e r m a n i u m species (GeS2, GeS and hexagonal-GeO2) are g e n e r a t e d d u r i n g coal gasification and retained in fly ash. This fact together with the high m a r k e t value of this e l e m e n t and the relatively high contents in the fly ashes of the Puertollano I n t e g r a t e d Gasification in C o m b i n e d Cycle ( I G C C ) plant directed the research towards the d e v e l o p m e n t of an extraction process for this element. Major objectives of this research were to find a low cost and environmentally suitable process. Several water based extraction tests were carried out using different Puertollano I G C C fly ash samples, under different temperatures, water/fly ash ratios, and extraction times. High Ge extraction yields (up to 84%,) were obtained at room t e m p e r a t u r e (25:C) but also high proportions of other trace elements (impurities) were simultaneously extracted. Increasing the extraction t e m p e r a t u r e to 50, 90
Fuel and Energy Abstracts
March 2006
93
06/00599 Activated-carbon electric-double-layer capacitors: electrochemical characterization and adaptive algorithm implementation Verbrugge, M. W. et al. Journal o f Power Sources, 2005, 141, (2), 369 385. A n activated-carbon electric-double-layer capacitor is characterized and an adaptive algorithm is derived and i m p l e m e n t e d that is c o m m e n s u r a t e with p o t e n t i a l traction applications of these energy storage devices. The electrochemical characterization relies on a simplified equivalent circuit interpretation extracted from a morecomplete m a t h e m a t i c a l r e p r e s e n t a t i o n of the capacitor system. In addition to the high power capability and potentially low costs of this class of capacitors, we clarify the substantial invariance of the device performance with respect to temperature, a distinct advantage over battery systems. The robustness of the equivalent circuit in terms of capturing the salient features of the e x p e r i m e n t a l data over the t e m p e r a t u r e and voltage range of interest enables the formulation of a model-reference adaptive algorithm. The algorithm developed and i m p l e m e n t e d in this work is fully recursive in that the only variables required for on-line regression are those of the previous time step and the current time step. Successful comparisons of the algorithm's a d a p t e d state of charge and power predictions provide an initial validation of the algorithm.
06•00600 Application of zeolitised coal fly ashes to the depuration of liquid wastes Otal, E. et al. Fuel, 2005, 84, (11), 1440 1446. In this study, the application of some zeolitized fly ashes and synthetic zeolites to the d e c o n t a m i n a t i o n of the leachate produced in a municipal solid waste (MSW) t r e a t m e n t plant and to the liquid waste from a pig farm was analysed. Thus, the reduction of organic matter ( B O D and COD), a m m o n i u m and total nitrogen, phosphorus and metals contents after a zeolite t r e a t m e n t was evaluated. Several synthetic zeolites were tested: some commercial zeolites and other synthetic zeolites and zeolitized ashes obtained after a coal fly ash alkaline h y d r o t h e r m a l process. Two forms of contact between the zeolitic m a t e r i a l and the liquid waste were tested: in a stirred tank and in a column. In addition, other variables d e t e r m i n e d were the a m o u n t of zeolite and the residence time. The results showed that zeolites, especially zeolitized fly ash, clearly produced a strong reduction in the leachate nitrogen and p h o s p h o r u s content.
06/00601 Capacitance limits of high surface area activated carbons for double layer capacitors Barbieri, O. et al. Carbon, 2005, 43, (6), 1303 1310. A large specific surface area (SSA) of carbon materials used for electrochemical double layer capacitors ( E D L C ) is the most i m p o r t a n t p a r a m e t e r leading to a large gravimetric capacitance (Cg). However, for a SSA determined with the differential functional theory (DFT) model above a value of 1200 m2/g the plot of Cg versus SDFT exhibits a plateau. We suggest that this limitation of Cg can be ascribed to a space constriction for charge a c c o m m o d a t i o n inside the pore walls. As a consequence, the use of extremely high surface area carbons for E D L C s may be unprofitable.
06/00602 resins
Carbon adsorbents from waste ion-exchange
Gun'ko, V. M. et al. Carbon, 2005, 43, (6), 1143 1150. A series of activated carbons was p r e p a r e d from different waste commercial ion-exchange resins and studied by means of adsorption, S E M and I R methods. Samples were additionally w a s h e d or washed/ frozen. This resulted in increases in micro- and mesoporosity in comparison with initial activated carbons. For some samples, the latter t r e a t m e n t gives e n h a n c e m e n t of mesoporosity but reduction of microporosity and vice versa comparing with only w a s h e d carbons due to different localization of water droplets in m e s o p o r e s or micropores. Changes in the m o r p h o l o g y of chars and activated samples d e p e n d e d on resin composition and history. Relatively high values of
porosity (f2p ~ 0.4 cm3/g) and specific surface area (SBET ~ 600 m2/g) show that activated carbons prepared from waste ion-exchange resins can be utilized for different purposes, especially afier a d d i t i o n a l treatment (such as washing, i m p r e g n a t i o n by certain c o m p o u n d s and subsequent thermal activation).
06/00603
CFBC ash hydration studies
Anthony, E. J. et al. Fuel, 2005, 84, (11), 1393 1397. H y d r a t i o n studies on C F B C ashes have shown that the acetone technique to prevent hydration in stored samples is relatively effective, only allowing some slight degree of hydration over days in the presence of excess water. In the presence of large excesses of water sufficient to control t e m p e r a t u r e increases, the degree of b u l k mixing has no effect on the degree of hydration, which is shown to be relatively slow at a m b i e n t conditions, taking hours to complete. Finally, the effect of salt addition on hydration has been shown to be negligible at the low levels typical of wastewater, but there may be effects at ion concentrations typical of seawater. This work suggests that experience gained from lime hydration should be applied with caution to studies on hydration of C F B C ashes.
06/00604 ashes
Economic utilisation of activated fiuidized fly
Sykurski, H. G. IG1rbo, 2005, L, (3), 175. A review of methods was discussed of fluidised fly ashes (FFA) mechanically activated by an E M D C method. The activation by E M D C m e t h o d is a waste-free process at which 100%, of raw material mass is being changed into a final product. The application of F F A was described in power sector for production of binders, as an additive to construction and road building concretes in engineering building and in hydro technique.
06/00605 Effect of pre-oxidation on the porosity development in a heavy oil fly ash by CO2 activation Seggiani, M. et al. Fuel, 2005, 84, (12 13), 1593 1596. The effect of pre-oxidation on the porosity evolution in heavy oil fly ash subjected to activation with CO2 has been investigated. After preliminary acid leaching, used to reduce the m i n e r a l m a t t e r content, the leached fly ash has been oxidized in air at 250:C for 36 h. Pyrolysis was conducted on the un-oxidized and oxidized leached fly ash at 900:C for 2 h and the resultant chars were activated with CO2 at 900:C for different times. The activated samples have been characterized as regards the surface area and the pore volume. The pre-oxidation enhances the porosity d e v e l o p m e n t mainly in terms of mesoporosity leading to obtain activated products with higher surface area (about 270 m-/g at a 40%, burn-off).
06/00606 Fly ash - a potential source of soil amendment and a component of integrated plant nutrient supply system Mittra, B. N. et al. Fuel, 2005, 84, (11), 1447 1451. In sub-tropical climate the high rainfall and high t e m p e r a t u r e is responsible for low soil productivity due to losses of bases and low organic matter content in soil. In acid lateritic soil low availability of P and high content of A1 and Fe posses nutritional imbalance which is generally corrected by lime materials. Alkaline fly ash can be used in such problematic soil as an a m e n d e d m a t e r i a l and also it acts as source of plant nutrition for crop production. A n a t t e m p t was m a d e to develop an integrated plant n u t r i e n t supply system utilizing the fly ash along with other organic wastes like p a p e r factory sludge, farm yard manure, crop residue and chemical fertilizers for rice p e a n u t cropping system. Direct and residual effects of fly ash were assessed based on crop yield, n u t r i e n t uptake and changes in soil characteristics. The application 10 t ha 1 of fly ash in combination with organic sources and chemical fertilizer increased the grain yield and n u t r i e n t uptake of rice, and pod yield of p e a n u t c o m p a r e d to chemical fertilizers alone. The heavy metal contents in plant and soil system was analysed and found to r e m a i n below the permissible level. The results indicated that fly ash could be applied safely to tropical agro eco-systems for retaining productivity of acid lateritic soil.
06/00607
Ge extraction from gasification fly ash
Font, O. et al. Fuel, 2005, 84, (11), 1384 1392. W a t e r - s o l u b l e g e r m a n i u m species (GeS2, GeS and hexagonal-GeO2) are g e n e r a t e d d u r i n g coal gasification and retained in fly ash. This fact together with the high m a r k e t value of this e l e m e n t and the relatively high contents in the fly ashes of the Puertollano I n t e g r a t e d Gasification in C o m b i n e d Cycle ( I G C C ) plant directed the research towards the d e v e l o p m e n t of an extraction process for this element. Major objectives of this research were to find a low cost and environmentally suitable process. Several water based extraction tests were carried out using different Puertollano I G C C fly ash samples, under different temperatures, water/fly ash ratios, and extraction times. High Ge extraction yields (up to 84%,) were obtained at room t e m p e r a t u r e (25:C) but also high proportions of other trace elements (impurities) were simultaneously extracted. Increasing the extraction t e m p e r a t u r e to 50, 90
Fuel and Energy Abstracts
March 2006
93