12 Matching Results

Search Results

Advanced search parameters have been applied.

Conversion of coal wastes into waste-cleaning materials. Quarterly progress report, April 1, 1996--June 30, 1996

Description: Work on this project has concentrated on studying fly ash provided by PECO Energy. This ash has a composition, 52 wt% SiO{sub 2}, 30 wt% Al{sub 2}O{sub 3}, 10 wt% Fe{sub 3}O{sub 4}, and others. Previously, we have shown that this particular ash, which will be called Eddystone I, can be converted to faujasite and zeolite A at 38{degrees} C curing. In the last three months, we began to investigate whether the same treatment procedure can be applied to other ashes. Ashes from three different power plants were solicited and studied. In order to overcome the problem of wide variation in composition, a general approach needs to be found to treat different ashes. We adopted a fusion method that combines NaOH and silicon source more efficiently than simple dissolution of silicate in NaOH solution.
Date: October 1, 1996
Creator: Shih, Wei-Heng
Partner: UNT Libraries Government Documents Department

Conversion of coal wastes into waste-cleaning materials. Quarterly progress report, January 1, 1995--January 31, 1995

Description: As indicated in the last quarterly report, the objective of our research in this quarter is studying the ion-exchange properties of the zeolites converted from fly ash. It is well known that zeolites Y and A have good ion-exchange capabilities with ions such as Cs and Co which are abundant in nuclear wastes, and NH{sub 4} ions which are abundant in waste water. Since zeolites are formed within the fly ash, and it is not a simple task to separate them from the fly ash, the ion-exchange study was done on the treated fly ash without separating the zeolites from the fly ash.
Date: September 1, 1995
Creator: Shih, Wei-Heng
Partner: UNT Libraries Government Documents Department

Conversion of coal wastes into waste-cleaning materials. Quarterly progress report, July 1, 1995--September 30, 1995

Description: In the last three months we studied the phase composition of the fly ash in order to better understand the important parameters in the zeolite formation process using fly ash. In addition, since the zeolites exist in powder form, for practical applications, some ways of binding them into a piece of material is necessary. For that purpose, we began exploring ways of forming porous materials using fly ash. It was found that mixing fly ash, phosphoric acid, and calcium oxide can generate a porous material with good integrity. Meanwhile, the research on forming mesoporous materials from fly ash continued. Some results on the formation of double lamellar phase was found during the study.
Date: December 31, 1995
Creator: Shih, Wei-Heng
Partner: UNT Libraries Government Documents Department

Conversion of coal wastes into waste-cleaning materials. Quarterly progress report, April 1, 1995--June 30, 1995

Description: In the last three months we have studied the ion exchange behavior of the zeolites, converted from fly ash in more detail. In particular, the ion-exchange isotherms of the treated fly ash containing zeolite Y with Cs+ ions were studied. For comparison, the ion exchange isotherms of synthetic zeolite Y and commercial zeolite A were also studied. These results showed that the background materials in the fly ash do not affect the ion exchange performance of the zeolites that the fly ash contains. It is also found that a higher total ion concentration (Na+ plus Cs+) in the solutions results in a higher amount of ions exchanged with the zeolites. The ion exchange of treated fly ash with Co{sup 2+} ions was studied as well. This part of the research was done by Mr. Jorge Moller who was hired starting April 3 for 6 months as a co-op student. In an attempt to broaden the applications of fly ash, investigation into the formation of mesoporous materials from fly ash was initiated. Mesoporous materials were discovered three years ago by scientists at Mobil and have been under active research by many researchers since then. Mesoporous materials have large surface areas with variable pore sizes in the range of >20 angstroms. Potential applications of mesoporous materials include catalysts, absorbents, molecular sieves, etc. If mesoporous materials can be converted from fly ash, it will open up another area of applications for fly ash.
Date: December 1, 1995
Creator: Shih, Wei-Heng
Partner: UNT Libraries Government Documents Department

CONVERSION OF COAL WASTES INTO WASTE-CLEANING MATERIALS. FIANL REPORT (8/1/94-12/31/97)

Description: In the beginning part of this project, we successfully converted the fly ash from the Eddystone plant of PECO Energy into faujasites and zeolite A. However, when we used the same approach to convert ashes from other power plants, it was not successful. Because of the differences in chemical compositions between different ashes, the conversion process has to be modified. Therefore the first goal in this project is to find a general method that can convert ashes of a wide variety of chemical compositions into zeolites. The zeolites synthesized from fly ash are then studied for their ion exchange behavior for the application in removing heavy metal ions from waste streams. In an attempt to broaden the applications of fly ash, investigation into the formation of mesoporous materials from fly ash was initiated. Mesoporous materials were discovered three years ago by scientists at Mobil and have been under active research by many researchers since then. Mesoporous materials have large surface areas with variable pore sizes in the range of >20 {angstrom}. Potential applications of mesoporous materials include catalysts, absorbents, molecular sieves, etc. If mesoporous materials can be converted from fly ash, it will open up another area of applications for fly ash. The second goal of this project is to convert fly ash into mesoporous materials.
Date: January 1, 1998
Creator: Shih, Wei-Heng
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION

Description: The authors propose to use microporous aluminosilicate as a suitable candidate for CO{sub 2}/N{sub 2} separation because the pore size is less than 10 {angstrom}. If a CO{sub 2} adsorbent is added to the microporous silica, the adsorption of CO{sub 2} can block the passage of N{sub 2} and an effective CO{sub 2}/N{sub 2} separator will be found. It was first demonstrated that microporous silica could be synthesized. The microporous silica was then impregnated with Ba(OH){sub 2}. No adsorption of CO{sub 2} was observed. Alumina must be added to facilitate CO{sub 2} adsorption. However, no microporous aluminosilicates have been shown before. In this six-month study, they developed a process that partially coat alumina on microporous silica. Microporous aluminosilicates were synthesized by the coating process.
Date: October 1, 2002
Creator: Shih, Wei-Heng & Patil, Tejas
Partner: UNT Libraries Government Documents Department

Conversion of coal wastes into waste-cleaning materials. Quarterly progress report, July 1, 1996--September 30, 1996

Description: In the last few months we have been working on the conversion of various fly ashes into zeolites. It was reported in the last report that by fusing fly ash with sodium hydroxide, all fly ashes that were studied can be converted into zeolites. Apparently, the fusion between the fly ash and sodium hydroxide produced sodium silicates which dissolve more readily than fly ash itself. The higher concentration of silicates within the solutions enhances the formation of zeolites. In this report, we summarize the results on the ion-exchange behavior of those treated fly ash with Cs{sup +}, Co{sup 2+} and Cu{sup 2+} ions as well as the characterization of the concentration of Si, Al, and Na in the curing solutions.
Date: December 31, 1996
Creator: Shih, Wei-Heng
Partner: UNT Libraries Government Documents Department

Conversion of coal wastes into waste-cleaning materials. Quarterly report, October 1--December 31, 1996

Description: Besides working on the conversion of fly ash to zeolites, we have been studying the possibility of converting fly ash to mesoporous molecular sieves. It was reported in previous reports that fly ash can participate in the formation of mesoporous materials. However, fly ash has not been converted to mesoporous materials directly. In the last report, we showed that by fusing the fly ash with sodium hydroxide, the yield of zeolites increased significantly. The fusion process increases the amount of silicates and aluminates that are dissolved in the precursor solutions. Therefore, in the last three months, we have been studying the conversion of fly ash into mesoporous materials using the fusion process. As expected, we succeeded in converting fly ash into mesoporous molecular sieves. Due to their uniform molecular pore sizes and large surface areas, the mesoporous materials are very useful materials for a wide range of applications such as molecular sieves, adsorbents, and catalysts. Therefore converting fly ash into mesoporous materials not only eliminates the disposal problem but also turns an otherwise waste material into a useful one. The successful conversion of fly ash into mesoporous molecular sieves broadens the possible application of fly ash.
Date: April 1, 1997
Creator: Shih, Wei-Heng
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION

Description: The huge emissions of carbon dioxide from fossil fuel fired power plants and industrial plants over the last century have resulted in an increase of the atmospheric carbon dioxide concentration. Climatological modeling work has predicted severe climate disruption as a result of the trapping of heat due to CO{sub 2}. As an attempt to address this global warming effect, DOE has initiated the Vision 21 concept for future power plants. We first synthesized mesoporous aluminosilicates that have high surface area and parallel pore channels for membrane support materials. Later we synthesized microporous aluminosilicates as the potential thin membrane materials for selective CO{sub 2} adsorption. The pore size is controlled to be less that 1 nm so that the adsorption of CO{sub 2} on the pore wall will block the passage of N{sub 2}. Mesoporous and precipitated alumina were synthesized as the base material for CO{sub 2} adsorbent. The porous alumina is doped with Ba to enhance its CO{sub 2} affinity due to the basicity of Ba. It is shown by gas chromatograph (GC) that the addition of Ba enhances the separation CO{sub 2} from N{sub 2}. It was found that mesoporous alumina has larger specific surface area and better selectivity of CO{sub 2} than precipitated alumina. Ba improves the affinity of mesoporous alumina with CO{sub 2}. Phase may play an important role in selective adsorption of CO{sub 2}. It is speculated that mesoporous alumina is more reactive than precipitated alumina creating the xBaO {center_dot}Al{sub 2}O{sub 3} phase that may be more affinitive to CO{sub 2} than N{sub 2}. On the other hand, the barium aluminates phase (Ba{sub 3}Al{sub 2}O{sub 6}) in the mesoporous sample does not help the adsorption of CO{sub 2}. Microporous aluminosilicate was chosen as a suitable candidate for CO{sub 2}/N{sub 2} separation because the pore size is ...
Date: March 25, 2003
Creator: Shih, Wei-Heng; Patil, Tejas & Zhao, Qiang
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION

Description: The authors propose to use microporous silica as a suitable candidate for CO{sub 2}/N{sub 2} separation because the pore size is less than 10 {angstrom}. If a CO{sub 2}adsorbent is added to the microporous silica, the adsorption of CO{sub 2} can block the passage of N{sub 2} and an effective CO{sub 2}/N{sub 2} separator will be found. It was first demonstrated that microporous silica could be synthesized. The microporous silica was then impregnated with Ba(OH){sub 2}. The results of GC study showed that at temperatures between 50 C and 90 C, Ba-doped microporous silica can separate CO{sub 2} from N{sub 2} and the idea of a microporous membrane for CO{sub 2}/N{sub 2} separation is feasible. The new result gives strong support to the proposed research that was outlined in the Phase II proposal. They hope to be able to continue the research and build an effective CO{sub 2}/N{sub 2} membrane separator in the Phase II of this project.
Date: May 1, 2002
Creator: Shih, Wei-Heng; Zhao, Qiang & Patil, Tejas
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION

Description: Mesoporous and precipitated alumina were synthesized as the base material for CO{sub 2} adsorbent. The porous alumina is doped with Ba to enhance it CO{sub 2} affinity due to the basicity of Ba. it is shown by gas chromatograph (GC) that the addition of Ba enhances the separation CO{sub 2} from N{sub 2}. It was found that mesoporous alumina has larger specific surface area and better selectivity of CO{sub 2} than precipitated alumina. Ba improves the affinity of mesoporous alumina with CO{sub 2}. Phase may play an important role in selective adsorption of CO{sub 2}. It is speculated that mesoporous alumina is more reactive than precipitated alumina creating the xBaO {center_dot} Al{sub 2}O{sub 3} phase that may be more affinity to CO{sub 2} than N{sub 2}. On the other hand, the barium aluminate phase (Ba{sub 3}Al{sub 2}O{sub 6}) in the mesoporous sample does not help the adsorption of CO{sub 2}.
Date: May 1, 2002
Creator: Shih, Wei-Heng; Zhao, Qiang & Wang, Nanlin
Partner: UNT Libraries Government Documents Department

ULTRASENSITIVE HIGH-TEMPERATURE SELECTIVE GAS DETECTION USING PIEZOELECTRIC MICROCANTILEVERS

Description: We have obtained very promising results in the Phase I study. Specifically, for temperature effects, we have established that piezoelectric cantilever sensors could retain their resonance peak strength at high temperatures, i.e., the Q values of the resonance peaks remained above 10 even when the temperature was very close to the Curie temperature. This confirms that a piezoelectric cantilever sensor can be used as a sensor up to its Curie temperature. Furthermore, we have shown that the mass detection sensitivity remained unchanged at different temperatures. For selective gas detection, we have demonstrated selective NH{sub 3} detection using piezoelectric cantilever sensors coated with mesoporous SiO{sub 2}. For high-temperature sensor materials development, we have achieved highly oriented Sr-doped lead titanate thin films that possessed superior dielectric and ferroelectric properties. Such highly oriented films can be microfabricated into high-performance piezoelectric microcantilever sensors that can be used up to 490 C. We have accomplished the goal of Phase I study in exploring the various aspects of a high-temperature gas sensor. We propose to continue the study in Phase II to develop a sensor that is suitable for high-temperature applications using piezoelectrics with a high Curie temperature and by controlling the effects of temperature. The lead titanate based thin film developed in Phase I is good for applications up to 490 C. In phase II, we will develop lithium niobate thin film based cantilevers for applications up to 1000 C.
Date: March 5, 2004
Creator: Shih, Wan Y.; Patil, Tejas; Zhao, Qiang; Chiu, Yi-Shi & Shih, Wei-Heng
Partner: UNT Libraries Government Documents Department