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Byung Su Kim - One of the best experts on this subject based on the ideXlab platform.
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a novel cyclic process using caso4 cas pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants part i feasibility and kinetics of the reduction of sulfur dioxide with Calcium Sulfide pellets
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2002Co-Authors: H Y Sohn, Byung Su KimAbstract:Certain new Sulfide-smelting processes and coal-gasification processes generate high-strength sulfur dioxide streams, for which a new process for converting sulfur dioxide to elemental sulfur needs to be developed because no process exists that is generally and economically applicable to the treatment of such streams. A thermodynamic and experimental investigation to develop a new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving Calcium Sulfide and Calcium sulfate without generating secondary pollutants was carried out. In this process, the starting raw material, Calcium sulfate, is reduced by a suitable reducing agent, such as hydrogen, to produce Calcium Sulfide, which is used to reduce sulfur dioxide to elemental sulfur vapor and Calcium sulfate. The latter is, in turn, reduced to regenerate Calcium Sulfide. In this Part I, detailed experimental results are presented on the kinetics of the reaction between sulfur dioxide and Calcium-Sulfide pellets, which produces elemental sulfur and Calcium sulfate. The experiments were carried out at temperatures between 1023 and 1088 K and sulfur-dioxide partial pressures between 9 and 60 kPa by the use of a thermogravimetric analysis (TGA) technique. The rate of this reaction was demonstrated by the conversion of 40 pct Calcium-Sulfide pellets obtained from the hydrogen reduction of fresh Calcium sulfate in 10 minutes at 1073 K under a sulfur-dioxide partial pressure of 43 kPa. The reactivity decreased somewhat during the first three cycles but remained largely unchanged thereafter up to the tenth cycle. This characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. A pore-blocking model was found to fit the reaction rate. The reaction is first order with respect to sulfur-dioxide partial pressure and has an activation energy of 101 to 134 kJ/mol (24 to 32 kcal/mol) for Calcium-Sulfide pellets reacted and regenerated several different times. Sulfur dioxide-containing streams from certain sources, such as the regenerator off-gas from an integrated-gasification, combined-cycle, desulfurization unit and new Sulfide-smelting plants, contain much higher partial pressures of SO2. In these cases, the rate of the first reaction is expected to be proportionally higher than in the test conditions reported in this article. The reduction kinetics of Calcium-sulfate pellets with hydrogen gas is reported in the accompanying Part II.
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a novel cyclic process using caso4 cas pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants part ii hydrogen reduction of Calcium sulfate pellets to Calcium Sulfide
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2002Co-Authors: Byung Su Kim, H Y SohnAbstract:The reduction of Calcium sulfate to produce Calcium Sulfide is a part of the cyclic process for converting sulfur dioxide to elemental sulfur that is described in Part I. The kinetics of the hydrogen reduction of nickel-catalyzed Calcium-sulfate pellets were investigated using a thermogravimetric analysis (TGA) technique at reaction temperatures between 1023 and 1088 K and hydrogen partial pressures between 12.9 and 86.1 kPa. The reactivity of nickel-catalyzed Calcium-sulfate pellets was demonstrated by the conversion of 70 pct fresh nickel-catalyzed Calcium sulfate to Calcium Sulfide in 20 minutes at 1073 K under a hydrogen partial pressure of 86.1 kPa. Furthermore, the reactivity remained relatively intact after ten cycles of reactions and regenerations. This observed characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. The nucleation and growth rate expression was found to be useful in describing the kinetics of the reaction, which had an activation energy of about 167 kJ/mol (∼40 kcal/mol) in all reaction cycles except for the first regenerated samples that were lower at 146 kJ/mol (35 kcal/mol). The reaction order with respect to hydrogen partial pressure was 0.22 in all cycles with the exception of the first regenerated sample for which it was 0.37.
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a novel cyclic reaction system involving cas and caso4 for converting sulfur dioxide to elemental sulfur without generating secondary pollutants 2 kinetics of the reduction of sulfur dioxide by Calcium Sulfide powder
Industrial & Engineering Chemistry Research, 2002Co-Authors: H Y Sohn, Byung Su KimAbstract:The process feasibility for converting sulfur dioxide to elemental sulfur by the cyclic reaction involving Calcium Sulfide and Calcium sulfate was established in part 1 of this series. In this part, detailed experimental results are presented on the kinetics of the reaction between Calcium Sulfide and sulfur dioxide, which produces elemental sulfur and Calcium sulfate. The experiments were carried out in the temperature range of 973−1153 K under sulfur dioxide partial pressures between 9 and 60 kPa by the use of a thermogravimetric analysis technique. As an example, about 60% of the Calcium Sulfide powder from the hydrogen reduction of fresh Calcium sulfate was converted in 10 min at 1153 K under a sulfur dioxide partial pressure of 25.8 kPa. The reactivity decreased somewhat during the first five cycles of reaction and regeneration but remained largely intact thereafter up to the tenth cycle. A pore-blocking model was found to fit the reaction rate. The reaction is first order with respect to sulfur diox...
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a novel cyclic reaction system involving cas and caso4 for converting sulfur dioxide to elemental sulfur without generating secondary pollutants 3 kinetics of the hydrogen reduction of the Calcium sulfate powder to Calcium Sulfide
Industrial & Engineering Chemistry Research, 2002Co-Authors: Byung Su Kim, H Y SohnAbstract:The reduction of Calcium sulfate to produce Calcium Sulfide is not only a part of the cyclic process for converting sulfur dioxide to elemental sulfur described in part 1 of this series but also of interest as a means of producing elemental sulfur from gypsum. This reaction was investigated using a thermogravimetric analysis technique in the absence and presence of an impregnated nickel catalyst at reaction temperatures between 973 and 1153 K and hydrogen partial pressures between 1.7 and 86.1 kPa. As an example of the reactivity of the nickel-catalyzed Calcium sulfate powder, more than 95% of fresh nickel-catalyzed Calcium sulfate powders was converted to Calcium Sulfide in 20 min at 1123 K under a hydrogen partial pressure of 86.1 kPa. Furthermore, the reactivity remained relatively intact after 10 cycles of reactions and regenerations, which is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. The Erofeev nucleation and growth kinetics equation ...
H Y Sohn - One of the best experts on this subject based on the ideXlab platform.
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a novel cyclic process using caso4 cas pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants part i feasibility and kinetics of the reduction of sulfur dioxide with Calcium Sulfide pellets
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2002Co-Authors: H Y Sohn, Byung Su KimAbstract:Certain new Sulfide-smelting processes and coal-gasification processes generate high-strength sulfur dioxide streams, for which a new process for converting sulfur dioxide to elemental sulfur needs to be developed because no process exists that is generally and economically applicable to the treatment of such streams. A thermodynamic and experimental investigation to develop a new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving Calcium Sulfide and Calcium sulfate without generating secondary pollutants was carried out. In this process, the starting raw material, Calcium sulfate, is reduced by a suitable reducing agent, such as hydrogen, to produce Calcium Sulfide, which is used to reduce sulfur dioxide to elemental sulfur vapor and Calcium sulfate. The latter is, in turn, reduced to regenerate Calcium Sulfide. In this Part I, detailed experimental results are presented on the kinetics of the reaction between sulfur dioxide and Calcium-Sulfide pellets, which produces elemental sulfur and Calcium sulfate. The experiments were carried out at temperatures between 1023 and 1088 K and sulfur-dioxide partial pressures between 9 and 60 kPa by the use of a thermogravimetric analysis (TGA) technique. The rate of this reaction was demonstrated by the conversion of 40 pct Calcium-Sulfide pellets obtained from the hydrogen reduction of fresh Calcium sulfate in 10 minutes at 1073 K under a sulfur-dioxide partial pressure of 43 kPa. The reactivity decreased somewhat during the first three cycles but remained largely unchanged thereafter up to the tenth cycle. This characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. A pore-blocking model was found to fit the reaction rate. The reaction is first order with respect to sulfur-dioxide partial pressure and has an activation energy of 101 to 134 kJ/mol (24 to 32 kcal/mol) for Calcium-Sulfide pellets reacted and regenerated several different times. Sulfur dioxide-containing streams from certain sources, such as the regenerator off-gas from an integrated-gasification, combined-cycle, desulfurization unit and new Sulfide-smelting plants, contain much higher partial pressures of SO2. In these cases, the rate of the first reaction is expected to be proportionally higher than in the test conditions reported in this article. The reduction kinetics of Calcium-sulfate pellets with hydrogen gas is reported in the accompanying Part II.
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a novel cyclic process using caso4 cas pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants part ii hydrogen reduction of Calcium sulfate pellets to Calcium Sulfide
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2002Co-Authors: Byung Su Kim, H Y SohnAbstract:The reduction of Calcium sulfate to produce Calcium Sulfide is a part of the cyclic process for converting sulfur dioxide to elemental sulfur that is described in Part I. The kinetics of the hydrogen reduction of nickel-catalyzed Calcium-sulfate pellets were investigated using a thermogravimetric analysis (TGA) technique at reaction temperatures between 1023 and 1088 K and hydrogen partial pressures between 12.9 and 86.1 kPa. The reactivity of nickel-catalyzed Calcium-sulfate pellets was demonstrated by the conversion of 70 pct fresh nickel-catalyzed Calcium sulfate to Calcium Sulfide in 20 minutes at 1073 K under a hydrogen partial pressure of 86.1 kPa. Furthermore, the reactivity remained relatively intact after ten cycles of reactions and regenerations. This observed characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. The nucleation and growth rate expression was found to be useful in describing the kinetics of the reaction, which had an activation energy of about 167 kJ/mol (∼40 kcal/mol) in all reaction cycles except for the first regenerated samples that were lower at 146 kJ/mol (35 kcal/mol). The reaction order with respect to hydrogen partial pressure was 0.22 in all cycles with the exception of the first regenerated sample for which it was 0.37.
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a novel cyclic reaction system involving cas and caso4 for converting sulfur dioxide to elemental sulfur without generating secondary pollutants 2 kinetics of the reduction of sulfur dioxide by Calcium Sulfide powder
Industrial & Engineering Chemistry Research, 2002Co-Authors: H Y Sohn, Byung Su KimAbstract:The process feasibility for converting sulfur dioxide to elemental sulfur by the cyclic reaction involving Calcium Sulfide and Calcium sulfate was established in part 1 of this series. In this part, detailed experimental results are presented on the kinetics of the reaction between Calcium Sulfide and sulfur dioxide, which produces elemental sulfur and Calcium sulfate. The experiments were carried out in the temperature range of 973−1153 K under sulfur dioxide partial pressures between 9 and 60 kPa by the use of a thermogravimetric analysis technique. As an example, about 60% of the Calcium Sulfide powder from the hydrogen reduction of fresh Calcium sulfate was converted in 10 min at 1153 K under a sulfur dioxide partial pressure of 25.8 kPa. The reactivity decreased somewhat during the first five cycles of reaction and regeneration but remained largely intact thereafter up to the tenth cycle. A pore-blocking model was found to fit the reaction rate. The reaction is first order with respect to sulfur diox...
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a novel cyclic reaction system involving cas and caso4 for converting sulfur dioxide to elemental sulfur without generating secondary pollutants 3 kinetics of the hydrogen reduction of the Calcium sulfate powder to Calcium Sulfide
Industrial & Engineering Chemistry Research, 2002Co-Authors: Byung Su Kim, H Y SohnAbstract:The reduction of Calcium sulfate to produce Calcium Sulfide is not only a part of the cyclic process for converting sulfur dioxide to elemental sulfur described in part 1 of this series but also of interest as a means of producing elemental sulfur from gypsum. This reaction was investigated using a thermogravimetric analysis technique in the absence and presence of an impregnated nickel catalyst at reaction temperatures between 973 and 1153 K and hydrogen partial pressures between 1.7 and 86.1 kPa. As an example of the reactivity of the nickel-catalyzed Calcium sulfate powder, more than 95% of fresh nickel-catalyzed Calcium sulfate powders was converted to Calcium Sulfide in 20 min at 1123 K under a hydrogen partial pressure of 86.1 kPa. Furthermore, the reactivity remained relatively intact after 10 cycles of reactions and regenerations, which is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. The Erofeev nucleation and growth kinetics equation ...
Edu Suarez - One of the best experts on this subject based on the ideXlab platform.
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use of levitated cells n3d bioassay system to determine cytotoxicity of Calcium Sulfide cas clusters in malignant cells as potential cancer cell targeted therapy lb583
The FASEB Journal, 2014Co-Authors: Nestor Carrasco, Carlos Ortiz, Jaileen Quinones, Geishamarie Feliciano, Angel Ortiz, Daniel Rivera, Miguel Castro, Edu SuarezAbstract:Preliminary results in our lab showed that naked Calcium Sulfide (CaS) nanoparticles (5.0nm) decreased cell proliferation in the carcinoma cell lines CRL-2124. Objective: The objective of this stud...
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Determination of the IC50 and LD50 of Calcium Sulfide (CaS) Clusters on Malignant Carcinoma and Normal Fibroblasts Cell Lines (LB580)
The FASEB Journal, 2014Co-Authors: Michael Anand Manoharan-valerio, Jaileen Quinones, Geishamarie Feliciano, Daniel Rivera, Miguel Castro, Carlos A. Ortiz, Angel Diaz, Edu SuarezAbstract:Preliminary results in our lab showed that naked Calcium Sulfide (CaS) nanoparticles (5.0nm) decreased cell proliferation in the carcinoma cell lines CRL-2124. Objective: The objective of this study was to determine the IC50 and LD50 for CaS clusters (measuring < 3.0 nm) in the carcinoma cell lines CRL-2124 and the normal fibroblasts CRL-2522 by using the n3D BiOAssay (Biosciences, Inc.). Methods: A total of 100,000 cells per cell line were seeded in T-75 flasks. When reaching 80% confluence, they were incubated with the n3D nano-shuttles overnight (ON) at 37oC, 5% CO2, and 98% relative humidity. Next day, cells were trypsinized, counted, and seeded (1.4 - 1.6 M/per well) in 6-well plates using the n3D BiOAssay to levitate the cells. A total of 150,000 cells/well were seeded in a 96-well plate in triplicates with a total volume of 300ul (150ul of cells, 120ul of media, and 30ul of the treatments). The treatments consist of doses ranging 10-100 pmoles of CaS, 2% DMSO, or growth media. A 24-hours recording ...
Fenghuei Lin - One of the best experts on this subject based on the ideXlab platform.
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silica modified fe doped Calcium Sulfide nanoparticles for in vitro and in vivo cancer hyperthermia
Journal of Nanoparticle Research, 2011Co-Authors: Ching Li Tseng, Fenghuei Lin, Kai Chiang Yang, Jung Chih ChenAbstract:In this study, Sulfide-based magnetic Fe-doped CaS nanoparticles modified with a silica layer were investigated for cancer hyperthermia. A polyvinyl pyrrolidone polymer was used as the coupling agent. The developed nanoparticles contained 11.6 wt% iron concentration, and their X-ray diffraction pattern was similar to those of CaS and Fe–CaS nanoparticles. The average particle size was approximately 47.5 nm and homogeneously dispersed in aqueous solutions. The major absorption bands of silica were observed from the FTIR spectrum. The magnetic properties and heating efficiency were also examined. The specific absorption ratio of nanoparticles at a concentration of 10 mg/mL at 37 °C in an ethanol carrier fluid was 37.92 W/g, and the nanoparticles would raise the temperature to over 45 °C within 15 min. A cytotoxicity analysis revealed that the nanoparticles had good biocompatibility, which indicated that the nanoparticles did not affect cell viability. The therapeutic effects of the nanoparticles were investigated using in vitro and animal studies. Cells seeded with nanoparticles and treated under an AC magnetic field revealed a percentage of cytotoxicity (60%) that was significantly higher from that in other groups. In the animal study, during a hyperthermia period of 15 days, tumor-bearing Balb/c mice that were subcutaneously injected with nanoparticles and exposed to an AC magnetic field manifested a reduction in tumor volume. The newly developed silica-modified Fe–CaS nanoparticles can thus be considered a promising and attractive hyperthermia thermoseed.
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a newly developed fe doped Calcium Sulfide nanoparticles with magnetic property for cancer hyperthermia
Journal of Nanoparticle Research, 2010Co-Authors: Ching Li Tseng, Fenghuei LinAbstract:In this study, a magnetic iron-doped Calcium Sulfide (Fe–CaS) nanoparticle was newly developed and studied for the purpose of hyperthermia due to its promising magnetic property, adequate biodegradation rate, and relatively good biocompatibility. Fe–CaS nanoparticles were synthesized by a wet chemical co-precipitation process with heat treatment in a N2 atmosphere, and were subsequently cooled in N2 and exposed to air at a low temperature. The crystal structure of the Fe–CaS nanoparticles was similar to that of the CaS, which was identified by an X-ray diffractometer (XRD). The particle size was less than 40 nm based on a Debye–Scherrer equation and transmission electron microscope (TEM) examination. Magnetic properties obtained from the SQUID magnetometer demonstrated that the synthesized CaS was a diamagnetic property. Once the Fe ions were doped, the synthesized Fe–CaS converted into paramagnetism which showed no hysteresis loop. Having been heated above 600 °C in N2, the Fe–CaS showed a promising magnetic property to produce enough energy to increase the temperature for hyperthermia. 10 mg/ml of the Fe–CaS was able to generate heat to elevate the media temperature over 42.5 °C within 6 min. The area of the hysteresis loop increased with the increasing of the treated temperature, especially at 800 °C for 1 h. This is because more Fe ions replaced Ca ions in the lattice at the higher heat treatment temperature. The heat production was also increasing with the increasing of heat treatment temperature, which resulted in an adequate specific absorption ratio (SAR) value, which was found to be 45.47 W/g at 37 °C under an alternative magnetic field of f = 750 KHz, H = 10 Oe. The in vitro biocompatibility test of the synthesized Fe–CaS nanoparticles examined by the LDH assay showed no cytotoxicity to 3T3 fibroblast. The result of in vitro cell hyperthermia shows that under magnetic field the Fe–CaS nanoparticles were able to generate heat and kill the CT-26 cancer cells significantly. We believe that the developed Fe–CaS nanoparticles have great potential as thermo-seeds for cancer hyperthermia in the near future.
M Suchea - One of the best experts on this subject based on the ideXlab platform.
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europium and samarium doped Calcium Sulfide thin films grown by pld
Applied Surface Science, 2007Co-Authors: S Christoulakis, M Suchea, N Katsarakis, E KoudoumasAbstract:Abstract Europium and samarium doped Calcium Sulfide thin films (CaS:Eu,Sm) with different thickness were prepared by the pulsed laser deposition technique using sintered targets. A typical homemade deposition chamber and XeCl excimer laser (308 nm) were employed and the films were deposited in helium atmosphere onto silicon and corning glass substrates. Structural investigations carried out by X-ray diffraction and atomic force microscopy showed a strong influence of the deposition parameters on the film properties. The films grown had an amorphous or polycrystalline structure depending on growth temperature and the number of pulses used, the same parameters affecting the film roughness, the grain shape and dimensions, the film thickness and the optical transmittance. This work indicates that pulsed laser deposition can be a suitable technique for the preparation of CaS:Eu,Sm thin films, the film characteristics being controlled by the growth conditions.
