Elemental mercury（Hg^0）re-emissions from slurries and solutions were evaluated in a lab-scale simulated scrubber.Oxidized mercury（Hg^2 ＋）standard solution was injected into the simulated scrubber at a desired rat...Elemental mercury（Hg^0）re-emissions from slurries and solutions were evaluated in a lab-scale simulated scrubber.Oxidized mercury（Hg^2 ＋）standard solution was injected into the simulated scrubber at a desired rate to simulate absorbing and dissolving of Hg^2 ＋in the flue gas across wet flue gas desulfurization（WFGD）systems. PS analytical mercury analyzer was used to continuously determine Hg0re-emission concentrations in the carrier gas from the scrubber.Sulfite ion in the slurry of CaSO3 was validated to reduce Hg ^2＋to Hg^ 0,while no Hg ^0 re-emission occurred from slurries of CaSO4 and CaO.Transitional metal ions with low chemical valence such as Fe^2 ＋,Pb ^2＋,Ni ^2＋, AsO2^-and Cu ^＋were used to prepare solutions with concentration levels of mmol·L^-1.Reduction reaction of Hg^2 ＋to Hg 0was observed from these solutions.Reduction capabilities for the different transitional metal ions in the solutions were：Pb^2 ＋〉Cu ^＋〉Fe^ 2＋〉 AsO2^-〉Ni ^2＋.展开更多
Liquid scintillators are widely used as the neutrino target in neutrino experiments.The absorption and emission of different components of a ternary liquid scintillator （Linear Alkyl Benzene （LAB） as the solvent,2,...Liquid scintillators are widely used as the neutrino target in neutrino experiments.The absorption and emission of different components of a ternary liquid scintillator （Linear Alkyl Benzene （LAB） as the solvent,2,5-diphenyloxazole （PPO） as the fluor and p-bis-（o-methylstyryl）-benzene （bis-MSB） as wavelength shifter） are studied.It is shown that the absorption of this liquid scintillator is dominant by LAB and PPO at wavelengths less than 349 nm,and the absorption by bis-MSB becomes prevalent at the wavelength larger than 349 nm.The fluorescence quantum yields,which are the key parameters to model the absorption and re-emission processes in large liquid scintillation detectors,are measured.展开更多
Mercury(Hg) is a toxic and bio-accumulating heavy metal that is predominantly released via the combustion of coal. Due to its toxicity, the Environmental Protection Agency(EPA)has introduced Mercury and Air Toxics Sta...Mercury(Hg) is a toxic and bio-accumulating heavy metal that is predominantly released via the combustion of coal. Due to its toxicity, the Environmental Protection Agency(EPA)has introduced Mercury and Air Toxics Standards(MATS) Rule regarding allowable Hg emissions. In order to reduce emissions, power plants have widely adopted activated carbon(AC) injection. AC injection has proven to be an effective method to reduce Hg emissions, but the re-emission of previously adsorbed Hg during unit operation, likely due to changing temperature or flue gas composition, could be problematic. This study specifically examined the effects of temperature and sulfur trioxide(SO3) concentration,by ramping temperature and SO3 concentration independently and simultaneously, on AC samples that are already exposed to flue gas and saturated in presence of Hg, sulfur dioxide(SO2) and nitric oxide(NO). Of these two suspected factors to cause re-emission,temperature had the greater impact and resulted in re-emission of both elemental and oxidized Hg with a greater fraction of oxidized Hg, which can be attributed to elemental Hg being more strongly bonded to the AC surface. Surprisingly, exposing the samples to increasing concentrations of SO3 had nearly no effect under the conditions examined in this study, possibly as a result of the samples being already saturated with sulfur prior to the SO3 ramp tests to simulate transient conditions in the plant.展开更多
A semi-analytical Monte Carlo (SMC) simulation was developed to simulate the propagation of laser-induced fluo- rescence (LIF) in an optically participating spray, which simultaneously exhibits spectrally dependent em...A semi-analytical Monte Carlo (SMC) simulation was developed to simulate the propagation of laser-induced fluo- rescence (LIF) in an optically participating spray, which simultaneously exhibits spectrally dependent emission, anisotropic scattering, absorption, and re-emission. The SMC simulation is described and then applied to an experimental configuration of a cloud of polydisperse droplets composed of water and sulforhodamine B dye. In the SMC simulation, the collected LIF flux on the remote receptor element is calculated as the global contribution from the emissive source, single, twice, … and nth collision events in any sequence. The effects on the fluorescence photons propagation of spray parameters like the dye concentration, droplets concentration, and droplets size are examined. Three spectral bands representing different optical properties are chosen to analyze the interference of absorption, scattering and re-emission on the detected LIF flux. The obtained spectral LIF flux distribution on the receptor demonstrates a “red shift” phenomenon.展开更多
The process described here is well at the heart of the appearance of pigmentary materials and their interactions with light. It is indeed based on the property of colored materials to reflect, in a selective way, the ...The process described here is well at the heart of the appearance of pigmentary materials and their interactions with light. It is indeed based on the property of colored materials to reflect, in a selective way, the colored radiations of light. The innovation is here based on a more subtle and more complete process, using the trichromy, i.e., all the possibilities of the white light, which is split in three primary radiations： red^een--blue. One can, indeed, animate a pigmentary surface by the alternate projection of these three colors, and thus reveal three different images on the same support, or create a motion effect. However, in this process, the weakness of bhie, compared to green and red, might constitute an obstacle. But that will be compensated by the use of fluorescent colors, instead of ordinary colors. This process may provide very spectacular applications in the fields of lighting, architecture, design, scenography, booths, display windows, etc.. We shall propose a step-to-step approach.展开更多
Accelerating the(NH_4)_(2)SO_(3) oxidation gives rise to the reclaiming of byproduct, while there are secondary environmental risks from reduction of the coexisted selenium species by sulfite. In this study, a bi-func...Accelerating the(NH_4)_(2)SO_(3) oxidation gives rise to the reclaiming of byproduct, while there are secondary environmental risks from reduction of the coexisted selenium species by sulfite. In this study, a bi-functional Co-SBA-15-SH, were synthesized through Co impregnation and sulfhydryl(-SH) decoration, which can simultaneously uptake Se and accelerate sulfite oxidation efficiently. Meanwhile, the adsorption kinetics and migration mechanism of Se species were revealed through characterization and density functional calculations, with maximum adsorption capacity of 223 mg/g. The inhibition of Se~0 re-emission and poisonous effect of Se on sulfite oxidation was also investigated. Using the findings of this study, the ammonia desulfurization can be improved by enabling purification of the byproduct and lowering the toxicity of effluent by removing toxic pollutants.展开更多
The most abundant and typical reducing agent for oxidized mercury in the slurry of wet flue-gas desulphurization(FGD)is the absorbed sulphur dioxide(SO_(2)),which is present as different species of bisulphite or sulph...The most abundant and typical reducing agent for oxidized mercury in the slurry of wet flue-gas desulphurization(FGD)is the absorbed sulphur dioxide(SO_(2)),which is present as different species of bisulphite or sulphite,depending on the pH of the slurry.In this study,two different measurement principles for continuous sulphite measurement in the slurry of lab-scale FGD were investigated to check their feasibility to be implemented in a wet FGD.The first method is based on light absorbance at the characteristic wavelength of sulphite measurement using a spectrophotometer and,in the second method,sulphite is measured as sulphur dioxide using a gas sensor.In addition,the correlation of sulphite concentration and mercury(Hg)in the slurry can be shown by measuring sulphite semi-continuously.It was concluded that using a spectrophotometer leads to distorted results.In contrast,measuring sulphite as SO2 in the gas phase proved to be more selective.The implementation of the measurement technique in the lab-scale FGD showed promising results for sulphite measurement.Thus,the correlation of Hg and sulphite concentration could be shown at different synthetic slurries containing different halides.Using a slurry without halides demonstrated the ambivalent influence of sulphite in reactions involving Hg,in which sulphite acts as a ligand for Hg complexes as well as a reducing agent,depending on the existing concentration.However,in the presence of halides,the role of sulphite was less significant.展开更多
基金Supported by the US Agency for International Development(USAID)cooperation agreement(486-A-00-06-000140-00)
文摘Elemental mercury（Hg^0）re-emissions from slurries and solutions were evaluated in a lab-scale simulated scrubber.Oxidized mercury（Hg^2 ＋）standard solution was injected into the simulated scrubber at a desired rate to simulate absorbing and dissolving of Hg^2 ＋in the flue gas across wet flue gas desulfurization（WFGD）systems. PS analytical mercury analyzer was used to continuously determine Hg0re-emission concentrations in the carrier gas from the scrubber.Sulfite ion in the slurry of CaSO3 was validated to reduce Hg ^2＋to Hg^ 0,while no Hg ^0 re-emission occurred from slurries of CaSO4 and CaO.Transitional metal ions with low chemical valence such as Fe^2 ＋,Pb ^2＋,Ni ^2＋, AsO2^-and Cu ^＋were used to prepare solutions with concentration levels of mmol·L^-1.Reduction reaction of Hg^2 ＋to Hg 0was observed from these solutions.Reduction capabilities for the different transitional metal ions in the solutions were：Pb^2 ＋〉Cu ^＋〉Fe^ 2＋〉 AsO2^-〉Ni ^2＋.
基金Supported by Nation Natural Science Foundation of China (211202037)
文摘Liquid scintillators are widely used as the neutrino target in neutrino experiments.The absorption and emission of different components of a ternary liquid scintillator （Linear Alkyl Benzene （LAB） as the solvent,2,5-diphenyloxazole （PPO） as the fluor and p-bis-（o-methylstyryl）-benzene （bis-MSB） as wavelength shifter） are studied.It is shown that the absorption of this liquid scintillator is dominant by LAB and PPO at wavelengths less than 349 nm,and the absorption by bis-MSB becomes prevalent at the wavelength larger than 349 nm.The fluorescence quantum yields,which are the key parameters to model the absorption and re-emission processes in large liquid scintillation detectors,are measured.
基金financial support provided by Electric Power Research Institute(EPRI)funded through the Research Experiences for Undergraduates(REU)Program of the National Science Foundation(award number 1358931)
文摘Mercury(Hg) is a toxic and bio-accumulating heavy metal that is predominantly released via the combustion of coal. Due to its toxicity, the Environmental Protection Agency(EPA)has introduced Mercury and Air Toxics Standards(MATS) Rule regarding allowable Hg emissions. In order to reduce emissions, power plants have widely adopted activated carbon(AC) injection. AC injection has proven to be an effective method to reduce Hg emissions, but the re-emission of previously adsorbed Hg during unit operation, likely due to changing temperature or flue gas composition, could be problematic. This study specifically examined the effects of temperature and sulfur trioxide(SO3) concentration,by ramping temperature and SO3 concentration independently and simultaneously, on AC samples that are already exposed to flue gas and saturated in presence of Hg, sulfur dioxide(SO2) and nitric oxide(NO). Of these two suspected factors to cause re-emission,temperature had the greater impact and resulted in re-emission of both elemental and oxidized Hg with a greater fraction of oxidized Hg, which can be attributed to elemental Hg being more strongly bonded to the AC surface. Surprisingly, exposing the samples to increasing concentrations of SO3 had nearly no effect under the conditions examined in this study, possibly as a result of the samples being already saturated with sulfur prior to the SO3 ramp tests to simulate transient conditions in the plant.
基金Project supported by the National Natural Science Foundation of China (No. 60534030)the Scholarship of French Embassy in China and the Doctoral Grant from French Embassy in China
文摘A semi-analytical Monte Carlo (SMC) simulation was developed to simulate the propagation of laser-induced fluo- rescence (LIF) in an optically participating spray, which simultaneously exhibits spectrally dependent emission, anisotropic scattering, absorption, and re-emission. The SMC simulation is described and then applied to an experimental configuration of a cloud of polydisperse droplets composed of water and sulforhodamine B dye. In the SMC simulation, the collected LIF flux on the remote receptor element is calculated as the global contribution from the emissive source, single, twice, … and nth collision events in any sequence. The effects on the fluorescence photons propagation of spray parameters like the dye concentration, droplets concentration, and droplets size are examined. Three spectral bands representing different optical properties are chosen to analyze the interference of absorption, scattering and re-emission on the detected LIF flux. The obtained spectral LIF flux distribution on the receptor demonstrates a “red shift” phenomenon.
文摘The process described here is well at the heart of the appearance of pigmentary materials and their interactions with light. It is indeed based on the property of colored materials to reflect, in a selective way, the colored radiations of light. The innovation is here based on a more subtle and more complete process, using the trichromy, i.e., all the possibilities of the white light, which is split in three primary radiations： red^een--blue. One can, indeed, animate a pigmentary surface by the alternate projection of these three colors, and thus reveal three different images on the same support, or create a motion effect. However, in this process, the weakness of bhie, compared to green and red, might constitute an obstacle. But that will be compensated by the use of fluorescent colors, instead of ordinary colors. This process may provide very spectacular applications in the fields of lighting, architecture, design, scenography, booths, display windows, etc.. We shall propose a step-to-step approach.
文摘Accelerating the(NH_4)_(2)SO_(3) oxidation gives rise to the reclaiming of byproduct, while there are secondary environmental risks from reduction of the coexisted selenium species by sulfite. In this study, a bi-functional Co-SBA-15-SH, were synthesized through Co impregnation and sulfhydryl(-SH) decoration, which can simultaneously uptake Se and accelerate sulfite oxidation efficiently. Meanwhile, the adsorption kinetics and migration mechanism of Se species were revealed through characterization and density functional calculations, with maximum adsorption capacity of 223 mg/g. The inhibition of Se~0 re-emission and poisonous effect of Se on sulfite oxidation was also investigated. Using the findings of this study, the ammonia desulfurization can be improved by enabling purification of the byproduct and lowering the toxicity of effluent by removing toxic pollutants.
文摘The most abundant and typical reducing agent for oxidized mercury in the slurry of wet flue-gas desulphurization(FGD)is the absorbed sulphur dioxide(SO_(2)),which is present as different species of bisulphite or sulphite,depending on the pH of the slurry.In this study,two different measurement principles for continuous sulphite measurement in the slurry of lab-scale FGD were investigated to check their feasibility to be implemented in a wet FGD.The first method is based on light absorbance at the characteristic wavelength of sulphite measurement using a spectrophotometer and,in the second method,sulphite is measured as sulphur dioxide using a gas sensor.In addition,the correlation of sulphite concentration and mercury(Hg)in the slurry can be shown by measuring sulphite semi-continuously.It was concluded that using a spectrophotometer leads to distorted results.In contrast,measuring sulphite as SO2 in the gas phase proved to be more selective.The implementation of the measurement technique in the lab-scale FGD showed promising results for sulphite measurement.Thus,the correlation of Hg and sulphite concentration could be shown at different synthetic slurries containing different halides.Using a slurry without halides demonstrated the ambivalent influence of sulphite in reactions involving Hg,in which sulphite acts as a ligand for Hg complexes as well as a reducing agent,depending on the existing concentration.However,in the presence of halides,the role of sulphite was less significant.
