ABSTRACT Considering that Phenanthrene (Phe) is one of the main pollutants in the waste flue gase... more ABSTRACT Considering that Phenanthrene (Phe) is one of the main pollutants in the waste flue gases from organic material combustion, the aim of this paper is to examine the use of carbon materials to remove low concentrations of Phe from a hot exhaust gas stream as a function of its moisture and CO2 content. Adsorption isotherms were measured with steam, CO2 and Phe concentrations in the ranges of 0–20%, 0–30% and 0.02–3.8 ppmv, respectively searching for operating conditions close to the ones observed in energy generation systems. Two classic models [Freundlich and Dubinin-Radushkevich (DR)] were applied and their parameters were then determined by regression analysis. It was found that those isotherms obtained when steam was present in the inlet gas stream fitted the DR model. The determined parameters showed that, for a carbonaceous material, the higher the steam percentage (in volume) in the gas stream, the lower its Phe adsorption capacity. Regarding to the CO2 influence on the Phe adsorption process, a negative influence of CO2 in Phe adsorption capacity was observed, probably due to a competitive effect between CO2 and Phe molecules for the adsorption sites within the carbonaceous material. However, it was found that high CO2 concentrations did not affect the Phenanthrene adsorption more negatively than low CO2 concentrations. In addition, isotherms obtained when CO2 is present were fitted to the Freundlich equation in all the concentration range.
The aim of this work has been centered on the development of a detection system which could be us... more The aim of this work has been centered on the development of a detection system which could be useful to determine polycyclic aromatic hydrocarbon (PAH) emissions in power generation processes where PAHs are released to the atmosphere in the gas phase. In this way, a suitable sensor based on gas phase fluorescence spectroscopy was designed to facilitate the PAH analysis,
Three-ring polycyclic aromatic hydrocarbons (PAH) are one of the most abundant PAH groups emitted... more Three-ring polycyclic aromatic hydrocarbons (PAH) are one of the most abundant PAH groups emitted during coal combustion. Four of them-acenaphthene (Ac), phenanthrene (Phe), fluorene (Fu), and anthracene (An)-have been listed by the U.S. EPA as priority pollutants. The aim in this paper is to study the abatement of this particular group of three-ring PAH from hot gas emissions during energy generation in coal combustion. The three-ring PAH adsorption capacities are related to the morphological and chemical properties of the 16 sorbents used in this work. Single and multiple linear regressions-principal component regression (PCR)-were applied in this study. The main conclusions reached are, first, that the micropore volume is the most determinant parameter for removal of these PAHs and, second, that the adsorption of three-ring PAH by sorbents from waste hot gas emissions is inversely proportional to their volatility: the lower the PAH volatility, the higher the adsorbent adsorption capacity. The adsorption isotherms show that Phe and An, both examples of PAH with three aromatic rings, behave similarly. However, their behavior differs from that of Ac and Fu, compounds in which only two of their three rings exhibit an aromatic nature.
ABSTRACT The aim of this paper is to study the performance of several carbon materials on PAH aba... more ABSTRACT The aim of this paper is to study the performance of several carbon materials on PAH abatement. For this purpose, hot gas cleaning from an atmospheric fluidized bed combustor pilot plant was analyzed by using five different porous materials. Combustion experiments were carried out at similar conditions to those in power stations: 850 °C, 2% oxygen excess, 0.260 m/s gas speed, and low rank coal as fuel. An aliquot of the combustion gases was flowed through a sampling system consisting of a Teflon filter and two adsorbents: the first was a blend of 0.1 mg of active carbon and 8.0 g of sand and the second was 1.0 g XAD-2 resin used as test adsorbent. The temperature and the space velocity of the adsorption bed were 150 °C and 5 × 104 h-1, respectively. Since there was a considerable decrease in the PAH emission concentration under ppbv levels, it was concluded that active carbons might be a promising technological solution for hazardous emission control. The active carbons that were found more appropriate for this abatement were those with a high porosity development and mean pore size around 1.4 nm, which is approximately twice the PAH molecular size.
An Au/Fe2O3 catalyst prepared using a two-stage calcination procedure achieves target conversion ... more An Au/Fe2O3 catalyst prepared using a two-stage calcination procedure achieves target conversion and selectivity for the competitive oxidation of dilute CO in the presence of moist excess H2 and CO2.
ABSTRACT The effect of adding Pt to a highly active ceria polycyclic aromatic hydrocarbon total o... more ABSTRACT The effect of adding Pt to a highly active ceria polycyclic aromatic hydrocarbon total oxidation catalyst has been investigated for the oxidation of naphthalene. The addition of Pt to ceria suppressed the performance of the catalyst for total oxidation. The addition of Pt reduced catalyst surface area, decreased the ceria crystallite size, decreased the concentration of ceria defects and increased the reducibility of the catalyst. The suppression of activity has been attributed to strong metal-support interaction between Pt and ceria, which limits the availability of lattice oxygen for the oxidation process, which follows the Mars-Van Krevelen redox mechanism in the absence of Pt. It is postulated that the presence of dispersed Pt, alters the mechanism of naphthalene oxidation over the ceria catalyst. Graphical Abstract: The addition of platinum to a highly active naphthalene oxidation ceria catalyst modifies activity.[Figure not available: see fulltext.]
Nano-crystalline ceria catalysts prepared by homogeneous precipitation with urea were tested for ... more Nano-crystalline ceria catalysts prepared by homogeneous precipitation with urea were tested for the total oxidation of naphthalene, a model polycyclic aromatic hydrocarbon (PAH). Systematic variation of preparation conditions, including calcination temperature, calcination time ...
... Spain. b Department of Applied Physics and Electromagnetism, Universitat de València, C/Dr. M... more ... Spain. b Department of Applied Physics and Electromagnetism, Universitat de València, C/Dr. Moliner 50, 46100 Burjassot, Valencia, Spain. c SCSIE, Universitat de València, C/Dr. Moliner 50, 46100 Burjassot, Valencia, Spain. d ...
Identification of patients with acute chest pain at high risk for cardiovascular complications is... more Identification of patients with acute chest pain at high risk for cardiovascular complications is a common and difficult challenge for clinicians and must be based initially on data from the history, physical examination, electrocardiogram, and chest radiograph. Some data suggest that elevations in cardiac troponin T (cTnT) may be useful for detection of less severe degrees of myocardial injury that may occur in some patients with unstable angina. Therefore we designed a prospective follow-up study to assess the diagnostic performance and prognostic value of cTnT in a population of patients presenting to the emergency department with acute chest pain. The patient population included all 1477 admitted patients aged 30 years or more who presented to the emergency department of an urban teaching hospital from October 1992, through February 1994, with a chief symptom of acute chest pain not explained by trauma or chest radiograph abnormalities. The 1303 patients (88%) who had 2 or more measurements of cTnT during the first 24 hours after presentation comprised the final study population. Sensitivity, specificity, positive predictive value, negative predictive value, and receiver operator characteristics curve (ROC) were determined for cTnT and creatine kinase-MB (CK-MB) (measured using activity and mass assays) data from the first 24 hours after admission for the outcomes of acute myocardial infarction (AMI) and major cardiac events during the first 72 hours of hospitalization. The sensitivity and specificity of cTnT (threshold of 0.1 ng/mL) for detecting AMI during the first 24 hours after presentation were 99% and 86%, respectively. The CK-MB activity and mass assays had diagnostic performance for detecting AMI similar to cTnT. Among patients who did not meet study criteria for AMI, cTnT was elevated during the first 24 hours in 31% of patients who had major complications, compared with a 17% rate for the CK-MB activity assay and a 3% rate for the CK-MB mass assay. In these patients, the cTnT assay had superior diagnostic performance compared with the CK-MB mass assay as a marker for cardiac complications as assessed with ROC analysis (P <.0004). In a heterogeneous population of patients seen in the emergency department with acute chest pain, cTnT was similar to CK-MB (activity and mass assays) for detection of AMI and superior to the CK-MB mass assay as a marker for major cardiac events early in the hospital course among those who were ruled out for an AMI. Further study is required to determine how this assay can be used to provide more appropriate, cost-effective care.
ABSTRACT Considering that Phenanthrene (Phe) is one of the main pollutants in the waste flue gase... more ABSTRACT Considering that Phenanthrene (Phe) is one of the main pollutants in the waste flue gases from organic material combustion, the aim of this paper is to examine the use of carbon materials to remove low concentrations of Phe from a hot exhaust gas stream as a function of its moisture and CO2 content. Adsorption isotherms were measured with steam, CO2 and Phe concentrations in the ranges of 0–20%, 0–30% and 0.02–3.8 ppmv, respectively searching for operating conditions close to the ones observed in energy generation systems. Two classic models [Freundlich and Dubinin-Radushkevich (DR)] were applied and their parameters were then determined by regression analysis. It was found that those isotherms obtained when steam was present in the inlet gas stream fitted the DR model. The determined parameters showed that, for a carbonaceous material, the higher the steam percentage (in volume) in the gas stream, the lower its Phe adsorption capacity. Regarding to the CO2 influence on the Phe adsorption process, a negative influence of CO2 in Phe adsorption capacity was observed, probably due to a competitive effect between CO2 and Phe molecules for the adsorption sites within the carbonaceous material. However, it was found that high CO2 concentrations did not affect the Phenanthrene adsorption more negatively than low CO2 concentrations. In addition, isotherms obtained when CO2 is present were fitted to the Freundlich equation in all the concentration range.
The aim of this work has been centered on the development of a detection system which could be us... more The aim of this work has been centered on the development of a detection system which could be useful to determine polycyclic aromatic hydrocarbon (PAH) emissions in power generation processes where PAHs are released to the atmosphere in the gas phase. In this way, a suitable sensor based on gas phase fluorescence spectroscopy was designed to facilitate the PAH analysis,
Three-ring polycyclic aromatic hydrocarbons (PAH) are one of the most abundant PAH groups emitted... more Three-ring polycyclic aromatic hydrocarbons (PAH) are one of the most abundant PAH groups emitted during coal combustion. Four of them-acenaphthene (Ac), phenanthrene (Phe), fluorene (Fu), and anthracene (An)-have been listed by the U.S. EPA as priority pollutants. The aim in this paper is to study the abatement of this particular group of three-ring PAH from hot gas emissions during energy generation in coal combustion. The three-ring PAH adsorption capacities are related to the morphological and chemical properties of the 16 sorbents used in this work. Single and multiple linear regressions-principal component regression (PCR)-were applied in this study. The main conclusions reached are, first, that the micropore volume is the most determinant parameter for removal of these PAHs and, second, that the adsorption of three-ring PAH by sorbents from waste hot gas emissions is inversely proportional to their volatility: the lower the PAH volatility, the higher the adsorbent adsorption capacity. The adsorption isotherms show that Phe and An, both examples of PAH with three aromatic rings, behave similarly. However, their behavior differs from that of Ac and Fu, compounds in which only two of their three rings exhibit an aromatic nature.
ABSTRACT The aim of this paper is to study the performance of several carbon materials on PAH aba... more ABSTRACT The aim of this paper is to study the performance of several carbon materials on PAH abatement. For this purpose, hot gas cleaning from an atmospheric fluidized bed combustor pilot plant was analyzed by using five different porous materials. Combustion experiments were carried out at similar conditions to those in power stations: 850 °C, 2% oxygen excess, 0.260 m/s gas speed, and low rank coal as fuel. An aliquot of the combustion gases was flowed through a sampling system consisting of a Teflon filter and two adsorbents: the first was a blend of 0.1 mg of active carbon and 8.0 g of sand and the second was 1.0 g XAD-2 resin used as test adsorbent. The temperature and the space velocity of the adsorption bed were 150 °C and 5 × 104 h-1, respectively. Since there was a considerable decrease in the PAH emission concentration under ppbv levels, it was concluded that active carbons might be a promising technological solution for hazardous emission control. The active carbons that were found more appropriate for this abatement were those with a high porosity development and mean pore size around 1.4 nm, which is approximately twice the PAH molecular size.
An Au/Fe2O3 catalyst prepared using a two-stage calcination procedure achieves target conversion ... more An Au/Fe2O3 catalyst prepared using a two-stage calcination procedure achieves target conversion and selectivity for the competitive oxidation of dilute CO in the presence of moist excess H2 and CO2.
ABSTRACT The effect of adding Pt to a highly active ceria polycyclic aromatic hydrocarbon total o... more ABSTRACT The effect of adding Pt to a highly active ceria polycyclic aromatic hydrocarbon total oxidation catalyst has been investigated for the oxidation of naphthalene. The addition of Pt to ceria suppressed the performance of the catalyst for total oxidation. The addition of Pt reduced catalyst surface area, decreased the ceria crystallite size, decreased the concentration of ceria defects and increased the reducibility of the catalyst. The suppression of activity has been attributed to strong metal-support interaction between Pt and ceria, which limits the availability of lattice oxygen for the oxidation process, which follows the Mars-Van Krevelen redox mechanism in the absence of Pt. It is postulated that the presence of dispersed Pt, alters the mechanism of naphthalene oxidation over the ceria catalyst. Graphical Abstract: The addition of platinum to a highly active naphthalene oxidation ceria catalyst modifies activity.[Figure not available: see fulltext.]
Nano-crystalline ceria catalysts prepared by homogeneous precipitation with urea were tested for ... more Nano-crystalline ceria catalysts prepared by homogeneous precipitation with urea were tested for the total oxidation of naphthalene, a model polycyclic aromatic hydrocarbon (PAH). Systematic variation of preparation conditions, including calcination temperature, calcination time ...
... Spain. b Department of Applied Physics and Electromagnetism, Universitat de València, C/Dr. M... more ... Spain. b Department of Applied Physics and Electromagnetism, Universitat de València, C/Dr. Moliner 50, 46100 Burjassot, Valencia, Spain. c SCSIE, Universitat de València, C/Dr. Moliner 50, 46100 Burjassot, Valencia, Spain. d ...
Identification of patients with acute chest pain at high risk for cardiovascular complications is... more Identification of patients with acute chest pain at high risk for cardiovascular complications is a common and difficult challenge for clinicians and must be based initially on data from the history, physical examination, electrocardiogram, and chest radiograph. Some data suggest that elevations in cardiac troponin T (cTnT) may be useful for detection of less severe degrees of myocardial injury that may occur in some patients with unstable angina. Therefore we designed a prospective follow-up study to assess the diagnostic performance and prognostic value of cTnT in a population of patients presenting to the emergency department with acute chest pain. The patient population included all 1477 admitted patients aged 30 years or more who presented to the emergency department of an urban teaching hospital from October 1992, through February 1994, with a chief symptom of acute chest pain not explained by trauma or chest radiograph abnormalities. The 1303 patients (88%) who had 2 or more measurements of cTnT during the first 24 hours after presentation comprised the final study population. Sensitivity, specificity, positive predictive value, negative predictive value, and receiver operator characteristics curve (ROC) were determined for cTnT and creatine kinase-MB (CK-MB) (measured using activity and mass assays) data from the first 24 hours after admission for the outcomes of acute myocardial infarction (AMI) and major cardiac events during the first 72 hours of hospitalization. The sensitivity and specificity of cTnT (threshold of 0.1 ng/mL) for detecting AMI during the first 24 hours after presentation were 99% and 86%, respectively. The CK-MB activity and mass assays had diagnostic performance for detecting AMI similar to cTnT. Among patients who did not meet study criteria for AMI, cTnT was elevated during the first 24 hours in 31% of patients who had major complications, compared with a 17% rate for the CK-MB activity assay and a 3% rate for the CK-MB mass assay. In these patients, the cTnT assay had superior diagnostic performance compared with the CK-MB mass assay as a marker for cardiac complications as assessed with ROC analysis (P <.0004). In a heterogeneous population of patients seen in the emergency department with acute chest pain, cTnT was similar to CK-MB (activity and mass assays) for detection of AMI and superior to the CK-MB mass assay as a marker for major cardiac events early in the hospital course among those who were ruled out for an AMI. Further study is required to determine how this assay can be used to provide more appropriate, cost-effective care.
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