Capacity of ferric oxide particles to oxidize sulfur dioxide in air

Chung, Kyong C.; Quon, James E.

doi:10.1021/es60078a004

Cited by 30 publications

(17 citation statements)

References 5 publications

(5 reference statements)

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“…The slight decrease in intensity of the peak at 1219 cm −1 after it reaches the maximum may be due to partial dissolution of hematite along with consumption of surface acidic species, which would lead to the formation of Fe 3+ ions and some other surface species on the water-containing surface (Chun and Quon, 1973;Shi et al, 2011). Figure 1b shows typical spectra of the oxidation of SO 2 on FN-24 recorded as a function of time in the range of 1500 to 900 cm −1 .…”

Section: Surface Sulfur-containing Speciesmentioning

confidence: 99%

The effects of nitrate on the heterogeneous uptake of sulfur dioxide on hematite

et al. 2014

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Abstract. Nitrate is often found to be associated with atmospheric particles. Surface nitrate can change the hygroscopicity of these particles, and thus impact their chemical reactivity. However, the influence of nitrate on heterogeneous reactions of atmospheric trace gases is poorly understood. In this work, the effects of nitrate on heterogeneous conversion of SO2 with hematite at 298 K are investigated using an in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and a White cell coupled with Fourier transform infrared spectroscopy (White cell-FTIR). It is found that nitrate participates in heterogeneous reactions of SO2, accelerates the formation rate of sulfate, and leads to the formation of surface-adsorbed HNO3 and gas-phase N2O and HONO. The results indicate that low to moderate amounts of nitrate significantly enhance the reactivity of hematite–nitrate mixtures, the uptake of SO2, and the formation of sulfate on hematite. For mixtures, the sample containing 24% nitrate exhibits the highest sulfate formation rate, and its corresponding uptake coefficient calculated by geometric surface area is about 5.5 times higher than that of hematite alone. The sample containing 48% nitrate presents the highest Brunauer–Emmett–Teller (BET) uptake coefficient, and the value is about 8 times higher than that of pure hematite. No uptake of SO2 and formation of sulfate are observed on pure nitrate. Evidence presented herein implies a significant contribution of the unreleased HNO3 and HONO in the particles for the conversion of SO2 and the enhanced formation of sulfate in the atmosphere. A possible mechanism for the influence of nitrate on the heterogeneous conversion of SO2 on hematite is proposed, and atmospheric implications based on these results are discussed.

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Section: Surface Sulfur-containing Speciesmentioning

confidence: 99%

The effects of nitrate on the heterogeneous uptake of sulfur dioxide on hematite

et al. 2014

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“…Summers 14demonstrated that in the presence of 02, SO2 can be readily adsorbed on Al203 and oxidized to S03 --presumably over the iron oxide impurities contained in Al203. Iron oxides are known to catalyze the oxidation of SO2 (15,16). The S02 adsorbed on the Al203 does not desorb at temperatures lower than 800°C( 17 ).…”

Section: Sorption Chemistry In Wet Gas Stream Bearing So2mentioning

confidence: 99%

Removal of Alkali Vapors by a Fixed Granular-Bed Sorber Using Activated Bauxite as a Sorbent

Lee

Henry

Myles

1985

Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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Studies have been conducted to develop a fixed granular-bed sorber for the removal of alkali vapors in a pressurized fluidized-bed combustion (PFBC) combined-cycle system. A laboratory-scale pressurized alkali-vapor sorption test unit was used to characterize activated bauxite, the most effective sorbent identified earlier, for its alkali vapor sorption capability in a gas stream with temperature (≤900°C), pressure (10 atm absolute), and composition closely simulating the actual PFBC flue gas. A scale-up of laboratory tests is being conducted in a 15.2-cm-dia (6-in.-dia) PFBC system to demonstrate the granular-bed sorber concept. The NaCl-vapor sorption chemistry of activated bauxite is described. The extent of alkali-vapor evolution from the activated bauxite bed itself is discussed, along with an evaluation of the significance of its alkali vapor contribution to a downstream gas turbine. Details of the design of a high-temperature/high-pressure alkali sorber system for the demonstration of the sorber are presented.

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“…This is due to the presAugust 1974 ence of other air contaminants which in general greatly facilitate the oxidation of sulfur dioxide. Two processes appear to be involved: oxidation by components derived from photochemical processes (7)(8)(9)(10)(11)(12)34) and catalytic oxidation predominantly by certain types of particulate aerosols (13)(14)(15)(16)(17)(18)(19)(20)(21) Table 4.…”

Section: Summary Of Key Problemsmentioning

confidence: 99%

Review of the Health Effects of Sulfur Oxides

Rall¹

1974

Environmental Health Perspectives

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The pollution in the air is a complex mixture of chemical substances of varying toxicity of which the sulfur oxides are a principal component. Those components which pose the primary hazards to human health have not yet been fully identified, nor have their respective contributions to human disease been fully determined. Efficient and effective control strategies are dependent upon the identification and understanding of these toxic components. Ultimately, the goal of standard-setting should be the development of composite pollution indices rather than control of individual pollutants.Concentrations of SO2' in the ambient air twice the current standards are associated with adverse health effects. A consider'able body of evidence suggests that there may be discernible human health effects from exposure to concentrations approximating the current standards. There is therefore no basis for'relaxation of the present standards for sulffr oxides at this time. Since the scientific basis for this judgment is incomplete, further scientific'information will, be required either to validate the present standards or to justify alteration of these standards. and experimental or laboratory studies, including matters of agreement or disagreement among the findings produced by the various study approaches; (3) the variable susceptibility to adverse effects' of sulfur oxides among different population groups; (4) a quantification of health effects in relation to various levels of exposure; and (5) the relationship between various levels of sulfur oxide exposure and costs in terms of impaired health, including the costs of care and loss of productivity among those who are or may be adversely affected by exposure to sulfur oxides. Review of Health Effects of Sulfur OxidesThis study has examined the existing scientific information and answered, insofar as is possible, these important questions. It is clear that additional information on the health effects of sulfur oxides is urgently needed. A program of research studies designed to develop such information is therefore included. Summary of Available InformationThe chemical form of sulfur oxides in the ambient air which is associated' in epidemiological studies with morbidity and mortality has not yet been clearly identified. The sulfur-containing products which have been implicated include SO2, sulfuric acid, and inorganic sulfates. SO, gas is generated primarily by the process of burning fossil fuels containing sulfur. SO remains in the ambient air for 1-7 days, during which time it can be converted to sulfates and sulfuric acid by sunlight, photochemical oxidants, or by the catalytic effect of certain particulates in the air. These processes are complex and not quantitatively understood. SO in the ambient air therefore provides a reservoir from which the more toxic sulfates and sulfuric acid derive. On a nationwide basis, the average ambient air concentrations of SO2 have been decreasing in the last few years because fossil fuels with a lower sulfur content have been used. The co...

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Capacity of ferric oxide particles to oxidize sulfur dioxide in air

Cited by 30 publications

References 5 publications

The effects of nitrate on the heterogeneous uptake of sulfur dioxide on hematite

The effects of nitrate on the heterogeneous uptake of sulfur dioxide on hematite

Removal of Alkali Vapors by a Fixed Granular-Bed Sorber Using Activated Bauxite as a Sorbent

Review of the Health Effects of Sulfur Oxides

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