SO3 Concentrations Research Articles

Barrier properties of surface sulfonated HDPE films

AbstractFilms of high‐density polyethylene (HDPE) have been sulfonated by solid–gas phase reaction using gaseous sulfur trioxide (SO3) of different concentrations in nitrogen. The effect of concentration of SO3 in an SO3 + N2 gas mixture and time of sulfonation on solvent and gas barrier properties of sulfonated HDPE films was studied by determining toluene and oxygen permeability of HDPE films sulfonated with different concentrations of SO3 for different times. The color developed in sulfonated HDPE films during sulfonation could be bleached by aqueous sodium hypochloride solution. The effect of sodium hypochloride solution treatment on oxygen permeability of sulfonated HDPE films was also studied. © 1995 John Wiley & Sons, Inc.

Cause and Remediation of Hydrogen Sulfide Emissions from a Sodium‐Based Flue Gas Desulfurization Sludge Disposal Pond

AbstractA flue gas desulfurization (FGD) sludge disposal pond with a history of H2S emissions to the atmosphere was studied to determine the cause of emissions and remediation strategies. The pond receives sludge and associated waters from a single‐pass Na2CO3 flue gas scrubber unit. The pond water is a sodic alkaline brine with large SO3 and S2O3 concentrations (>5000 mg L−1), and hence, an elevated chemical O2 demand. The pond water H2S concentrations are small as a result of periodic H2O2 additions. The sediments, however, have as much as 3500 mg L−1 H2S in the pore water. The production of H2S appeared to originate from the sediments and diffuses through the anoxic water column with little oxidation. Large concentrations of the reduced sulfur species SO3 and S2O3 were present as a result of the flue gas desulfurization process and incomplete oxidation of H2S. The pond was reconstructed to circulate the water through an air injection system that was designed to oxidize the SO3 and S2O3 to SO4, and thereby reduce the chemical O2 demand. After the installation of the air injection system, emissions of H2S ceased and the concentrations of SO3 and S2O3 were reduced by at least a factor of 10 within 3 to 4 wk. The production of H2S in the sediments, however, did not appear to be affected, nor did it appear that it will be reduced in the future by the air injection system.

Opacity Reduction Using Dry Hydrated Lime Injection

Abstract This investigation studied the effects of injecting dry hydrated lime into flue gas to reduce sulfur trioxide, (SO3) concentrations and consequently stack opacity at the University of Missouri-Columbia power plant. The opacity was due to sulf uric acid mist forming at the stack from high SO3 concentrations. As a result of light scattering by the mist, a visible plume leaves the stack. Therefore, reducing high concentrations of SO3 reduces the sulfuric acid mist and consequently the opacity. To reduce SO3 concentrations, dry hydrated lime is periodically injected into the flue gas upstream of a baghouse and downstream of an induced draft fan. The hydrated lime is transported downstream by the flue gas and deposited on the filter bags in the baghouse forming a filter cake. The reaction between the SO3 and the hydrated lime takes place on the filter bags. The hydrated lime injection system has resulted in at least 95% reduction in the SO3 concentration and has reduced the opacity to acceptable limit...

Heterogeneous sulfur conversion in sea-salt aerosol particles: the role of aerosol water content and size distribution

Meteorological and chemical conditions during the July 1988 Bermuda-area sampling appear to have been favorable for conversion of sulfur gases to particulate excess sulfate (XSO4). Observed average XSO4 and SO4 concentrations of 11 and 2.1 nmol m−3, respectively, at 15 m a.s.l. in the marine boundary layer (MBL) upwind of Bermuda, indicate that conversion of SO2 to XSO4, over and above homogeneous conversion, may be necessary to explain the > 5.0 average molar ratio of XSO4 to SO2. Given an observed cloud cover of <15% over the region and the <3 nmol m−3 SO3 concentrations observed by aircraft, heterogeneous conversion mechanisms, in addition to cloud conversion of SO2, are necessary to explain the observed 11 nmol XSO4 m−3. Aerosol water content, estimated as a function of particle size distribution plus consideration of SO2 mass transfer for the observed particle size distribution, shows that SO2 was rapidly transferred to the sea-salt aerosol particles. Assuming that aqueous-phase SO2 reaction kinetics within the high pH sea-salt aerosol water are controlled by O3 oxidation, and considering mass-transfer limitations, SO2 conversion to XSO4 in the sea-salt aerosol water occurred at rates of approximately 5% h−1 under the low SO2 concentration, Bermuda-area sampling conditions. All of the 2 nmol XSO4 m−3 associated with sea-salt aerosol particles during low-wind-speed, Bermuda-area sampling can be explained by this conversion mechanism. Higher wind speed, greater aerosol water content and higher SO2 concentration conditions over the North Atlantic are estimated to generate more than 4 nmol XSO4 m−3 by heterogeneous conversion of SO2 in sea-salt aerosol particles.

O2-dependent methionine auxotrophy in Cu,Zn superoxide dismutase-deficient mutants of Saccharomyces cerevisiae

Mutant strains of the yeast Saccharomyces cerevisiae which lack functional Cu,Zn superoxide dismutase (SOD-1) do not grow aerobically unless supplemented with methionine. The molecular basis of this O2-dependent auxotrophy in one of the mutants, Dscd1-1C, has been investigated. Sulfate supported anaerobic but not aerobic mutant growth. On the other hand, cysteine and homocysteine supported aerobic growth while serine, O-acetylserine, and homoserine did not, indicating that the interconversion of cysteine and methionine (and homocysteine) was not impaired. Thiosulfate (S2O3(2-] and sulfide (S2-) also supported aerobic growth; the activities of thiosulfate reductase and sulfhydrylase in the aerobic mutant strain were at wild-type levels. Although the levels of SO4(2-) and adenosine-5'-sulfate (the first intermediate in the SO4(2-) assimilation pathway) were elevated in the aerobically incubated mutant strain, this condition could be attributed to a decrease in protein synthesis caused by the de facto sulfur starvation and not to a block in the pathway. Therefore, the activation of SO4(2-) (to form 3'-phosphoadenosine-5'-phosphosulfate) appeared to be O2 tolerant. Sulfite reductase activity and substrate concentrations [( NADPH] and [SO3(2-)]) were not significantly different in aerobically grown mutant cultures and anaerobic cultures, indicating that SOD-1- mutant strains could reductively assimilate sulfur oxides. However, the mutant strain exhibited an O2-dependent sensitivity to SO3(2-) concentrations of less than 50 microM not exhibited by any SOD-1+ strain or by SOD-1- strains supplemented with a cytosolic O2(-)-scavenging activity. This result suggests that the aerobic reductive assimilation of SO4(2-) at the level of SO3(2-) may generate a cytotoxic compound(s) which persists in SOD-(1-) yeast strains.

Sulfur trioxide in the lower atmosphere of Venus?

Inconsistencies and ambiguities are noted by the present consideration of Pioneer Venus and Venera atmospheric composition measurement of Venus in the context of lower atmosphere thermodynamic equilibrium. Among the scenarios projected on the basis of assumed correctness for selected data subsets, the O2 and SO2 concentrations reported by the Pioneer Venus chromatograph and the H2O concentrations reported by Venera 11 suggest that large concentrations of SO3 are present in the lower atmosphere of Venus. Such SO3 concentrations lead, however, to difficulties in explaining the atmosphere at and above the cloud tops, and in addition require specific assumptions concerning chemical reaction rates at and near the surface.

Mechanism of oxidation-sulfation reactions of coo in the presence of na2so4

Sulfation studies were conducted on CoO samples coated with a thin film of Na2SO4 and exposed at 600 to 900 °C in O2-SO2-SO3 environments containing 0.02 to 2 pct (SO2+SO3). Within this range of conditions, Co3O4 (s), CoSO4 (s), and liquid Na2SO4-CoSO4 solutions were observed as reaction products. At lower concentrations of SO3 where CoSO4 (s) was unstable, the reaction product consisted of a thick Co3O4 layer close to the CoO, a layer of Na2SO4-CoSO4 liquid, and large Co3O4 particles at the gas/salt interface. At higher concentrations of SO3, the reaction procuct was a two phase mixture of solid CoSO4 and an Na2SO4-CoSO4 liquid. In gas mixtures containing 0.15 pct and 1 pct (SO2+SO3), the highest reaction rates were observed at about 750 to 800 °C. Some of these results are quite similar to those observed during low temperature hot corrosion of cobalt-base alloys. The overall reaction mechanism has been described in terms of two processes: oxidation of CoO to Co3O4 and sulfation of cobalt oxides.

Sulphur dioxide atmospheric oxidation in the presence of ammonia

Concentrations of SO3 and NH3 were measured daily for 3 yr. Monthly average concentrations obtained from daily data showed two seasonal cycles: in winter high SO2 and low NH3 concentrations; in summer low SO2 and high NH3 concentrations.

Alkali Iron Trisulfate Formation Within Deposits in an Oil-Fired Laboratory Combustor

Alkali iron trisulfates have been recognized as a major contributor to corrosion of super-heater lubes of boiler furnaces. Factors effecting formation of trisulfate were studied in an oil-fired laboratory combustor that simulates a boiler-furnace environment. Catalysis of SO2 to SO3 by fly ash to produce the high SO3 concentrations necessary for stability of trisulfates at superheater temperatures was investigated. Effects of deposit composition, deposit thickness, temperature, and SO3 concentration on formation of trisulfates were examined.

THE REACTION OF METHANESULFONIC ACID WITH SULFUR TRIOXIDE

The reaction of sulfur trioxide with methanesulfonic acid has been studied by examination of the nuclear magnetic resonance (n.m.r.) and Raman spectra of solutions containing up to 0.8 stoichiometric mole fraction of SO3.At relatively low SO3 concentrations the polysulfonic acid CH3S2O6H is formed initially and reacts with excess methane sulfonic acid to give methanesulfonic anhydride.[Formula: see text]CH3S2O6H and CH3SO3H exchange protons and SO3 rapidly and a single methyl resonance peak only is observed for these species in the n.m.r. spectrum. A separate methyl resonance is observed for (CH3)2S2O5 at relatively low concentrations of SO3, but at higher concentrations the peak merges with that due to CH3SO3H and CH3S2O6H because of the rapid equilibration of (CH3)2S2O5 with H2S2O7.[Formula: see text]At higher concentrations of SO3 it is likely that the system contains polymers of the three series CH3Sn+1O3n+3H, (CH3)2Sn+2O3n+5, and H2Sn+1O3n+4 in rapid equilibrium. Free SO3 is not found in the system at concentrations less than 60 mole %.

Infrared Spectra of the Vapors above Sulfuric and Deuteriosulfuric Acids1,2

Abstract : The infrared absorption spectra in the range 4000 to 400/cm of the vapors above liquid H2SO4, 1:1 H2-SO4 D2SO4, and D2SO4 were measured and assigned to the respective gaseous molecules as well as equilibrium concentrations of SO3. SO2 was observed as a decomposition product. Assignment of the frequencies to the normal modes was made using correlations with the related near-tetrahedral molecules X-SO2-Y and with spectra of the condensed phases. Some frequencies are predicted for H2CrO4 and for unassociated gaseous chlorosulfonic acid. (Author)

Aqueous systems at high temperature—IX: Investigations on the system Li 2SO 4H 2SO 4H 2O and its D 2O analogue, 200–470°C: Solubilities and critical phenomena

The solubilities of Li 2SO 4 in H 2SO 4H 2O and in D 2SO 4D 2O solutions in equilibrium with vapour were determined at temperatures between 200 and 350°C, and at concentrations of free acid from 0 to 1·5 molal. Solubilities in H 2O media at 200° varied from 2·75 m in H 2O to 2·83 m in 0·85 m H 2SO 4, and at 350° from 0118 m in H 2O to 2·38 m in 1·46 m H 2SO 4. Corresponding solubilities in D 2O media were from 10 to 40 percent lower. The solubilities of stoicheiometric Li 2SO 4 in H 2O were in good agreement with those published recently by Elenevskaya and Ravich. Temperatures of critical phenomena (where liquid  vapour) varying between 374° and 470° were determined visually for solutions of Li 2SO 4, D 2SO 4, and D 2O at concentrations of SO 3 from 0·02 to 2·5 molal and at molal ratios, MLi20: MS03, varying from 0 to approximately 0·5. At higher molal ratios than about 0·5 and at concentrations of SO3 of approximately 0·05 m and above, Li 2SO 4 crystallized from the liquid phases. The formation of DSO4- ions can be responsible both for the high solubility of lithium in the supercritical fluid and, except at low SO3 molalities, the limit of the critical curves to a maximum molal ratio near 0·5.