Concentration of sulfur compounds

We know rather well the concentration of oxidized sulfur compounds (S02 and SOJ ) over industralized North America and Europe as well as over the Atlantic Ocean. However, our knowledge of the concentration of reduced sulfur is much poorer because of analytical problems. 

In the atmosphere of the Northern equatorial Atlantic Ocean the concentration of hydrogen sullide has been recently studied by Slatt et al. (1978) using a sensitive fluorescence technique. They report concentrations ranging from 5 x 10 3 to 5 x 10-2 ppb(0.0C76-0.C76/igm 3 STP)which are much lower than the mean level of 0.2 ppbm used by Friend (1973). Slatt and her co-workers also state, on the basis of their results, that the residence time of H2S in the atmosphere cannot be more than a few hours. On the other hand, they estimate that the oceanic production rate of this substance given by Friend is probably correct. 

Unfortunately, very little information is available concerning the concentrations of other reduced sulfur species in the atmosphere. According to Maroulis and Bandy (1977) the DMS level is around 0.005 ppb on the Atlantic Coast, and generally below 0.03 ppb in Virginia (both in U.S.A.). The preliminary results of Sandalls and Penkett (1977) show that in Harwell, England, the mean carbonyl sulfide (COS) level is 0.51 ppb, while the concentration of carbon disulfide (CS2) is found on average to be 0.19 ppb. Much work has to be done, however, before generally accepted values of mean atmospheric levels are obtained. 

The results of surface air concentration measurements of gaseous S02 and particulate SO have recently been reviewed by E. Meszaros (1978). The 

Concentration of sulfur dioxide and sulfates as a function of the latitude over the Atlantic Ocean according to information available (E. Meszaros, 1978). (By courtesy of Atmospheric Environment) 

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A duplex heat exchanger tube containing a single small perforation was examined. Perforation occurred due to internal surface wastage beneath a deposit layer containing large concentrations of sulfur compounds (Fig. 4.28). 

The presence (and concentration, if known) of corrosive materials, other than the typical concentrations of sulfur compounds in petroleum hydrocarbon streams. 

Thiophene and methylthiophenes have been found in virgin petroleum. 3,4,5-Trimethyl-2-methylthiothiophene has been isolated from a concentrate of sulfur compounds obtained in the refining of Middle East kerosene. ... 

Figure 14.4 Schematic diagram of the cliromatographic system used for the analysis of very low concentrations of sulfur compounds in ethene and propene CP, pressure regulator CF, flow regulator SL, sanrple loop R, restriction to replace column 2 VI, injection valve V2, tliree-way valve to direct the effluent of column 1 to either column 2 or the restriction column 1, non-polar- capillary column column 2, tliick-film capillary column SCD, sulfur chemiluminescence detector FID, flanre-ionization detector.

Increasing Vanadium and ADA Content. Raising the concentration of vanadium in the Stretford solution can increase the rate of elemental sulfur formation in the absorber/reactor, and thus lower the concentration of sulfur compounds that are converted to thiosulfate in the oxidizer (Moyes 1974 and Nicklin 1977). It may also be necessary to increase the ADA concentration as well, in order to convert the additional tetravalent vanadium that will be formed back into its pentavalent state. 

Even before the first small facility was placed into operation, the field operators funded an environmental survey to determine baseline concentrations of hydrogen sulfide, sulfur dioxide, and particulates in the air. As might be expected in a rural area, no measurable concentrations of sulfur compounds were observed. The baseline survey also included soil, water, and vegetation sampling throughout the field to determine the before condition of the local environment. A 1-year biological study of the Escambia River and adjacent uplands near the field was also conducted by the U. of West Florida. 

A first-order plot of logi0 [Hydroperoxide] vs. time (Figure 1) was linear, at least until the amount of hydroperoxide decomposed approached a value equal to the initial concentration of sulfur compound. After this point the rate of decomposition increased. Confirmation that the reaction was first order with respect to hydroperoxide was obtained by measuring the initial slopes of the rates of decomposition of varying amounts of... 

Unfortunately as Kellogg et al., Robinson and Robbins, Junge, and Eriksson have all pointed out, most of the atmospheric measurements have been made in polluted areas of the United States and Europe, so not much is known about normal background concentrations of sulfur compounds and their global distribution. Therefore the atmospheric cycle is somewhat speculative, as are also estimates of individual sinks, sources, and concentrations. 

These reactions may be important for several reasons. It may be possible to use the chemiluminescent reaction of ozone with organic sulfides to monitor the low concentrations of sulfur compounds in urban atmospheres. Also, excited species are being formed, and these reactive intermediates may be important in high altitude atmospheric reactions. Finally, identifying these emitting species should give information about the mechanisms of gas phase ozone reactions. Current progress on these reactions by the authors is reviewed here. 

Kummer et al. 8) have reported that at pressures of about 0.5 torr, the relative emission intensities of the higher olefins and of the organic sulfides were substantially greater than that of ethylene Table II summarizes the reported relative emission intensities. Since a recently developed commercial ozone monitor is based on the chemiluminescent reaction between ozone and ethylene, this suggests the possibility of using the sulfide-ozone chemiluminescent reaction to monitor the low concentration of sulfur compounds in ambient air. This possibility is being further investigated now. 

Polysulfanes with the general formula H2S (n — 2-S) are reactive oils in their pure state. Heating aqueous sulfide solutions yields polysulfide ions most typically with n = 3 or 4. The presence of sulfanes has been used to explain the high concentrations of sulfur compounds in some hydrothermal fluids (Migdisov and Bychkov, 1998). 

Because of the small concentration of sulfur compounds in canola oil, there is a somewhat greater tendency of sulfur poisoning of the catalyst, with the result that slightly higher trans-isomer concentrations may come about compared with, for example, soybean oil. Hatfield (91) has focused on this aspect of canola oil hydrogenation. 

Meszaros, E., 1978 Concentration of sulfur compounds in remote continental and oceanic areas. Atmospheric Environment 12, 699-705. 

The Beavon sulfur removal process for the cleanup of Claus plant tail gas is a two-step process in which the sulfur contaminants are first catalytically hydrolyzed and/or hydrogenated to hydrogen sulfide and the hydrogen sulfide is then converted to elemental sulfur and recovered in a Stretford process unit. Commercial plants reduce the concentration of sulfur compounds as hydrogen sulfide in the tail gas from 1-3 vol % to less than 100 ppm. The treated gas contains less than 1 ppm hydrogen sulfide. The chemistry, design criteria, operating experience, and economics of the process are discussed. 

A number of intra- and intervarietal comparisons of cheese volatiles have been published. An early example is that of Manning and Moore (1979) who analyzed head-space volatiles of nine fairly closely related varieties considerable intervarietal differences were evident but the four samples of Cheddar also differed markedly. The intensity of cheese flavor was reported to be related to the concentration of sulfur compounds (peaks 1 and 2) 2-pentanone was also considered to be important for Cheddar cheese flavor. 

The first recognized type of air pollution was that typified by high concentrations of sulfur compounds (SOj and sulfates) and particles, resulting from combustion of coal and high-sulfur-containing fuels. Cities with this characteristic type of air pollution are often in cold climates where electric power generation and domestic heating are major sources of emissions. 

This section has been included because it is a good example of the use of selective detectors in petroleum analysis, where the need often arises to analyze for small amounts of heterocompounds in a complex hydrocarbon matrix. Another good example is the use of the flame photometric detector for the determination of small concentrations of sulfur compounds in various plant streams. The analysis of oxygenated compounds can, however, be carried out in a totally different manner using column switching instead of the selective detector. 

Mass Concentration of Sulfur Compounds as Sulfur—After identifying the sulflir compounds of interest by retention time, measure the area of each sulfur peak. 

Mass Concentration of Stdjur Compounds as Compound—In 9.1 the concentration of sulfur compounds is reported on a sulfur basis. In some instances the concentration of sulfur compounds as compound is of interest. This conversion is made according to 5 ... 

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