Sulfate formation

Cerium oxide acts as a catalytic oxidizer in a spinel-based additive (38) that aids SO2 to SO conversion and promotes the required sulfate formation. Bastnasite itself is the most economical source of cerium and can be used directly at 1% as the capture additive (39). 

Figure 1 illustrates the complexity of the Cr(III) ion in aqueous solutions. The relative strength of anion displacement of H2O for a select group of species follows the order perchlorate < nitrate < chloride < sulfate < formate < acetate < glycolate < tartrate < citrate < oxalate (12). It is also possible for any anion of this series to displace the anion before it, ie, citrate can displace a coordinated tartrate or sulfate anion. These displacement reactions are kineticaHy slow, however, and several intermediate and combination species are possible before equiUbrium is obtained. 

Air or biological oxidation of pyrite leads to sulfate formation and dilute sulfuric acid in the mine drainage. This pollutes streams and the water supphes into which the mine water is drained. Means of controlling this problem are under study. 

NOTE Hydrochloric acid is usually employed as a regenerant to avoid risks of calcium sulfate formation when using sulfuric acid. (lfH2S04 is used, it must not exceed 0.8% w/w strength.) HCl can be used at 120% of theoretical to obtain the maximum capacity and quality, but at the expense of some mineral acidity during the early part of the run. Therefore it is prudent to operate at only 100% of theory, which provides minimal alkalinity leakage and loss of capacity. 

FIGURE 2.14 Phase 2 biotransformation—conjugation. (1) Glucuronide formation. (2) Sulfate formation. (3) Glutathione conjugation. 

The vanadium content of some fuels presents an interesting problem. When the vanadium leaves the burner it may condense on the surface of the heat exchanger in the power plant. As vanadia is a good catalyst for oxidizing SO2 this reaction may occur prior to the SCR reactor. This is clearly seen in Fig. 10.13, which shows SO2 conversion by wall deposits in a power plant that has used vanadium-containing Orimulsion as a fuel. The presence of potassium actually increases this premature oxidation of SO2. The problem arises when ammonia is added, since SO3 and NH3 react to form ammonium sulfate, which condenses and gives rise to deposits that block the monoliths. Note that ammonium sulfate formation also becomes a problem when ammonia slips through the SCR reactor and reacts downstream with SO3. 

Sulfated zirconia, 5 331-333 Sulfate esters, 23 653 Sulfate formation, on Claus catalysts, 23 610-614... 

Peck HD, Stulberg MP. 1962. studies on the mechanism of sulfate formation and phosphorylation in extracts of Thiobacillus thioparus. J Biol Chem 237 1648-52. 

Funk, C. et al. (2001) Troglitazone-induced intrahepatic cholestasis by an interference with the hepatobiliary export ofbile acids in male and female rats. Correlation with the gender difference in troglitazone sulfate formation and ihe inhibition of the canalicular bile salt export pump (Bsep) by troglitazone and troglitazone sulfate. Toxicology, 167 (1), 83-98. 

The banning of calcium chloride during the last decade provided the impetus for the development of alternative materials which accelerated the hydration of cement without the potential for corrosion. A number of inorganic and organic compounds including aluminates, sulfates, formates, thiosulfates, nitrates, silicates, alkali hydroxides, carbonates, nitrites and calcium salts have been evaluated. Commercialization and field experience, however, is limited to only a few of these materials. 

Novakov, T. "Role of Carbon Soot In Sulfate Formation", presented at the ACS/CSJ Chemical Congress, Honolulu,... 

Studying the oxidation of S(IV) by 02 in pure water without traces of catalysts or inhibitors has proven extremely difficult. Based on a compilation of many studies, Radojevic (1984) has recommended that the uncatalyzed rate of oxidation (in terms of the rate of sulfate formation) is given by... 

Seigneur, C., and P. Saxena, A Theoretical Investigation of Sulfate Formation in Clouds, Atmos. Environ., 22, 101-115 (1988). 

Tanner, R. L., and D. E. Schorran, Measurements of Gaseous Peroxides near the Grand Canyon—Implication for Summertime Visibility Impairment from Aqueous-Phase Secondary Sulfate Formation, Atmos. Environ., 29, 1113-1122 (1995). 

The significance of this oxidation of S(IV) in sea salt particles is that if it occurs in existing aerosol particles, sulfate formation will not result in new particles and hence potentially new CCN, but rather contribute to the mass of existing particles (e.g., O Dowd et al., 1997b). A significant fraction of all particulate nss is believed to be generated by this oxidation in existing sea salt particles. 

Measurement of Biodegradation. Numerous studies have documented the aerobic biodegradability of various AS compounds (see ref. 12). Most of these studies used methylene blue active substance (MBAS) and other colorimetric determinations, change in surface tension, foaming capacity, and sulfate formation as an indication of primary AS degradation. 

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