Sulfur dioxide grades available

Sulfur dioxide is available in technical and food grades for use in both commercial and industrial applications. 

Another area where improved air quaUty has impacted on sulfur use is ia agriculture. As sulfur dioxide emissions have decreased, sulfur content of soils has also decreased. Sulfur, recognized as the fourth most important plant nutrient, is necessary for the most efficient use of other nutrients and optimum plant growth. Because many soils are becoming sulfur-deficient, a demand for sulfur-containing fertilizers has been created. Farmers must therefore apply a nutrient that previously was freely available through atmospheric deposition and low grade fertilizers. 

Commercially available hydrogen fluoride usually is not suitable for catalytic hydrogenation because of its sulfur dioxide content An oxidative treatment with manganese dioxide and distillation are needed for the preparation of hydrogena tion-grade hydrogen fluoride [d, 4]... 

Information regarding the physical and chemical properties of benzene is shown in Table 3-2. The major impurities found in commercial products are toluene, xylene, phenol, thiophene, carbon disulfide, acetylnitrile and pyridine (NIOSH 1974). Commercial refined benzene-535 is free of hydrogen sulfide and sulfur dioxide, but contains a maximum of 1 ppm thiophene and a maximum of 0.15% nonaromatics. Refined nitration-grade benzene is free of hydrogen sulfide and sulfur dioxide. Benzene is also commercially available as thiophene-free, 99 mole%, 99.94 mole% and nanograde quality (HSDB 1996). 

Anhydrous hydrogen fluoride is available from a number of suppliers with grades ranging from 99.0 to 99.96 percent. The major impurities are water (H2O) and sulfur dioxide (SO2). A normal specification for 99.90 mole percent hydrogen fluoride is as follows ... 

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