Chlorine sulfite

Beardmore et al (30) and Tiburzy (31) showed that epidermal (31) and mesophyll (30,31) cells of resistant wheat plants, penetrated by haus-toria of an avirulent race of the fungus, can be stained with phlorogluci-nol/HCl (31) and chlorine/sulfite (30,31). These cells show yellow autofluorescence under UV-light (30,31), the emission spectrum is identical to that of lignified tracheary elements (31). 

Chlorine sulfite can be used to detect syringyl lignin. The specimen is placed above a tissue soaked in a sodium hypochlorite ( bleach ) solution for 30 minutes. A 3% (w/v) solution of sodium sulfite (Na2S03) is applied to the specimen for 5-10 minutes. Lignin will stain orange to red. 

Removal of brine contaminants accounts for a significant portion of overall chlor—alkali production cost, especially for the membrane process. Moreover, part or all of the depleted brine from mercury and membrane cells must first be dechlorinated to recover the dissolved chlorine and to prevent corrosion during further processing. In a typical membrane plant, HCl is added to Hberate chlorine, then a vacuum is appHed to recover it. A reducing agent such as sodium sulfite is added to remove the final traces because chlorine would adversely react with the ion-exchange resins used later in the process. Dechlorinated brine is then resaturated with soHd salt for further use. 

Uses. The dominant use of sulfur dioxide is as a captive intermediate for production of sulfuric acid. There is also substantial captive production in the pulp and paper industry for sulfite pulping, and it is used as an intermediate for on-site production of bleaches, eg, chlorine dioxide or sodium hydrosulfite (see Bleaching agents). There is a substantial merchant market for sulfur dioxide in the paper and pulp industry. Sulfur dioxide is used for the production of chlorine dioxide at the paper (qv) mill site by reduction of sodium chlorate in sulfuric acid solution and also for production of sodium dithionite by the reaction of sodium borohydride with sulfur dioxide (315). This last appHcation was growing rapidly in North America as of the late 1990s. 

Water Treatment. Sodium sulfite is an agent in the reduction of chlorine or oxygen in water. Dissolved oxygen in boiler water tends to enhance pitting and other types of corrosion. In boilers operated at below 4.82 MPa (700 psi), a residual concentration of 30 ppm of sodium sulfite is generally effective. Catalytic amounts of cobalt are often added to accelerate the reaction of oxygen with sulfite (321,322) (see Water, industrial water treatment). 

In removing excess free chlorine from municipal or industrial water and from wastewater, sodium sulfite competes with bisulfite or sulfur dioxide. Other commercial appHcations of sodium sulfite in wastewater treatment include the reduction of hexavalent chromium to the less toxic Cr " salts as well as the precipitation of silver and mercury. 

Miscellaneous. In ore flotation, sodium sulfite functions as a selective depressant. In textile processing, sodium sulfite is used as a bleach for wood (qv) and polyamide fibers and as an antichlor after the use of chlorine bleach. Synthetic appHcations of sodium sulfite include production of sodium thiosulfite by addition of sulfur and the introduction of sulfonate groups into dyestuffs and other organic products. Sodium sulfite is useful as a scavenger for formaldehyde in aminoplast—wood compositions, and as a buffer in chrome tanning of leather. 

This method is also used with alcohols of the stmcture Cl(CH2) OH (114). HaloaLkyl chlorosulfates are likewise obtained from the reaction of halogenated alkanes with sulfur trioxide or from the chlorination of cycHc sulfites (115,116). Chlorosilanes form chlorosulfate esters when treated with sulfur trioxide or chlorosulfuric acid (117). Another approach to halosulfates is based on the addition of chlorosulfuric or fluorosulfuric acid to alkenes in nonpolar solvents (118). 

Porous carbon and graphite are used ia filtration of hydrogen fluoride streams, caustic solutions, and molten sodium cyanide ia diffusion of chlorine iato molten aluminum to produce aluminum chloride and ia aeration of waste sulfite Hquors from pulp and paper manufacture and sewage streams. 

Tetrachloroethane [79-34-5] acetylene tetrachloride, CHCI2CHCI2, is a heavy, nonflammable Hquid with a sweetish odor. It is miscible with the chlorinated solvents and shows high solvency for a number of natural organic materials. It is also a solvent for sulfur and a number of inorganic compounds, eg, sodium sulfite. 

NOTE Sulfite, bisulfite, and metabisulfite are commonly used as a reducing agent for chromate in industrial water and chlorine in potable water. 

The compound, prepared by by co-condensation of diethyl sulfite (3.5 mmol) and chlorine fluoride (10 mmol) at —196°C, followed by slow warming to —78, then —20°, is unstable. Trap-to-trap distillation must be effected with great care, as violent explosions occurred (even on this small scale) when cryogenic cooling was removed from the traps. Scaling up is not recommended. 

The EPA passed its "Cluster Rule that requires kraft and soda pulp mills to utilize elemental chlorine-free (ECF) bleaching and all sulfite mills to use ECF or totally chlorine-free (TCF) bleaching. 

Ocular Effects. Workers employed at a sulfite-cellulose production facility reported ocular discomfort that was associated with periods when equipment failure resulted in relatively high air concentrations of chlorine dioxide (Gloemme and Lundgren 1957). However, this finding was confounded by concurrent exposure to chlorine gas and sulfur dioxide. 

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