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Sulfites used in food processing (but not as a preservative) are required to be listed if they are not incidental additives (21 CFR 101.100(a)(3)), and if there are more than 10 ppm in the finished product (21 CFR 101.100(a)(4)) On July 8, 1986, sodium bisulfite (and other sulfites : "The chemicals affected by the order are sulfur dioxide ...
The sulfite ion is the conjugate base of bisulfite. Although its acid (sulfurous acid) is elusive, [1] its salts are widely used. Sulfites are substances that naturally occur in some foods and the human body. They are also used as regulated food additives. [2] When in food or drink, sulfites are often lumped together with sulfur dioxide. [3]
Chemical processes quickly followed, first with Julius Roth's use of sulfurous acid to treat wood in 1857, followed by Benjamin Chew Tilghman's US patent on the use of calcium bisulfite, Ca(HSO 3) 2, to pulp wood in 1867. [3] Almost a decade later in 1874 the first commercial sulfite pulp mill was built in Sweden.
Sodium bisulfite (or sodium bisulphite, sodium hydrogen sulfite) is a chemical mixture with the approximate chemical formula NaHSO 3.Sodium bisulfite is not a real compound, [2] but a mixture of salts that dissolve in water to give solutions composed of sodium and bisulfite ions.
Chemical pulping involves dissolving lignin in order to extract the cellulose from the wood fiber. The different processes of chemical pulping include the Kraft process, which uses caustic soda and sodium sulfide and is the most common; alternatively, the use of sulfurous acid is known as the sulfite process, the neutral sulfite semichemical is treated as a third process separate from sulfite ...
Solutions of bisulfite are typically prepared by treatment of sulfur dioxide with aqueous base: [3] SO 2 + OH − → HSO − 3. HSO − 3 is the conjugate base of sulfurous acid, (H 2 SO 3). HSO − 3 is a weak acidic species with a pK a of 6.97. Its conjugate base is sulfite, SO 2− 3: HSO − 3 ⇌ SO 2− 3 + H +
Ultrafiltration can also be used to separate lignosulfonates from the spent pulping liquid. [1] A list of CAS numbers for the various metal salts of lignosulfonate is available. [4] The electrophilic carbocations produced during ether cleavage react with bisulfite ions (HSO 3 −) to give sulfonates. R-O-R' + H + → R + + R'OH R + + HSO 3 − ...
Its reducing properties are exploited in its use as a preservative to prevent dried fruit from discoloring, and for preserving meats. It is used as a reagent in sulfonation and sulfomethylation agent. It is used in the production of sodium thiosulfate. The Wellman–Lord process utilizes sodium sulfite for flue gas desulfurization.