Chlorine from bleach

In one variation, S02 is sparged into a stainless steel absorber through which a solution of Na2C03 is passed. Formation of product crystals from the saturated solution is achieved by lowering the temperature. The crystals are centrifuged off and dried rapidly in a flash dryer in order to avoid air oxidation to sulfate. The markets for sodium metabisulfite include chemical intermediates, pharmaceuticals, food preservatives, and dye fixing. Additionally, sodium metabisulfite is used in photography, as an antichlor to remove excess chlorine from bleached kraft pulps, and for the manufacture of sodium hydrosulfite. 

Best type of filter in gas-mask canister (16) Gaseous chlorine bleach liquor Breathe low concentrations of chlorine from bleaching-pow-dcr bottle Candle destroyer smoke attack burning-type air bombs 1 green band DAI gas... 

Chlorine retention n. A characteristic of several resins and textile finishes whereby they retain some of the chlorine from bleach. On heating of the goods, the chlorine forms hydrochloric acid, causing tendering of the cloth. This is especially true of certain wrinkle resistant finishes for cotton and rayon. 

The reducing action of sulphurous acid and sulphites in solution leads to their use as mild bleaching agents (for example magenta and some natural dyes, such as indigo, and the yellow dye in wool and straw are bleached). They are also used as a preservative for fruit and other foodstuffs for this reason. Other uses are to remove chlorine from fabrics after bleaching and in photography. 

Miscellaneous. Both whiting and hydrated lime are used as diluents and carriers of pesticides, such as lime—sulfur sprays, Bordeaux, calcium arsenate, etc. The most widely used bleach and sterilizer, high test calcium hypochlorite, is made by interacting lime and chlorine (see Bleaching AGENTS). Calcium and magnesium salts, such as dicalcium phosphate, magnesium chloride, lithium salts, etc, are made directly from calcific and dolomitic lime and limestone. 

In solutions, the concentration of available chlorine in the form of hypochlorite or hypochlorous acid is called free-available chlorine. The available chlorine in the form of undissociated A/-chloro compounds is called combined-available chlorine. Several analytical methods can be used to distinguish between free- and combined-available chlorine (8). Bleaches that do not form hypochlorite in solution like chlorine dioxide and nonchlorine bleaches can be characterized by thek equivalent available chlorine content. This can be calculated from equation 5 by substituting the number of electrons accepted divided by two for the number of active chlorine atoms. It can also be measured by iodomettic titration. 

Sodium thiosulfate is a common analytical reagent used in iodometric titration to analyze chlorine, bromine, and sulfide. Other uses are in bleaching paper pulp, bleaching straw, ivory, and bones, for removing chlorine from solutions, silver extraction from its ores, a mordant in dyeing and printing textiles, and as an antidote to cyanide poisoning. 

Benzoquinone-l,4 di(chloro-iniine) [called Benzo-chinon-(1.4)-bis-chlorimid or p-Chinon-bis-chlor-imid in Ger], C1N CBH4 NC1 mw 175.02, N 16.01% ndls(from w) having a si aromatic odor, mp 124 -6°(dec) expl when heated rapidly above the mp readily sol in hot ale, hot AcOH, eth or benz si sol in hot w almost insol in cold w was first prepd by Krause(Ref 2) by treating an ice-cold soln of p-phenylenediamine in dil HC1 with, an excess of chlorinated lime(bleaching powder). 

---