Chlorine dioxide handling

The aqueous solution is safe to handle, the dissolution being essentially physical. On standing in sunlight the solution slowly decomposes to a mixture of acids. In alkaline solution a mixture of chlorate(lll), CIO2, and chlorate(V), CIO J, ions is rapidly produced. Chlorine dioxide is paramagnetic, the molecule containing an odd electron and having a structure very like that of NOj (p. 231). 

Sodium hypochlorite could also be dangerous when hot, and alkaline chlorites also in this case however it is not guaranteed that the acid character of this example is sufficient to form chlorine dioxide. Caution is still required when handling these mixtures to which chlorates and perchlorates can be added. 

Chlorites do not explode on impact if the metal surfaces are carefull y cleaned and org matter is not present the film of oxide normally occurringona hammer is sometimes sufficient to cause d eton. In other respects chlorites should be handled with the same precautions reqd for hypochlorites or chlorates(qv). A chlorite soln should be removed from any surface at once by thorough washing and should not be allowed to dry on a fabric as this combination is very flammable. Also strong acids should not come in contact with chlorites as the chlorine dioxide(qv) evolved is very expl. In addn, strong chlorite solns react violently with sulfur so that a rubber stopper should not be used in a bottle contg chlorite solns(Ref 7)... 

There have been incidents involving chlorine dioxide generation from time to time these have mostly centered around improper storage or handling of sodium chlorite. 

Over a dozen oxides of the halogens have boon characterized, many of them quite unstable. Perhaps the most important are chlorine dioxide, CJ02, and iodine pentoxide, I2O5. Chlorine dioxide (boiling point 11° C) is an odd molecule (p. 62), but apparently it shows no tendency to dimerize. Although it has been used as an antiseptic in water purification and as a bleach, it must be handled in diluted form for it is explosive when alone. It is formed, along with HCIO4, when chlorates are treated with concentrated sulfuric acid, but a safer preparation involves reduction of a chlorate with oxalic acid. 

Chlorine dioxide is similarly explosive and reactive but can be handled at temperatures below -40°C and pressures below 50 mbar. At room temperature it... 

In the bleach plant the corrosion problems are somewhat different than in the digester area but they are no less severe. One of the most corrosive and unstable chemicals in the bleach plant is chlorine dioxide. The decomposition products of chlorine dioxide can be even more corrosive than chlorine dioxide itself. Acid brick is thus typically used in much of the equipment handling chlorine dioxide. 

Secondary disinfectants provide an essential residual that prevents regrowth in the distribution system. Although chlorine is the most widely used secondary disinfectant, chlorine dioxide and monochloramine are appropriate as well. As secondary disinfectants, chlorine and chlorine dioxide are handled in the same manner as for primary disinfectants. The use of monochloramine as a secondary disinfectant is discussed in detail in this section. 

Solid chlorine dioxide polyhydrate cem be handled safely at low temperatures, usually in the form of blocks encased in ice coatings (227), and it is frequently shipped cold and regenerated as a gas (228) for bleaching flour. Stable liquid mixtures of chlorine dioxide with chlorine at low temperatures are also reported (212). It has been alleged that pyridine and chlorine dioxide form a stable solid complex that can be used to furnish free chlorine dioxide on addition of water (216). Chlorine dioxide is reported (2) to form a complex of low volatility in solution with neutral or basic perborate, which supposedly can be again dissociated by acidification of the solution with release of chlorine dioxide. In fact, the stabilized solutions have all the properties of neutral or slightly basic solutions of chlorite ion, which disproportionate upon the addition of acid. 

Titanium is fully resistant to solutions of chlorites, hypochlorites, chlorates, perchlorates, and chlorine dioxide. Titanium equipment has been used to handle these chemicals in the pulp and paper industry for many years with no evidence of corrosion. Titanium is used today in nearly every piece of equipment handling wet chlorine or chlorine chemicals in a modern bleach plant, such as chlorine-dioxide mixers, piping, and washers. In the future it is expected that these applications will expand to include the use of titanium in equipment for ClOj generators and wastewater recovery. 

Although chlorine dioxide has replaced sodium hypochlorite use in kraft pulp bleaching, hypochlorite bleach is widely used as an ordinary household bleach because of its ease of manufacture, cost, and handling convenience. Sodium hypochlorite is produced mostly by reaction of liquid chlorine with 20 percent NaOH. Soda bleaches vary in their NaOCl content up to about 15 percent and the higher the NaOCl content is, the higher the required excess of caustic to maintain stability. For this reason, household bleach contains 5.5 percent NaOCl. In the trade it is common to speak of the available chlorine level of soda bleach as the trade percent. This is related to the NaOCl concentration, expressed in grams per liter, as ... 

National Joint Health and Safety Committee for Water Service, Safety Aspects of Storage, Handling and Use of Chlorine and Sulfur Dioxide, London. April 1982. 

Chlorine trifluoride dioxide resembles chlorine fluorides and oxy-fluorides in its corrosive and oxjidizing properties. It must be handled in systems consisting of corrosion-resistant metals, Teflon, or sapphire. It appears to be marginally stabli in a well-passivated system at ambient temperature, It is a strong oxidative fluorinator as evidenced by its... 

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