Chlorine dioxide sodium chlorite

More than 80% of all the sodium chlorite produced is used for the generation of chlorine dioxide. Sodium chlorite or the chlorine dioxide generated from it or from sodium chlorate must be registered with the USEPA for each specific appHcation use as a biocide for microbial growth control or disinfection. These regulations are covered under the Eederal Insecticide, Eungicide, and Rodenticide Act (EIERA). 

Chemical name Chlorine dioxide Sodium chlorite... 

Chlorine Gas—Sodium Chlorite System. In this method, chlorine gas reacts direcdy with a concentrated sodium chlorite solution under a vacuum and chlorine dioxide gas is removed from the reaction chamber using a water-based eductor (117). The reaction has a 100% theoretical molar conversion of chlorite ... 

Electrochemical Generation of Chlorine Dioxide from Chlorite. The electrochemical oxidation of sodium chlorite is an old, but not weU-known method of generating chlorine dioxide. Concentrated aqueous sodium chlorite, with or without added conductive salts, is oxidized at the anode of an electrolytic cell having a porous diaphragm-type separator between the anode and cathode compartments (122—127). The anodic reaction is... 

Sodium chlorite has also been used for treatment and removal of toxic and odorous gases such as hydrogen sulfide and mercaptans. Chlorine dioxide from chlorite is also useful for microbial and slime control in paper mills and alkaline paper machine systems (164,165). The use of sodium chlorite in textile bleaching and stripping is well known. Cotton is not degraded by sodium chlorite because the oxidation reactions are specific for the hemiceUulose and lignin components of the fibers. 

The Olin Corporation has developed an electrochemical chlorine dioxide generator technology that safely and conveniently produces aqueous chlorine free solutions of chlorine dioxide at chlorite molar conversion efficiencies of 95% or better [221-224]. The chlorine dioxide is produced by direct oxidation of sodium chlorite, Fig. 21. The electrochemical C102 generator system is shown in Fig. 22. 

The database for health effects related to dermal exposure to chlorine dioxide or chlorite is extremely limited. No reports were located regarding adverse effects in humans following dermal exposure to chlorine dioxide or chlorite. Available information in animals is restricted to a report that a solution containing chlorine dioxide concentrations of approximately 9.7-11.4 mg/L was nonirritating to the skin of mice in a 48-hour test. Dermal exposure to high concentrations would be expected to result in irritation, due to the oxidizing properties of chlorine dioxide and chlorite. Sodium chlorite was not carcinogenic in mice treated dermally for 51 weeks. Nor did sodium chlorite appear to be a cancer promoter in mice... 

Sodium chlorite (NaC102) is manufactured from chlorine dioxide, sodium hydroxide, and calcium hydroxide. 

More economical than the above mentioned method are processes in which the chlorine dioxide is absorbed in a solution of sodium hydroxide in the presence of a suitable mild reducing agent, which reduces chlorine dioxide to chlorite only. This reaction proceeds according to the equation ... 

Another method for generating chlorine dioxide involves the acidification of sodium chlorite with hydrochloric acid to from chlorine dioxide, sodium chloride, and water ... 

Yonkos, L. T. Fisher, D. J. Burton, D. T. Whitekettle, W. K. Petrille, J. C. Effectiveness of the Sulfur(IV) Compound, Sodium Bisulfite, in Reducing Chlorine, Chlorine Dioxide, and Chlorite Toxicity to Daphnia Magna in Well Water and Pond Water, Environ. Toxicol. Chem. 2001, 20, 530-536. 

Chlorine Dioxide. Chlorine peroxide. C102 mol wt 67.46. Cl 52,56%, O 47.44%. Prepn from chlorine and sodium chlorite Derby, Hutchinson, Inorg, Syn. 4, 152... 

Gaseous chlorine dioxide, CIO2, is used to bleach flour and in water treatment. It is produced by the reaction of chlorine with sodium chlorite Clj + 2 NaC102 2 CIO2 + 2 NaCl. How many liters of ClOj, measured at 0.961 atm and 31°C, will be produced by 283 L CI2 at 2.92 atm and 21 °C ... 

It is important to follow equipment manufacturer s instructions to generate chlorine dioxide efficiently. Adjustments to chlorine and sodium chlorite feed may be necessary to optimize production and minimize forming unwanted by-products (chlorate, chlorite, or excess chlorine). The high-yield production of chlorine dioxide depends on the relationship of chlorine to sodium chlorite, pH, and other factors. Precise and accurate control of all variables is necessary to produce the highest-purity product and to minimize undesirable byproducts. 

The feed rate of chlorine and sodium chlorite is linked to the feed of chlorine dioxide because these are the primary chemicals used in most generation systems. The most common sources of chlorine are compressed gas and liquid sodium hypochlorite (12 percent trade is a common solution strength). Sodium chlorite is commonly used as a solid (about 65 percent sodium chlorite) and as a 25 percent strength solution. 

Amperometric titration (Standard Methods for the Examination of Water and Wastewater [Eaton and Franson 2005], method 4500) of the generator effluent is used to determine the concentration of the various products of the reaction of chlorine with sodium chlorite. This test method determines the concentration of chlorine dioxide, chlorite, chlorate, and excess chlorine. The ratio of chlorine dioxide to the total of all chemical species is the efficiency. 

Chlorine dioxide, CIO2, is another chlorine derivative. This unstable, potentially explosive gas must be generated at the point of appHcation. The most common method of generating CIO2 is through the reaction of chlorine gas with a solution of sodium chlorite. 

After World War I, other chlohne-based bleaches were developed. In 1921 the use of chlorine dioxide for bleaching fibers was reported followed by the development of the commercial process for large-scale production of sodium chlorite. In 1928 the first dry calcium hypochlorite containing 70% available chlorine was produced in the United States. This material largely replaced bleaching powder as a commercial bleaching agent. 

Hypochlorous acid can also be used, but the reaction is slower. Chlorine dioxide is also made by adding acid to sodium chlorite solutions by the overall reaction in equation 11 ... 

Some chlorine and chlorate also form through competing reactions. Chlorine dioxide is also evolved from mixtures of powdered sodium chlorite and acidic clays or alumina. 

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