Hazard
Explodes when heated or by reaction with
organic materials. Very irritating to skin and mucous
membranes. Lower respiratory tract irritant. Broncitis.
Potential Exposure
Chlorine dioxide is used in bleaching
cellulose pulp; bleaching flour; water purification; as a liquid sterilizer in an ultrasonic cleaner.
First aid
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately.
If this chemical has been inhaled, remove from exposure,
begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if
heart action has stopped. Transfer promptly to a medical
facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce
vomiting. Do not make an unconscious person vomit.
Medical observation is recommended for 24 to 48 hours
after breathing overexposure, as pulmonary edema may be
delayed. As first aid for pulmonary edema, a doctor or
authorized paramedic may consider administering a drug or
other inhalation therapy.
Shipping
UN/NA 9191 Chlorine dioxide, hydrate, frozen,
Hazard class: 5.1; Labels: 5.1-Oxidizer, 6.1-Poison
Inhalation. Explosive: It may only be shipped in the frozen
state and then only by private or contract motor carrier.
Incompatibilities
Unstable in light. A powerful oxidizer.
Chlorine dioxide gas is explosive at concentrations over
10% and can be ignited by almost any form of energy,
including sunlight, heat (explosions can occur in air in
temperature above 130C), or sparks, shock, friction, or
concussion. This chemical reacts violently with dust, combustible materials; and reducing agents. Reacts violently
with mercury, phosphorus, sulfur, and many compounds,
causing fire and explosion hazard. Contact with water
forms perchloric and hydrochloric acid. Corrosive to
metals.
Chemical Properties
Chlorine dioxide is a flammable, reddishyellow gas, or reddish-brown liquid (below 11C/52F)
with an irritating odor like chlorine or nitric acid.
Chemical Properties
Chlorine dioxide,CI02, is a yellow-reddish gas.It is a very effective bleaching and water treatment agent. Chlorine dioxide is preparedby the reaction of chlorine and sodium chlorite. It is quite unstable and is commonly prepared immediately before use.
Waste Disposal
Use large volume of concentrated solution of ferrous salt or bisulfite solution as reducing agent. Then neutralize and flush to sewer with
abundant water.
Physical properties
Yellow to red-yellow gas at room temperature; pungent chlorine-like odor; density 9.99 g/L at 11°C; liquefies to a reddish brown liquid at 11°C; liquid density 1.64 g/mL at 0°C; freezes at -59.5° C to red crystals (explodes); soluble in water, decomposes in hot water; soluble in alkalis and H2SO4.
Definition
An orange gas formed by the action
of concentrated sulfuric acid on potassium
chlorate. It is a powerful oxidizing
agent and its explosive properties in the presence of a reducing agent were used to
make one of the first matches. It is widely
used in the purification of water and as a
bleach in the flour and wood-pulp industry.
On an industrial scale an aqueous solution
of chlorine dioxide is made by
passing nitrogen dioxide up a tower
packed with a fused mixture of aluminum
oxide and clay, down which a solution of
sodium chlorate flows.
Definition
chlorine dioxide: A yellowish-redexplosive gas, ClO2; d. 3.09 g dm–3;m.p. –59.5°C; b.p. 9.9°C. It is solublein cold water but decomposed by hotwater to give chloric(VII) acid, chlorine,and oxygen. Because of its highreactivity, chlorine dioxide is bestprepared by the reaction of sodiumchlorate and moist oxalic acid at90°–100°C, as the product is then dilutedby liberated carbon dioxide.Commercially the gas is produced bythe reaction of sulphuric acid containingchloride ions with sulphurdioxide. Chlorine dioxide is widelyused as a bleach in flour milling andin wood pulping and also finds applicationin water purification.
Preparation
Chlorine dioxide is prepared by passing nitrogen dioxide through sodium chlorate packed in a column:
NaClO3 + NO2 → NaNO3 + ClO2
Also, it may be prepared by the reaction of chlorine with sodium chlorite:
2NaClO2 + Cl2 → 2ClO2 + 2NaCl
Alternatively, it may be obtained by the treatment of sodium chlorate or potassium chlorate with sulfur dioxide and sulfuric acid:
2NaClO3 + SO2 + H2SO4 → 2ClO2 + 2 NaHSO4.
Production Methods
Chlorine dioxide is manufactured from the oxidation of
chlorite or the reduction of chlorate. The latter method is
used for large-volume production and is carried out in
strongly acidic solution using reducing agents such as
NaCl, HCl, sulfur dioxide, and methanol.
Health Hazard
Chlorine dioxide is highly irritating to theeyes, nose, and throat. Inhalation can causecoughing, wheezing, respiratory distress, andcongestion in the lungs. Its toxicity inhumans is moderate to high. Its irritanteffects in humans can be intense at a con centration level of 5 ppm in air. A concen tration of 19 ppm of the gas inside a bleachtank caused the death of one worker (Elkins 1959). The chronic toxicity signs are mainlydyspnea and asthmatic bronchitis, and in cer tain cases irritation of the gastrointestinaltract. Ingestion of the liquid may cause som nolence and respiratory stimulation.
Fire Hazard
Nonflammable gas; however, it is highly
reactive and a strong oxidizing agent. Chlo rine dioxide explodes violently upon heating,
exposure to sunlight, contact with dust, or
when subjected to a spark. Detonation occurs
at concentrations above 10% in air in the
presence of an energy source or catalyst.
It undergoes violent reactions with organic
matter; explosion occurs when the mixture is
subjected to shock or a spark. It reacts spon taneously with sulfur or phosphorus, caus ing ignition and/or explosion. Liquid chlorine
dioxide may explode violently when mixed
with mercury, caustic potash, caustic soda, or
many metal hydrides. The gas reacts explo sively with fluorine and with difluoroamine
(Lawless and Smith 1968).
Flammability and Explosibility
Notclassified
storage
Color Code—Red Stripe: Flammability Hazard:Store separately from all other flammable materials. Prior toworking with chlorine dioxide you should be trained on itsproper handling and storage. This chemical is a powerful oxidizer, and is shock-, light- and heat-sensitive. It is violentlyexplosive in air at concentrations over 10%. Keep frozenwhen not in use. Store in tightly closed containers in a cool,dark, well-ventilated area at temperatures well below 130℃.Gas explosions may occur above 130℃. Use only nonsparking tools and equipment, especially when opening and closingcontainers of this chemical. Sources of ignition, such assmoking and open flames, are prohibited where this chemicalis used, handled, or stored in a manner that could create apotential fire or explosion hazard. Use explosion-proof electrical equipment and fittings in storage area. See OSHAStandard 1910.104 and NFPA 43A Code for the Storage ofLiquid and Solid Oxidizers for detailed handling and storageregulations.
