Sodium Chlorite Chlorine Dioxide Health & Safety

Basic Chemicals

Introduction

Chlorine dioxide (ClO2) is an effective Chlorine Dioxide Exposure Limits disinfectant and an oxidant that is widely used in water treatment. At ambient temperatures, 8 Hour Time-Weighted Average (TWA) chlorine dioxide is a reactive gas that is ACGIH – TLV 0.1 ppm potentially explosively unstable at OSHA – PEL 0.1 ppm concentrations above 10% by volume in air. It is normally generated on site and used as a dilute Short-term Exposure Limits (STEL) aqueous solution. ACGIH - STEL (15 min) 0.3 ppm

Chlorine Dioxide Gas Immediately Dangerous to life or health Chlorine dioxide is a yellow to reddish-yellow IDLH 5 ppm gas with a pungent, sharp odor similar to that of chlorine and ozone It has an odor threshold Direct eye contact may cause severe irritation concentration of 0.1-0.3 ppm, and will become and possibly burns. Symptoms may include irritating at concentrations above 0.5 ppm. The tearing, redness and in severe cases, eye density of chlorine dioxide gas is about 2.4 times damage due to burns. that of air, allowing it to collect in low-lying areas. All users should read the appropriate Chemical Health Hazards Fact Sheet or Material Safety Data Sheet Chlorine dioxide is a severe respiratory and eye (MSDS) before handling chlorine dioxide in any irritant in humans. It is harmful if swallowed or form. inhaled. Reactivity Inhalation may cause irritation of the mucous Chlorine dioxide gas is normally stable at membranes and respiratory tract. Symptoms concentrations up to 10% (v/v) in air, but contact may include coughing, wheezing, and severe with oxidizable materials can cause breathing difficulties which may be delayed in decomposition at lower concentrations. onset. Pulmonary edema is common following severe exposure. Chlorine dioxide gas is explosive at concentrations above 10% (v/v) in air and can be ignited by almost any form of energy such as sunlight, heat or sparks. The reaction is as follows:

ClO2 → ½Cl2 + O2 600-114 Sodium Chlorite 08/2018

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Basic Chemicals

At concentrations between 10% and 14% the The stability of chlorine dioxide solutions is also reaction is categorized as a low order explosion, dependent on the pH of the solution and the because the flame propagation is only 1 presence of UV light. Chlorine dioxide is meter/second. This decomposition is often decomposed by UV light. Decomposition is a referred to as a “puff” (figure 2). At function of time and intensity of the UV light concentrations of chlorine dioxide in air above source. 14% (v/v) there is the potential for sustained - - + decomposition and a violent reaction. 10ClO2 + 5H2O + h → 6ClO3 + 4Cl + 10H + 3.5O2 Chlorine Dioxide Dilute Solutions Chlorine dioxide gas does not react with water. Normally chlorine dioxide solutions are Chlorine dioxide is soluble in water but remains generated and used immediately. However, as a dissolved gas, which can be removed from acidified aqueous solutions of chlorine dioxide dilute aqueous solutions by aeration or by heat. (below pH 7) retain their strength for several Its solubility is a function of both temperature months when stored in a cool, well-ventilated and pressure following a linear relationship. See place away from heat, extreme cold, ignition Figure 1. sources, light and or direct sunlight. Chlorine dioxide will decompose in basic solutions (pH >8) hydrolyzing to form chlorate and chlorite ions.

- - - 2ClO2 + 2OH → ClO3 + ClO2 + H2O

Chlorine dioxide may be safely handled in dilute aqueous solutions providing:

600-114 Sodium Chlorite 08/2018

Basic Chemicals

 The solution is maintained at a rubber and coatings. Store chlorine dioxide concentration and temperature that the ONLY in containers that are approved for partial pressure of the gas is always below chlorine dioxide use. 50 mmHg. This equates to 6-7% (v/v) of  DO NOT allow chlorine dioxide gas to come chlorine dioxide gas in the vapor phase into contact with dust and other combustible (Figure 1). materials such as organic matter and sulfur  The maximum solution concentration at as this may cause fires and explosions. 25ºC (77ºF) is below 3.0 g/L (0.3% by  Chlorine dioxide gas is incompatible with weight, 3000 ppm). mercury, carbon monoxide, hydrocarbons, fluoramines, and potassium hydroxide, Chlorine dioxide solutions should be applied to phosphorous and sulfur. the processing system at a point, and in a  DO NOT allow chlorine dioxide gas to build manner, which permits adequate mixing and up in any enclosed space. Ventilation is uniform distribution. The feed point should be required for all handling operations. well below the water level to prevent  DO NOT breathe chlorine dioxide vapors. volatilization of the chlorine dioxide. Toxic gases and vapors (such as chlorine gas) may be released when chlorine dioxide For specific information regarding the suitability decomposes. or dosage requirements for your application  DO NOT enter confined spaces such as consult the sodium chlorite product label or tanks or pits without following proper entry contact your OxyChem representative. procedures. Entry into these spaces must be in accordance with 29CFR§1910.146. Storage and Handling Precautions Before entering tanks or opening pipelines Water should always be readily accessible that have contained chlorine dioxide whenever chlorine dioxide is used. Safety solutions, they should be drained or pumped showers and eye wash stations should be close out and thoroughly flushed with water. by and clearly marked. Portable or temporary Contact with the liquid draining from the systems are available and may be used where equipment should be avoided. permanent installations are not available. Every  Avoid breathing vapors. After handling, precaution should be taken to ensure that a always wash hands thoroughly with soap suitable system is in place and operational and water. before generating chlorine dioxide. Only trained personnel should be allowed to enter areas Good housekeeping practices are important where chlorine dioxide is generated. where chlorine dioxide is used. All spills should be contained and immediately recovered or The following precautions should be followed flushed with water into a chemical sewer or when handling chlorine dioxide solutions: segregated holding tank or pond, which is provided for the specific purpose of  DO NOT store chlorine dioxide solutions at neutralization. Chlorine dioxide solutions must temperatures above 100 oF (38 oC). NEVER be flushed to a sanitary sewer or other  DO NOT expose chlorine dioxide solutions outlet, which connects to waterways or to ultra-violet light, as this will reduce uncontrolled runoff streams. Contact local and product strength. federal authorities for applicable regulations.  Chlorine dioxide gas and concentrated solutions will attack some forms of plastic, 600-114 Sodium Chlorite 08/2018

Basic Chemicals

Personal Protective Equiupment  Call a poison control center or doctor for Personnel working with chlorine dioxide should treatment advice if burning or irritation of the always wear the proper protective equipment. skin persists. OxyChem recommends that employees be provided with, and required to use personal If swallowed: protective equipment and clothing necessary to  Have person drink a glass of water prevent any possibility of skin or eye contact immediately if able to swallow. with chlorine dioxide. Remember the use of  Call a poison control center or doctor personnel protective equipment is not a immediately for treatment advice. substitute for safe handling practices.  Do not induce vomiting unless told to do so by the poison control center or doctor. Avoid breathing vapors. After handling, always  Do not give anything by mouth to an wash hands thoroughly with soap and water. unconscious person.

Where vapor concentration of chlorine dioxide If inhaled: exceeds or is likely to exceed 0.1 ppm, a NIOSH  Move person to fresh air and monitor for approved full-face acid gas respirator is respiratory distress. acceptable. A NIOSH approved self-contained  If cough or difficulty in breathing develops, breathing apparatus, with full- face piece, is consult a physician immediately. required for vapor concentrations above 5 ppm  If person is not breathing, call 911 or an and for leaks and/or emergencies. Follow any ambulance, then give artificial respiration. applicable respirator use standards and  Call a poison control center or doctor for regulations. further treatment advice.

First Aid Notes to Physician: If chlorine dioxide vapors Due to the toxic characteristics of chlorine are inhaled, monitor patient closely for delayed dioxide if someone receives accidental exposure development of pulmonary edema, which may it is extremely important to seek first aid occur up to 48-72 hours post-inhalation. immediately Following ingestion, neutralization and use of activated charcoal is not indicated. If in eyes:  Hold eye open and rinse slowly and gently Further Information with water for 15-20 minutes. More detailed information on sodium chlorite is  Remove contact lenses, if present, after the available on request through the OxyChem first 5 minutes, then continue rinsing eye. Technical Service Department. Call or write:  Call a poison control center or doctor immediately for treatment advice. Technical Service Department OxyChem If on skin or clothing: Post Office Box 12283  Take of contaminated clothing. Wichita, Kansas 67277-2283  Rinse skin immediately with plenty of water 800-733-1165 option #1 for 15-20 minutes. www.oxy.com

600-114 Sodium Chlorite 08/2018