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    SodiumHypochlorite – Commercial Grade

    Product Specification

    NaOCl

    Formula Weight

     
    Properties
    Molecular formula NaOCl
    Molar mass NaOCl
    Appearance white solid
    Density 1.07-1.14 g/cm³ liquid
    Melting point

    18°C Pentahydrate

    Structure
    Molecular shape  
    Dipole moment  
    Hazards
    Main hazards Irritant(-5%) or Corrosive(+10%), Oxidizing
    NFPA 704  
    Risks Contact with acids liberates toxic gas, Causes burns, Very toxic to aquatic organisms.
    Safety Keep locked up and out of the reach of children, After contact with skin, wash immediately, In case of accident or if you feel unwell seek medical advice immediately, Do not mix with ... (to be specified by the manufacturer), Avoid release to the environment.
    Flash point  
    Autoignition
    temperature
     
    Related compounds
    Other anions  
    Other cautions  
    Related  
    Related compounds  

    Description

     

    Sodium hypochlorite is a chemical compound with the formula NaClO. Sodium hypochlorite solution, commonly known as bleach, is frequently used as a disinfectant and as a bleaching agent.

     

    Uses

    Bleaching
    In household bleach form, sodium hypochlorite is used for removal of stains from laundry. It is particularly effective on cotton fiber, which stains easily but bleaches well. 50 to 250 ml per load is usually recommended for a standard-size washer. The properties of household bleach that make it effective for removing stains also result in cumulative damage to organic fibers such as cotton, and the useful lifespan of these materials will be shortened with regular bleaching. The sodium hydroxide (NaOH) that is also found in household bleach (as noted later) causes fiber degradation as well. It is not volatile, and residual amounts of NaOH not rinsed out will continue slowly degrading organic fibers in the presence of humidity. For these reasons, if stains are localized, spot treatments should be considered whenever possible. With safety precautions, post-treatment with weak organic acids such as acetic (vinegar) will neutralize the NaOH, and volatilize the chlorine from residual hypochlorite. Old t-shirts and cotton sheets that rip easily demonstrate the costs of laundering with household bleach. Hot water increases the activity of the bleach, owing to the thermal decomposition of hypochlorite which ultimately generates environmentally-undesirable chlorate.

    Disinfection
    A weak solution of 1% household bleach in warm water is used to sanitize smooth surfaces prior to brewing of beer or wine. Surfaces must be rinsed to avoid imparting flavors to the brew; these chlorinated byproducts of sanitizing surfaces are also harmful.

    US Government regulations (21 CFR Part 178) allow food processing equipment and food contact surfaces to be sanitized with solutions containing bleach provided the solution is allowed to drain adequately before contact with food, and the solutions do not exceed 200 parts per million (ppm) available chlorine (for example, one tablespoon of typical household bleach containing 5.25% sodium hypochlorite, per gallon of water). If higher concentrations are used, the surface must be rinsed with potable water after sanitizing.

    A 1 in 5 dilution of household bleach with water (1 part bleach to 4 parts water) is effective against many bacteria and some viruses, and is often the disinfectant of choice in cleaning surfaces in hospitals (Primarily in the United States). The solution is corrosive, and needs to be thoroughly removed afterwards, so the bleach disinfection is sometimes followed by an ethanol disinfection.

    Water treatment
    For shock chlorination of wells or water systems, a 2% solution of household bleach is used. For larger systems, HTH is more practical because lower rates can be used. The alkalinity of the sodium hypochlorite solution also causes the precipitation of minerals such as calcium carbonate, so that the shock chlorination is often accompanied by a clogging effect. The precipitate also preserves bacteria, making this practice somewhat less effective.

    Sodium hypochlorite has been used for the disinfection of drinking water. A concentration equivalent to about 1 liter of household bleach per 4000 liters of water is used. The exact amount required depends on the water chemistry, temperature, contact time, and presence or absence of sediment. In large-scale applications, residual chlorine is measured to titrate the proper dosing rate. For emergency disinfection, the United States Environmental Protection Agency recommends the use of 2 drops of 5%ac household bleach per quart of water. If the treated water doesn't smell of bleach, 2 more drops are to be added.

    The use of chlorine-based disinfectants in domestic water, although widespread, has led to some controversy due to the formation of small quantities of harmful byproducts such as chloroform.

    Endodontics
    Sodium hypochlorite is now used in endodontics during root canal treatments. It is the medicament of choice due to its efficacy against pathogenic organisms and pulp digestion. Historically, Henry Drysdale Dakin's solution (0.5%) had been used. Its concentration for use in endodontics today varies from 0.5% to 5.25%. At low concentrations it will dissolve mainly necrotic tissue; whereas at higher concentrations tissue dissolution is better but it also dissolves vital tissue, a generally undesirable effect. It has been shown clinical effectiveness does not increase conclusively for concentrations higher than 1% .

    Wastewater treatment
    An alkaline solution (pH 11.0) of sodium hypochlorite is used to treat dilute (< 1 g/L) cyanide wastewater, e.g. rinse water from an electroplating shop. In batch treatment operations, sodium hypochlorite has been used to treat more concentrated cyanide wastes, such as silver cyanide plating solutions. A well-mixed solution is fully treated when an excess of chlorine is detected.

    Sodium hypochlorite in the form of household bleach is often used to oxidize foul-smelling thiol wastes generated in a chemistry laboratory.

    Oxidation
    Household bleach, with a phase-transfer catalyst, has been reported to oxidize alcohols to the corresponding carbonyl compound.

     

    SAFETY

      Sodium hypochlorite is a strong oxidizer. Products of the oxidation reactions are corrosive. Solutions burn skin and cause eye damage, particularly when used in concentrated forms. However, as recognized by the NFPA, only solutions containing more than 40% sodium hypochlorite by weight are considered hazardous oxidizers. Solutions less than 40% are classified as a moderate oxidizing hazard.

    Household bleach and pool chlorinator solutions are typically stabilized by a significant concentration of lye (caustic soda, NaOH) as part of the manufacturing reaction. Skin contact will produce caustic irritation or burns due to defatting and saponification of skin oils and destruction of tissue. The slippery feel of bleach on skin is due to this process.

    Sodium thiosulfate (hypo) is an effective chlorine neutralizer. Rinsing with a 5mg/L solution, followed by washing with soap and water, quickly removes chlorine odor from the hands.

    Chlorination of drinking water can oxidize organic contaminants, producing trihalomethanes (also called haloforms), which are carcinogenic. The extent of the hazard thus created is a subject of disagreement.

    Mixing bleach with some household cleaners can be hazardous. For example, mixing an acid cleaner with sodium hypochlorite bleach generates chlorine gas. Mixing with ammonia solutions (including urine) produces chloramines. Both chlorine gas and chloramine gas are toxic. Bleach can react violently with hydrogen peroxide and produce oxygen gas:
    It is estimated that there are about 3300 accidents needing hospital treatment caused by sodium hypochlorite solutions each year in British homes.

    A number of commonly used household cleaning products (bleaches, mildew stain removers, toilet cleaners, cleaning sprays, gels, and scouring powders) contain sodium hypochlorite that is often accompanied by many other chemicals (e.g., surfactants and fragrances). Mixing bleach with ammonia-based cleaners results in formation of chloramines while mixing it with an acid-based cleaner will cause chlorine gas release. Therefore, the main concern associated with the use of chlorine-bleach-containing cleaning-products has been mixing them with other cleaning products that can generate hazardous fumes.

    A recent study [5] indicated for the first time that sodium hypochlorite and organic chemicals (e.g., surfactants, fragrances) contained in several household cleaning products react to generate chlorinated volatile organic compounds (VOCs). These chlorinated compounds are emitted during cleaning applications and most of them are toxic and probable human carcinogens.The study showed that indoor air concentrations significantly increase (8-52 times for chloroform and 1-1170 times for carbon tetrachloride) during the use of bleach containing products. The increase in chlorinated volatile organic compound concentrations was the lowest for plain bleach and the highest for the products in the form of “thick liquid and gel”. The significant increases observed in indoor air concentrations of several chlorinated VOCs (especially carbon tetrachloride and chloroform) indicate that the household bleach use is a newly identified source that could be important in terms of inhalation exposure to these compounds [6]. Preliminary risk assessment suggested that using these cleaning products may significantly increase the cancer risk. Further studies are also needed for a detailed investigation of the health risks associated with the use of these products and other possible exposure routes (i.e., dermal). However, these are not the only adverse environmental effects of the released VOCs, they are also ozone depleting compounds and powerful greenhouse gases.

     

    International Chemical Safety Card

     

     

       
     

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