차아염소산나트륨(락스)

[박대선]

Sodium hypochlorite

From Wikipedia, the free encyclopedia

Jump to navigationJump to search

Sodium cation

Hypochlorite anion

Names

IUPAC name

Sodium hypochlorite

Other names

• Antiformin
• Bleach
• Chloride of soda

In dilution:

• Carrel-Dakin solution
• Modified Dakin's solution
• Surgical chlorinated soda solution

Identifiers

CAS Number

• 7681-52-9 (anhydrous)^[1]
• 7681-52-8 (pentahydrate)^[1]

3D model (JSmol)

• Interactive image

ChEBI

• CHEBI:32146 

ChemSpider

• 22756 

ECHA InfoCard

100.028.790

EC Number

• 231-668-3

KEGG

• D01711 

PubChem CID

• 23665760

RTECS number

• NH3486300

UNII

• DY38VHM5OD 

UN number

1791

CompTox Dashboard (EPA)

• DTXSID8021276 

InChI[show]

SMILES[show]

Properties

Chemical formula

NaOCl

Molar mass

74.442 g/mol

Appearance

greenish-yellow solid (pentahydrate)

Odor

chlorine-like and sweetish

Density

1.11 g/cm³

Melting point

18 °C (64 °F; 291 K) pentahydrate

Boiling point

101 °C (214 °F; 374 K) (decomposes)

Solubility in water

29.3 g/100mL (0 °C)^[2]

Acidity (pK_a)

7.5185

Basicity (pK_b)

6.4815

Thermochemistry

Std enthalpy of
formation (Δ_fH^⦵₂₉₈)

-347.1 kJ/mol

Pharmacology

ATC code

D08AX07 (WHO)

Hazards

Safety data sheet

ICSC 1119 (solution, >10% active chlorine)
ICSC 0482 (solution, <10% active chlorine)

EU classification (DSD) (outdated)

Corrosive (C)
Dangerous for the environment (N)

R-phrases (outdated)

R31, R34, R50

S-phrases (outdated)

(S1/2), S28, S45, S50, S61

NFPA 704 (fire diamond)

0

2

1

OX

Related compounds

Other anions

Sodium chloride
Sodium chlorite
Sodium chlorate
Sodium perchlorate

Other cations

Lithium hypochlorite
Calcium hypochlorite
Potassium hypochlorite

Related compounds

Hypochlorous acid

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

 verify (what is  ?)

Infobox references

Sodium hypochlorite is a chemical compound with the formula NaOCl or NaClO, comprising a sodium cation (Na+
) and a hypochlorite anion (OCl−
or ClO−
). It may also be viewed as the sodium salt of hypochlorous acid. The anhydrous compound is unstable and may decompose explosively.^[3][4] It can be crystallized as a pentahydrate NaOCl·5H
2O, a pale greenish-yellow solid which is not explosive and is stable if kept refrigerated.^[5][6]

Sodium hypochlorite is most often encountered as a pale greenish-yellow dilute solution commonly known as liquid bleach or simply bleach, a household chemical widely used (since the 18th century) as a disinfectant or a bleaching agent. The compound in solution is unstable and easily decomposes, liberating chlorine, which is the active principle of such products. Indeed, sodium hypochlorite is the oldest and still most important chlorine-based bleach.^[7][8]

Its corrosive properties, common availability, and reaction products make it a significant safety risk. In particular, mixing liquid bleach with other cleaning products, such as acids or ammonia, may produce toxic fumes.^[9]

Contents

• 1Chemistry
  • 1.1Stability of the solid
  • 1.2Equilibria and stability of solutions
  • 1.3Decomposition to chlorate or oxygen
  • 1.4Titration
  • 1.5Oxidation of organic compounds
  • 1.6Oxidation of metals and complexes
  • 1.7Other reactions
  • 1.8Neutralization
• 2Production
  • 2.1Chlorination of soda
  • 2.2From calcium hypochlorite
  • 2.3Electrolysis of brine
  • 2.4From hypochlorous acid and soda
  • 2.5From ozone and salt
• 3Packaging and sale
• 4Uses
  • 4.1Bleaching
  • 4.2Cleaning
  • 4.3Disinfection
  • 4.4Deodorizing
  • 4.5Waste water treatment
  • 4.6Endodontics
  • 4.7Nerve agent neutralization
  • 4.8Reduction of skin damage
• 5Safety
  • 5.1Oxidation and corrosion
  • 5.2Storage hazards
  • 5.3Reactions with other common products
  • 5.4Limitations in health care
• 6Environmental impact
• 7See also
• 8References
• 9Bibliography
• 10External links

Chemistry[edit]

Stability of the solid[edit]

Anhydrous sodium hypochlorite can be prepared; however, like many hypochlorites, it is highly unstable and decomposes explosively on heating or friction.^[3] The decomposition is accelerated by carbon dioxide at atmospheric levels.^[4][9] It is a white solid with the orthorhombic crystal structure.^[1]

Sodium hypochlorite can also be obtained as a crystalline pentahydrate NaOCl·5H
2O, which is not explosive and is much more stable than the anhydrous compound.^[4][5] The formula is sometimes given as 2NaOCl·10H
2O.^{[citation needed]} The transparent light greenish yellow orthorombic^[10][11] crystals contain 44% NaOCl by weight and melt at 25–27 °C. The compound decomposes rapidly at room temperature, so it must be kept under refrigeration. At lower temperatures, however, it is quite stable: reportedly only 1% decomposition after 360 days at 7 °C.^[6][12]

A 1966 US patent claims that stable solid sodium hypochlorite dihydrate NaOCl·2H
2O can be obtained by carefully excluding chloride ions (Cl−
), which are present in the output of common manufacturing processes and are said to catalyze the decomposition of hypochlorite into chlorate (ClO−
3) and chloride. In one test, the dihydrate was claimed to show only 6% decomposition after 13.5 months storage at −25 °C. The patent also claims that the dihydrate can be reduced to the anhydrous form by vacuum drying at about 50 °C, yielding a solid that showed no decomposition after 64 hours at −25 °C.^[13]

Equilibria and stability of solutions[edit]

At typical ambient temperatures, sodium hypochlorite is more stable in dilute solutions that contain solvated Na+
 and OCl−
 ions. The density of the solution is 1.093 g/mL at 5% concentration,^[14] and 1.21 g/mL at 14%, 20 °C.^[15] Stoichometric solutions are fairly alkaline, with pH 11 or more^[6] since hypochlorous acid is a weak acid:

OCl−
 + H
2O ⇌ HOCl + OH−

The following species and equilibria are present in solutions of NaOCl:^[16]

HOCl (aq) ⇌ H+
 + OCl−

HOCl (aq) + Cl−
 + H+
 ⇌ Cl
2 (aq) + H
2O

Cl
2 (aq) + Cl−
 ⇌ Cl−
3

Cl
2 (aq) ⇌ Cl
2 (g)

The second equilibrium equation above will be shifted to the right if the chlorine Cl
2 is allowed to escape as gas. The ratios of Cl
2, HOCl, and OCl−
 in solution are also pH dependent. At pH below 2, the majority of the chlorine in the solution is in the form of dissolved elemental Cl
2. At pH greater than 7.4, the majority is in the form of hypochlorite ClO−
.^[7] The equilibrium can be shifted by adding acids (such as hydrochloric acid) or bases (such as sodium hydroxide) to the solution:

ClO−
 (aq) + 2 HCl (aq) → Cl
2 (g) + H
2O (aq) + Cl−
 (aq)

Cl
2 (g) + 2 OH−
 → ClO−
 (aq) + Cl−
 (aq) + H
2O (aq)

At a pH of about 4, such as obtained by the addition of strong acids like hydrochloric acid, the amount of undissociated (nonionized) HOCl is highest. The reaction can be written as:

ClO−
 + H+
 ⇌ HClO

Sodium hypochlorite solutions combined with acid evolve chlorine gas, particularly strongly at pH < 2, by the reactions:

HOCl (aq) + Cl−
 + H+
 ⇌ Cl
2 (aq) + H
2O

Cl
2 (aq) ⇌ Cl
2 (g)

At pH > 8, the chlorine is practically all in the form of hypochlorite anions (OCl−
). The solutions are fairly stable at pH 11–12. Even so, one report claims that a conventional 13.6% NaOCl reagent solution lost 17% of its strength after being stored for 360 days at 7 °C.^[6] For this reason, in some applications one may use more stable chlorine-releasing compounds, such as calcium hypochlorite Ca(ClO)
2 or trichloroisocyanuric acid (CNClO)
3.

Anhydrous sodium hypochlorite is soluble in methanol, and solutions are stable.^{[citation needed]}

Decomposition to chlorate or oxygen[edit]

In solution, under certain conditions, the hypochlorite anion may also disproportionate (autoxidize) to chloride and chlorate:^[17]

3 ClO−
 + H+
 → HClO
3 + 2 Cl−

In particular, this reaction occurs in sodium hypochlorite solutions at high temperatures, forming sodium chlorate and sodium chloride:^[17][18]

3 NaOCl (aq) → 2 NaCl (aq) + NaClO
3 (aq)

This reaction is exploited in the industrial production of sodium chlorate.

An alternative decomposition of hypochlorite produces oxygen instead:

2 OCl−
 → 2 Cl−
 + O
2

In hot sodium hypochlorite solutions, this reaction competes with chlorate formation, yielding sodium chloride and oxygen gas:^[17]

2 NaOCl (aq) → 2 NaCl (aq) + O
2 (g)

These two decomposition reactions of NaClO solutions are maximized at pH around 6. The chlorate-producing reaction predominates at pH above 6, while the oxygen one becomes significant below that. For example, at 80 °C, with NaOCl and NaCl concentrations of 80 mM, and pH 6–6.5, the chlorate is produced with ∼95% efficiency. The oxygen pathway predominates at pH 10.^[17] This decomposition is affected by light^[18] and metal ion catalysts such as copper, nickel, cobalt,^[17] and iridium.^[19] Catalysts like sodium dichromate Na
2Cr
2O
7 and sodium molybdate Na
2MoO
4 may be added industrially to reduce the oxygen pathway, but a report claims that only the latter is effective.^[17]

Titration[edit]

Titration of hypochlorite solutions is often done by adding a measured sample to an excess amount of acidified solution of potassium iodide (KI) and then titrating the liberated iodine (I
2) with a standard solution of sodium thiosulfate or phenyl arsine oxide, using starch as indicator, until the blue color disappears.^[11]

According to one US patent, the stability of sodium hypochlorite content of solids or solutions can be determined by monitoring the infrared absorption due to the O–Cl bond. The characteristic wavelength is given as 140.25 μm for water solutions, 140.05 for the solid dihydrate NaOCl·2H
2O, and 139.08 μm for the anhydrous mixed salt Na
2(OCl)(OH).^[13]

Oxidation of organic compounds[edit]

Oxidation of starch by sodium hypochlorite, that adds carbonyl and carboxyl groups, is relevant to the production of modified starch products.^[20]

In the presence of a phase-transfer catalyst, alcohols are oxidized to the corresponding carbonyl compound (aldehyde or ketone).^[21][6] Sodium hypochlorite can also oxidize organic sulfides to sulfoxides or sulfones, disulfides or thiols to sulfonyl chlorides or bromides, imines to oxaziridines.^[6] It can also de-aromatize phenols.^[6]

Oxidation of metals and complexes[edit]

Heterogeneous reactions of sodium hypochlorite and metals such as zinc proceed slowly to give the metal oxide or hydroxide:

NaOCl + Zn → ZnO + NaCl

Homogeneous reactions with metal coordination complexes proceed somewhat faster. This has been exploited in the Jacobsen epoxidation.

Other reactions[edit]

If not properly stored in airtight containers, sodium hypochlorite reacts with carbon dioxide to form sodium carbonate:

2 NaOCl + CO
2 + H
2O → Na
2CO
3 + 2 HOCl

Sodium hypochlorite reacts with most nitrogen compounds to form volatile monochloramine, dichloramines, and nitrogen trichloride:

NH
3 + NaOCl → NH
2Cl + NaOH

NH
2Cl + NaOCl → NHCl
2 + NaOH

NHCl
2 + NaOCl → NCl
3 + NaOH

Neutralization[edit]

Sodium thiosulfate is an effective chlorine neutralizer. Rinsing with a 5 mg/L solution, followed by washing with soap and water, will remove chlorine odor from the hands.^[22]

Production[edit]

Chlorination of soda[edit]

Potassium hypochlorite was first produced in 1789 by Claude Louis Berthollet in his laboratory on the Quai de Javel in Paris, France, by passing chlorine gas through a solution of potash lye. The resulting liquid, known as "Eau de Javel" ("Javel water"), was a weak solution of potassium hypochlorite. Antoine Labarraque replaced potash lye by the cheaper soda lye, thus obtaining sodium hypochlorite (Eau de Labarraque).^[23][24]

Cl₂ (g) + 2 NaOH (aq) → NaCl (aq) + NaClO (aq) + H₂O (aq)

Hence, chlorine is simultaneously reduced and oxidized; this process is known as disproportionation.

The process is also used to prepare the pentahydrate NaOCl·5H
2O for industrial and laboratory use. In a typical process, chlorine gas is added to a 45–48% NaOH solution. Some of the sodium chloride precipitates and is removed by filtration, and the pentahydrate is then obtained by cooling the filtrate to 12 °C .^[6]

From calcium hypochlorite[edit]

Another method involved by reaction of sodium carbonate ("washing soda") with chlorinated lime ("bleaching powder"), a mixture of calcium hypochlorite Ca(OCl)
2, calcium chloride CaCl
2, and calcium hydroxide Ca(OH)
2:

Na
2CO
3 (aq) + Ca(OCl)
2 (aq) → CaCO
3 (s) + 2 NaOCl (aq)

Na
2CO
3 (aq) + CaCl
2 (aq) → CaCO
3 (s) + 2 NaCl (aq)

Na
2CO
3 (aq) + Ca(OH)
2 (aq) → CaCO
3 (s) + 2 NaOH (aq)

This method was commonly used to produce hypochlorite solutions for use as a hospital antiseptic that was sold after World War I under the names "Eusol", an abbreviation for Edinburgh University Solution Of (chlorinated) Lime – a reference to the university's pathology department, where it was developed.^[25]

Electrolysis of brine[edit]

Near the end of the nineteenth century, E. S. Smith patented the chloralkali process: a method of producing sodium hypochlorite involving the electrolysis of brine to produce sodium hydroxide and chlorine gas, which then mixed to form sodium hypochlorite.^[26][24][27] The key reactions are:

2 Cl⁻ → Cl₂ + 2 e⁻ (at the anode)

2 H
2O + 2 e⁻ → H
2 + 2 HO−
 (at the cathode)

Both electric power and brine solution were in cheap supply at the time, and various enterprising marketers took advantage of the situation to satisfy the market's demand for sodium hypochlorite. Bottled solutions of sodium hypochlorite were sold under numerous trade names.

Today, an improved version of this method, known as the Hooker process (named after Hooker Chemicals, acquired by Occidental Petroleum), is the only large-scale industrial method of sodium hypochlorite production. In the process, sodium hypochlorite (NaClO) and sodium chloride (NaCl) are formed when chlorine is passed into cold dilute sodium hydroxide solution. The chlorine is prepared industrially by electrolysis with minimal separation between the anode and the cathode. The solution must be kept below 40 °C (by cooling coils) to prevent the undesired formation of sodium chlorate.

Commercial solutions always contain significant amounts of sodium chloride (common salt) as the main by-product, as seen in the equation above.

From hypochlorous acid and soda[edit]

A 1966 patent describes the production of solid stable dihydrate NaOCl·2H
2O by reacting a chloride-free solution of hypochlorous acid HClO (such as prepared from chlorine monoxide ClO and water), with a concentrated solution of sodium hydroxide. In a typical preparation, 255 mL of a solution with 118 g/L HClO is slowly added with stirring to a solution of 40 g of NaOH in water 0 °C. Some sodium chloride precipitates and is removed by fitration. The solution is vacuum evaporated at 40–50 °C and 1–2 mmHg until the dihydrate crystallizes out. The crystals are vacuum-dried to produce a free-flowing crystalline powder.^[13]

The same principle was used in another 1991 patent to produce concentrated slurries of the pentahydrate NaClO·5H
2O. Typically, a 35% solution (by weight) of HClO is combined with sodium hydroxide at about or below 25 °C. The resulting slurry contains about 35% NaClO, and are relatively stable due to the low concentration of chloride.^[28]

From ozone and salt[edit]

Sodium hypochlorite can be easily produced for research purposes by reacting ozone with salt.

NaCl + O₃ → NaClO + O₂

This reaction happens at room temperature and can be helpful for oxidizing alcohols.

Packaging and sale[edit]

Household bleach Eau de Javel with 2.6% sodium hypochlorite

Household bleach sold for use in laundering clothes is a 3–8% solution of sodium hypochlorite at the time of manufacture. Strength varies from one formulation to another and gradually decreases with long storage. Sodium hydroxide is usually added in small amounts to household bleach to slow down the decomposition of NaClO.^[7]

A 10–25% solution of sodium hypochlorite is, according to Univar's safety sheet, supplied with synonyms or trade names bleach, Hypo, Everchlor, Chloros, Hispec, Bridos, Bleacol, or Vo-redox 9110.^[29]

A 12% solution is widely used in waterworks for the chlorination of water, and a 15% solution is more commonly^[30] used for disinfection of waste water in treatment plants. Sodium hypochlorite can also be used for point-of-use disinfection of drinking water.^[31]

Dilute solutions (50 ppm to 1.5%) are found in disinfecting sprays and wipes used on hard surfaces.^[32][33]

Uses[edit]

Bleaching[edit]

Household bleach is, in general, a solution containing 3–8% sodium hypochlorite, by weight, and 0.01–0.05% sodium hydroxide; the sodium hydroxide is used to slow the decomposition of sodium hypochlorite into sodium chloride and sodium chlorate.^[34]

Cleaning[edit]

Sodium hypochlorite has destaining properties.^[35] Among other applications, it can be used to remove mold stains, dental stains caused by fluorosis,^[36] and stains on crockery, especially those caused by the tannins in tea. It has also been used in laundry detergents and as a surface cleaner.

Its bleaching, cleaning, deodorizing and caustic effects are due to oxidation and hydrolysis (saponification). Organic dirt exposed to hypochlorite becomes water-soluble and non-volatile, which reduces its odor and facilitates its removal.

Disinfection[edit]

See also: Hypochlorous acid

Sodium hypochlorite in solution exhibits broad spectrum anti-microbial activity and is widely used in healthcare facilities in a variety of settings.^[37] It is usually diluted in water depending on its intended use. "Strong chlorine solution" is a 0.5% solution of hypochlorite (containing approximately 5000 ppm free chlorine) used for disinfecting areas contaminated with body fluids, including large blood spills (the area is first cleaned with detergent before being disinfected).^[37][38] It may be made by diluting household bleach as appropriate (normally 1 part bleach to 9 parts water).^[39] Such solutions have been demonstrated to inactivate both C. difficile^[37] and HPV.^[40] "Weak chlorine solution" is a 0.05% solution of hypochlorite used for washing hands, but is normally prepared with calcium hypochlorite granules.^[38]

"Dakin's Solution" is a disinfectant solution containing low concentration of sodium hypochlorite and some boric acid or sodium bicarbonate to stabilize the pH. It has been found to be effective with NaOCl concentrations as low as 0.025%.^[41]

US government regulations allow food processing equipment and food contact surfaces to be sanitized with solutions containing bleach, provided that the solution is allowed to drain adequately before contact with food, and that 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).^[42] If higher concentrations are used, the surface must be rinsed with potable water after sanitizing.

A similar concentration of bleach in warm water is used to sanitize surfaces prior to brewing of beer or wine. Surfaces must be rinsed with sterilized (boiled) water to avoid imparting flavors to the brew; the chlorinated byproducts of sanitizing surfaces are also harmful. The mode of disinfectant action of sodium hypochlorite is similar to that of hypochlorous acid.

Solutions containing more than 500 ppm available chlorine are corrosive to some metals, alloys and many thermoplastics (such as acetal resin) and need to be thoroughly removed afterwards, so the bleach disinfection is sometimes followed by an ethanol disinfection. Liquids containing sodium hypochlorite as the main active component are also used for household cleaning and disinfection, for example toilet cleaners.^[43] Some cleaners are formulated to be viscous so as not to drain quickly from vertical surfaces, such as the inside of a toilet bowl.

The undissociated (nonionized) hypochlorous acid is believed to react with and inactivate bacterial and viral enzymes.

Neutrophils of the human immune system produce small amounts of hypochlorite inside phagosomes, which digest bacteria and viruses.

Deodorizing[edit]

Sodium hypochlorite has deodorizing properties, which go hand in hand with its cleaning properties.^[35]

Waste water treatment[edit]

Sodium hypochlorite solutions have been used to treat dilute cyanide waste water, such as electroplating wastes. In batch treatment operations, sodium hypochlorite has been used to treat more concentrated cyanide wastes, such as silver cyanide plating solutions. Toxic cyanide is oxidized to cyanate (OCN⁻) that is not toxic, idealized as follows:

CN⁻ + OCl⁻ → OCN⁻ + Cl⁻

Sodium hypochlorite is commonly used as a biocide in industrial applications to control slime and bacteria formation in water systems used at power plants, pulp and paper mills, etc., in solutions typically of 10–15% by weight.

Endodontics[edit]

Sodium hypochlorite is the medicament of choice due to its efficacy against pathogenic organisms and pulp digestion in endodontic therapy. Its concentration for use varies from 0.5% to 5.25%. At low concentrations it dissolves mainly necrotic tissue; at higher concentrations it also dissolves vital tissue and additional bacterial species. One study has shown that Enterococcus faecalis was still present in the dentin after 40 minutes of exposure of 1.3% and 2.5% sodium hypochlorite, whereas 40 minutes at a concentration of 5.25% was effective in E. faecalis removal.^[44] In addition to higher concentrations of sodium hypochlorite, longer time exposure and warming the solution (60 °C) also increases its effectiveness in removing soft tissue and bacteria within the root canal chamber.^[44] 2% is a common concentration as there is less risk of an iatrogenic hypochlorite incident.^[45] A hypochlorite incident is an immediate reaction of severe pain, followed by edema, haematoma, and ecchymosis as a consequence of the solution escaping the confines of the tooth and entering the periapical space. This may be caused by binding or excessive pressure on the irrigant syringe, or it may occur if the tooth has an unusually large apical foramen.^[46]

Nerve agent neutralization[edit]

This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Sodium hypochlorite" – news · newspapers · books · scholar · JSTOR (March 2020) (Learn how and when to remove this template message)

At the various nerve agent (chemical warfare nerve gas) destruction facilities throughout the United States, 50% sodium hypochlorite is used to remove all traces of nerve agent or blister agent from Personal Protection Equipment after an entry is made by personnel into toxic areas. 50% sodium hypochlorite is also used to neutralize any accidental releases of nerve agent in the toxic areas. Lesser concentrations of sodium hypochlorite are used in similar fashion in the Pollution Abatement System to ensure that no nerve agent is released in furnace flue gas.

Reduction of skin damage[edit]

Dilute bleach baths have been used for decades to treat moderate to severe eczema in humans,^[47][48] but it has not been clear why they work. According to work published by researchers at the Stanford University School of Medicine in November 2013, a very dilute (0.005%) solution of sodium hypochlorite in water was successful in treating skin damage with an inflammatory component caused by radiation therapy, excess sun exposure or aging in laboratory mice. Mice with radiation dermatitis given daily 30-minute baths in bleach solution experienced less severe skin damage and better healing and hair regrowth than animals bathed in water. A molecule called nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is known to play a critical role in inflammation, aging, and response to radiation. The researchers found that if NF-κB activity was blocked in elderly mice by bathing them in bleach solution, the animals' skin began to look younger, going from old and fragile to thicker, with increased cell proliferation. The effect diminished after the baths were stopped, indicating that regular exposure was necessary to maintain skin thickness.^[47][49]

Safety[edit]

It is estimated that there are about 3,300 accidents needing hospital treatment caused by sodium hypochlorite solutions each year in British homes (RoSPA, 2002).

Oxidation and corrosion[edit]

Sodium hypochlorite is a strong oxidizer. Oxidation reactions are corrosive. Solutions burn the skin and cause eye damage, especially when used in concentrated forms. As recognized by the NFPA, however, 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 (NFPA 430, 2000).

Household bleach and pool chlorinator solutions are typically stabilized by a significant concentration of lye (caustic soda, NaOH) as part of the manufacturing reaction. This additive will by itself cause 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.

Storage hazards[edit]

Contact of sodium hypochlorite solutions with metals may evolve flammable hydrogen gas. Containers may explode when heated due to release of chlorine gas.^[9]

Hypochlorite solutions are corrosive to common container materials such as stainless steel^[6] and aluminium. The few compatible metals include titanium (which however is not compatible with dry chlorine) and tantalum.^[7] Glass containers are safe.^[6] Some plastics and rubbers are affected too; safe choices include polyethylene (PE), high density polyethylene (HDPE, PE-HD), polypropylene (PP),^[6] some chlorinated and fluorinated polymers such as polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF); as well as ethylene propylene rubber, and Viton.^[7]

Containers must allow venting of oxygen produced by decomposition over time, otherwise they may burst.^[3]

Reactions with other common products[edit]

Mixing bleach with some household cleaners can be hazardous.

Sodium hypochlorite solutions, such as liquid bleach, may release toxic chlorine gas when heated above 35 °C^[9] or mixed with an acid, such as hydrochloric acid or vinegar.

A 2008 study indicated that sodium hypochlorite and organic chemicals (e.g., surfactants, fragrances) contained in several household cleaning products can react to generate chlorinated volatile organic compounds (VOCs).^[50] These chlorinated compounds are emitted during cleaning applications, some of which 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, respectively, above baseline quantities in the household) 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 bleach use may be a source that could be important in terms of inhalation exposure to these compounds. The authors suggested that using these cleaning products may significantly increase the cancer risk.^[50]

In particular, mixing hypochlorite bleaches with amines (for example, cleaning products that contain or release ammonia, ammonium salts, urea, or related compounds and biological materials such as urine) produces chloramines.^[51][9] These gaseous products can cause acute lung injury. Chronic exposure, for example, from the air at swimming pools where chlorine is used as the disinfectant, can lead to the development of atopic asthma.^[52]

Bleach can react violently with hydrogen peroxide and produce oxygen gas:

H₂O₂ (aq) + NaOCl (aq) → NaCl (aq) + H₂O (aq) + O₂ (g)

Explosive reactions or byproducts can also occur in industrial and laboratory settings when sodium hypochlorite is mixed with diverse organic compounds.^[9]

Limitations in health care[edit]

The UK's National Institute for Health and Care Excellence in October 2008 recommended that Dakin's solution should not be used in routine wound care.^[53]

Environmental impact[edit]

In spite of its strong biocidal action, sodium hypochlorite per se has limited environmental impact, since the hypochlorite ion rapidly degrades before it can be absorbed by living beings.^[54]

However, one major concern arising from sodium hypochlorite use is that it tends to form persistent chlorinated organic compounds, including known carcinogens, that can be absorbed by organisms and enter the food chain. These compounds may be formed during household storage and use as well during industrial use.^[34] For example, when household bleach and wastewater were mixed, 1–2% of the available chlorine was observed to form organic compounds.^[34] As of 1994, not all the byproducts had been identified, but identified compounds include chloroform and carbon tetrachloride.^[34] The estimated exposure to these chemicals from use is estimated to be within occupational exposure limits.^[34]

See also[edit]

• Calcium hypochlorite Ca(OCl)
  2 ("bleaching powder")
• Potassium hypochlorite KOCl (the original "Javel water")
• Lithium hypochlorite LiOCl

References[edit]

1. ^ Jump up to:^a b c Carl L. Yaws (2015): The Yaws Handbook of Physical Properties for Hydrocarbons and Chemicals, 2nd edition, p. 734. Gulf Professional Publishing. ISBN 0128011467, 9780128011461.
2. ^ BS. udavari editor (1996): The Merck Index, p. 1478. Published by Merck Inc.
3. ^ Jump up to:^a b c Peter Urben, editor (2006), Bretherick's Handbook of Reactive Chemical Hazards. 4th edition, p. 984; 7th Edition; vol. 1, pg 1433. ISBN 9780123725639, 9780080523408
4. ^ Jump up to:^a b c Arihiro Hamano (1997): "The formation and decomposition of sodium hypochlorite anhydrous salt and its pentahydrate". Science and Technology of Energetic Materials, volume 58, issue 4, pp. 152–155.
5. ^ Jump up to:^a b Malcolm Percival Applebey (1919): "Sodium hypochlorite". Journal of the Chemical Society, Transactions, volume 115, article XCVI, pp. 1106–1109. doi:10.1039/CT9191501106
6. ^ Jump up to:^{a b c d e f g h i j k} Masayuki Kirihara, Tomohide Okada, Yukihiro Sugiyama, Miyako Akiyoshi, Takehiro Matsunaga, and Yoshikazu Kimura (2017): "Sodium Hypochlorite Pentahydrate Crystals (NaOCl·5H2O): A Convenient and Environmentally Benign Oxidant for Organic Synthesis". Organochemistry Process Research and Development, volume 21, pp. 1925–1937. doi:10.1021/acs.oprd.7b00288
7. ^ Jump up to:^{a b c d e} "OxyChem Sodium Hypochlorite Handbook" (PDF). oxy.com. OxyChem.
8. ^ "Pamphlet 96, The Sodium Hypochorite Manual". www.chlorineinstitute.org. The Chlorine Institute.
9. ^ Jump up to:^{a b c d e f} (2013): "Sodium Hypochlorite" Stanford Linear Accelerator Laboratory Safe Handling Guideline, chapter 53, product 202. Accessed on 2018-06-12
10. ^ "Sodium Hypochlorite Pentahydrate, NaOCl·5H
    2O". MatWeb Material Property Data website. Accessed on 2018-07-12.
11. ^ Jump up to:^a b "Sodium Hypochlorite". Web page at StudFiles, accessed on 2018-06-14.
12. ^ Tomohide Okada, Tomotake Asawa, Yukihiro Sugiyama, Toshiaki Iwai, Masayuki Kirihara, Yoshikazu Kimura (2016): "Sodium hypochlorite pentahydrate (NaOCl·5H2O) crystals; An effective re-oxidant for TEMPO oxidation". Tetrahedron, volume 72, issue 22, pp. 2818–2827. doi:10.1016/j.tet.2016.03.064
13. ^ Jump up to:^a b c Robert H Walsh, Albert Dietz (1966): "Process for preparing stable sodium hypochlorites". US Patent US3498924A.
14. ^ USCG (1999). Cited by PubChem.
15. ^ Environment Canada (1985): "Tech Info for Problem Spills: Sodium Hypochlorite (Draft)".
16. ^ L. Wang; et al. (2007), "Hypochlorous Acid as a Potential Wound Care Agent", Journal of Burns and Wounds, 6: e5, PMC 1853323, PMID 17492050
17. ^ Jump up to:^{a b c d e f} Staffan Sandin, Rasmus K. B. Karlsson, and Ann Cornell (2015): "Catalyzed and Uncatalyzed Decomposition of Hypochlorite in Dilute Solutions". Industrial Engineering Chemical Research, volume 54, issue 15, pp. 3767–3774. doi:10.1021/ie504890a
18. ^ Jump up to:^a b Arihiro Hamano and Akie Ikeda (1995): "The pH effect on the photodecomposition of sodium hypochlorite solution". Science and Technology of Energetic Materials, volume 56, issue 2, pp. 59–63.
19. ^ Gilbert H. Ayres and Max H. Booth (1955): "Catalytic Decomposition of Hypochlorite Solution by Iridium Compounds. I. The pH-Time Relationship". Journal of the American Chemical Society, volume 77, issue 4, pp. 825–827. doi:10.1021/ja01609a001
20. ^ ASC – PT Asahimas Chemical (2009): "Sodium hypochlorite". Online product description. Accessed on 2018-06-14.
21. ^ G. A. Mirafzal; A. M. Lozeva (1998). "Phase transfer catalyzed oxidation of alcohols with sodium hypochlorite". Tetrahedron Letters. 39 (40): 7263–7266. doi:10.1016/S0040-4039(98)01584-6.
22. ^ "Standard Methods for the Examination of Water and Wastewater" (PDF). www.umass.edu. American Public Health Association, American Water Works Association, Water Environment Federation. Retrieved 26 January 2017.
23. ^ Helmut Vogt; Jan Balej; John E. Bennett; Peter Wintzer; Saeed Akhbar Sheikh; Patrizio Gallone (2007), "Chlorine Oxides and Chlorine Oxygen Acids", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, p. 2
24. ^ Jump up to:^a b "Sodium hypochlorite as a disinfectant". Lenntech.com. Retrieved 7 August 2011.
25. ^ "eusol". Oxford English Dictionary. Retrieved 3 July 2014.
26. ^ Paul May. "Bleach (Sodium Hypochlorite)". University of Bristol. Archived from the original on 13 December 2016. Retrieved 13 December 2016.
27. ^ "How Products Are Made Volume 2". May 2011.
28. ^ Budd L. Duncan and Richard C. Ness (1991): "Process for the production of highly pure concentrated slurries of sodium hypochlorite". US Patent US5194238A.
29. ^ "SAFETY DATA SHEET Sodium Hypochlorite" (PDF). Univar. 9 August 2007.
30. ^ Wastewater Engineering: Treatment, Disposal, & Reuse (3rd ed.). Metcalf & Eddy, Inc. 1991. p. 497.
31. ^ Daniele S. Lantagne (2008). "Sodium hypochlorite dosage for household and emergency water treatment". e-Journal AWWA. 100 (8).
32. ^ Vieira, Ernest R. (1999). Elementary Food Science. Springer. pp. 381–382. ISBN 978-0-8342-1657-0.
33. ^ Marotz, Lynn R. (2011). Health, Safety, and Nutrition for the Young Child. Cengage Learning. pp. 126–127. ISBN 978-1-111-29837-1.
34. ^ Jump up to:^{a b c d e} Smith WT. (1994). Human and Environmental Safety of Hypochlorite. In: Proceedings of the 3rd World Conference on Detergents: Global Perspectives, pp. 183–5.
35. ^ Jump up to:^a b "Benefits and Safety Aspects of Hypochlorite Formulated in Domestic Products"(PDF). AISE – International Association for Soaps, Detergents and Maintenance Products. March 1997. Archived from the original (PDF) on 30 March 2014. This Support Dossier deals with information on the environmental and human safety eval‎uation of hypochlorite, and on its benefits as a disinfecting, deodorising and stain removing agent.
36. ^ Cárdenas Flores, A; Flores Reyes, H; Gordillo Moscoso, A; Castanedo Cázares, JP; Pozos Guillén Ade, J (2009). "Clinical efficacy of 5% sodium hypochlorite for removal of stains caused by dental fluorosis". The Journal of Clinical Pediatric Dentistry. 33 (3): 187–91. doi:10.17796/jcpd.33.3.c6282t1054584157. PMID 19476089.
37. ^ Jump up to:^a b c Rutala, William A.; Weber, David J. (15 February 2017) [2008]. "Guideline for Disinfection and Sterilization in Healthcare Facilities" (PDF). www.cdc.gov. Retrieved 29 August 2017.
38. ^ Jump up to:^a b "For General Healthcare Settings in West Africa: How to Prepare and Use Chlorine Solutions". Ebola Hemorrhagic Fever. Centers for Disease Control and Prevention. Retrieved 27 April 2016.
39. ^ "How to Make Strong (0.5%) Chlorine Solution from Liquid Bleach" (PDF). Centers for Disease Control and Prevention.
40. ^ Meyers, Jordan; Ryndock, Eric; Conway, Michael J.; Meyers, Craig; Robison, Richard (1 June 2014). "Susceptibility of high-risk human papillomavirus type 16 to clinical disinfectants". Journal of Antimicrobial Chemotherapy. 69 (6): 1546–1550. doi:10.1093/jac/dku006. ISSN 0305-7453. PMC 4019329. PMID 24500190.
41. ^ J. P. Heggers, J. A. Sazy, B. D. Stenberg, L. L. Strock, R. L. McCauley, D. N. Herndon, and M. C. Robson (1991): "Bactericidal and Wound-Healing Properties of Sodium Hypochlorite Solutions: The 1991 Lindberg Award". Journal of Burn Care & Rehabilitation, volume 12, issue 5, pp. 420–424. doi:10.1097/00004630-199109000-00005
42. ^ 21 CFR Part 178
43. ^ "Toilet Cleaners: Learn About Chemicals Around Your House: Pesticides: US EPA". United States Environmental Protection Agency. 9 May 2012.
44. ^ Jump up to:^a b Root Canal Irrigants and Disinfectants. Endodontics: Colleagues for Excellence. Published for the Dental Professional Community by the American Association of Endodontists. Winter 2011.
45. ^ Torabinejad, Mahmoud, Richard Walton. Endodontics, 4th Edition. p. 265. W.B. Saunders Company, 2008. VitalBook file
46. ^ Hülsmann, M.; Hahn, W. (2000). "Complications during root canal irrigation – literature review and case reports" (PDF). International Endodontic Journal. 33 (3): 186–193. doi:10.1046/j.1365-2591.2000.00303.x. PMID 11307434.
47. ^ Jump up to:^a b Conger, Krista (15 November 2013). "Inflammatory skin damage in mice blocked by bleach solution, study finds". Stanford School of Medicine. Archived from the original on 7 December 2013.
48. ^ Pett, Karen; Batta, Kapila; Vlachou, Christina; Nicholls, Geoff. "Bleach baths using Milton Sterilising Fluid for recurrent infected atopic eczema". Archived from the original on 12 December 2013.
49. ^ Leung TH, Zhang LF, Wang J, Ning S, Knox SJ, Kim SK (2013). "Topical hypochlorite ameliorates NF-κB–mediated skin diseases in mice". Journal of Clinical Investigation. 123(12): 5361–5370. doi:10.1172/JCI70895. PMC 3859383. PMID 24231355.
50. ^ Jump up to:^a b Odabasi, Mustafa (1 March 2008). "Halogenated Volatile Organic Compounds from the Use of Chlorine-Bleach- Containing Household Products". Environmental Science & Technology. 42 (5): 1445–1451. Bibcode:2008EnST...42.1445O. doi:10.1021/es702355u. PMID 18441786. Lay summary.
51. ^ Krieger, Gary R.; Sullivan, John B. Jr. (2001). Clinical environmental health and toxic exposures (2 ed.). Philadelphia, Pa. [u.a.]: Lippincott Williams & Wilkins. p. 968. ISBN 9780683080278. Retrieved 30 August 2016.
52. ^ Nickmilder, Marc; Carbonnelle, Sylviane; Bernard, Alfred (2007). "House cleaning with chlorine bleach and the risks of allergic and respiratory diseases in children". Pediatric Allergy and Immunology. 18 (1): 27–35. doi:10.1111/j.1399-3038.2006.00487.x. PMID 17295796.
53. ^ Do not use Eusol and gauze to manage surgical wounds that are healing by secondary intention, October 2008, NICE, London Archived 14 July 2014 at the Wayback Machine.Accessed 3 July 2014.
54. ^ ASC – PT Asahimas Chemical (2009): "Sodium hypochlorite 10%". Online Material Safety Data Sheet (MSDS). Accessed on 2018-06-14.

Bibliography[edit]

• Jones, F.-L. (1972). "Chlorine poisoning from mixing household cleaners". J. Am. Med. Assoc. 222 (10): 1312. doi:10.1001/jama.222.10.1312.
• Institut National de Recherche et de Sécurité. (2004). "Eaux et extraits de Javel. Hypochlorite de sodium en solution." Fiche toxicologique n° 157, Paris.

External links[edit]

• International Chemical Safety Card 0482 (solutions<10% active Cl)
• International Chemical Safety Card 1119 (solutions >10% active Cl)
• Institut national de recherche et de sécurité (in French)
• Home and Leisure Accident Statistics 2002 (UK RoSPA)
• Emergency Disinfection of Drinking Water (United States Environmental Protection Agency)
• Chlorinated Drinking Water (IARC Monograph)
• NTP Study Report TR-392: Chlorinated & Chloraminated Water (US NIH)
• Guidelines for the Use of Chlorine Bleach as a Sanitizer in Food Processing Operations (Oklahoma State University)

show

• v
• t
• e

Antiseptics and disinfectants (D08)

show

• v
• t
• e

Sodium compounds

Categories: 

• Antiseptics
• Bleaches
• Disinfectants
• Hypochlorites
• Oxidizing agents
• Sodium compounds

[박대선]

https://namu.wiki/w/%EB%9D%BD%EC%8A%A4