Instructions for use of sodium hypochlorite. Impact on the environment and humans. Indications for use

Sodium hypochlorite (NaOCl)- This Chemical substance, which is effectively used in industry, medicine and in everyday life for water disinfection, including drinking water, bleaching, odor removal, antiseptic treatment, surface cleaning and much more.

When was sodium hypochlorite discovered?

Sodium hypochlorite has a long history. Around 1785 Frenchman Claude Louis Berthollet discovered bleaching agents based on sodium hypochlorite. The Parisian company Societé Javel introduced a product called "javel liqueur". At first it was used to bleach cotton. Due to its specific characteristics, "javel liqueur" has become a popular composition. Hypochlorite had the ability to remove stains from clothing at room temperature. In France, sodium hypochlorite is still known as "eau de Javel" ("javel water").

What are the characteristics of sodium hypochlorite?

Sodium hypochlorite is a clear, slightly yellow solution with a characteristic odor. Sodium hypochlorite has a relative density of 1.1 (5.5% aqueous solution). A home whitening agent typically contains 5% sodium hypochlorite (pH about 11) and is irritating to the skin. A more concentrated mixture containing 10-15% sodium hypochlorite (with a pH of about 13) can cause skin burns and corrosion of surfaces. Sodium hypochlorite is unstable. Active chlorine is released from the solution at a rate of 0.75 grams per day. Heating accelerates the release of chlorine, during which sodium hypochlorite decomposes. Also, decay occurs when exposed to sunlight, when the substance comes into contact with acids, certain metals or gases. A solution of sodium hypochlorite is non-combustible, but the decomposition of anhydrous sodium hypochlorite at a temperature of 70 ° proceeds with an explosion. Sodium hypochlorite is a strong oxidizing agent that reacts with many reducing agents. These characteristics must be kept in mind when transporting, storing and using sodium hypochlorite.

What happens after sodium hypochlorite is added to water

When industrial sodium hypochlorite is added to water, the pH of the water increases, due to the fact that sodium hypochlorite contains caustic soda. When sodium hypochlorite dissolves in water, two substances are formed that play a role in oxidation and disinfection. This is hypochlorous acid (HOCl) and a less active product of its decomposition - hypochlorite anion (OCl -). The pH of water is a measure of the amount of hypochlorous acid formed. Using sodium hypochlorite for water disinfection, a pH corrector is used to stabilize the pH level - a preparation based on an inorganic acid.

How is sodium hypochlorite obtained?

Sodium hypochlorite is usually produced in two ways:

1. By dissolving table salt in softened water, getting a concentrated brine. The solution is subjected to electrolysis, during which sodium hypochlorite dissolved in water is formed. This solution contains up to 150 g of active chlorine (Cl 2) per litre. During this reaction, very explosive hydrogen is formed, so the process must be accompanied by ventilation.

2. Saturating sodium hydroxide (NaOH) with chlorine gas. As a result of the reaction, sodium hypochlorite, water (H 2 O) and common salt (NaCl) are formed:

Cl 2 + 2NaOH + → NaOCl + NaCl + H 2 O

How is sodium hypochlorite used?

Sodium hypochlorite has a wide range of applications. For example, in agriculture, chemical industry, paint industry, Food Industry, in the production of glass, paper, in the pharmaceutical industry, in the production of synthetics, for the disinfection of drinking water and purification Wastewater. In the textile industry, sodium hypochlorite is used to bleach fabrics. Sodium hypochlorite is sometimes added to industrial wastewater to reduce odors. Sodium hypochlorite neutralizes hydrogen sulfide (H 2 S) and ammonia (NH 3). It is also used to detoxify cyanide baths in metallurgy. Sodium hypochlorite can be used to prevent the growth of algae and shellfish in cooling towers. In water treatment systems, sodium hypochlorite is used to disinfect water. In households, hypochlorite is used to clean and disinfect the home.

How sodium hypochlorite disinfection works

When sodium hypochlorite is added to water, hypochlorous acid HOCl is formed:

NaOCl + H 2 O → HOCl + NaOH -

Hypochlorous acid is a strong oxidizing agent. It is on the oxidizing properties of hypochlorous acid HOCl that the disinfecting effect of HCN is based. In general, sodium hypochlorite disinfection is similar to chlorine disinfection.

How sodium hypochlorite is used for swimming pools

Sodium hypochlorite is used to disinfect and oxidize water. The advantage of hypochlorite is that microorganisms cannot defend themselves against it. Sodium hypochlorite is effective against Legionella bacteria and the biofilm in which these bacteria can grow. Hypochlorous acid is the result of the reaction of sodium hypochlorite with chlorine gas. The so-called active chlorine is formed in the water.

There are many uses for sodium hypochlorite. For on-site electrolysis systems, an aqueous solution of NaCl is used as the raw material for the production of hypochlorite. When dissolved in water, sodium ions Na + and chlorine Cl - are obtained:

4NaCl - → 4Na + + 4Cl -

When the saline solution passes through the electrolyzer, the following reaction occurs on the electrodes:

Process at the anode:

2Cl - - 2e - \u003d Cl 2

Process at the cathode:

2H + + 2e - = H 2

The process in the electrolyzer due to the chemical interaction of the resulting products:

Cl 2 + OH - \u003d Cl - + HOCl

General scheme of the process:

NaCl + H 2 O \u003d NaOCl + H 2

The advantage of the salt electrolysis system is that there is no need to transport and store sodium hypochlorite. With long storage of sodium hypochlorite, it loses its activity. Explosive hydrogen is released during electrolysis, so the operation of the system must be ensured by constant ventilation. The system is slow and requires a buffer to store hypochlorous acid. The cost of buying and maintaining an electrolysis system far exceeds the cost of buying concentrated sodium hypochlorite, which means that the payback period is very long.

When using grade A sodium hypochlorite, acetic or sulfuric acid must be added to the water. An overdose of acids can lead to the release of harmful gases. If the dosage is insufficient, the pH level remains too high, which can lead to eye irritation. Because sodium hypochlorite is used both for the oxidation of contaminants (from urine, sweat, cosmetics) and for the removal of pathogenic microorganisms, the required level of its concentration depends on the concentration of contaminants. If the water was filtered before adding sodium hypochlorite, a lower dosage is required.

What are the effects of sodium hypochlorite on health

There is no definite threshold beyond which the effects of sodium hypochlorite on human health appear. Its solutions can be dangerous due to the possibility of releasing toxic chlorine, the inhalation of which causes a suffocating effect and irritation of the respiratory tract. Diluted sodium hypochlorite ingestion causes burning sensation, stomach pain, cough, diarrhea, irritation respiratory tract and vomiting. Concentrated solutions can cause serious damage, and even perforation of the gastrointestinal tract. Contact of a weak hypochlorite solution with the skin or eyes causes redness and pain. Direct eye contact with concentrated hypochlorite can cause partial or complete loss of vision. Sodium hypochlorite is toxic to all aquatic organisms. But, despite the strong chemical activity, the safety of sodium hypochlorite for humans has been confirmed by studies of the toxicological centers of North America and Europe, which experimentally showed that the substance in working concentrations does not have a serious effect on health after accidental ingestion or contact with the skin. It is also confirmed that sodium hypochlorite is not a mutagenic and carcinogenic substance, as well as a skin allergen.

Sodium hypochlorite in swimming pools

Sodium hypochlorite is not harmful to humans in the concentrations used in swimming pools. Too much chlorine in the water causes irritation of the skin and mucous membranes, and can even cause damage to the respiratory tract, esophagus, eyes and skin. At normal concentrations, it can cause redness in the eyes and produce the characteristic pool chlorine smell. Where a sufficient mixture of urine and sweat is present, the components of this mixture react with hypochlorous acid to form chloramines. Chloramines irritate mucous membranes and can cause a bleach smell. In most swimming pools, these problems are solved by cleaning and circulating the water and treating the pool with chlorine.

Sodium hypochlorite is the salt of hypochlorous acid. The solution is obtained in a factory way - by the absorption of chlorine with a solution of caustic soda. In some industries, hypochlorite solutions are waste products. In accordance with the technical specifications, sodium hypochlorite solutions are produced in three grades A, B and C, which differ from each other in the content of active chlorine, residual alkalinity and appearance. Grades A and B are transparent greenish-yellow liquids (suspension is allowed) with an active chlorine content of 17%. Grade B is a liquid from yellow to brown in color, grades I and II are produced, containing 12 and 9.5% active chlorine, respectively.

At manufacturing plants, hypochlorite solutions are poured into rubber-lined steel tanks or containers, as well as into polyethylene canisters or barrels with a capacity of 20-60 liters. Sodium hypochlorite solution decomposes during storage, and therefore it is stored in a closed, dry, cool, well-ventilated non-residential area.

In view of the weak stability of the hypochlorite solution and possible violations of the rules for storage and preparation of working solutions, it is necessary to check the preparations and prepared working solutions by the iodometric method for the content of active chlorine. Hypochlorite has a bactericidal and sporicidal effect.

2. Application of sodium and calcium hypochlorite solutions:

Sodium hypochlorite solution is used instead of bleach and DTSGK. during current, final and preventive disinfection for the disinfection of various objects and secretions in the foci of infectious diseases, as well as for the disinfection of special objects. Disinfection is carried out by irrigation, wiping, washing, soaking objects that do not deteriorate with this method of processing. Linen and other fabrics, as well as metal objects, if they are not protected from corrosion, and painted things are not subject to disinfection with hypochlorite solutions. In infections caused by vegetative forms of microorganisms, sodium hypochlorite solution is used according to the following regimens:

Disinfection of premises (floor, walls), simple wooden furniture, outdoor installations is carried out by irrigation with solutions at a concentration of 1% in active chlorine at the rate of 300-500 ml / m 2 with an exposure of 1 hour. At the end of the disinfection, the premises must be ventilated.

To disinfect low-value soft things, as well as rags, cleaning material, solutions containing 1% active chlorine are used, at the rate of 4-5 liters per 1 kg of dry weight of things and kept for 1 hour.

The dishes are disinfected when completely immersed in a 0.25-1% active chlorine solution, depending on the presence of food residues, for 1 hour at the rate of 1.5 liters of solution per 1 set. At the end of disinfection, the dishes are thoroughly washed with water.

Bathtubs, toilet bowls, sinks and other sanitary equipment are irrigated twice abundantly with solutions of 1% concentration.

Liquid secretions, food debris and other waste are poured with undiluted hypochlorite solutions in a ratio of 1: 1. To disinfect overnight dishes, after removing the disinfected contents, 0.25% active chlorine solutions of hypochlorites are used, after which the dishes are washed with water.

Disinfection of the upper layers of soil, asphalt and other outdoor objects is carried out with hypochlorite solutions at a concentration of 1% in terms of active chlorine at the rate of 1.5 ml/m 2 .

3. Measures of personal prevention

When performing disinfection work with sodium hypochlorite solution, each worker must strictly observe personal safety measures, for which you should use personal protective equipment (RU-60 respirator with brand A cartridge; goggles, rubber gloves; protective aprons). If a solution of sodium hypochlorite gets on the skin and mucous membranes of the eyes, rinse quickly and abundantly with a stream of clean water.

4. Preparation of working solutions of sodium hypochlorite

Industrial waste containing hypochlorites with a non-standard amount of active chlorine can also be used for disinfection purposes in the manner prescribed by this instruction.

Structural formula

Molecular mass: 74.442

Sodium hypochlorite(sodium hypochlorous acid) - NaOCl, inorganic compound, sodium salt of hypochlorous acid. The trivial (historical) name of an aqueous solution of salt is "Labarrac water" or "javel water". The compound in the free state is very unstable, usually used as a relatively stable NaOCl 5H2O pentahydrate or an aqueous solution, which has a characteristic pungent chlorine odor and is highly corrosive. The compound is a strong oxidizing agent, contains 95.2% active chlorine. It has antiseptic and disinfectant action. It is used as a household and industrial bleach and disinfectant, a water purification and disinfection agent, an oxidizing agent for some industrial chemical production processes. As a bactericidal and sterilizing agent, it is used in medicine, food industry and agriculture. According to The 100 Most Important Chemical Compounds (Greenwood Press, 2007), sodium hypochlorite is one of the 100 most important chemical compounds.

Discovery history

Chlorine was discovered in 1774 by the Swedish chemist Carl Wilhelm Scheele. After 11 years in 1785 (according to other sources - in 1787), another chemist, the Frenchman Claude Louis Berthollet, discovered that an aqueous solution of this gas (see equation (1)) has bleaching properties:

Cl+H 2 O=HCl+HOCl

The small Parisian enterprise Societé Javel, opened in 1778 on the banks of the Seine and headed by Leonard Alban, adapted Berthollet's discovery to industrial conditions and began to produce bleaching liquid by dissolving chlorine gas in water. However, the resulting product was very unstable, so the process was modified in 1787. Chlorine was passed through an aqueous solution of potash (potassium carbonate), resulting in a stable product with high bleaching properties. Alban called it "Eau de Javel" ("javel water"). The new product became instantly popular in France and England due to its ease of transportation and storage.

In 1820, the French pharmacist Antoine Labarraque replaced potash with cheaper caustic soda (sodium hydroxide). The resulting sodium hypochlorite solution was named "Eau de Labarraque" ("Labarraque water"). It became widely used for bleaching and disinfection.

Despite the fact that the disinfecting properties of hypochlorite were discovered in the first half of the 19th century, its use for the disinfection of drinking water and wastewater treatment began only at the end of the century. The first water purification systems were opened in 1893 in Hamburg; In the United States, the first plant for the production of purified drinking water appeared in 1908 in Jersey City.

Physical Properties

Anhydrous sodium hypochlorite is an unstable colorless crystalline substance.

Elemental composition: Na (30.9%), Cl (47.6%), O (21.5%).

Very soluble in water: 53.4 g in 100 grams of water (130 g per 100 g of water at 50 °C).

The compound has three crystalline hydrates:

• monohydrate NaOCl H 2 O - extremely unstable, decomposes above 60 ° C, at higher temperatures - with an explosion
• NaOCl 2.5H 2 O - more stable, melts at 57.5 °C.

NaOCl 5H 2 O pentahydrate - the most stable form, is a pale greenish-yellow (technical quality - white) rhombic crystals (a = 0.808 nm, b = 1.606 nm, c = 0.533 nm, Z = 4). Non-hygroscopic, highly soluble in water (in g / 100 grams of water, in terms of anhydrous salt): 26 (-10 ° C), 29.5 (0 ° C), 38 (10 ° C), 82 (25 ° C), 100 (30°C). In the air, it blurs, turning into a liquid state, due to rapid decomposition. Melting point: 24.4 °C (according to other sources: 18 °C), decomposes when heated (30-50 °C).

Density of an aqueous solution of sodium hypochlorite at 18 °C:

Freezing point aqueous solutions sodium hypochlorite of various concentrations:

Thermodynamic characteristics of sodium hypochlorite in an infinitely dilute aqueous solution:

• standard enthalpy of formation, ΔHo 298: −350.4 kJ/mol;
• standard Gibbs energy, ΔGo 298: −298.7 kJ/mol.

Chemical properties

Decomposition and disproportionation Sodium hypochlorite is an unstable compound that easily decomposes with the release of oxygen. Spontaneous decomposition occurs slowly even at room temperature: in 40 days, pentahydrate (NaOCl · 5H 2 O) loses 30% of active chlorine. At a temperature of 70 °C, the decomposition of anhydrous hypochlorite proceeds with an explosion. When heated, a disproportionation reaction occurs in parallel.

Hydrolysis and decomposition in aqueous solutions

Dissolving in water, sodium hypochlorite dissociates into ions. Since hypochlorous acid (HOCl) is very weak (pKa = 7.537), the hypochlorite ion undergoes hydrolysis in an aqueous medium.

It is the presence of hypochlorous acid in aqueous solutions of sodium hypochlorite that explains its strong disinfecting and bleaching properties. Aqueous solutions of sodium hypochlorite are unstable and decompose over time even at normal temperatures (0.085% per day). Decay accelerates illumination, heavy metal ions and chlorides alkali metals; on the contrary, magnesium sulfate, orthoboric acid, silicate and sodium hydroxide slow down the process; in this case, solutions with a strongly alkaline medium (pH > 11) are the most stable.

Oxidizing properties

An aqueous solution of sodium hypochlorite is a strong oxidizing agent that enters into numerous reactions with various reducing agents, regardless of the acid-base nature of the medium.

Identification

Among the qualitative analytical reactions to hypochlorite ion, one can note the precipitation of a brown precipitate of metahydroxide when the test sample is added at room temperature to an alkaline solution of monovalent thallium salt (detection limit 0.5 µg of hypochlorite).

Another option is a starch iodo reaction in a strongly acidic medium and a color reaction with 4,4'-tor n, n'-dioxytriphenylmethane in the presence of potassium bromate. common method quantitative analysis sodium hypochlorite in solution is a potentiometric analysis by adding the analyzed solution to the standard solution (MDA) or the method of reducing the concentration of the analyzed solution by adding it to the standard solution (MBA) using a bromine-ion-selective electrode (Br-ISE). A titrimetric method using potassium iodide (indirect iodometry) is also used.

Corrosion

Sodium hypochlorite has a fairly strong corrosive effect on various materials, as evidenced by the data below:

Physiological action and effect on environment

NaOCl is one of the best known agents, exhibiting strong antibacterial activity due to the hypochlorite ion. It kills microorganisms very quickly and already at very low concentrations. The highest bactericidal ability of hypochlorite is manifested in a neutral environment, when the concentrations of HClO and hypochlorite anions ClO− are approximately equal (see subsection "Hydrolysis and decomposition in aqueous solutions"). The decomposition of hypochlorite is accompanied by the formation of a number of active particles and, in particular, singlet oxygen, which has a high biocidal effect. The resulting particles take part in the destruction of microorganisms, interacting with biopolymers in their structure that are capable of oxidation. Research has established that this process is similar to what occurs naturally in all higher organisms. Some human cells (neutrophils, hepatocytes, etc.) synthesize hypochlorous acid and associated highly active radicals to fight microorganisms and foreign substances. Yeast-like fungi that cause candidiasis, Candida albicans, die in vitro within 30 seconds when exposed to a 5.0-0.5% NaOCl solution; at a concentration of the active substance below 0.05%, they show stability 24 hours after exposure. Enterococci are more resistant to the action of sodium hypochlorite. For example, pathogenic Enterococcus faecalis dies 30 seconds after treatment with a 5.25% solution and 30 minutes after treatment with a 0.5% solution. Gram-negative anaerobic bacteria such as Porphyromonas gingivalis, Porphyromonas endodontalis and Prevotella intermedia die within 15 seconds after treatment with 5.0-0.5% NaOCl solution. Despite the high biocidal activity of sodium hypochlorite, it should be borne in mind that some potentially dangerous protozoa, such as giardiasis or cryptosporidiosis pathogens, are resistant to its action. The high oxidizing properties of sodium hypochlorite allow it to be successfully used to neutralize various toxins. The table below shows the results of toxin inactivation during 30-minute exposure to various concentrations of NaOCl (“+” - the toxin was inactivated; “-” - the toxin remained active). Sodium hypochlorite can have harmful effects on the human body. NaOCl solutions can be hazardous by inhalation due to the possibility of releasing toxic chlorine (irritant and asphyxiant). Direct contact with hypochlorite in the eyes, especially at high concentrations, can cause chemical burns and even lead to partial or complete loss of vision. Household bleaches based on NaOCl can cause skin irritation, while industrial bleaches can lead to serious ulcers and tissue death. Ingestion of dilute solutions (3-6%) of sodium hypochlorite usually leads only to irritation of the esophagus and sometimes acidosis, while concentrated solutions can cause quite serious damage, up to perforation of the gastrointestinal tract. Despite its high chemical activity, the safety of sodium hypochlorite for humans has been documented by studies by poison control centers in North America and Europe, which show that the substance at working concentrations does not carry any serious health effects after unintentional ingestion or contact with the skin. It is also confirmed that sodium hypochlorite is not mutagenic, carcinogenic and teratogenic, as well as a skin allergen. The International Agency for Research on Cancer has concluded that drinking water treated with NaOCl does not contain human carcinogens.

Oral toxicity of the compound:

• Mice: LD 50(English) LD 50) = 5800 mg/kg;
• Human (women): minimum known toxic dose eng. (English) TD Lo) = 1000 mg/kg.

Intravenous toxicity of the compound:

• Human: minimum known toxic dose TD Lo) = 45 mg/kg.

During normal household use, sodium hypochlorite breaks down in the environment into table salt, water and oxygen. Other substances may be formed in small quantities. According to the Swedish Institute for Environmental Research, sodium hypochlorite is unlikely to create environmental issues when used in the recommended order and quantities. Sodium hypochlorite poses no fire hazard.

industrial production

World production

Estimating the world volume of sodium hypochlorite production presents a certain difficulty due to the fact that a significant part of it is produced by the electrochemical method according to the “in situ” principle, that is, at the place of its direct consumption (we are talking about the use of the compound for disinfection and water treatment). As of 2005, the estimated global production of NaOCl was about 1 million tons, with almost half of this volume used for domestic use and the other half for industrial use.

Overview of industrial production methods

The outstanding bleaching and disinfecting properties of sodium hypochlorite led to an intensive growth in its consumption, which in turn gave an impetus to the creation of large-scale industrial production.

In modern industry, there are two main methods for the production of sodium hypochlorite:

• chemical method - chlorination of aqueous solutions of sodium hydroxide;
• electrochemical method - electrolysis of an aqueous solution of sodium chloride.

Application

Overview of areas of use

Sodium hypochlorite is the undisputed leader among hypochlorites of other metals of industrial importance, occupying 91% of the world market. Almost 9% remains for calcium hypochlorite, potassium and lithium hypochlorites have insignificant volumes of use.

The entire wide range of use of sodium hypochlorite can be divided into three conditional groups:

• use for domestic purposes;
• use for industrial purposes;
• use in medicine.

Domestic use includes:

• use as a means for disinfection and antibacterial treatment;
• use for bleaching fabrics;
• chemical dissolution of sanitary deposits.

Industrial uses include:

• industrial bleaching of fabric, wood pulp and some other products;
• industrial disinfection and sanitation;
• purification and disinfection of drinking water for public water supply systems;
• cleaning and disinfection of industrial effluents;
• chemical production.

According to IHS experts, about 67% of all sodium hypochlorite is used as bleach and 33% for disinfection and cleaning needs, with the latter trending upward. The most common area of ​​industrial use of hypochlorite (60%) is the disinfection of industrial and domestic wastewater. The overall global growth in industrial consumption of NaOCl in 2012-2017 is estimated at 2.5% annually. Growth in global demand for sodium hypochlorite for domestic use in 2012-2017 is estimated at about 2% annually.

Application in household chemicals

Sodium hypochlorite finds wide application in household chemicals and is included as an active ingredient in numerous products intended for bleaching, cleaning and disinfecting various surfaces and materials. In the US, approximately 80% of all hypochlorite used by households is for household bleaching. Usually, solutions with a concentration in the range of 3 to 6% hypochlorite are used in everyday life. The commercial availability and high efficiency of the active substance determines its widespread use by various manufacturing companies, where sodium hypochlorite or products based on it are produced under various trademarks.

Application in medicine

The use of sodium hypochlorite for wound disinfection was first proposed no later than 1915. In modern medical practice, antiseptic solutions of sodium hypochlorite are used mainly for external and topical use as an antiviral, antifungal and bactericidal agent in the treatment of skin, mucous membranes and wounds. Hypochlorite is active against many gram-positive and gram-negative bacteria, most pathogenic fungi, viruses and protozoa, although its effectiveness is reduced in the presence of blood or its components. The low cost and availability of sodium hypochlorite makes it an important ingredient in maintaining high hygiene standards throughout the world. This is especially true in developing countries where the use of NaOCl has become a critical factor in stopping cholera, dysentery, typhoid fever and other aquatic biotic diseases. For example, with a cholera outbreak in countries Latin America and the Caribbean at the end of the 20th century, sodium hypochlorite was able to minimize morbidity and mortality, as reported at the Tropical Diseases Symposium held under the auspices of the Pasteur Institute. For medical purposes in Russia, sodium hypochlorite is used as a 0.06% solution for intracavitary and external use, as well as an injection solution. In surgical practice, it is used for the treatment, washing or drainage of surgical wounds and intraoperative sanitation of the pleural cavity with purulent lesions; in obstetrics and gynecology - for perioperative treatment of the vagina, treatment of bartholinitis, colpitis, trichomoniasis, chlamydia, endometritis, adnexitis, etc.; in otorhinolaryngology - for rinsing the nose and throat, instillation into the ear canal; in dermatology - for wet dressings, lotions, compresses for various types infections. In dental practice, sodium hypochlorite is most widely used as an antiseptic irrigation solution (NaOCl concentration 0.5-5.25%) in endodontics. The popularity of NaOCl is determined by the general availability and cheapness of the solution, as well as the bactericidal and antiviral effect against such dangerous viruses as HIV, rotavirus, herpes virus, hepatitis A and B viruses. There is evidence of the use of sodium hypochlorite for the treatment of viral hepatitis: it has a wide range of antiviral, detoxifying and antioxidant effects. NaOCl solutions can be used to sterilize some medical devices, patient care items, dishes, linen, toys, rooms, hard furniture, sanitary equipment. Due to its high corrosivity, hypochlorite is not used for metal appliances and tools. We also note the use of sodium hypochlorite solutions in veterinary medicine: they are used for disinfection of livestock buildings.

Industrial Application

Application as an industrial bleach

The use of sodium hypochlorite as a bleach is one of the priority areas industrial use along with disinfection and purification of drinking water. The world market in this segment alone exceeds 4 million tons. Usually, for industrial needs, aqueous solutions of NaOCl containing 10-12% of the active substance are used as a bleach. Sodium hypochlorite is widely used as a bleach and stain remover in the textile industry and industrial laundries and dry cleaners. It can be safely used on many types of fabrics including cotton, polyester, nylon, acetate, linen, viscose and more. It is very effective in removing soil and a wide range of stains including blood, coffee, grass, mustard, red wine, etc. Sodium hypochlorite is also used in the pulp and paper industry for wood pulp bleaching. NaOCl bleaching usually follows a chlorination step and is one of the wood chemical processing steps used to achieve high pulp whiteness. Processing of fibrous semi-finished products is carried out in special hypochlorite bleaching towers in an alkaline environment (pH 8-9), temperature 35-40 °C, for 2-3 hours. During this process, lignin is oxidized and chlorinated, as well as the destruction of the chromophore groups of organic molecules.

Use as an industrial disinfectant

The widespread use of sodium hypochlorite as an industrial disinfectant is associated primarily with the following areas:

• disinfection of drinking water before it is supplied to the distribution systems of urban water supply;
• disinfection and algaecidal water treatment of swimming pools and ponds;
• treatment of domestic and industrial waste water, purification from organic and inorganic impurities;
• in brewing, winemaking, dairy industry - disinfection of systems, pipelines, tanks;
• fungicidal and bactericidal treatment of grain;
• disinfection of water of fishery reservoirs;
• disinfection of technical premises.

Hypochlorite as a disinfectant is included in some automated in-line dishwashing products and some other liquid synthetic detergents. Industrial disinfectants and bleach solutions are available from many manufacturers under various brand names.

Use for water disinfection

Oxidative disinfection with the help of chlorine and its derivatives is perhaps the most common practical method of water disinfection, the beginning of the mass use of which by many countries of Western Europe, the USA and Russia dates back to the first quarter of the 20th century.

The use of sodium hypochlorite as a disinfectant instead of chlorine is promising and has a number of significant advantages:

• the reagent can be synthesized by the electrochemical method directly at the place of use from readily available table salt;
• the necessary indicators of the quality of drinking water and water for hydraulic structures can be achieved due to a smaller amount of active chlorine;
• the concentration of carcinogenic organochlorine impurities in water after treatment is significantly less;
• replacement of chlorine with sodium hypochlorite improves environmental situation and hygiene safety: [p. 36].
• hypochlorite has a wider range of biocidal action on various types of microorganisms with less toxicity;

For domestic water treatment purposes, dilute sodium hypochlorite solutions are used: the typical concentration of active chlorine in them is 0.2-2 mg/l versus 1-16 mg/l for chlorine gas. Dilution of industrial solutions to a working concentration is carried out directly on site.

Also from a technical point of view, taking into account the condition of use in the Russian Federation, experts note:

• a significantly higher degree of safety of the reagent production technology;
• relative safety of storage and transportation to the place of use;
• loyal safety requirements when working with the substance and its solutions at the facilities;
• non-subordination of water disinfection technology with hypochlorite to Rostekhnadzor of the Russian Federation.

The use of sodium hypochlorite for water disinfection in Russia is becoming increasingly popular and is being actively introduced into practice by the leading industrial centers of the country. So, at the end of 2009, in Lyubertsy, the construction of a plant for the production of NaOCl with a capacity of 50 thousand tons / year for the needs of the Moscow municipal economy began. The Moscow government decided to transfer the water disinfection systems of Moscow water treatment plants from liquid chlorine to sodium hypochlorite (since 2012). The sodium hypochlorite plant will be commissioned in 2015.

Hydrazine production

Sodium hypochlorite is used in the so-called Raschig Process (eng. Raschig Process, oxidation of ammonia with hypochlorite) - the main industrial method for obtaining hydrazine, discovered by the German chemist Friedrich Raschig in 1907. The chemistry of the process is as follows: in the first stage, ammonia is oxidized to chloramine, which then reacts with ammonia, forming hydrazine itself.

Other uses

Among other areas of use of sodium hypochlorite, we note:

• in industrial organic synthesis or hydrometallurgical production for the degassing of toxic liquid and gaseous wastes containing hydrogen cyanide or cyanides;
• oxidizer for wastewater treatment industrial enterprises from impurities of hydrogen sulfide, inorganic hydrosulfides, sulfur compounds, phenols, etc.;
• in electrochemical industries as an etchant for germanium and gallium arsenide;
• V analytical chemistry as a reagent for the photometric determination of bromide ion;
• in the food and pharmaceutical industries for the production of food modified starch;
• in the military as a means for degassing chemical warfare agents such as mustard gas, Lewisite, sarin and V-gases.

Hypochlorous acid sodium salt

Chemical properties

Sodium hypochlorite, what is it? This is an inorganic compound, which contains up to 95% active chlorine. The substance has several non-trivial, historical names: “labarraque water”, “javel water”. Chemical formula of sodium hypochlorite: NaOCl. Molecular weight of the compound = 74.4 grams per mole. Due to the fact that the substance is quite unstable in the free state, it is most often used in the form pentahydrate or water solution. The solution has a strong, pungent smell of chlorine. The anhydrous form of the substance is synthesized in the form of colorless crystals that dissolve well in water. pentahydrate has a yellow-green tint, rhombic crystals.

By their own chemical properties is a strong oxidizing agent. Hypochlorite easily decomposes to Na chloride And oxygen ; when heated, it undergoes disproportionation. Dissociates into ions in water. The substance is corrosive to most metals.

Sodium hypochlorite is produced in huge quantities. About half of the synthesized substance is used in household chemicals and medicine, the rest - in industry. There are two methods for the production of the product: chemical, chlorination of an aqueous solution sodium hydroxide (concentrated and basic) and electrolytic, electrolysis plants are used for water electrolysis.

The chemical compound is actively used in industry:

• as a bleach for fabric, wood and other products;
• at industrial and sanitary and hygienic processing of grain, pipelines, tanks in winemaking and brewing, etc.;
• V chemical production anthranilic acid , chloropicrin , starch , and analytical chemistry with photometry;
• for disinfection and purification of industrial wastewater and water in public water supply systems;
• in the food industry and pharmaceuticals;
• in military affairs during the degassing of toxic substances.

The substance is used in household chemicals, it can often be found in the composition of bleaches, disinfectants and cleaners. In medicine, they are used externally or topically as an antiviral, bactericidal and antifungal agent; in small concentrations - for the treatment of surgical wounds, in gynecology and obstetrics, otorhinolaryngology, in dentistry ( endodontics ).

The chemical compound can have a harmful effect on the human body, if inhaled, it can have a suffocating and irritating effect. If the product gets into the eyes, the substance causes a chemical burn, which can lead to loss of vision. The agent irritates the skin, in high concentrations causes tissue death, ulcers and burns. After ingestion of 3-6% of the solution, a person develops acidosis , irritation of the esophagus, higher concentrations may cause perforation of the digestive tract. Despite this, subject to the recommendations for the use of drugs, water and household chemicals, hypochlorite is considered a fairly safe remedy. Does not possess carcinogenic, mutagenic and teratogenic agents. The toxic dose for intravenous administration for humans is 45 mg per kg of body weight; oral - 1 gram per kg. It is also believed that the substance does not create environmental problems, as it quickly decomposes in the environment to water, oxygen and sodium chloride. Hazard class for concentrated solutions (up to 20%): 1 - by chemical activity; 3 - danger to human health. Not territories Russian Federation hypochlorite Na issued according to GOST 11086-76.

pharmachologic effect

Disinfectant, detoxifying, antiseptic, antimicrobial.

Pharmacodynamics and pharmacokinetics

Sodium Hypochlorite is one of the strongest antibacterial agents. Hypochlorite ion exhibits high activity against a variety of known microorganisms, and acts in fairly low concentrations. The activity is highest at neutral pH. The particles formed during the decomposition of a substance oxidize biopolymers in the structure of harmful agents, destroy the molecules of almost all org. substrates. The agent is active against gram-negative bacteria, coli, serrations, Pseudomonas aeruginosa, gram-positive bacteria, pathogenic fungi, protozoa, viruses. However, the drug does not act on pathogens cryptosporidiosis And . The tool does not have teratogenic, carcinogenic and mutagenic properties.

Indications for use

Applied externally and injected into the cavity at a concentration of 0.06%:

• for prophylaxis during operations on the chest, pleural and abdominal cavity;
• with injuries, widespread peritonitis , ;
• during peritoneal dialysis on the abdominal cavity;
• patients with pleural empinema (, pus in the pleural cavity);
• when treating the vagina before and after surgery, with, hysteroscopy , ventiotomy;
• as a prophylactic and for the treatment of purulent-septic complications after cesarean section;
• after operations on the urinary tract and kidneys, after prostatectomy ;
• with purulent otitis media , ;
• for treatment and;
• with true and eczema of microbial etiology;
• patients with staphyloderma , streptoderma , herpes simplex And .

The solution is used for injection in endo- and exotoxicoses , poisoning, sepsis , burns, diseases of the liver and kidneys.

In the form of liquids and gels, the substance is used to disinfect equipment in the food industry, when treating surfaces.

Contraindications

Sodium Hypochlorite is contraindicated for use:

• at ;
• hypovolemic syndrome , hypoglycemia (intravenous administration);
• intravenously, during

Side effects

Rarely, the substance causes:

• allergic reactions;
• sensation of dryness and burning at the site of application;
• when injected - a decrease in blood sugar;
• with rapid intravenous administration - phlebitis , extravasation .

Sodium hypochlorite, instructions for use (Method and dosage)

The substance is used to treat the premises and various surfaces in accordance with the recommendations.

The drug is used intravenously, externally and injected into the cavity in the form of a 0.06% solution. The instructions for use must be observed.

Overdose

Amukin, Unicept ; it is added to the composition of disinfectant solutions.

Sodium hypochlorite solutions used for disinfection and disinfection of water about 100 years old. Long-term practice of using solutions sodium hypochlorite for water treatment, both in our country and abroad, shows that the reagents can be used in a wide range:

• For disinfection of water in swimming pools and reservoirs for various purposes;
• for the treatment of natural and waste water in the system of domestic and drinking water supply;
• in the treatment of domestic and industrial wastewater, etc.

Use of solutions sodium hypochlorite For swimming pool water disinfection and ponds allows you to get clean, clear water, devoid of algae and bacteria. When processing swimming pools with sodium hypochlorite solutions content needs to be carefully controlled. active chlorine in water. It is important maintaining Ph at a certain level, usually 7.4-8.0, and preferably 7.6-7.8. Ph regulation carried out by the introduction of special additives.

The content of residual chlorine in the water of swimming pools should be at the level of 0.3-0.5 mg/dm 3 . Reliable disinfection within 30 min. provide solutions containing 0.1-0.2% sodium hypochlorite. At the same time, the content of active chlorine in the breathing zone should not exceed 0.1 mg / dm 3 in public swimming pools and 0.03 mg / m 3 in sports swimming pools. Replacing the gaseous chlorine with sodium hypochlorite results in a reduction in the release of chlorine into the air and also makes it easier to maintain a residual amount of active chlorine in the water.

Use of solutions sodium hypochlorite for the treatment of drinking water, preferably at the pre-oxidation stage, and for the sterilization of water before it enters the distribution network. Usually in water treatment system sodium hypochlorite solutions injected after diluted by about 100 times. However, in addition to reducing active chlorine concentration, the Ph value also decreases (from 12-13 to 10-11), which contributes to an increase disinfectant capacity of the solution.

Sodium hypochlorite widely used: for the treatment of domestic and industrial wastewater; for the destruction of animal and plant microorganisms; eliminate odors; neutralization of industrial effluents, including those containing cyanide compounds. It can also be used to treat water containing ammonium, phenols and humic substances.

Sodium hypochlorite also used to neutralize industrial effluents from cyanide compounds; for the removal of mercury from wastewater and for the treatment of cooling condenser water in power plants.

The main properties of sodium hypochlorite:

Sodium hypochlorite(sodium salt of hypochlorous acid) - NaClO, obtained by chlorination of aqueous sodium hydroxide (NaOH). The industry produces in the form of aqueous solutions of various concentrations. Low concentration solutions sodium hypochlorite obtained by electrolysis of a solution of sodium chloride (NaCl) in special electrochemical installations, as a rule, directly at the consumer.

Aqueous solutions of sodium hypochlorite have been used for disinfection since the dawn of the chlorine industry. Due to the high antibacterial activity and a wide spectrum of action on various microorganisms, this disinfectant is used in many areas of human activity.

Disinfectant action of sodium hypochlorite It is based on the fact that when dissolved in water, just like chlorine, it forms hypochlorous acid, which has a direct oxidizing and disinfecting effect.

NaClO + H 2 O→← NaOH + HClO

There are solutions sodium hypochlorite various brands.

Basic physical and chemical indicators sodium hypochlorite solutions produced in the Russian Federation:

Sodium hypochlorite solutions various brands are used:

• brand A solution - in the chemical industry, for the disinfection of drinking water and swimming pool water, for disinfection and bleaching;
• brand B solution - in the vitamin industry, as an oxidizing agent;
• brand A solution - for disinfection of natural and waste water in domestic and drinking water supply, disinfection of water in fishery reservoirs, in the food industry, for the production of bleaching agents;
• brand B solution - for disinfection of areas contaminated with fecal discharges, food and household waste; wastewater disinfection;
• solution of brand V, G according to - for disinfection of water of fishery reservoirs;
• solution brand E po - for disinfection similar to brand A, as well as disinfection in health care institutions, enterprises Catering, sanatoriums, children's institutions, swimming pools, civil defense facilities, etc., as well as disinfection of drinking water, wastewater, bleaching.

It should be noted that in order to make sodium hypochlorite solutions grades A and B po and solutions of grade A po, it is not allowed to use off-gas chlorine from chlorine-consuming organic and inorganic industries, as well as caustic soda obtained by the mercury method.

Brand B solutions are obtained from off-gas chlorine of organic and inorganic industries and diaphragm or mercury caustic soda.

Solutions of grades C and G according to are obtained from off-gas chlorine of the stage of liquefaction of the production of chlorine and diaphragm caustic soda with the addition of a stabilizing additive - citral of the “Perfumerny” variety according to . Solutions of grade E are obtained by electrolysis of sodium chloride solution.