Bleach is a generic name for every chemical product used by industry and domestic to whiten clothing, brighten hair color and remove stains. This often refers specifically to a dilute sodium hypochlorite solution, also called "liquid bleach".
Many bleaches have broad-spectrum bactericidal properties, making them useful for disinfection and sterilization and are used in pool sanitation to control bacteria, viruses, and algae and in many places where sterile conditions are required. They are also used in many industrial processes, especially in bleaching wood pulp. Bleach also has other small uses such as eliminating fungi, killing weeds, and increasing the longevity of cut flowers.
Bleach works by reacting with many colored organic compounds, such as natural pigments, and turning them into colorless ones. While most bleaches are oxidizing agents (chemicals that can remove electrons from other molecules), some reducing agents (which contribute electrons).
Chlorine, a strong oxidiser, is an active agent in many household bleaches. Since pure chlorine is a toxic corrosive gas, this product usually contains hypochlorite which releases chlorine when necessary. "Whitening powder" usually means a formulation containing calcium hypochlorite.
An oxidation-containing bleaching agent containing no chlorine is usually based on peroxides such as hydrogen peroxide, sodium percarbonate, and sodium perborate. This bleach is called 'non-chlorine bleach,' 'oxygen bleach' or 'safe color bleach'.
Reduced bleach has special uses, such as sulfur dioxide used to whiten wool, either as a gas or from sodium dithionite solution; and sodium borohydride.
Bleach generally reacts with many other organic substances in addition to the intended colored pigment, so they can weaken or damage natural materials such as fibers, fabrics, and leather, and dyes that are deliberately used such as indigo denim. For the same reason, product consumption, smoke inhalation, or contact with skin or eyes can cause health damage.
Video Bleach
Histori
The earliest form of bleaching involves spreading fabrics and fabrics in bleachfield to be bleached by the action of the sun and water. In the 17th century, there was a significant cloth bleaching industry in Western Europe, using alternating alkaline baths (generally alkaline) and acid baths (such as lactic acid from sour milk, and then diluted sulfuric acid). The whole process lasts up to six months.
Chlorine-based bleach, which shortens the process from month to hour, was discovered in Europe at the end of the 18th century. Swedish chemist Scheele discovered chlorine in 1774, and in 1785 French scientist Claude Berthollet admitted that it could be used to whiten the fabric. Berthollet also invented sodium hypochlorite, which became the first commercial bleach, named Eau de Javel ("Javel water") after the borough in Paris where it was produced. Scottish chemist and industrialist Charles Tennant in 1798 proposed a solution of calcium hypochlorite as an alternative to Javel water, and patented bleaching powder (calcium hypochlorite solids) in 1799. Around 1820, the French chemist Labarraque discovered the ability of disinfectants and deodorizing hypochlorites, and play a role in popularizing its use for that purpose. His work greatly enhances medical practice, public health, and sanitary conditions in hospitals, slaughterhouses, and all industries dealing with animal products.
Louis Jacques ThÃÆ' Â © nard first produced hydrogen peroxide in 1818 by reacting barium peroxide with nitric acid. Hydrogen peroxide was first used for bleaching in 1882, but did not become commercially important until after 1930. Sodium perborate as a laundry bleach had been used in Europe since the early twentieth century, but did not become popular in North America until the 1980s.
Maps Bleach
Action mechanism
Bleaching
The color of natural organic matter usually arises from organic pigments, such as beta carotene. Chemical bleach works in one of two ways:
- The oxidizing bleach works by breaking the chemical bonds that make up the chromophore. It converts molecules into different substances that do not contain chromophores, or contain chromophores that do not absorb visible light. This is a chlorine-based bleaching mechanism.
- The reducing bleach works by converting the double bond in the chromophore into a single bond. This removes the ability of the chromophore to absorb visible light. This is a bleaching mechanism based on sulfur dioxide.
Sunlight acts as a bleach through a process that leads to the same result: high light energy photons, often in violet or ultraviolet ranges, can disrupt the bonds in the chromophore, resulting in a colorless substance produced. Expanding exposure often causes enormous color changes that typically reduce color to a normally faded blue spectrum.
Antimicrobial efficacy
The broad-spectrum effectiveness of most bleaches is due to their common chemical reactivity to organic compounds, rather than selective inhibition or toxic action of antibiotics. They can alter or destroy many proteins, making them a very versatile disinfectant.
However, hypochlorite bleach in low concentrations was found to also attack bacteria by interfering with heat shock proteins in their walls.
Bleach class
Most industrial and household bleach belongs to three broad classes:
- Chlorine-based bleach, whose active agent is chlorine, usually from the decomposition of some chlorine compounds such as hypochlorite or chlorine
- Peroxide-based bleach, whose active agent is oxygen, almost always from the decomposition of peroxide compounds such as hydrogen peroxide
- Bleach-based sulfur dioxide, whose active agent is sulfur dioxide, possibly from the decomposition of some oxosulfur anions
Chlorine-based bleach
Chlorine-based bleach is found in many household "bleach" products, as well as specialty products for hospitals, public health, water chlorination, and industrial processes.
Chlorine based bleach levels are often expressed as percent of active chlorine. One gram of 100% active chlorine bleach has the same bleaching power as one gram of chlorine element.
Mixing this bleach with acids such as vinegar can liberate chlorine gas, which is a respiratory irritant that attacks the mucous membranes and burns the skin. Combine these bleach with other ordinary household chemicals such as or ammonia to produce other toxic gases.
The most common chlorine-based bleaches are:
- Sodium hypochlorite ( NaClO ), usually as a 3-6% solution in water, is usually called "bleach liquid" or simply "bleach". Historically called "Javel water". Used in many households to whiten laundry, disinfect hard surfaces in kitchens and bathrooms, treat water for drinking and keep swimming pools free of infectious agents.
- Bleaching powder (formerly referred to as "chlorinated lime"), is usually a mixture of calcium hypochlorite ( Ca (ClO)
2 ), calcium hydroxide (lime, Ca (OH) 2 ), and calcium chloride ( CaCl
2 ) in the number of variables. Sold as a white powder or tablet, used in many of the same applications as sodium hypochlorite, but is more stable and contains more chlorine available. - Chlorine gas ( Cl
2 ). It is used as a disinfectant in water treatment, especially for making drinking water and in large public swimming pools. It is widely used to whiten wood pulp, but this usage has decreased significantly due to environmental concerns. - Chlorine dioxide ( ClO
2 ). This unstable gas is generated in situ or stored as aqueous aqueous solution. He invented large-scale applications for bleaching wood pulp, fats and oils, cellulose, flour, textiles, beeswax, leather, and in a number of other industries.
Another example of chlorine-based bleach, which is used mostly as a disinfectant, is chloramine, halazone, and sodium dichloroisocyanurate.
Peroxide-based bleaching
Peroxide-based bleaching is characterized by peroxide chemical groups, ie two oxygen atoms connected by a single bond, (-O-O-). This bond is easily damaged. resulting in a highly reactive oxygen species, which is an active bleach agent.
The main products in this class are:
- Hydrogen peroxide itself ( H
2 O
2 ). It is used, for example, to whiten pulp and wood hair or to prepare other whitening agents such as perborate, peroxide, peracid, etc. - Sodium percarbonate ( Na
2 H < span>
3 CO
6 ), adducts of hydrogen peroxide and sodium carbonate (" soda ash " , Na
2 CO > 3 ). Dissolved in water, resulting in a solution of two products, which combine the degreasing action of carbonate with the action of peroxide bleaching. - Sodium perborate ( Na
2 H < span>
4 B
2 O
8 ). Dissolved in water forms some hydrogen peroxide, but also anion perborate ( B (OOH) (OH) -
3 ) that can do oxidation nucleophilic. - Peracetic acid (peroxsoacetate) ( H
3 CC (O) OOH ). Made in place by some detergents, and also marketed for use as industrial and agricultural disinfection and water treatment. - benzoyl peroxide ( (C
6 H
5 COO 2 ). It is used in topical medications for acne and to whiten flour. - Ozon ( O
3 ). Although peroxide is not true, the mechanisms work similarly. It is used in the manufacture of paper products, especially newsprint and white Kraft paper.
In the food industry, other oxidizing products such as bromates are used as flour bleaching and agent maturation.
Reduce bleaching
Sodium dithionite (also known as sodium hydrosulfite ) is one of the most important reducing bleaching agents. It is a white crystalline powder with a weak sulfur smell. This can be obtained by reacting sodium bisulfite with zinc
- 2 NaHSO 3 Zn -> Na 2 S 2 O 4 Zn (OH) 2
It is used as in some industrial dyeing processes to remove excess dyes, residual oxides, and unwanted pigments and for bleaching wood pulp.
Reaksi natrium ditionit dengan formaldehida menghasilkan Rongalite,
- Na 2 S 2 O 4 2 CH 2 O H 2 O -> NaHOCH 2 SO 3 NaHOCH 2 SO 2
used in the bleaching of wood pulp, cotton, wool, leather and clay.
Environmental impact
A RAR report conducted by the European Union on sodium hypochlorite conducted under EEC Regulation 793/93 concluded that this substance is safe for the environment in all current normal use. This is because of its high reactivity and instability. The loss of hypochlorite is practically direct in a natural aquatic environment, achieving in short time concentrations as low as 10 -22 ? G/L or less in all emissions scenarios. In addition, it was found that while volatile chlorine species may be relevant in some indoor scenarios, they have negligible impacts in open environment conditions. Furthermore, the role of hypochlorite pollution is assumed to be negligible in the soil.
Bleaching agents industry can also be a source of concern. For example, the use of chlorine elements in bleaching wood pulp produces organochlorines and persistent organic pollutants, including dioxins. According to industrial groups, the use of chlorine dioxide in this process has reduced the generation of dioxin to a level that can be detected. However, the respiratory risk of chlorine and chlorine by-products is highly toxic.
A recent European study showed that sodium hypochlorite and organic chemicals (eg, surfactants, fragrances) contained in some household cleaning products can react to produce chlorinated volatile organic compounds (VOCs). This chlorinated compound is emitted during cleaning applications, some of which are toxic and possible human carcinogens. This study showed that indoor air concentrations increased significantly (8-52 times for chloroform and 1-1170 times for carbon tetrachloride, respectively, above the baseline quantity in the household) during use of bleach-containing products. Increased concentrations of chlorinated volatile organic compounds are the lowest for plain bleach and the highest for products in the form of "thick liquid and gel". Significant improvements observed in indoor air concentrations of some chlorinated VOCs (especially carbon tetrachloride and chloroform) suggest that the use of bleach may be a potentially important source of inhalation exposure to these compounds. Although the authors suggest that using these cleaning products may increase cancer risk significantly, this conclusion appears to be hypothetical:
-
- The highest level mentioned for the concentration of carbon tetrachloride (which seems most important) is 459 micrograms per cubic meter, translated to 0.073 ppm (parts per million), or 73 ppb (parts per billion). The weighted average concentration of OSHA time allowed during the eight hour period is 10 ppm, almost 140 times higher;
- The highest peak concentration allowed by OSHA (5 minutes exposure for five minutes in a 4 hour period) was 200 ppm, twice as high as the highest peak rate reported (from the main room of the bleach sample bottle plus detergent)).
Disinfection
Sodium hypochlorite solution, 3-6%, (ordinary household bleach) is usually diluted for safe use when disinfecting surfaces and when used to treat drinking water.
The weak solution of 2% household bleach in warm water is typical to clean the smooth surface before brewing a beer or wine.
The US Government Regulation (21 CFR Part 178) allows food processing equipment and food contact surfaces to be cleaned with a bleach-containing solution, provided that the solution is allowed to flow sufficiently before contact with food, and that the solution does not exceed 200 parts per million (ppm) of available chlorine ( for example, one tablespoon of typical household bleach containing 5.25% sodium hypochlorite, per gallon of water).
Dilution of 1-in-5 household bleach with water (1 part bleach to 4 parts water) is effective against many bacteria and some viruses, and often a disinfectant of choice in cleaning surfaces in hospitals (especially in the United States). Even "scientific-class", commercially produced disinfection solutions such as Virocidin-X usually have sodium hypochlorite as their only active ingredient, although they also contain surfactants (to prevent beading) and fragrances (for hide bleach odor).
See Hypochlorous acid for a discussion of the mechanisms for disinfecting action.
Treatment of gingivitis
Sodium hypochlorite dilute at the level of 2000-1 (0.05% concentration) can represent a efficacious, safe and affordable antimicrobial agent in the prevention and treatment of periodontal disease.
Secure bleach color
Safe color bleach is a chemical that uses hydrogen peroxide as an active ingredient (to help remove stains) rather than sodium hypochlorite or chlorine. It also has chemicals in it that help brighten the color. Hydrogen peroxide is also used for sterilization and water treatment purposes, but the ability of disinfectants may be limited because of the concentration in the bleach solution of color compared to other applications.
Health hazards
The safety of bleach depends on the compounds present, and the concentration. In general, consuming bleach can cause damage to the esophagus and stomach, which may cause death. If contact with skin or eyes, they may cause irritation, drying, and potentially burning. Inhaling bleach smoke can damage the lungs.
See also
- Teeth whitening
References
Further reading
- Bodkins, Dr. Bailey. Bleach . Philadelphia: Virginia Printing Press, 1995.
- Trotman, E.R. Scouring and Textile Bleaching . London: Charles Griffin & amp; Co., 1968. ISBNÃ, 0-85264-067-6.
External links
- Bleach at Britannica
- Bleach (MSDS)
Source of the article : Wikipedia
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