Creosote is a category of carbon chemicals formed by distillation of tar and pyrolysis derivative materials, such as wood or fossil fuels. They are usually used as preservatives or antiseptics.
Some creosote types are used historically as a treatment for outdoor and outdoor wood structure components to prevent spoilage (eg, bridgework and train ties, see figure). Samples can be found commonly in a chimney chimney, burning coal or wood in varying conditions, resulting in soot and smoke dwelling. Creosotes are the main chemicals responsible for the stability, aroma, and flavor characteristics of bacon; this name comes from the Greek ????? (kreas) , meaning 'meat', and ????? (s? t? r) , which means 'preserver'.
The two main types recognized in the industry are kreosote coal tar and wood-tar creosote . Taro coal varieties, have stronger and more toxic properties, mainly used as wood preservatives; coal-tar creosote was also previously used as an escharotic, to burn malignant skin tissue, and in dentistry, to prevent necrosis, before its carcinogenic properties are known. Various tar-woods have been used for meat preservation, ship maintenance, and medical purposes such as anesthesia, antiseptics, substances, expectorants, and laxatives, although this has largely been supplanted by modern formulations.
The creosote variety has also been made from oil and oil shale, and is known as creosote tar oil when it comes from oil tar, and as water-gas-tar creosote when it comes from tar gas water. Creosote is also made from pre-coal formations such as lignite, producing lignite-tar creosote , and peat, yielding creosote-tar peat .
Video Creosote
Creosote oils
The term creosote has various definitions depending on the origin of coal tar oil and the end use of the material. In relation to wood preservatives, the United States Environmental Protection Agency (EPA) considers the term creosote to mean pesticides to be used as wood preservatives that meet the American Wood Protection Standards (AWPA) P1/P13 and P2. The AWPA standard requires that creosote "is a pure coal tar product derived entirely from tar produced by bituminous coalization of coal." Currently, all creosote-processed wood products - the foundation and buildup of marine, timber, poles, rail crossty, wood, and power poles - are produced using this type of wood preservative. The manufacturing process can only be a pressure process under the supervision of licensed applicators certified by the State Department of Agriculture. No use of brush-on, spray, or non-pressure creosote is allowed, as determined by the EPA-approved label for creosote use. The use of creosot in accordance with the AWPA Standards makes it impossible to mix with other types of "creosot" materials - such as lignite-tar creosot, oily creosote, tar tar kreosote, water-gas-tar kreosote, or tar-wood creosote. However the Standard AWPA P3 enables the mixing of high petroleum oil that meets the P4 AWPA Standard.
The information that follows describes the different types of creosote materials and their use should be regarded as the only historical value. This history is important, as it traces the origins of different materials used during the 19th and early 20th centuries. In addition, it should be considered that other types of creosote - lignite-tar, wood-tar, water-gas-tar, etc. - are currently not being manufactured and have been replaced with more economical materials, or replaced by more efficacious products.
For some parts of their history, kleosote coal tar and wooden taro kreosote are regarded as equivalent substances - albeit different origins - explain their common names; both are determined and then become chemically different. All types of creosote consist of phenol derivatives and share a number of phenol monosubstitutions, but these are not the only active elements of creosote. For a beneficial effect, coal taro kreosote depends on the presence of naphthalene and anthracenes, whereas wooden tarre creosote depends on the presence of phenolic methyl ether. Otherwise, the type of tar will dissolve in water.
Creosote was first discovered in wood-tar form in 1832, by Carl Reichenbach, when he found it both in tar and pyroligneous acid obtained by dry distillation of beechwood. Because pyroligneous acid is known as an antiseptic and meat preservative, Reichenbach experiments by dipping meat into dilute dilute dilute solutions. He found that the meat was dried without decomposition and had reached a smoky taste. This led him to reason that the creosote is an antiseptic component contained in the smoke, and he further argues that the creosote he found in wood tar was also in coal tar, as well as tar and tar of animals, in the same abundance as in wood. ter.
Soon afterwards, in 1834, Friedrich Ferdinand Runge discovered carbolic acid in tar-coal, and Auguste Laurent obtained it from phenylhydrate, which was soon determined to be the same compound. There is no clear view of the relationship between carbolic acid and creosote; Runge describes it has similar caustic and antiseptic properties, but notes that it is different, because it is acidic and forms salt. However, Reichenbach argues that creosote is also an active element, as in pyroligneous acid. Despite contradictory evidence, his view holds power with most chemists, and it becomes generally accepted wisdom that kreosot, carbolic acid, and phenylhydrate are identical substances, with different degrees of purity.
Carbolic acid is soon commonly sold under the name "creosote", and the scarcity of wood-tar creosot in some places causes chemists to believe that it is the same substance as described by Reichenbach. In the 1840s, Eugen Freiherr von Gorup-Besanez, after realizing that two samples of substances labeled as distinct creosote, initiated a series of investigations to determine the chemical properties of carbolic acid, leading to the conclusion that it was more like chlorinated quinon and the necessity had become different substances, totally unrelated.
Independently, there is investigation of the chemical nature of creosote. A study by F.K. VÃÆ'¶lkel revealed that a purified creosote odor similar to guaiacol, and later studies by Heinrich Hlasiwetz identified a substance common to guaiacum and creosote which he called creosol, and he decided that creosote contained a mixture of creosol and guaiacol. Further investigation by Gorup-Besanez, A.E. Hoffmann, and Siegfried Marasse show that the wood tar kreosote also contains phenol, giving it similarity to the coal tar kreosote.
Historically, coal tar kreosote has been distinguished from what is considered a proper kreosot - the original substance of the Reichenbach discovery - and has been specifically referred to as "creosote oil". However, since creosote from tar-coal and wood tar are obtained from the same process and have some general uses, they have also been placed in the same class of substances, with the term "creosote" or "creosote oil" referring to the product.
Kreoset kayu-tar
Creosote wood tar is a colorless, oily liquid with a smoky odor, generates a flame when burned, and has a burning flavor. It does not float in water, weighing 1,037-1,087, maintains fluidity at very low temperatures, and boils at 205-225 ° C. When transparent, it is in its purest form. Dissolution in water requires up to 200 times the amount of water as a base of creosote. Creosote is a combination of natural phenols: especially guaiacol and creosol (4-methylguaiacol), which is usually 50% of oil; second in prevalence, cresol and xylenol; the rest is a combination of monophenols and polyphenols.
Simple phenol is not the only active ingredient in tar wood creosote. In solution, they clot albumin, which is a water-soluble protein found in meat; so they function as preservative agents, but also cause denaturation. Most of the phenols in the creosote are methoxy derivatives - they contain methoxy groups associated with benzene nuclei (O-CH 3 ). The high levels of methyl derivatives created from heat action in wood (also seen in methyl alcohol produced by distillation) make the tarwood creosot substantially different from the coal tar kreosote. Guaiacol is a methyl ether of pyrocatechin, while creosol is methyl ether methyl-pyrocatechin, the next pyrocatechin homologue. Methyl ether differs from simple phenol because it is less hydrophilic, caustic and toxic. This allows the meat to be successfully maintained without tissue denaturation, and allows the creosot to be used as a medical ointment.
Because wood-tar creosote is used for guaiacol and creosol content, it is generally derived from beechwood rather than other wood, as it extracts a higher proportion of the chemical to other phenolics. Kreosote can be obtained by distilling the wood tar and treating fractions heavier than water with sodium hydroxide solution. The alkaline solution is then separated from an insoluble oily layer, boiled in contact with air to reduce impurities, and broken down by dilute sulfuric acid. This produces a crude creosote, purified by re-solution in alkali and reconstituted with acids and then redistilled by a fraction passing between 200 ° and 225 ° which forms a purified creosote.
When iron chloride is added to the aqueous solution, it will turn green; ortho-oxy derived characteristics of benzene. It dissolves in sulfuric acid into the red liquid, which slowly turns into violet-violet. Shaken with hydrochloric acid in the absence of air, becomes red, the color changes in the air to dark brown or black.
In the preparation of foods with smoking, guaiacol contribute primarily to smoky flavors, whereas dimethyl ether pirogallol, syringol, is the main chemical responsible for the smoky aroma.
Historical usage
Industrial
Once found and recognized as the principle of smoked meat, kreosote tar is used as a substitute for the process. Some methods are used to apply creosote. The first is to dip the meat in pyroligneous acid or dilute creosote water, as the Reichenbach does, or brush it with them, and within an hour the meat will have the same quality as traditionally cooked. Sometimes creosote is diluted in vinegar rather than water, because vinegar is also used as a preservative. The other is placing the meat in a sealed box, and placing it a few drops of creosote in a small bottle. Because of creosote volatility, the atmosphere is filled with steam that contains it, and it will cover the meat.
The application of tar wood to sailing vessels in the sea was practiced through the 18th and early 19th centuries, before kreosot was isolated as a compound. The creosote-wood tar is found to be ineffective in the care of wood, as it is more difficult to impregnate the creosote into wood cells, but still experiments are carried out, including by many governments, as it proves to be cheaper in the market.
Medical
Even before creosote as a chemical compound was discovered, it is an active component of the main drug treatment in various cultures around the world.
In ancient times, pitches and resins were used generally as drugs. Pliny mentions various substances such as tar used as a drug, including cedria and pissinum . Cedria is the pitch and resin of the cedar tree, equivalent to the tar oil and pyroligneous acid used in the first stage of creosote distillation. He recommends cedria to relieve the pain of toothache, as an injection in the ear in the case of hearing loss, to kill parasitic worms, as a precaution for impregnation, as a treatment for phthiriasis and porrigo, as an antidote to the poison of sea rabbits, as a liniment for elephantiasis, and as an ointment to treat ulcers both on the skin and in the lungs. He further talked about the cedria used as an embalming agent to prepare mummies.
The PharmacopÃÆ' Â © e de Lyon , published in 1778, says that cedar oil is believed to cure vomiting and help treat tumors and ulcers. Doctors who are contemporary with the invention of creosote creams and recommended creams are made from tar or pitch to treat skin diseases. Air Tar has been used as a traditional medicine since the Middle Ages to treat affections such as dyspepsia. Bishop Berkeley wrote several works on the medical goodness of tar water, including a 1744 philosophical work entitled Siris: the philosophical reflex chain and the question of the virtue of water, and the divers of other subjects connected together and arising from one another. and a poem in which he praised his kindness. The pyroligneous acid is also used at the time in the water of a drug called Aqua Binelli .
Given this history, and the antiseptic nature known as kreosot, it became popular among physicians in the 19th century. The dilution of creosote in water is sold in pharmacies as Aqua creosoti , as suggested by prior use of pyroligneous acid. It is prescribed to extinguish stomach and intestinal irritability and detoxification, treat ulcers and abscesses, neutralize bad odors, and stimulate mucous tissue of the mouth and throat. Creosote is generally listed as an irritant, blood-stopping, antiseptic, narcotic, and diuretic, and in small doses when taken internally as a sedative and anesthetic. It is used to treat ulcers, and as a way to sterilize teeth and kill the pain in case of toothache.
Creosote was advised as a treatment for tuberculosis by the Reichenbach soon after 1833. After Reichenbach, it was disputed by John Elliotson and Sir John Rose Cormack. Elliotson, inspired by the use of creosote to retain vomiting during the cholera outbreak, suggested its use for tuberculosis through inhalation. He also suggested for epilepsy, neuralgia, diabetes and chronic glander. The idea of ​​use for tuberculosis failed to hold, and the use of this goal was dropped, until the idea was revived later in 1876 by the British physician G. Anderson Imlay, who suggested it was applied locally in spray to the bronchial mucous membranes. This was followed up in 1877 when it was disputed in a clinical paper by Charles Bouchard and Henri Gimbert. The germ theory was established by Pasteur in 1860, and Bouchard, arguing that bacillus was responsible for the disease, sought to rehabilitate creosote to be used as an antiseptic to treat it. He started a series of trials with Gimbert to convince the scientific community, and claimed a promising cure rate. A number of German publications justify their results in subsequent years.
After that, it was a period of experimental techniques and different chemicals using creosote in tuberculosis, which lasted until about 1910, when radiation therapy seemed to be a more promising treatment. Guaiacol, instead of a full creosote solution, was suggested by Hermann Sahli in 1887; he believes it has active creosote chemicals and has the advantage of a definite composition and has unpleasant flavors and odors. A number of solutions from both creosote and guaiacol appear on the market, such as phosphotal and guaicophosphal , fossa of creosote and guaiacol; eosot and geosot , valerinates of creosote and guaicol; phosot and taphosot , phosphate and tannophospate from creosote; and kreosotal and tanosal , preservatives of creosote. Creosote and eucalctus oil are also drugs that are used simultaneously, administered via vaporizor and inhaler. Since then, more effective and safe tuberculosis treatment has been developed.
In the 1940s, Canada-based Eldon Boyd experimented with guaiacol and recent synthetic modifications - glycerol guaiacolate (guaifenesin) - in animals. Her data indicate that both drugs are effective in increasing secretion to the airways in laboratory animals, when a sufficiently high dose is given.
Current use
Industry
Wood tar kreosit to some extent is used for wood preservation, but is generally mixed with coal tar creosot, since the former is ineffective. Preparation of "liquid smoke" sold on the market, is marketed to add smoked flavor to the meat and helps as a preservative, consisting mainly of creosote and other smoke elements. Creosote is the material that gives the liquid smoke its function; guaicol is suitable for flavor and creosote oil helps act as a preservative. Creosote can be destroyed by treatment with chlorine, either sodium hypochlorite, or calcium hypochlorite solution. The phenol ring is essentially exposed, and the molecule is then subject to normal digestion and normal respiration.
Medical
Guaifenesin developed by Eldon Boyd is still commonly used today as an expectorant, sold on a table, and is usually drunk to help raise sputum from the airways in acute respiratory infections. Guaifenesin is a component of Mucinex, Robitussin DAC, Cheratussin DAC, AC Robitussin, AC Cheratussin, Benylin, DayQuil Mucous Control, Meltus, and Bidex 400.
Seirogan is a popular Kampo drug in Japan, used as anti-diarrhea, and contains kreosote wood from beech, pine, maple or oak wood of 133 μg per adult dose as the main ingredient. Seirogan was first used as a gastrointestinal drug by the Japanese Imperial Army in Russia during the 1904-1905 Russian-Japanese War.
Creomulsion is a cough medicine in the United States, introduced in 1925, which is still sold and contains beechwood kreosote wood. Beechwood creosote is also found under the name kreosotum or kreosote .
Kreos-tar coal
Coal-tar creosote is a greenish brownish liquid, with different levels of darkness, viscosity, and fluorescence depending on how it is made. When freshly made, creosot is yellow oil with a greenish casts and is very fluorescent; fluorescence increases due to exposure to air and light. After deposition, the oil is dark green by reflecting light and dark red with the transmitted light. For the naked eye, it will generally look brown. Creosote (often called "creosote oil") is composed almost entirely of aromatic hydrocarbons, with a number of bases and acids and other neutral oils. The flash point is 70-75 Â ° C and the burning point is 90-100 Â ° C, and when burned it emits greenish smoke. Odor greatly depends on naptha content in creosote; if there is a high amount, will have a smell like naptha; otherwise it will smell more tar.
In the process of tar-coal distillation, the distillate is collected into four fractions; "light oils", which remain lighter than water, "middle oil" that is passed when light oil is released; "heavy oil", which sank; and "anthracene oil", which when cold is mostly dense and oily, from the consistency of butter. Creosote refers to the section of distilled coal tar as "heavy oil", usually between 230-270 ° C, also called "dead oil"; it sank into the water but still quite liquid. Carbolic acids are produced in the second fraction of distillation and are often distilled into what are termed "carbolic oils".
Commercial creosote will contain substances from six groups. Both groups occur in the largest amount and are the product of the distillation process - "tar acid", which distills below 205 Ã, Â ° C and mainly comprises phenols, cresols, and xylenols, including carbolic acids - and aromatic hydrocarbons. , which divides into naphthalene, which distills approximately between 205 ° and 255 ° C, and constituents of anthracene properties, distilling above 255 ° C. The amount of each varies based on the quality of the tar and the temperature used, but Generally, tar acid will not exceed 5%, naphthalene will reach 15 to 50%, and anthracenes will form 45% to 70%. Hydrocarbons are mainly aromatic; derivatives of benzene and related cyclic compounds such as naphthalene, anthracene, phenanthrene, acenapthene, and fluorene. Creosote from vertical-retort and low temperature ter contain, in addition, some paraffinic and olefinic hydrocarbons. The content of tar-acid also depends on the source of tar - probably less than 3% in the creosote of tar coke-oven and 32% high in the creosote of the vertical tar retort. All of these have antiseptic properties. Tart acid is the strongest antiseptic but has the highest solubility in water and is the most volatile; so, as with the tar wood creosot, phenol is not the most valuable component, because by itself they will lend to a bad preservative. In addition, creosot will contain some products that naturally occur in coal-containing heterocycles, which contain nitrogen such as carbides, carbazoles, and quinolines, which are referred to as "tar bases" and generally form about 3% of creosote-sulfur-containing heterocycles, generally benzothiophenes - and heterocycles containing oxygen, dibenzofuran. Finally, creosote will contain small amounts of aromatic amine produced by other substances during the distillation process and possibly resulting from a combination of thermolysis and hydrogenation. The tar bases are often extracted by washing creosote with aqueous mineral acids, although they are also advised to have an antiseptic ability similar to tar acid.
Creosote used commercially is often processed to extract carbolic, naphthalene, or anthracene acid content. Carbolic acid or naphthalene is generally extracted for use in other commercial products. The American produced creosote oil will usually have a low amount of anthracene and a high amount of naphthalene, because when imposing distillate at temperatures that produce anthracene, the soft pitch will be crushed and only the remaining hard pitch; these ruins are for use in roofing purposes, and leaving only commercially useless products.
Historical usage
Industry
The use of coal-tar creosote on a commercial scale began in 1838, when a patent covering the use of creosote oil for wood processing was taken by inventor John Bethell. The "Bethell process" - or later known, the full cell process - involves placing the wood to be treated in an enclosed space and applying a vacuum to remove air and moisture from the wood "cell". The wood is then pressured to impregnate it with creosote or other preservative chemicals, after which the vacuum is re-applied to separate the chemicals from the excessive wood treatment. Along with the zinc chloride-based "Burnett process", the use of creole wood prepared by the Bethell process is the primary means of conserving rail timber (eg, bonding, sleeping) so that rotting wood and replacement needs can be avoided.
In addition to caring for wood, it is also used for lighting and fuel. Initially, it was only used for lighting needed at ports and outside work, where the smoke generated from the combustion was slightly uncomfortable. In 1879, lights were made to ensure a more complete combustion by using compressed air, eliminating the weakness of the smoke. Creosote is also processed into gas and used for such illumination. As fuel, it is used to drive ships at sea and blast furnaces for different industrial needs, having been found to be more efficient than coal or unrefined wood. It also used the industry for hard field softening, and burned to produce black lights. In 1890, creosote production in the UK reached about 29.9 million gallons per year.
In 1854, Alexander McDougall and Angus Smith developed and patented a product called McDougall's Powder as a deodorant sewer; it mainly consists of carbolic acid derived from creosote. McDougall, in 1864, experimented with his solution to remove entozoose parasites from cattle grazing on a waste farm. This then causes the widespread use of creosote as a sweep of cattle and sheep. The external parasite will be killed in dilute dilute sauce, and the wet tube will be used to give the dosage to the animal's stomach to kill the internal parasite.
Two later methods for creosoting woods were introduced after the turn of the century, referred to as empty cell processes, as they involved compressing the air inside the wood so that preservatives could only coat the inner cell walls rather than saturate interior cell cavities. This is a less effective, though usually satisfactory, method of caring for wood, but is used because it requires less creosot material. The first method, the process of "RÃÆ'¼ping" was patented in 1902, and the second, the "Lowry process" patented in 1906. Then in 1906, the "Allardyce process" and "Card Process" were patented to care for wood with a combination of both creosote and zinc chloride. In 1912, it was estimated that a total of 150,000,000 gallons were produced in the United States per year.
Medical
Coal-tar creosote, despite its toxicity, is used as a stimulant and escharotic, as a caustic agent used to treat ulcers and malignancies and burn wounds and prevent infection and decay. It's mainly used in dentistry to destroy tissue and catch necrosis.
Current use
Industry
Coal-tar creosote is the most widely used wood treatment today; either industrially, processed into wood using pressure methods such as "full cell process" or "empty cell process", and more often applied to wood through brushing. In addition to toxicity to fungi, insects, and sea borers, it serves as a natural water repellent. These are commonly used for preserving and crossing waterproof, poles, telephone poles, power poles, marine poles, and fence posts. Although suitable for use in preserving structural wood buildings, generally not used as such because it is difficult to apply. There is also concern about the environmental impact of creosote preservative secretion into the aquatic ecosystem.
Because of its carcinogenic nature, the EU has regulated creosote quality for the EU market and requires that creosote sales be limited to professional users. The US Environmental Protection Agency regulates the use of coal tar fuel as a wood preservative under Federal Insecticide, Fungicide, and Rodenticide Act provisions. Creosote is considered a limited-use pesticide and is only available for licensed pesticide applicators.
Health effects
According to the Agency for Toxic Substances and Disease Registry (ATSDR), eating food or drinking water contaminated with high levels of tarospot can cause burning in the mouth and throat, and stomach pain. ATSDR also states that a short direct contact with a large number of taroset tar can cause severe rash or irritation of the skin, chemical burns on the surface of the eyes, convulsions and mental confusion, kidney or liver problems, unconsciousness, and even death.. Longer skin contact with a low level of creosote or steam mixture can increase light sensitivity, corneal damage, and skin damage. Longer exposure to creosote vapors may cause irritation of the respiratory tract.
The International Agency for Research on Cancer (IARC) has determined that coal tarosauros may be carcinogenic in humans, based on sufficient animal evidence and limited human evidence. It is important to note that testing on animals that IARC relies on involves the continuous application of creosote in the shaved rats' skin. After weeks of application of creosote, the animal develops a skin cancer lesion and in one test, a lung lesion. The US Environmental Protection Agency has stated that coal tar is a human carcinogen based on human and animal studies. As a result, the Federal Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit of 0.2 milligrams of creosote coal tar per cubic meter of air (0.2 mg/m3) in the workplace for 8 hours a day, and the Environmental Protection Agency (EPA) requires that spillage or unintentional discharge to the environment of one pound (0.454 kg) or more of creosote be reported to them.
There is no child's unique exposure path to kreosot. Children exposed to creosote may experience the same health effects seen in adults exposed to creosote. It is not known whether children differ from adults in their vulnerability to the health effects of creosote.
A 2005 mortality study of creosote workers found no evidence to support an increased risk of death from cancer, as a result of creosote exposure. Based on the findings of the largest mortality study to date workers working in the creosote logs factory, there is no evidence that the work at the creosote wood-treating plant or creosote-based preservative exposure is associated with a significant increase in mortality from both sites- certain cancers or non-malignant diseases. The study consists of 2,179 employees in eleven factories in the United States where wood is treated with creosote preservatives. Some workers began work in the 1940s until the 1950s. The observation period of this study covers 1979-2001. The average length of work is 12.5 years. One-third of research subjects were employed for more than 15 years.
The greatest health effect of creosote is death caused by a fire chimney due to the buildup of chimney tar (creosote). It is entirely unrelated to the production or use of its industry.
Oil-tar creole
The tar oils come from the tar formed when using petroleum oil or flakes in the manufacture of gas. Distillation of tar from oil occurs at very high temperatures; about 980 ° C. The tar is formed at the same time as the gas, and after processing for creosote contains a high percentage of cyclic hydrocarbons, a very low amount of tar and tar acids, and no correct anthracenes have been identified. Historically, this was mainly produced in the United States on the Pacific coast, where petroleum is more abundant than coal. Limited quantities have been used industrially, either alone, mixed with coal tar creosot, or enriched with pentachlorophenol.
Water-gas-tar kreosote
Creosote water-gas-tar also comes from petroleum oil or shale oil, but with different processes; which is distilled during the production of water gas. Tar is a byproduct that results from gas enrichment of water with gases produced by thermal decomposition of petroleum. From the oil-derived creosote, the only practical one used for wood preservation. It has the same degree of solubility as the coal tar kreosote and is easy to impregnate into the wood. Like standard oil-tar creosote, it has a low amount of tar and tar acids, and has fewer antiseptic qualities. The Petri dish test shows that the sixth-tiered water-gas-tar kreosote is as effective anti-septic as tar-coal.
kreosote Lignite-tar
Creosote lignite-tar is produced from lignite and not bituminous coal, and varies greatly from coal-tar creosote. Also called "lignite oil", has a very high tar acid content, and has been used to increase tar acid in normal creosot when needed. When it has been produced, it has generally been applied in a mixture with coal tar or petroleum creosot. Its effectiveness when used alone has not been established. In an experiment with a southern pine pine pole in Mississippi, straight lignite-tar creosot gave good results after about 27 years of exposure, though not as good as the tarososal tar standards used in the same situation.
peat-tar kreosote
There was also an attempt to distill creosot from tar-peat, although most were unsuccessful due to problems with winning and peat-draining on an industrial scale. The tar's own peat in the past has been used as a wood preservative.
Maps Creosote
Build-up in chimneys
Burning wood and fossil fuels in the absence of adequate airflow (such as in a furnace or covered stove), causes incomplete burning of oil in wood, which is gaseous as volatile in smoke. When smoke rises through the chimney it cools, causing water, carbon, and volatiles to condense on the interior surfaces of the chimney. The black oily residue formed is called a creosote, which is similar in composition to a commercial product of the same name, but with a higher carbon black content.
During the season creosote deposits can be a few inches thick. This creates a compounding problem, because the creosote pile reduces the draft (airflow through the chimney) which increases the likelihood that the wood fire does not get enough air for perfect combustion. Because creosote is highly flammable, thick accumulation creates a fire hazard. If a hot flame is built on a stove or fireplace, and air control is left wide open, it allows hot oxygen to enter the chimney in contact with the creosot which then lights - causing a stack fire. Chimney fires often spread to the main building because the chimney gets so hot that it ignites the combustible material that comes into direct contact with it, like wood. The fire can also spread to the main building from sparks that emanate from the chimney and land on the surface of the combustible roof. To maintain good chimneys and heaters that burn wood or carbon-based fuels, creosote buildup should be eliminated. Chimney sweeps doing this service for a fee.
Between 2002 and 2004, 73% of fire heating and 27% of all residential fires in the United States were found to be caused by failure to clean out creosote buildup. Since 1990, creosote buildup has caused 75% less fire. This is partly due to the efficient use of fuelwood stoves that completely burn carbon from fuel, and partly because of the use of Class A pipes, insulated double wall stainless steel pipes.
Releasing to the environment
Although creosote is pressed into the wood, the release of chemicals can be seen from various events. During the period of ocean buildup, weathering occurs from the ebb and flow of water that slowly opens the oily outer layer and exposes the smaller internal pores to more water flow. Weathering is frequent every day, but more severe weather, like hurricanes, can cause damage or loss of wooden poles. Much of the buildup is broken into pieces from the debris, or completely drifted during this storm. When the poles drift, they will settle on the bottom of the body of water where they live, and then they release the chemicals into the water slowly for long periods of time. This long-term secretion is usually overlooked because the buildup is submerged beneath the hidden surface of view. Creosote is largely insoluble in water, but lower molecular weight compounds will dissolve as longer wood exposed to water. In this case, some chemicals are now becoming water soluble and further seeping into the water sediment while remaining insoluble chemicals remain together in a tar-like substance. Other sources of damage come from dull wooden fauna such as Shipworms and Limnoria. Although kreosot is used as a pesticide preservative, studies have shown that Limnoria is resistant to wood preservative pesticides and can cause small holes in the wood that can be emptied by creosote.
Chemical reactions with sediment and organism
Once the soluble compound of the creosote preservative is released into the water, the compound begins to react with the external environment or is consumed by the organism. The reaction varies depending on the concentration of each compound released from the creosote, but the major reactions are described below:
Alkylation
Alkylation occurs when a molecule replaces a hydrogen atom with an alkyl group generally derived from an organic molecule. The alkyl group found naturally in the environment is an organometallic compound. Organometallic compounds generally contain methyl, ethyl, or butyl derivatives which are alkyl groups that replace hydrogen. Other organic compounds, such as methanol, may provide alkyl groups for alkylation. Methanol is found naturally in environments in small concentrations, and has been associated with the release of biological decomposition of waste and even the by-products of vegetation. The following reactions are the alkylation of the soluble compounds found in the creosote preservatives with methanol.
m-Cresol
The diagram above illustrates the reaction between m-cresol and methanol in which the c-alkylation product is produced. The c-alkylation reaction means that instead of replacing the hydrogen atoms in the -OH group, the methyl group (from methanol) replaces the hydrogen in the carbon in the benzene ring. The products of this alkylation may be a para- or ortho orientation of the molecule, as seen in the diagram, and water, not shown. The isomer of dimethylphenol compounds (DMP) is a product of para- and ortho-c-alkylation. Dimethylphenol (DMP) compounds are listed as an aquatic hazard by characteristic, and are toxic with long-term effects.
Phenol
This diagram shows the o-alkylation between phenol and methanol. In contrast to c-alkylation, o-alkylation replaces the hydrogen atom in the -OH group with the methyl group (from methanol). The product of o-alkylation is methoxybenzene, better known as anisole, and water, which is not shown in the diagram. Anisole is listed as an acute danger to aquatic life with long-term effects.
Bioaccumulation
Bioaccumulation is the process by which organisms take chemicals through consumption, exposure, and inhalation. Bioaccumulation is broken down into bioconcentration (absorption of chemicals from water only) and biomagnification (absorption of chemicals from food sources). Certain species of aquatic organisms are affected differently from chemicals removed from creosote preservatives. One of the organisms studied is molluscs. Molluscs stick to wooden poles, sea and in direct contact with creosote preservatives. Many studies have been conducted using Polycyclic aromatic hydrocarbons (PAHs), which are low molecular hydrocarbons found in some creosot-based preservatives. In a study conducted from Pensacola, Florida, a group of original molluscs were kept in a controlled environment, and different groups of the original molluscs were stored in an environment contaminated with creosote preservatives. Mollusks in contaminated environments are shown to have a bioaccumulation up to ten times the concentration of PAHs than control species. The intake of an organism depends on whether the compound is in ionized or unionized form. To determine whether the compound is ionized or not ionized, the pH of the surrounding environment must be compared with the pKa or the acidity constant of the compound. If the pH of the environment is lower than pKa, then the compound is not ionized which means that the compound will behave as if it is non-polar. The bioaccumulation for the unionized compound comes from the balance partition between the aqueous phase and the lipids in the organism. If the pH is higher than pKa, then the compound is considered in ionized form. Unionized forms are preferred because bioaccumulation is easier for organisms to enter through the equilibrium partition. The table below shows the pKas list of the compounds found in the creosote preservatives and compares them with the mean pH of seawater (reported 8.1).
Each of the compounds in the above table is found in creosote preservatives, and they are all in the preferred un-ionized form. In another study, various small fish species were tested to see how time of exposure to PAH chemicals affects fish. This study shows that the 24-96 hour exposure time in various species of shrimp and fish affects the growth, reproduction, and survival function of the organism for most of the compounds tested.
Biodegradation
Biodegradation can be seen in several studies that biodegradation contributes to the absence of creosote preservatives on the early surface of sediments. In a study from Pensacola, Florida, PAHs were not detectable on the surface in water sediments, but the highest concentrations were detected at a depth of 8-13 centimeters. An anaerobic biodegradation of m-cresol is seen in a study using a sulfate reduction enriched enzyme and nitrate reduction. The reduction of m-cresol in this study was seen under 144 hours, while additional chemical intermediates were being established. Mid-chemistry is formed in the presence of bicarbonate. Products include 4-hydroxy-2-methylbenzoic acid and acetate compounds. Although the condition is enriched by the reduction of anaerobic compounds, sulphate and nitrate reducing bacteria are commonly found in the environment. For more information, see sulfate-reducing bacteria. The type of anaerobic bacteria ultimately determines the reduction of the creosote preservative compound, while each individual compound can only pass through the reduction under certain conditions. BTEX is a mixture of benzene, toluene, ethylbenzene, and xylene, studied in the presence of four different enriched anaerobic sediments. Although the compound, BTEX, is not found in creosote preservatives, the creosote oxidation-oxidation reaction products include some of these compounds. For the oxidation reduction reaction, see the following section. In this study, it appears that certain compounds such as benzene are only reduced under the enriched environments of sulfates, while toluene is reduced under various bacteria enriched environments, not just sulfates. The biodegradation of creosote preservatives in anaerobic enrichment depends not only on the type of bacteria that enriches the environment, but also the compounds that have been released from preservatives. In aerobic environments, preservative compounds are limited in the biodegradation process by the presence of free oxygen. In an aerobic environment, free oxygen comes from oxygen-saturated sediments, sediment sources, and edges of the feathers. Free oxygen allows the compound to be oxidized and decomposed into a new intermediate compound. Studies have shown that when the BTEX and PAH compounds are placed in an aerobic environment, oxidation of the ring structure causes cleavage of the aromatic ring and allows for other functional groups to be attached. When the aromatic hydrocarbons are introduced into molecular oxygen under experimental conditions, the dihydrodiol intermediates are formed, and then oxidation occurs converting aromatics into catechol compounds. Catechol allows aromatic ring division to occur, in which functional groups can then add in ortho or methane positions.
Oxidation Reduction
Although many studies perform testing under experimental or enriched conditions, oxidation reduction reactions occur naturally and allow chemicals to go through a process such as biodegradation, described above. Oxidation is defined as the loss of electrons to other species, whereas reduction is the acquisition of electrons from other species. As compounds through oxidation and sediment reduction, the preservative compounds are altered to form new chemicals, leading to decomposition. Examples of oxidation of p-cresol and phenol can be seen in the figure below:
p-Cresol
This reaction shows the oxidation of p-cresol in a sulphate-rich environment. P-cresol is seen most easily degraded through a sulphate-rich environment, while m-cresol and o-cresol are inhibited. In the graph above, p-cresol is oxidized under anaerobic sulphate reduction conditions and forms four distinct intermediates. After the formation of intermediates, the study reported further degradation of intermediates leading to the production of carbon dioxide and methane. P-hydroxylbenzyl alcohol, p-hydroxylbenzaldehye, p-hyrdoxylbenzoate, and benzoate intermediates are all produced from this oxidation and released into the sediment. Similar results are also produced by various studies using other forms of oxidation such as iron-reducing organisms, Copper/Manganese Oxide catalysts, and nitrate reduction conditions.
Phenol
This reaction shows the oxidation of phenol by iron and peroxide. This combination of iron, derived from iron oxides in sediments, and peroxides, commonly released by animals and plants to the environment, is known as the Fenton Reagent. This reagent is used to oxidize the phenol group by using a radical hydroxide group produced from peroxides in p-benzoquinone. This phenol oxidation product is now washed into the environment while other products include iron (II) and water. P-benzoquinone is listed as a highly toxic acute environmental hazard.
Environmental hazards
Sediment
In aquatic sediments, a number of reactions can alter the chemicals released by creosote preservatives into more harmful chemicals. Most of the creosote preservative compounds have a hazard associated with them before they are transformed. Cresol (m-, p-, and o-), phenol, guaiacol, and xylenol (1,3,4- and 1,3,5-) are all acute aquatic hazards prior to chemical reactions with sediments. Alkylation reactions allow compounds to transition into more toxic compounds by addition of R-groups to the main compounds found in creosote preservatives. The compounds formed by alkylation include: 3,4-dimethylphenol, 2,3-dimethylphenol, and 2,5-dimethylphenol, all of which are listed as acute environmental hazards. Biodegradation controls the rate at which sediments retain chemicals, and the number of reactions that can occur. The biodegradation process can take place under many different conditions, and varies depending on the compound being released. The oxidation reduction reaction allows the compound to be broken down into new forms of more toxic molecules. Studies have shown oxidation-reduction reactions of creosote preservative compounds including compounds listed as environmental hazards, such as p-benzoquinone in phenol oxidation. Not only are the early compounds in creosote harmful to the environment, but the by-products of chemical reactions are also harmful to the environment.
More
From sediment contamination, more ecosystems are affected. Organisms in the sediments are now exposed to new chemicals. The organism is then ingested by fish and other aquatic animals. These animals now contain the concentration of harmful chemicals secreted from the creosote. Other issues with the ecosystem include bioaccumulation. Bioaccumulation occurs when high levels of chemicals are passed into aquatic life near the creosote pile. Mollusks and other small crustaceans are at higher risk because they are attached directly to the surface of a wood pile filled with creosote preservatives. Studies show that mollusks in this environment take a high concentration of chemical compounds which will then be transferred through the ecosystem food chain. Bioaccumulation contributes to higher concentrations of chemicals in organisms in aquatic ecosystems.
Pole remediation
While the wood treated creosote is no longer used in the construction of structures and docks, damaged old columns can still contain these creosote preservatives. Many properties contain docks built before 2008 with creosote preservatives, and now remain in the water even if broken down. One simple remedy for this is moving the pile after it is broken or no longer used. On the beach, once the storm passes, the debris and debris break the dock built on the water. One of the more difficult solutions is for the buildup that has sunk to the bottom of the water and settled in the sediments. This buildup is invisible and more difficult to detect. The poles will then sit at the bottom and release chemicals into the sediments and ecosystems. Solutions to hidden stack problems can be an analytical or engineering method that can be used to track down creosote compounds or by-products in situ (from the contamination site). If there are techniques that can be used in the field that can track higher chemical concentrations in the sediment, then the hidden pile can be isolated and removed from the environment. Many methods, such as gas chromatography-mass spectroscopy (GCMS) and high performance liquid chromatography (HPLC), have been used to identify creosote creamer in groundwater and sediment, but most methods have to be taken back to the laboratory to be done properly because of time and instrument size. The new study shows that the use of more friendly and more friendly bio-assays is available to researchers so they can be used in the field for faster identification of chemical compounds. A test that can identify the kreosot compound or other toxic byproducts quickly and efficiently in the field will allow the researchers to remove the contaminated pile before further damage can be done.
See also
- Pentachlorophenol
- Creolin
Note
References
External links
Source of the article : Wikipedia
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