Tiffany Haney
Peroxyacetyl nitrate (PAN) is a prevalent peroxyacyl nitrate and a powerful respiratory and eye irritant present in photochemical smog. It is a secondary pollutant, formed from other pollutants through chemical reactions in the atmosphere. PAN is produced through the thermal oxidation of polyacrylonitrile (PAN) fibre, a synthetic organic polymer resin. PAN fibres are the chemical precursors of high-quality carbon fibres, which are used in various applications, including aircraft structures, missiles, and sporting goods. The first mass production of PAN fibre was in 1946, and it has since been utilised in the creation of numerous products, such as ultrafiltration membranes and textile fibres.
| Characteristics | Values |
|---|---|
| Full form | Peroxyacyl nitrates (PANs) or Polyacrylonitrile (PAN) |
| Composition | Peroxyacetyl nitrate, peroxypropionyl nitrate (PPN), peroxybenzoyl nitrate (PBzN), and methacryloyl peroxynitrate (MPAN) |
| Chemical properties | PAN is a powerful respiratory and eye irritant, toxic and thermally unstable |
| Use | PAN is used as the precursor for 90% of carbon fiber production |
| Glass transition temperature | 95 °C |
| Fusion temperature | 322 °C |
| Solvents | Polar solvents such as dimethylformamide, dimethylacetamide, ethylene and propylene carbonates, and in aqueous solutions of sodium thiocyanate, zinc chloride or nitric acid |
| Solubility parameters | 26.09 MPa1/2 (25 °C) are 25.6 to 31.5 J1/2 cm−3/2 |
| Dielectric constants | 5.5 (1 kHz, 25 °C), 4.2 (1 MHz, 25 °C) |
| Synthesis | Most commercial methods for the synthesis of PAN are based on free radical polymerization of acrylonitrile |
| First mass production | 1946 by American chemical conglomerate DuPont |
| Brand name | Orlon |
| Non-stick coating | Teflon |
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What You'll Learn
- Peroxyacetyl nitrate (PAN) is a pollutant and respiratory irritant
- PAN is produced through the oxidation of hydrocarbons in the atmosphere
- PAN is more stable than ozone, allowing it to be transported over long distances
- PAN is a precursor to high-quality carbon fibre used in aircraft and sports equipment
- Teflon is a chemical coating used in non-stick pans
Peroxyacetyl nitrate (PAN) is a pollutant and respiratory irritant
Peroxyacetyl nitrate (PAN) is a secondary pollutant and a powerful respiratory and eye irritant. It is a peroxyacyl nitrate that is formed by the action of sunlight on volatile organic compounds (VOCs) and nitrogen oxides. PAN is produced in the thermal equilibrium between organic peroxy radicals by the gas-phase oxidation of VOCs or by aldehydes and other oxygenated VOCs oxidizing in the presence of NO2.
PAN is a major component of photochemical smog, which is a type of air pollution that occurs when sunlight reacts with pollutants in the atmosphere. This reaction forms a variety of harmful compounds, including PAN, which can irritate the eyes, nose, throat, and lungs. It is more stable and has higher water solubility than ozone, making it more capable of long-range transport and more irritating to the eyes and respiratory system.
The formation of PAN involves the oxidation of hydrocarbons to peroxyacetic acid radicals, which then react with nitrogen dioxide (NO2) to form PAN. This process occurs in the atmosphere through photochemical reactions, and PAN can be transported over long distances, carrying nitrogen oxides to otherwise unpolluted regions. At lower temperatures, PAN is stable and can travel through cold regions of the atmosphere, while at higher temperatures, it decomposes into NO2 and peroxyacetyl radicals.
The toxicity of PAN is a concern, with studies showing its acute toxicity to be higher than that of ozone and similar to NO2. It is a weak point mutagen or clastogen, and exposure to PAN has been linked to pathological and histological changes in the respiratory system, particularly in the nasal passages. Studies on mice have also shown that long-term exposure to PAN can cause pulmonary lesions and increase susceptibility to acute and chronic bacterial infections.
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PAN is produced through the oxidation of hydrocarbons in the atmosphere
Peroxyacetyl nitrate (PAN) is a peroxyacyl nitrate and a secondary pollutant present in photochemical smog. It is formed in the atmosphere through the oxidation of hydrocarbons, specifically the oxidation of non-methane volatile organic compounds (NMVOCs) in the presence of nitrogen oxide radicals (NOx). This process involves the oxidation of unburned non-methane hydrocarbons to aldehydes, which then react with nitrogen dioxide (NO2) to form PAN. The principal carbonyl precursors of PAN are acetaldehyde (contributing 44% of the global source), methylglyoxal (30%), and acetone (7%).
PAN is a powerful respiratory and eye irritant, with higher toxicity than ozone. It dissolves more readily in water than ozone and causes eye irritation at very low concentrations. PAN is also a mutagen, potentially contributing to the development of skin cancer. Due to its stability and ability to transport NOx over long distances, PAN plays a significant role in enhancing ozone production in the lower troposphere.
The decay of PAN in the atmosphere is primarily thermal, with decomposition occurring at warmer levels. PAN can be photolysed by UV radiation, and its natural concentration in the atmosphere is typically below 0.1 μg/m3. However, measurements in certain urban areas, such as German cities and Los Angeles, have shown significantly higher values, emphasizing the impact of anthropogenic sources of PAN precursors.
It is important to distinguish peroxyacetyl nitrate PAN from polyacrylonitrile (PAN), which is a synthetic, semicrystalline organic polymer resin. Polyacrylonitrile PAN is used as a precursor for carbon fiber production and has various applications, including textiles and high-tech structures. The two PANs have distinct chemical compositions and should not be confused with each other.
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PAN is more stable than ozone, allowing it to be transported over long distances
Peroxyacetyl nitrate (PAN) is a secondary pollutant present in photochemical smog. It is a peroxyacyl nitrate, which is a type of nitrate produced in the thermal equilibrium between organic peroxy radicals by the gas-phase oxidation of volatile organic compounds (VOCs). PAN is produced in the atmosphere via the photochemical oxidation of hydrocarbons to peroxyacetic acid radicals, which react with nitrogen dioxide (NO2) to form PAN.
PAN is more stable than ozone, particularly at lower temperatures. This stability allows it to be transported over long distances, providing nitrogen oxides to otherwise unpolluted areas. The decay of PAN in the atmosphere is mainly thermal, with long-range transport occurring through cold regions of the atmosphere, and decomposition taking place at warmer levels. PAN can also be broken down by UV radiation.
PAN is a powerful respiratory and eye irritant, more so than ozone, which is sparingly soluble. PAN is toxic and dissolves more readily in water than ozone. At higher concentrations, it can cause extensive damage to vegetation. PAN is also toxic to humans, with high concentrations in some urban environments potentially posing mutagenic and carcinogenic risks.
PAN is an important photochemical product that affects ozone (O3) formation in the troposphere. It acts as a carrier and a reservoir for NOx, facilitating ozone formation on a global scale. While PAN concentrations have been decreasing in some urban areas, likely due to reductions in primary pollutants, PAN chemistry can still promote O3 formation by raising ROx levels.
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PAN is a precursor to high-quality carbon fibre used in aircraft and sports equipment
Polyacrylonitrile (PAN) is a synthetic, semi-crystalline organic polymer resin with the formula (CH2CHCN)n. It was first synthesized in 1930 by German chemists Hans Fikentscher and Claus Heuck, but further research was halted due to difficulties in dissolving the substance. In 1938, Herbert Rein discovered that PAN could be dissolved using an ionic liquid, and spun the first fibers based on PAN.
PAN is used to produce a variety of products, including ultrafiltration membranes, hollow fibers for reverse osmosis, and fibers for textiles. However, its most notable application is as a precursor to high-quality carbon fiber. PAN fibers undergo thermal oxidation in air at 230 °C to form oxidized PAN fibers, which are then carbonized in an inert atmosphere at temperatures above 1000 °C to produce carbon fibers.
These carbon fibers possess several desirable characteristics, including high strength, stiffness, lightweight, corrosion resistance, and excellent electrical performance. They find applications in both high-tech and everyday products, such as aircraft structures, missiles, solid propellant rocket motors, pressure vessels, sports equipment like fishing rods, tennis rackets, and bicycle frames. Approximately 20-25% of Boeing and Airbus wide-body airframes are constructed from carbon fibers.
Despite its advantages, the use of PAN-based carbon fibers is limited by their high price, typically around $15 per pound. However, advancements in technology, such as resonant acoustic mixing with boron nitride nanotubes, have led to the development of carbon fibers with enhanced tensile strength and storage modulus.
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Teflon is a chemical coating used in non-stick pans
There has been some controversy around the use of Teflon due to concerns about its potential health impact. Some sources claim that it is harmful and linked to health conditions such as cancer, while others insist that cooking with nonstick cookware is completely safe. One concern is related to the use of perfluorooctanoic acid (PFOA) in the manufacturing process, which has been linked to various health issues. However, the use of PFOA in the manufacturing of Teflon-coated cookware has been stopped.
Another concern is the potential for PTFE particles to flake off from the cookware and be ingested. While these particles are not considered harmful, heating Teflon above 300 degrees Celsius or 570 degrees Fahrenheit can release toxic fumes that are dangerous to both humans and birds. Therefore, it is important to follow basic safety precautions when using nonstick cookware, such as avoiding high heat and ensuring proper ventilation.
Despite the concerns, Teflon-coated nonstick pans have become common in most people's kitchens due to their convenience and ease of use. They are also approved by the US FDA as safe food processing equipment. Premium nonstick coatings, such as Teflon™ Platinum Plus, are tailored to withstand intense use and have been used by professional chefs for many years.
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Frequently asked questions
PAN can refer to Peroxyacyl Nitrate, a secondary pollutant and respiratory and eye irritant present in photochemical smog, or Polyacrylonitrile, a synthetic, semicrystalline organic polymer resin.
Peroxyacyl Nitrate is produced in the thermal equilibrium between organic peroxy radicals by the gas-phase oxidation of volatile organic compounds (VOCs). It is also formed from aldehydes and other oxygenated VOCs oxidizing in the presence of NO2.
Polyacrylonitrile is created through the polymerization of acrylonitrile. It was first synthesized in 1930 by Hans Fikentscher and Claus Heuck, although further research was halted due to the material's non-fusible nature.
Peroxyacyl Nitrate is a pollutant that irritates the eyes and lungs. It is more stable than ozone and is capable of long-range transport, causing ozone formation in the global troposphere.
