carbon monoxide[69]（carbon monoxide[69]）, a carbon oxygen compound, chemical formula CO[69], molecular weight 28.0101[69]Generally, it is colorless, odorless and tasteless gas.Physically, the melting point of carbon monoxide is - 205 ℃[69], boiling point is - 191.5 ℃[69], insoluble in water (solubility0.002838g[1]）It is not easy to liquefy and solidify.In terms of chemical properties, carbon monoxide has both reducing and oxidizing properties, and can produce oxidation reaction (combustion reaction), disproportionation reaction, etc;At the same time, it is toxic and can make people appear different degrees at higher concentrationspoisoningSymptoms, damage to human brain, heart, liver, kidney, lung and other tissues, and evenShock like deathThe minimum lethal concentration for human inhalation is 5000ppm (5 minutes).In industry, carbon monoxide isOne carbon chemistryIt can be made by coke oxygen method and other methods, and is mainly used for productionmethanolandphosgeneAnd organic synthesis.
Chinese name
carbon monoxide
Foreign name
carbon monoxide[2]
chemical formula
CO[2]
molecular weight
twenty-eight point zero one zero one[3]
CAS login number
630-08-0[2]
EINECS login number
211-128-3[2]
Melting point
-205 ℃[2]
Boiling point
-191.5℃（101.325 kPa）[2]
Water solubility
Insoluble in water
Appearance
Colorless and odorless gas[2]
Flash point
Below - 50 ℃[2]
Application
For production of methanol and phosgene and organic synthesis
In ancient Greece, philosophersAristotle(Aristotle, 384-322 BC) once recorded the phenomenon of toxic fumes emitted by burning coal.At that time, there was such a way to execute the death penalty: lock the criminals in a bathroom and place smouldering coals in the bathroom.In this regard, the ancient Greek doctorsGalen(Galen, 129-199) It is speculated that the composition of the air in the bathroom has changed, so the inhalation will cause harm to the human body.[5]
Later, the Belgian chemist Hermont (i.eJan Baptist van Helmont , Jan Baptista van Helmont, 1580-1644) studied the gas carbon generated by burning charcoal and other combustibles in experiments, found that a toxic gas generated by smouldering charcoal could endanger his own life, and recorded the symptoms of carbon monoxide poisoning when he was smoked by burning charcoal.[5]
In 1776, the French chemist Joseph Marie Fran ç ois de Lassone, from July 3, 1717 to December 6 or 8, 1788, also translated "J.M.F. Drathon"[6]"In the cable"[7]Larsen[8]Liesang[9]And "Larson"[10]Carbon monoxide gas is produced by heating zinc white and charcoal.However, due to carbon monoxide combustionhydrogenSimilar blue flame, Lasona in the Memorandum of the Royal Academy of Sciences（Mém. de l 'Acad. Roy des Sciences）(Vol. XC) mistakenly described the produced carbon monoxide gas as "a kind of combustible air with extremely strange properties" - hydrogen.[11-12]Later, Priestley (i.eJoseph PriestleyJoseph Priestley (1733-1804) prepared carbon monoxide by heating cast skin (iron oxide) with charcoal in 1785, but because of his belief in“Phlogiston theory”He also mistakenly thought that what he made was "combustible air".[5]
In 1801, Nixon Magazine（Nicholson’s Journal）The Scottish chemist Krukshank (William Cumberland Krukshank, June 27, 1745-1800, also translated as "William Krukshank")[6]), which proved that the so-called "combustible air" of Priestley is a compound composed of carbon and oxygen.[5][13-14]
In 1846, the French physiologist Claude Bernard (1813-1878) asked dogs to inhale carbon monoxide gas and found that the dog's blood "became redder than the blood in any artery", which was the first study of carbon monoxide toxicity (the phenomenon of blood becoming "cherry red" was later confirmed to becarbon monoxide poisoningSpecific clinical symptoms).[12]
molecular structure
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CO molecule is a heteronuclear diatomic molecule composed of a C atom and an O atom. The molecular shape is linear.[15-16]
According to the electron pairing method（Valence bond theory）, C atom (1stwo2stwo2px2py）And O atoms (1stwo2stwo2pxtwo2py2pz）Each contains two unpaired electrons, which can form two covalent bonds: one is 2pxσ bond formed by coupling along the x-axis, the other is 2pyElectrons form π bonds "side by side" along the x-axis.Its structure should be a general double bond structure:
。Correspondingly, the characteristics of its double bond should be the same as that of ordinary carbon oxygen double bond (carbonyl), that is, the bond length is 121 pm, the bond energy is 724 kJ/mol[17-18]], the dipole moment is 7.7 × 10-30C · m (about 2.3Debye）。However, the measured CO bond length is 113 pm, which is shorter than the common carbon oxygen double bond;The bond energy is 1071.1kJ/mol (about 256 kcal/g bond), which is larger than the common carbon oxygen double bond;The dipole moment is 3.3 × 10-31C · m (about 0.1 debye), about the average carbon oxygen double bond
。Due to the above contradiction, some scholars proposed the triple bond structure:
, that is, in CO molecule, except oneσ bondAnd api bondIn addition, there is a coordination key (represented by "←").[15][19-20]
According to the molecular orbital method (molecular orbital theory), it can be naturally obtained that CO molecule has a triple bond structure.According to the molecular orbital method, the CO molecular orbital is composed of the C atomic orbital and the O atomic orbital. The formation formula of the CO molecular orbital is
From the formation formula of CO molecular orbital, CO molecule and NtwoThe molecular structures are very similar, and they are all combined by triple bonds (σ+π+π):σ bond（
）One π bond is a coordination bond, and the shared electron pair is provided by O atom.The bonding process is as follows: the outermost layer of C atom has four electrons, and the outermost layer of O atom has six electrons. Two single electrons of C atom enter into the p orbital of O atom and two single electrons of O atom pair to form bonds, forming two covalent bonds. Then the lone electron pairs of O atom enter into the empty p orbital of C atom to form a coordination bond, forming three covalent bonds in total.[15-16][20-21]
The molecular orbital energy level diagram is as follows:
Molecular Orbital Energy Level Diagram of Carbon Monoxide[22]
As CO molecule is combined by triple bond, the bond length of CO is shorter than that of ordinary carbon oxygen double bond, and the bond energy is larger than that of ordinary carbon oxygen double bond;At the same time, because the electronegativity of O atom is higher than that of C atom, the electron cloud should be biased towards O atom, so that CO molecule should have a large dipole moment. However, the electron pair forming coordination bond in CO molecule is provided by O atom alone, which makes the electron cloud feedback to C atom, to some extent, compensating the polarity caused by the poor electronegativity between O atom and C atom, making the dipole moment of CO molecule very small,It is consistent with the fact that the dipole moment of CO molecule is very small.[15][20][23]
Physical and chemical properties
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physical property
Under normal conditions, carbon monoxide is colorless, odorless, tasteless and insoluble in water,[24]The physical constants are as follows:
nature
Condition or symbol
Company
numerical value
melting point
℃
-205
Three phase point
15.3kPa
℃
-205.1
boiling point
101.325kPa
℃
-191.5
relative density
Liquid, water=1
zero point seven nine three
Relative vapor density
Air=1
zero point nine six seven
Specific volume
21.1℃，101.325kPa
Cubic meter per kilogram (mthree/kg）
zero point eight six one five
Vapor pressure
-203.43℃
KPa
twenty
-180℃
three hundred and five
140℃
three thousand and five hundred
critical temperature
℃
-140.2
critical pressure
KPa
three thousand four hundred and ninety-nine
Critical density
Kg/m3 (kg/mthree）
three hundred and one
Octanol/water partition coefficient
one point seven eight
viscosity
101.325kPa，0℃
Millipascal second (mPa · s)
zero point zero one six six two
surface tension
-100℃
N/m
zero point zero zero nine eight
Flammable range in air
20℃，101.325kPa
12.5%～74%
Minimum ignition point in air
101.325kPa
℃
six hundred and thirty
(Table reference:[2]）
chemical property
Carbon monoxide is an unsaturated metastable molecule, which is chemically stable in terms of decomposition.Under normal temperature, carbon monoxide does not react with acid, alkali, etc., but can form explosive mixture when mixed with air. It can cause combustion and explosion when encountering open fire and high temperature. It is a flammable and explosive gas.Since the valence of carbon element in carbon monoxide molecule is+2, it can be oxidized to+4, which is reducible;It can be reduced to low valence state and has oxidation property.[25-29]
1. Oxidation reaction (combustion reaction)
Carbon monoxide can be burned in air or oxygen to produce carbon dioxide:
When burning, it emits blue flame and a large amount of heat.[28]
Because the carbon oxygen bond in carbon monoxide molecule is very strong and requires a high activation energy, carbon monoxide cannot be decomposed without catalyst in fact.Carbon monoxide can be decomposed only when it is actively adsorbed on the crystal surface of some substances.Iron ranks first among these substances, and the decomposition mechanism of carbon monoxide with iron participation can be expressed as follows:
The total chemical reaction equation is:
。[30-31]
3. Shift reaction
Under certain conditions, carbon monoxide and water vapor react equimolar to generate hydrogen and carbon dioxide: CO+HtwoO → Htwo+ COtwo。In industrial plants, the early CO shift reaction is usually carried out in two stages, namely high (medium) temperature shift and low temperature shift.The iron system is used as the catalyst for high (medium) temperature shift. The typical ratio of steam to carbon monoxide is about 3. When the temperature is 300~500 ℃Airspeed2000~4000 h-1The carbon monoxide content at the outlet of high temperature converter is 2%~5% under the condition of;High active copper zinc catalyst for low temperature shift at 180~280 ℃ and space velocity of 2000~4000 h-1The carbon monoxide content at the outlet of low temperature shift furnace is 0.2%~0.5% under the condition of.[25]
4. Hydrogenation reaction
Under different reaction conditions and catalysts, carbon monoxide hydrogenation can synthesize a variety of organic compounds, such as methanol synthesis, Fischer Tropsch synthesis of hydrocarbons（Fischer Tropsch synthesis）, synthesis of methane (methanation reaction), synthesis of ethylene glycol, synthesis of polymethylene, etc.[25]
(1) Synthetic methanol
Copper zinc chromium catalyst shall be used at 230 ～ 270 ℃, 5 ～ 10MPa and 20000-60000h-1Carbon monoxide reacts with hydrogen to produce methanol: CO+2Htwo→CHthreeOH。[25]
(2) Fischer Tropsch synthesis
The mixed gas of carbon monoxide and hydrogen can react to generate liquid hydrocarbon or hydrocarbon under catalyst (such as iron cobalt catalyst) and appropriate conditions (temperature 190 ～ 350 ℃, pressure 0.7 ～ 20MPa).[32]This reaction is heterogeneous, and the reaction product is a mixture of straight chain alkanes and olefins, which can be expressed by the following general formula:
or
。[25]
(3) Methanation reaction
Nickel is used as catalyst. When the temperature is 230~450 ℃, the pressure is 0.1~10 MPaAirspeed500-25000 h-1When the ratio of hydrogen to carbon monoxide is not less than 3, methane can be generated: CO+3Htwo→CHfour+HtwoO。This reaction is a heterogeneous catalytic gas phase reaction, which is a special case of Fischer Tropsch synthesis.[25]
(4) Synthetic ethylene glycol
With carbonyl rhodium complex as catalyst, hydrogen and carbon monoxide (the ratio of hydrogen to carbon monoxide is close to 1) are converted into polyols at 150~300 ℃ and extremely high pressure (about 300MPa)selectivity60%~70%.Wherein, ethylene glycol (HOCHtwoCHtwoOH) mainly: 2CO+3Htwo→HOCHtwoCHtwoOH。The reaction is carried out in liquid phase solution, and the by-products include propylene glycol, glycerol, methanol, methyl acetate and a small amount of higher alcohols.[25]
(5) Synthetic Polymethylene
Using metal ruthenium as catalyst, carbon monoxide and hydrogen are beneficial toMethylene（CHtwo）Under synthetic pressure (100~200MPa) and temperature (100~120 ℃), most of carbon monoxide reacts with hydrogen to produce polymethylene [n (CHtwo)〕：
。The reaction is still in the experimental stage due to the harsh reaction conditions, low selectivity for the formation of polymethylene and low space-time yield.[25]
5．Coordination reaction
Carbon monoxide can react with most transition metals to form carbonyl complex metals and their derivatives.[25]For example, under normal temperature and pressure, carbon monoxide can directly react with active metal nickel powder to produce colorless liquid tetracarbonyl nickel [Ni (CO)]four〕：
；At 200 ℃ and 200 atmospheric pressure, carbon monoxide and iron powder can form iron pentacarbonyl [Fe (CO)]five〕：
；Under more severe conditions, carbon monoxide can react directly with cobalt, rhodium, nails, molybdenum and tungsten, but the yield is low and has no practical value.It should be noted that the carbonyl compounds of metals are volatile toxic solids or liquids, and immediately decompose into corresponding metals and carbon monoxide when heated.(The metal can be purified and pure carbon monoxide can be produced accordingly)[33-34]
6．React with organics
(1) React with alcohol
① Methanol catalytic carbonylation: carbon monoxide can react with alcohol to produce carboxylic acid, such as methanol catalytic carbonylation to acetic acid: CO+CHthreeOH→CHthreeCOOH。Different catalysts are used, and the reaction conditions are different: BASF process uses iodine modified cobalt catalyst, the corresponding reaction temperature is 250 ℃, the pressure is 68 MPa, the selectivity of acetic acid is 90% based on methanol, and 70% based on carbon monoxide;Rhodium Iodine Catalyst (Rh/I) for Monsanto Processtwo）The corresponding reaction temperature is 150~250 ℃, the pressure is 1~4MPa, and the selectivity of acetic acid is 99% based on methanol and 90% based on carbon monoxide.
② Strong base catalyzed carbonylation: under the condition of 170~190 ℃ temperature and 1~2MPa pressure, carbon monoxide reacts with methanol to formMethyl formate：CO + CHthreeOH → HCOOCHthree。
③ Oxidative carbonylation: when the temperature is 90 ℃, the pressure is about 10 MPa, and there is oxygen involved in the reaction, carbon monoxide can react with methanol to formDimethyl carbonateorDimethyl oxalate：2CO + 4CHthreeOH+ Otwo→ 2(CHthreeO)twoCO + 2HtwoO or 4CO+4CHthreeOH+ Otwo→ 2CHthreeO-CO-CO-OCHthree+ 2HtwoO。If cuprous chloride catalyst is selected, carbonate will be generated;If the mixture of palladium chloride and copper chloride is selected as the catalyst, oxalate will be generated.
④ Homogeneous reaction of alcohol: carbon monoxide reacts with alcohol in the presence of hydrogen to produce higher alcohol.If carbonyl cobalt is used as catalyst, carbon monoxide reacts with methanol and hydrogen to produce ethanol: CO+CH at 200 ℃ and 30 MPathreeOH+ 2Htwo→ CHthreeCHtwoOH + HtwoO。[25]
(2) Reaction with unsaturated hydrocarbon carbonyl
① Reppe reaction (hydrogen carboxylation reaction): carbonylation reaction of carbon monoxide with unsaturated hydrocarbon and water.If cobalt or rhodium is used as catalyst, carbon monoxide reacts with ethylene and water to generate propionic acid: CO+H under the conditions of 175~195 ℃ and 3~7MPatwoC=CHtwo+HtwoO → CHthreeCHtwoCOOH。
② Hydroesterification: Carbonylation of carbon monoxide with unsaturated hydrocarbons and alcohols.If nickel carbonyl complex is used as the catalyst, carbon monoxide can react with acetylene and methanol to formMethyl acrylate：CO + HC≡CH+ CHthreeOH → HtwoC=CHCOOCHthree。
③ Oxidative carbonylation: carbon monoxide reacts with unsaturated hydrocarbon and oxygen to form carboxylic acid or ester.If palladium chloride or rhodium chloride is used as catalyst, carbon monoxide reacts with ethylene and oxygen at 110 ℃ and 10MPaAcrylic acid：2CO + 2HtwoC=CHtwo+Otwo→ 2HtwoC=CH-COOH。[25]
(3) Other reactions
In addition to reacting with alcohols and unsaturated hydrocarbons, carbon monoxide can also react with aldehydes, ethers, esters, amines, halogenated hydrocarbons, aromatic hydrocarbons and their derivatives.For example:
① With hydrofluoric acid as catalyst, carbon monoxide reacts with formaldehyde and water at room temperature and pressure of 7MPa to formGlycolic acid：CO + HCHO+ HtwoO→ HOCHtwoCOOH。
② Homogeneous reaction: the mixed gas of carbon monoxide and hydrogen is mixed withMethyl acetateReaction to produce ethylenediacetate: 2CO+2CHthreeCOOCHthree+ Htwo→ CHthreeCH(OOCCHthree)two+CHthreeCOOH。
③ With sodium methoxide as catalyst, carbon monoxide reacts with dimethylamine to formDimethylformamide（DMF）：CO + (CHthree)twoNH→(CHthree)twoNCHO。[25]
④Gatman Koch reaction: Under the action of cuprous chloride and aluminum chloride, aromatic hydrocarbons can react with carbon monoxide and dry hydrogen chloride to generate corresponding aromatic formaldehyde.For example, benzene can react with carbon monoxide and dry hydrogen chloride to formBenzaldehyde：Ph + CO +HCl → Ph-CHO + HCl。(Ph stands for phenyl)[35-36]
7. Reaction with metal oxide
At high temperatures, carbon monoxide can reduce many metal oxides to metalsSimple substance, such as: ① Turn the blackCupric oxideMetal copper reduced to red:
At 65~70 ℃, carbon monoxide can be mixed with iodine pentoxide (ItwoOfive）The reaction generates iodine (Itwo）：
。(Carbon monoxide can be identified quantitatively based on this)[38]
9．Reaction with chlorine
With activated carbon as catalyst, equimolar carbon monoxide and chlorine can react to formCarbonyl chloride(commonly known as "phosgene"):
。[25]
10. Reaction with palladium chloride
At room temperature, carbon monoxide can dissolve palladium chloride solutionPalladium chloride（PdCltwo）Reduction of to metalpalladium：
。(Usually used to detect the presence of carbon monoxide)[34][39]
application area
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chemical industry
In the chemical industry, carbon monoxide isOne carbon chemistryThe foundation of.[2]As the main component of synthesis gas and various kinds of gas, carbon monoxide is an important raw material for the synthesis of a series of basic organic chemical products and intermediates. Starting from carbon monoxide, almost all basic chemicals can be produced, such as ammonia, phosgene, alcohol, acid, anhydride, ester, aldehyde, ether, amine, alkane and olefin.At the same time, the properties of carbonyl complex metal or carbonyl complex metal derivatives generated by the reaction of carbon monoxide with transition metals can be used to prepare various homogeneous reaction catalysts required for organic chemical production.[25][40]In addition, carbon monoxide can be used as a terminator in the polymerization of polyethylene.
metallurgical industry
In metallurgical industry, carbon monoxide can be used to extract high-purity nickel from raw ore, obtain high-purity powder metal (such as zinc white pigment), and produce some high-purity metal films (such as tungsten film and molybdenum film) by thermal decomposition reaction of carbonyl complex metal.At the same time, carbon monoxide can be used as reducing agent for refining metal[2], such as the oxides used to reduce iron in the steelmaking blast furnace (see "physical and chemical properties · chemical properties" for the equation);In the production of polycrystalline diamond film, research grade carbon monoxide (≥ 99.99%) can be used to provide carbon source for chemical vapor deposition process.In addition, the mixture of carbon monoxide and hydrogen (syngas) can be used to produce some special steels, such as sponge iron produced by direct reduction of iron ore.[25][40]
other aspects
In addition to chemical and metallurgical applications, carbon monoxide can also be used as fuel[2]High purity carbon monoxide is mainly used as standard gas, carbon monoxide laser, environmental monitoring and scientific research.Among them, carbon monoxide standard gas can be used for calibration and detection of petrochemical process control instruments, quality control of petrochemical products, environmental pollutant detection, vehicle exhaust emission detection, calibration of mine alarm, detection of various factory exhaust, calibration of medical instruments, quality detection of transformer oil in power system, quality control of air separation productsCalibration of traffic safety detection instruments, geological exploration and seismic monitoring, metallurgical analysis, gas appliance experiment and calorific value analysis, calibration of chemical fertilizer industrial instruments, etc.[40]
In addition, carbon monoxide is often used for the fresh-keeping of fish, meat, fruits and vegetables, and bagged rice, especially sashimi. It is also used as a color fixative because it can make meat products ruddy.[41]
Calculate chemical data
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Drainage parameter calculation reference value (XlogP)
zero point seven
Number of hydrogen bond receptors
one
Topological molecular polar surface area (TPSA)
one
Number of heavy atoms
two
Complexity
ten
Number of covalent bond units
one
(Table reference:[2]）
Safety measures
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Food Safety
Chromogenic mechanism
The red pigments in animals mainly include myoglobin and hemoglobin. The muscle mainly contains myoglobin, which is responsible for receiving oxygen in capillaries and diffusing it to cell tissues.Myoglobin is composed of globulin molecules and iron containing heme molecules, which exist in the form of deoxymyoglobin (Mb)Oxymyoglobin（oxymyoglobin，MbOtwo）And methemoglobin (MetMb), in which the change of muscle color is mainly determined by the content of myoglobin and the existing form of myoglobin.The change form of myoglobin in animals is shown in the figure below:
Existing form of myoglobin[42]
In the survival of animals, myoglobin in muscles exists in two forms: bright red oxygenated myoglobin when combined with oxygen, and dark red deoxygenated myoglobin when not combined with oxygen.After animals die, when muscle tissue is exposed to the air, myoglobin automatically oxidizes to produce dark brown methemoglobin.How to maintain the existing form of myoglobin in meat after death and avoid the oxidation of myoglobin to produce brown methemoglobin is the key to control the color of meat products.Because carbon monoxide has a very strong affinity with myoglobin in meat, its affinity is generally 240 times higher than oxygen, and its binding stability with myoglobin is extremely high, preventing Fe in myoglobin2+To Fe3+Transforming, so as to achieve the effect of maintaining good color of meat for a long time.From the analysis of chromogenic mechanism, the combination of carbon monoxide and fish myoglobin does not change the structure of myoglobin, and the reaction is a reversible process, similar to the combination of myoglobin and oxygen, carbon monoxide is only transported by myoglobin to muscle tissue as a gas.[42]
The relationship between myoglobin changes and meat color[42]
Effects of Eating Carbon Monoxide Colored Meat Products on Health
According to the investigation results of Japan and Shanghai, China on products such as hair colored tilapia fillets and tuna, the highest carbon monoxide content in tilapia is 775 μ g/kg, while the highest carbon monoxide content in tuna is about 1000 μ g/kg.If this figure is doubled, it is assumed that the carbon monoxide content in the fish is 2000 μ g/kg, and the human body takes 500g of carbon monoxide treated fish within 30 minutes. If it is completely absorbed by the body, the carbon monoxide taken in is only 1mg, which is lower than the allowable safety limit.When the meat products treated with carbon monoxide are stored in the environment without carbon monoxide, the carbon monoxide in the meat products is also decreasing, and the half-life is about 3 days.
According to the regulations of the United States, the allowable concentration of carbon monoxide in the working environment of its workers is 57 mg/mthree。According to analysis, when working under such environmental conditions, the concentration of carbon monoxide in the human body will remain at a certain level, which is 14 times higher than that of 225 g meat with 100% saturated carbon monoxide of myoglobin.The premise is that the saturation of carbon monoxide of myoglobin and hemoglobin in meat is the largest (100%), and the proportion of carbon monoxide in meat transformed from gastrointestinal tract to blood is 100%.In fact, the carbon monoxide in fish treated in any way cannot reach 100%, generally below 50%, and the absorption rate of any substance in the body cannot reach 100%.Therefore, the human body is affected by the consumption of products containing carbon monoxideCarboxyhemoglobinThe impact of the level of (carbon hemoglobin, HbCO) is far below the safety limit.[42]
Protective measures
Family protection:In winter heating season, prevention knowledge should be publicized to prevent the occurrence of carbon monoxide poisoning accidents.
Public protection:In the production site, natural ventilation shall be strengthened to prevent air leakage of transmission pipeline and valve.When conditions permit, carbon monoxide alarm equipment shall be installed at appropriate locations for production devices that use or may produce carbon monoxide, families, public places, etc.After blasting in the mine, the operating procedures shall be strictly followed, and ventilation must be carried out for 20 minutes before entering the work.When entering an environment with high concentration of carbon monoxide, you must wear an oxygen supply respirator for operation.
Respiratory system protection:When the concentration in the air exceeds the standard, wear a self-priming filter gas mask (half mask).In case of emergency rescue or evacuation, it is recommended to wear air respirator and carbon monoxide filter self rescuer.
Eye protection:Generally, no special protection is required, and safety goggles can be worn when contacting high concentration carbon monoxide.
Body protection:Wear anti-static work clothes.
Hand protection:Wear general operation protective gloves.
Other protection:Smoking is strictly prohibited at the work site.Pre employment and regular physical examination shall be carried out.Avoid inhaling high concentrations of carbon monoxide.When entering tanks, confined spaces or other high concentration areas for operation, someone must supervise.[43]
(1) Immediately open the doors and windows for ventilation, quickly transfer the patient to a place with fresh air, rest in bed, keep quiet and keep warm.
(2) Ensure that the respiratory tract is unobstructed.For those with severe symptoms such as nausea and vomiting, the vomit or sputum in the mouth of the patient should be removed as far as possible, and the head should be turned to one side to avoid suffocation or inhalation pneumonia caused by vomit blocking the respiratory tract.
(3) For patients who have convulsions or become unconscious, ice bags can be placed on their heads to reduce brain edema, and they should be sent to the hospital for rescue in time. It is better to ask the ambulance station to send them to the hospital with hyperbaric oxygen chamber equipment.[44]
Hospital first aid
(1) Improve tissue hypoxia and protect important organs: ① rapidly correct hypoxia: give high concentration oxygen inhalation with a flow rate of 8~10L/min, then use continuous low flow oxygen inhalation according to the condition, and change to intermittent oxygen inhalation after waking up.If possible, it is better to take hyperbaric oxygen treatment as soon as possible.If necessary, mouth to mouth artificial respiration or tracheal intubation or tracheotomy shall be carried out, and cardiopulmonary cerebral resuscitation shall be carried out immediately in case of sudden death.[45-47]② Protect important organs such as heart and brain: availableCytochrome C30mg intravenous drip (skin test before use), orAdenosine triphosphate20mg、Coenzyme A50U and 4U ordinary insulin were added into 250mL of 25% glucose solution for intravenous drip. ③It can be used for patients with cerebral vasospasm and tremor paralysisatropine1mg or654-2(Anisodamine) 10mg intravenously.
(2) Prevention and treatment of brain edema: use hypertonic dehydrating agent, such as 20%mannitol125-250mL and 60mL hypertonic glucose solution were alternately intravenous drip, anddiuretic20 ～ 40mg anddexamethasone5mg。(Brain edema usually occurs 2~4h after poisoning.)
(3) Correction of respiratory disorders: respiratory stimulants can be used, such asLobelinEtc.For those with severe hypoxia and deep coma for more than 24 hours, tracheotomy can be performed. Those who have stopped breathing should be given artificial respiration immediately. If necessary, tracheal intubation, pressurized oxygen supply and artificial respirator should be used.
(4) Correction of hypotension: those who find signs of shock shall be given anti shock treatment immediately, such as supplementEffective circulating blood volume、dopamine60~120mg intravenous drip.
(5) Symptomatic treatment: for convulsionsPhenobarbital、diazepam (tranquilization) sedation;Tremorous paralysis suitBenzhexol(Antan) 2-4mg, 3 times a day;Muscle injection for paralyzed patientsGalanthamine hydrobromide2.5 ～ 5mg, oral vitamin B andDibazol, combined with new acupuncture and massage therapy.
(6) Prevention of infection: for long-term coma patientsantibioticTreatment, such as penicillin, cephalosporin, ofloxacin.[46]
2. Leakage emergency
(1) Eliminate all ignition sources.
(2) The warning area shall be demarcated according to the influence area of gas, and irrelevant personnel shall evacuate from crosswind and upwind to the safety area.
(3) It is recommended that emergency treatment personnel wear positive pressure self-contained air breathing apparatus and anti-static clothing.All equipment used in operation shall be grounded.Cut off the leakage source as much as possible.Spray water suppresses vapor or changes the flow direction of vapor cloud.Prevent gas from spreading through sewers, ventilation systems and confined spaces.Isolate the leakage area until the gas is exhausted.
(4) The isolation and evacuation distance shall be: in case of small leakage, the initial isolation shall be 30m; in case of downwind evacuation, the isolation shall be 100m in the daytime and 100m at night;In case of a large amount of leakage, the initial isolation shall be 150 m, and in case of downwind evacuation, the isolation shall be 700 m in the daytime and 2700 m at night.[48]
3. Fire extinguishing method
Cut off the air supply.If the air source cannot be cut off, it is not allowed to extinguish the flame at the leakage.Spray water to cool the container, and move the container from the fire site to an open place as far as possible.Extinguishing agents that can be used: spray water, foam, carbon dioxide, dry powder.[48]
Toxicological data
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Main sources
Carbon monoxide is an atmospheric pollutant with the largest amount and widest distribution in the atmosphere. It is the product of incomplete combustion of coal, oil and other carbonaceous substances. Its generation mechanism is: RH → R → ROtwo→ RCHO → RCO → CO (R represents hydrocarbon free group).It mainly comes from coking, ironmaking and other production processes in metallurgical industry;Synthetic ammonia, methanol and other production processes in the chemical industry;Mine blasting and gas explosion accidents;Exhaust emission of vehicles such as automobiles;Incomplete combustion of fuel in boiler;Gas or liquefied gas pipeline leakage caused by coal stove in family room and carbon monoxide release in natural disasters such as volcanic eruption, forest fire and earthquake.In addition, chemical reactions in the upper atmosphere, slight dissociation of carbon dioxide and animal metabolism also produce a small amount of carbon monoxide.[49-50]
The concentration of carbon monoxide in the atmospheric troposphere is about 0.1~2ppm (1 ppm=10-6, indicating volume fraction.Since the gaseous density of carbon monoxide is 1.2504 kg/mthreeTherefore, when the volume fraction is 1 ppm, the concentration of carbon monoxide is 1.2504 × 10-6kg/mthree=1.2504 mg/mthree[51]）This content is harmless to human body.However, due to the continuous development of transportation, industrial and mining enterprises around the world, the consumption of coal, oil and other fuels continues to grow, and carbon monoxide emissions also increase.[43]
Poisoning mechanism
Claude Bernard, a French physiologist, pointed out that carbon monoxide poisoning was caused by hypoxia due to the reversible combination of carbon monoxide and hemoglobin (Hb).It is generally believed that the affinity between carbon monoxide and hemoglobin is 230~270 times greater than that between oxygen and hemoglobin, which canOxyhemoglobin（HbOtwo）The oxygen in is squeezed out to form carboxyhemoglobin.Since the dissociation of carboxyhemoglobin is 3600 times slower than that of oxyhemoglobin, carboxyhemoglobin is more stable than oxyhemoglobin.
The carboxyhemoglobin not only has no function of carrying oxygen, but also affects the dissociation of oxyhemoglobin.The research shows that with the gradual increase of the content of carboxyhemoglobin, the oxygen dissociation in the oxyhemoglobin and the output of carbon dioxide in the tissue are blocked, which eventually leads to tissue hypoxia and carbon dioxide retention, resulting in poisoning symptoms.[52]
Metabolic mechanism
biodegradation
After carbon monoxide is inhaled with air, it enters the blood circulation through the alveoli, and joins the hemoglobin in the blood and some other substances outside the bloodFerritin(e.gmyoglobinFerrousCytochromeAnd so on) form a reversible combination.More than 90% of carbon monoxide combines with hemoglobin to form carboxyhemoglobin, about 7% of carbon monoxide combines with myoglobin to form carboxyhemoglobin, and only a small amount of carbon monoxide combines with cytochrome.The experiment shows that carbon monoxide does not accumulate in the body. Animals inhale 200ppm of carbon monoxide for one month, and carbon monoxide has been completely discharged 24 hours after detoxification. 98.5% of carbon monoxide is discharged through the lungs in its original form, and only 1% is oxidized into carbon dioxide in the body.The absorption and excretion of carbon monoxide depend on the partial pressure of carbon monoxide in the air and the saturation of carboxyhemoglobin in the blood (i.e. the percentage of total hemoglobin combined by carbon monoxide);The secondary factors were exposure time and pulmonary ventilation volume.The latter is directly related to labor intensity.[53]
Non biodegradable
The physical and chemical characteristics of carbon monoxide show that the removal of carbon monoxide in the atmosphere is mainly through carbon monoxide andhydroxylThe final product is carbon dioxide.About 85% of the vast majority of carbon monoxide emitted into the atmosphere every year is removed by reaction with hydroxyl, 10% is absorbed by the soil, and the rest is diffused into the stratosphere.In the process of annual emissions and removal, there is a small imbalance, which causes the carbon monoxide to increase by 1% every year.This imbalance may be caused by the increase of emissions caused by human activities.[53]
Toxicity data
acute toxicity
Acute inhalationLethal concentration(LC): 2300 ～ 5700mg/m ³ for mice, 1000 ～ 3300mg/m ³ for guinea pigs, 4600 ～ 17200mg/m ³ for rabbits, 4600 ～ 45800mg/m ³ for cats and 34400 ～ 45800mg/m ³ for dogs.Small warm blooded animals such as mice and birds are more sensitive to carbon monoxide.[52]
Rats inhaled 0.1-0.3mg/L carbon monoxide, maintained for 4-8 hours/day, after 1-2 weeks, caused slow growth, increased hemoglobin and red blood cell countSuccinate dehydrogenaseandCytochrome oxidaseThe activity of is destroyed.
The rats inhaled 0.047-0.053mg/L carbon monoxide and maintained it for 4-8 hours/day. After 30 days, the rats would grow slowly, the number of hemoglobin and red blood cells would increase, and the activities of succinate dehydrogenase and cytochrome oxidase in the liver would be damaged.
Monkeys inhale 0.11mg/L, and cause myocardial injury after 3-6 months.[54]
Reproductive toxicity
The lowest toxic concentration (TCLo) inhaled by rats: 150 ppm (1~22 days of pregnancy, 24 hours), which causes abnormal development of cardiovascular (circulatory) system, has an impact on the growth statistical index of newborn rats and the behavior of newborn rats.
The lowest inhalation toxic concentration (TCLo) of rats: 1 mg/mthree(72 days, 24 hours before mating), causing menstrual cycle changes or disorders, having an impact on delivery, female fertility index, the growth of newborn rats, causing delayed effects of newborn rats.
The lowest toxic concentration (TCLo) inhaled by mice: 65ppm (7~18 days of pregnancy, 24 hours), causing the influence on the behavior of newborn mice.
The lowest toxic concentration (TCLo) inhaled by mice: 250 ppm (6-15 days of pregnancy, 7 hours), which increased the mortality after implantation and caused abnormal musculoskeletal development.
The lowest toxic concentration (TCLo) inhaled by mice: 125 ppm (7~18 days of pregnancy, 24 hours), causing embryotoxicity.
The lowest toxic concentration (TCLo) inhaled by mice: 8ppm (8 days of pregnancy, 1 hour), has an impact on the number of fetuses per litter, causing embryotoxicity and stillbirth.
The lowest toxic concentration (TCLo) inhaled by mice: 8ppm (8 days of pregnancy, 1 hour), causing abnormal development of the central nervous system.[54]
If headache, dizziness, palpitation, nausea and other symptoms occur after carbon monoxide exposure, and the symptoms can disappear quickly after breathing fresh air, it is a general contact reaction.[55]
Mild poisoning
The concentration of carboxyhemoglobin in the blood of the slightly poisoned person is between 10% and 20%[56], severe headache, dizziness, nausea, vomiting, palpitations, dizziness, limb weakness, lethargy, irritability, gait instability, mild to moderate disturbance of consciousness (such as blurred consciousness, hazy state, but no coma), but no coma.At this time, if you can get out of the poisoned environment in time and inhale fresh air, the symptoms can be quickly alleviated and gradually fully recovered.[55][57]
Moderate poisoning
The concentration of carboxyhemoglobin in the blood of the moderately poisoned person is between 30% and 40%[56]In addition to headache, nausea, vomiting, palpitations, fatigue, lethargy, etc., there may be blush, cherry red lips, rapid pulse, sweating, coma, pupillary light reflex, corneal reflex and tendon reflex are sluggish, breathing and blood pressure may change, and although the initial stage of poisoning is clear, there is no self rescue ability,The disturbance of consciousness is characterized by shallow to moderate coma.At this time, if it can be moved away from the poisoning site in time and gradually recovered after rescue, there is generally no obvious complications or sequelae.[55][57]
Severe poisoning
The concentration of carboxyhemoglobin in the blood of the severely poisoned person is more than 50%[56], serious disturbance of consciousness, deep coma or vegetative state, various reflexes weakened or disappeared, common pupil narrowing, normal or dull light reflex, increased muscle tension of limbs, tight jaws, or paroxysmal cerebral rigidity, tendon wall reflex and testis raising reflex generally disappeared, tendon reflex existed or was dull, and urinary and fecal incontinence could occur.When brain edema continues to worsen, it shows continuous deep coma, continuous decancephalic ankylosis, pupillary light response and corneal reflex are sluggish, body temperature rises as high as 39~40 ℃, pulse is fast and weak, blood pressure drops, face is pale or cyanotic, limbs are cool, and tidal breathing occurs.Some patients' fundus examination showed irregular spasm of retinal artery, vein filling, or nipple edema, suggesting that intracranial pressure was increased and brain hernia might be formed.Many patients had negative fundus examination, and even normal pressure of cerebrospinal fluid examination, while serious brain edema was confirmed after pathological anatomy.
In the process of recovering from coma after treatment, severely poisoned people often suffer from restlessness, clouded consciousness, loss of orientation, or loss of near and far memory.After the recovery of consciousness of some patients, cortical dysfunction can be found, such as apraxia, agnosia, agraphia, aphasia, cortical blindness or transient deafness;Mental symptoms mainly due to mental retardation may also occur.In addition, transient mild hemiplegia, Parkinson's syndrome, chorea, athetoism of hands and feet or grand mal epilepsy have been reported.After active rescue and treatment, most patients with severe poisoning can still recover completely.A few patients with vegetative state have poor prognosis due to loss of consciousness, silence when opening eyes, and rigidity after brain removal.
In addition to the above manifestations of cerebral hypoxia, severe poisoning patients may also have anoxic changes or complications of other organs: ① some patients have arrhythmia, serious myocardial damage or shock; ②It occurs in the lungs of patients with pulmonary edemaMoist rale, dyspnea; ③About 1/5 of the patients found that the liver was large and often shrunk after 2 weeks; ④Some patients may have upper gastrointestinal bleeding due to stress gastric ulcer; ⑤Occasionally concurrentRhabdomyolysis syndrome(rhabdomyolysis) andCompartment syndrome (competition syndrome), acute renal failure may occur secondary to myoglobinuria; ⑥Some patients have skin autonomic neurotrophic disorder, which is manifested by large and small blisters or skin lesions similar to burns on the limbs or trunk, or patches of red and swollen skin similar to erysipelas, and it is not difficult to recover after symptomatic treatment; ⑦In some patients, hearing vestibular damage can be manifested as deafness, tinnitus and concussion; ⑧There are 2%~3% of patients with nerve damage. The most frequently affected are the lateral femoral cutaneous nerve, ulnar nerve, median nerve, tibial nerve, peroneal nerve, etc., which may be related to local compression after coma.[55][58]
sequela
Moderate and severe poisoning patients have neurasthenia, tremor paralysis, hemiplegia, hemianopsia, aphasia, dysphagia, mental retardation, toxic psychosis or decancephalic rigidity, and some patients may have secondary encephalopathy.[56]
delayed encephalopathy
Some patients with acute carbon monoxide poisoning recover to normal consciousness after waking up from coma, but after a 2 to 30 day recovery period, they have neuropsychiatric symptoms of encephalopathy, which is called acuteDelayed encephalopathy due to carbon monoxide poisoning。Due to the "biphasic" clinical process, some people also call it "acute carbon monoxide poisoning neurological sequela".Common clinical manifestations are as follows:
(1) Mental symptoms: sudden occurrenceDirectional forceLoss, indifferent expression, slow reaction, memory impairment, incontinence, and inability to take care of themselves;Or hallucinations, delusions, incoherent speech, behavior disorders, such as acute dementia and stupor psychosis.
(2) Focal brain damage: ① Extrapyramidal nerve damage:Parkinson's syndromeMost often, the patient's limbs are lead tube or gear like muscular tension, slow movement, loss of accompanying movement of both upper limbs when walking, or small writing and static tremor.A few patients may have chorea. ②Nerve damage of pyramidal system: mild hemiplegia on one or both sides, rigidity of upper limb flexion, hyperreflexia of tendon, positive ankle clonus, leading to pathological reflex on one or both sides, which may also occurMotor aphasiaorPseudobulbar paralysis。③Others: cortical blindness, seizuresParietal lobe syndrome(Loss of recognition, use, writing or calculation) has also been reported.[55]
Health hazards
Inhalation of excessive high concentration of carbon monoxide in a short time will cause acute carbon monoxide poisoning, resulting in poisoning symptoms and secondary malnutrition damage to brain, heart, liver, kidney, lung and other tissues.[59]The poisoned person often goes into a coma quickly, and dies quickly due to dyspnea and respiratory muscle paralysis, or even electric shock like death.[60]
Encyclopedia x confusion: illustration of carbon monoxide poisoning
As for whether long-term exposure to low concentrations of carbon monoxide will cause chronic poisoning, there are two views in the academic community: some scholars believe that the carboxyhemoglobin formed in the blood can be gradually dissociated, as long as the contact is disengaged, the toxic effect of carbon monoxide can be gradually eliminated, so there is no chronic poisoning of carbon monoxide;Some scholars believe that exposure to low concentrations of carbon monoxide can cause chronic poisoning.Many animal experiments and epidemiological investigations have shown that long-term exposure to low concentrations of carbon monoxide has an impact on health.The main manifestations are:
① Impact on cardiovascular system.S. M. Ayers et al. found that when the saturation of carboxyhemoglobin in the blood is 8%, the oxygen tension of venous blood decreases, which causes the reduction of myocardial oxygen uptake and the cessation of activities of some intracellular oxidase systems,Serum lactate dehydrogenase(LDH), hydroxybutyrate dehydrogenase (HBD)Creatine phosphokinase(CPK) increased.P. Astrup and others proved that carbon monoxide can promote the increase of lipid like deposition in large blood vessels.When the blood carboxyhemoglobin reaches 15%, it can increase the intake of cholesterol in the intima of large vessels and promote the deposition of cholesterol, making the original arteriosclerosis worse, thus affecting the myocardium. ECG can show arrhythmia, ST segment decline, QT interval extension or right bundle branch conduction block and other abnormalities.In addition, the population survey results show that about 20%~25% of smokers have more than 8%~10% carboxyhemoglobin in their blood, and the sudden death rate of myocardial infarction in these people is higher than that in non-smokers.A study of 63 patients with coronary atherosclerosis in the past 10 years found that after carbon monoxide exposure increased the carbon oxygen blood red egg level from 0.6% to 2% and 3.9%, the time of myocardial infarction and angina pectoris in patients with coronary atherosclerosis was earlier, and the tolerance to exercise was significantly reduced.
② Effects on nervous system (often manifested in patients with multiple mild acute carbon monoxide poisoning histories).The brain is the most oxygen consuming organ in the human body, and also the most sensitive organ to hypoxia.Animal experiments show that the absorption capacity of brain tissue to carbon monoxide is significantly higher than that of heart, lung, liver, kidney, etc.When carbon monoxide enters the human body, the cerebral cortex and pallidum are the most seriously affected.Hypoxia can also cause asphyxia in cell respiration, softening and necrosis, visual field reduction, hearing loss, etc;In light cases, neurasthenic symptoms such as headache, dizziness and memory loss will also occur, and there is also a sense of urgency in the precordial area and acupuncture like pain.
③ Causes hypoxemia.The compensatory increase of red blood cells, hemoglobin, etc. occurs, and its symptoms are similar to the pathological changes caused by hypoxia.
④ Impact on future generations.Through the study of smoking pregnant women and non-smoking pregnant women, it was found that the fetus of smoking pregnant women tended to be small at birth and retarded in intellectual development.[43][58]
Storage and transportation
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Storage safety requirements
1. Store in a cool and ventilated warehouse.Keep away from kindling, heat source and direct sunlight.The temperature in the warehouse should not exceed 30 ℃.
2. It is forbidden to use mechanical equipment and tools that are easy to generate sparks.
3. The storage area shall be equipped with leakage emergency treatment equipment.
4. The storage tank shall be loaded and unloaded gently to prevent damage to the cylinder and accessories.
5. Pay attention to lightning protection and anti-static. The storage tanks in the plant (workshop) shall be equipped with lightning protection facilities according to the provisions of Design Code for Protection of Structures against Lightning (GB 50057).[48]
Transportation safety requirements
1. Transport vehicles shall be equipped with dangerous goods transport signs and satellite positioning devices with driving record function.
2. Without the approval of the public security organ, the transport vehicles shall not enter the areas where the passage of hazardous chemical transport vehicles is restricted.
3. The exhaust pipe of the vehicle transporting this article must be equipped with fire arresting device.
4. It is forbidden to use mechanical equipment and tools that are easy to generate sparks for loading and unloading.
5. During the transmission, the cylinder and container must be grounded and bridged to prevent static electricity.More than 2 dry powder or carbon dioxide fire extinguishers and explosion-proof tools shall be prepared on the tank car.
6. In high temperature season, it should be transported in the morning and evening to prevent sunlight exposure.
7. When steel cylinders are transported by vehicles, the cylinder mouth shall face to the right of the driving direction of the vehicle, the stacking height shall not exceed the protective fence of the vehicle, and they shall be firmly clamped with triangular wood pads to prevent rolling.
8. It is not allowed to mix objects with conflicting nature in the same vehicle and let irrelevant personnel ride.
9. Keep away from kindling and heat sources during stopover.It is prohibited to stay in residential areas and densely populated areas.[48]
Relevant regulations
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Relevant Chinese regulations
In China, the Hygienic Standards for the Design of Industrial Enterprises (TJ 36-1979), issued on September 30, 1979 and implemented from November 1, 1979 to December 1, 1998, set requirements for the maximum allowable concentration of harmful substances in the atmosphere of residential areas. The primary value of the maximum allowable concentration of carbon monoxide is 3.00mg/m3, and the daily average value is 1.00mg/m3.[61]
Later, the requirements for carbon monoxide in the Ambient Air Quality Standard (GB 3095-2012) implemented on January 1, 2016 instead of the Ambient Air Quality Standard (GB 3095-1996) are as follows:
Quality requirements for ambient air functional area
average time
Concentration limit
class a
second level
24-hour average
4.00mg/m³
4.00mg/m³
1 hour average
10.00mg/m³
10.00mg/m³
Pollutant analysis method
Manual analysis method
Automatic analysis method
Analytical method
Standard No
Air quality Determination of carbon monoxide Non dispersive infrared method
GB 9801
Gas filter correlation infrared absorption method, non dispersive infrared absorption method
Minimum requirements for the validity of concentration data
average time
Data validity regulations
24-hour average
At least 20 hours of average concentration value or sampling time per day
1 hour average
At least 45 minutes of sampling time per hour
Terms and definitions:
① One hour average refers to the arithmetic mean value of pollutant concentration in any one hour.
② The 24-hour average refers to the arithmetic mean of the 24-hour average concentration of a natural day, also known as the daily average.
(Table reference:[63]）
In the Occupational Exposure Limits for Hazardous Agents in the Workplace Part 1: Chemical Hazardous Agents (GBZ 2.1-2019) issued on August 27, 2019 and implemented on April 1, 2020, carbon monoxide is the 313th substance, and the relevant requirements are as follows:
condition
OELs（mg/mthree）
Critical adverse health effects
MAC
PC-TWA
PC-STEL
Non plateau
-
twenty
thirty
Carboxyhemoglobinemia
plateau
2000-3000m above sea level
twenty
-
-
The altitude is more than 3000 meters
fifteen
-
-
remarks:
① OELs: occupational exposure limits.
② MAC: maximum allowable concentration.
③ PC-TWA: permissible concentration time weighted average.
④ PC-STEL: permissible concentration short term exposure limit.
(Table reference:[62][68]）
In addition, according to the Classification of Hazard Levels of Occupational Exposure to Poisons (GB 5044-1985) implemented from January 2, 1985 to March 23, 2017, the hazard classification of carbon monoxide is Level II (highly hazardous).[64-65]
Relevant US regulations
In the United States, for the concentration of carbon monoxide in the workplace, the TLV TWA given by the American Conference of Governmental Industrial Hygienists (ACGIH) is 25ppm, and the TLV STEL is 400ppm;The time weighted average (REL TWA) of indoor emergency exposure limit given by the National Institute for Occupational Safety and Health (NIOSH) is 35ppm, and the immediate dangerous to life or health concentration (IDLH) is 1200ppm;The time weighted average value of emergency exposure limit in public places given by the National Institute for Occupational Safety and Health (NIOSH) is 50ppm, and the maximum value of emergency exposure in public places (PEL) is 200ppm.[66]
Related disputes
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Can carbon monoxidepotassium permanganate（KMnOfour）The solution fades. Some people think that "potassium permanganate solution can oxidize carbon monoxide", that is, "carbon monoxide can make potassium permanganate solution fade". Scholars Xu Meiling and Ren Yinzhe concluded through experiments that carbon monoxide cannot fade potassium permanganate solution or its acidic solution at room temperature and normal pressure.[67]
