What Is Acetic Acid?
Acetic acid, also called acetic acid (36%-38%), glacial acetic acid (98%), the chemical formula CH 3 COOH, is an organic monobasic acid and is the main component of vinegar. Pure anhydrous acetic acid (glacial acetic acid) is a colorless hygroscopic solid with a freezing point of 16.6 ° C (62 ° F) and colorless crystals after solidification. Its aqueous solution is weakly acidic and corrosive. Irritating effect.
Acetic acid, also called acetic acid (36%-38%), glacial acetic acid (98%), the chemical formula CH 3 COOH, is an organic monobasic acid and is the main component of vinegar. Pure anhydrous acetic acid (glacial acetic acid) is a colorless hygroscopic solid with a freezing point of 16.6 ° C (62 ° F) and colorless crystals after solidification. Its aqueous solution is weakly acidic and corrosive. Irritating effect.
- Chinese name
- Acetic acid
- English name
- AceticAcid
- nickname
- acetic acid
- Chemical formula
- CH3COOH
- Molecular weight
- 60.05
- CAS Registry Number
- 64-19-7
- Melting point
- 16.6
- Boiling point
- 117.9
- Water soluble
- Soluble in water
- Density
- 1.050
- Exterior
- Colorless liquid
- Flash point
- 39
Acetic acid profile
Acetic acid is widely distributed in nature, such as in fruit or vegetable oils, but exists mainly in the form of esters. It is present as free acid in animal tissues, feces and blood. Many microorganisms can convert different organics to acetic acid through fermentation.
Acetic acid is the main component of vinegar, and vinegar has been throughout the history of human civilization. Acetic acid-fermenting bacteria (acetobacillus) can be found in every corner of the world. When every ethnic group makes wine, it is inevitable to find vinegar-it is a natural product of these alcoholic beverages when exposed to the air. For example, in China, Du Kang's son Heita got vinegar for too long.
People in ancient Rome boiled sour wine in lead containers and got a high-sweetness syrup called "sapa". "Sapa" is rich in a kind of sweet lead sugar, lead acetate. In the 8th century AD, Persian alchemist Jabir concentrated the acetic acid in vinegar by distillation.
During the Renaissance, glacial acetic acid was prepared by the dry distillation of metal acetates. In the 16th century, German alchemist Andreas Libaffeus compared the glacial acetic acid produced by this method with the acid extracted from vinegar. Because of the presence of water, the properties of acetic acid have changed so much that for centuries, chemists have considered them to be two distinct substances. Until the French chemist Pierre Adet proved that the main components of the two substances are the same. [1]
In 1847, German scientist Adolf William Hermann Colbey first synthesized acetic acid from inorganic raw materials. The reaction process is as follows: first, carbon disulfide is converted to carbon tetrachloride through chlorination; then, high temperature decomposition of tetrachloroethylene is hydrolyzed and chlorinated to produce trichloroacetic acid; the final step is to produce acetic acid through electrolytic reduction.
In 1910, most of the glacial acetic acid was extracted from coal tar obtained from retorted wood. The process firstly treats coal tar by calcium hydroxide, and then acidifies the formed calcium acetate with sulfuric acid to obtain acetic acid therein. In 1911, the world's first industrial plant for the oxidation of acetaldehyde to acetic acid was completed in Germany, and then a method for producing acetic acid by oxidation of low-carbon alkanes was developed.
Acetic acid physical properties
English name: AceticAcid
Other names: glacial acetic acid, acetic acid
Indications: Different concentrations of this product are used to treat a variety of superficial skin fungal infections, lavage wounds and corns and warts. [2]
Drug Category: Disinfection and Preservatives-Glacial Acetic Acid
Molecular weight: 60.05
Molecular formula: CH 3 COOH
Boiling point (° C): 117.9
Freezing point (° C): 16.6
Relative density (water is 1): 1.050
Viscosity (mPa.s): 1.22 (20 ° C)
Vapor pressure at 20 ° C (KPa): 1.5
Appearance and odor: colorless liquid with pungent acetic acid smell.
Solubility: soluble in organic solvents such as water, ethanol, ether, carbon tetrachloride and glycerol.
Compatible materials: It is highly corrosive to metals after dilution. 316 # and 318 # stainless steel and aluminum can be used as good structural materials.
National Product Standard Number: GB / T 676-2007
The following are the national standards of the People's Republic of China on industrial acetic acid:
| Indicator name | index |
|---|
| Top grade | First grade | Qualified product |
|---|
Chroma, Hazen unit (platinum-cobalt color number) | 10 | 20 | 30 |
Acetic acid content,% | 99.8 | 99.0 | 98.0 |
Moisture,% | 0.15 | - | - |
Formic acid content,% | 0.06 | 0.15 | 0.35 |
Acetaldehyde content,% | 0.05 | 0.05 | 0.10 |
Evaporation residue,% | 0.01 | 0.02 | 0.03 |
Iron content (as Fe),% | 0.00004 | 0.0002 | 0.0004 |
Reduction of potassium permanganate, min | 30 | 5 | - |
Acetic acid properties
Acidity of acetic acid
The carboxyl hydrogen atom of acetic acid can be partially ionized to become hydrogen ions (protons) and released, resulting in acidity of the carboxylic acid. Acetic acid is a monobasic weak acid in aqueous solution, with an acidity coefficient of 4.8, pK a = 4.75 (25 ° C), and a 1mol / L acetic acid solution (similar to the concentration of household vinegar) has a pH of 2.4, which is only 0.4% The acetic acid molecule is dissociated.
Reaction description
Acetic acid dimer
The crystal structure of acetic acid shows that intermolecular bonds are formed as dimers (also known as diads) through hydrogen bonding. Dimers also exist in a vapor state at 120 ° C. Dimers have higher stability. It has been confirmed by molecular weight determination of freezing point reduction and X- ray diffraction that smaller molecular weight carboxylic acids such as formic acid, acetic acid exist in solid and liquid, and even gaseous form as dimers. When acetic acid dissolves with water, the hydrogen bonds between the dimers are quickly broken. Other carboxylic acids have similar dimerization. [3]
Acetic acid inorganic chemical reaction
1. Acetic acid can undergo the typical chemical reaction of ordinary carboxylic acids, and can be reduced to ethanol at the same time. Acetyl chloride can be generated through the nucleophilic substitution mechanism, and bimolecular dehydration can be used to generate anhydride.
Typical chemical reaction of acetic acid:
Acetic acid and sodium carbonate: 2CH 3 COOH + Na 2 CO 3 == 2CH 3 COONa + CO 2 + H 2 O
Acetic acid and calcium carbonate: 2CH 3 COOH + CaCO 3 == (CH 3 COO) 2 Ca + CO 2 + H 2 O
Acetic acid and sodium bicarbonate: NaHCO 3 + CH 3 COOH == CH 3 COONa + H 2 O + CO 2
Reaction of acetic acid and base: CH 3 COOH + OH - == CH 3 COO-+ H 2 O
Reaction of acetic acid and weak acid salt: 2CH 3 COOH + CO 3 2- == 2CH 3 COO-+ H 2 O + CO 2
Reaction of acetic acid with active metals: Fe + 2CH 3 COOH == (CH 3 COO) 2 Fe + H 2
Zn + 2CH 3 COOH == CH 3 COO 2 Zn + H 2
2Na + 2CH 3 COOH == 2CH 3 COONa + H 2
Reaction of acetic acid and zinc oxide: 2CH 3 COOH + ZnO == (CH 3 COO) 2 Zn + H 2 O
Reaction of acetic acid and ethanol: CH 3 COOH + C 2 H 5 OH = = CH 3 COOC 2 H 5 + H 2 O (Note: The condition is heating, concentrated sulfuric acid catalyzed, reversible reaction) [4]
2. Acetic acid can also form esters or amino compounds. For example, acetic acid and ethanol can form ethyl acetate in the presence of concentrated sulfuric acid and heating (this reaction is a reversible reaction, and the reaction type is an esterification reaction in a substitution reaction).
CH 3 COOH + CH 3 CH 2 OH <==> CH 3 COOCH 2 CH 3 + H 2 O
3. Due to the nature of weak acids, acetic acid is corrosive to many metals, such as iron, magnesium and zinc, and reacts to form hydrogen and metal acetates. Although the surface of aluminum in the air will form a protective layer of aluminum oxide, but under the action of acetic acid, the oxide film will be destroyed, and the aluminum inside can directly react with acid.
4. Metal acetates can also be reacted with acetic acid and corresponding alkaline substances, such as the reaction of baking soda and vinegar. With the exception of chromium (II) acetate, almost all acetates are soluble in water. [2]
Mg (S) + 2 CH 3 COOH (aq) (CH 3 COO) 2 Mg (aq) + H 2 (g)
NaHCO 3 (s) + CH 3 COOH (aq) CH 3 COONa (aq) + CO 2 (g) + H 2 O (l)
5. At a high temperature of 440 ° C, acetic acid can be decomposed to form methane and carbon dioxide or ketene and water.
Acetic acid biochemical reaction
Acetyl in acetic acid is the basis of all life in biochemistry. When combined with CoA, it becomes the center of carbohydrate and fat metabolism. However, the concentration of acetic acid in the cells is strictly controlled in a very low range to avoid destructive changes in the cytoplasmic pH. Unlike other long-chain carboxylic acids, acetic acid is not present in triglycerides. However, artificial acetic acid-containing triglycerides, also known as glycerol acetate (glycerol triacetate) [5] , is an important food additive and is also used to make cosmetics and topical medicines.
Acetic acid is produced or secreted by some specific bacteria. Of note is Clostridium acetobutylicum, a species of the genus Clostridium aceticus, which is widely found in food, water, and soil worldwide. Acetate is also naturally produced when fruits or other foods are spoiled. Acetic acid is also a component of the vaginal lubricating fluid of all primates, including humans, and is used as a mild antibacterial agent.
Acetic acid
Acetic acid can be used as an acidity regulator, acidifier, pickling agent, flavor enhancer, perfume, and the like. It is also a good antimicrobial agent, mainly due to its ability to lower the pH below the pH required for optimal growth of microorganisms. Acetic acid is the earliest and most used sour agent in China. It is mainly used in compound seasonings, formulated waxes, canned, cheese, jelly, etc. When used for seasoning, acetic acid can be diluted with water to a 4% ~ 5% solution, and then added to various seasonings for application. Beverages made with vinegar as a sour agent and supplemented with pure natural nutrition and health products are called international third-generation drinks [6] .
Preparation method of acetic acid
The acetic acid can be prepared by two methods: artificial synthesis and bacterial fermentation. Biosynthesis, which uses bacterial fermentation, accounts for only 10% of the world s production, but it is still the most important method of producing acetic acid, especially vinegar, because food safety regulations in many countries require that vinegar in food must pass the biological Preparation, and the fermentation method is divided into aerobic fermentation method and anaerobic fermentation method.
Acetic acid aerobic fermentation
In the presence of sufficient oxygen, Acetobacter bacteria can produce acetic acid from foods containing alcohol. Cider or wine mixed cereals, malt, rice, or potatoes are usually used to mash and ferment. The chemical equation of fermentation reaction by these bacteria is:
CH 5 OH + O CHCOOH + HO
The specific method is to inoculate bacteria of the genus Acetobacter in a diluted alcohol solution and maintain a certain temperature, and place it in a ventilated place. After a few months, it can undergo fermentation and finally produce vinegar. The method of industrial production of vinegar accelerates the reaction process by providing sufficient oxygen. This method has been adopted for commercial production and is also known as the "fast method" or "German method". It was named for its first successful application in Germany in 1823. . In this method, fermentation is carried out in a tower packed with wood chips or charcoal. Raw materials containing alcohol drip in from the top of the tower, and fresh air naturally enters or forces convection from below. The fortified air volume allows this process to be completed within a few weeks, greatly reducing the time required to make vinegar.
Otto Hromatka and Heinrich Ebner first mentioned the production of vinegar in liquid bacterial culture in 1949. In this method, alcohol is fermented to acetic acid with continuous stirring, and air is filled into the solution in the form of bubbles. In this way, vinegar containing 15% acetic acid can be prepared in two to three days.
Acetic acid anaerobic fermentation
Some anaerobic bacteria, including some members of the genus Clostridium, can convert sugars directly to acetic acid without the need for ethanol as an intermediate. The overall reaction equation is as follows:
C 6 H 12 O 6 == 3 CH 3 COOH
In addition, many bacteria are capable of producing acetic acid from compounds containing only a single carbon, such as methanol, carbon monoxide, or a mixture of carbon dioxide and hydrogen.
2 CO 2 + 4 H 2 CH 3 COOH + 2 H 2 O
2 CO + 2 H 2 CH 3 COOH
Clostridium reduces costs due to its ability to react to sugars, which means that these bacteria have the potential to produce acetic acid more efficiently than ethanol oxidation of acetic bacteria. However, Clostridium bacteria are less acid resistant than Acetobacter bacteria. The most acid-resistant Clostridium bacteria can only produce less than 10% acetic acid, and some acetic acid bacteria can produce 20% acetic acid. Using acetic acid bacteria to make vinegar is still more economical than using Clostridium bacteria to prepare and concentrate. Therefore, although Clostridium bacteria have been discovered as early as 1940, its industrial application scope is relatively narrow.
In addition to the above biological methods, industrial acetic acid is mostly synthesized by the following methods:
Acetic acid methanol carbonylation
Most acetic acid is synthesized by methylcarbonylation. In this reaction, methanol and carbon monoxide react to form acetic acid. The equation is as follows
CH 3 OH + CO CH 3 COOH
This process uses iodomethane as an intermediate, which is completed in three steps, and requires a multi-metal catalyst (in the second step)
CHOH + HI CHI + HO
CHI + CO CHCOI
CHCOI + HO CHCOOH + HI
By controlling the reaction conditions, acetic anhydride can also be produced by the same reaction. Because both carbon monoxide and methanol are commonly used chemical raw materials, methylcarbonylation has always been favored. As early as 1925, the British Celanese company developed the first pilot plant for methyl carbonylation to acetic acid. However, the application of this method has been limited due to the lack of containers capable of withstanding high pressures (200 atm or higher) and corrosion resistance. In 1963, BASF Chemicals, Germany, used cobalt as a catalyst to develop the first process suitable for industrial production of acetic acid. In 1968, the rhodium catalyst greatly reduced the difficulty of the reaction. A catalyst system consisting of a rhodium carbonyl compound and an iodide is used to react methanol and carbon monoxide in a water-acetic acid medium at 175 ° C and a pressure lower than 3 MPa to obtain an acetic acid product. Because of the high activity and selectivity of the catalyst, there are few by-products in the reaction. The low-pressure carbonylation of methanol to acetic acid has the advantages of cheap raw materials, moderate operating conditions, high acetic acid yield, good product quality, and simple process flow, but the reaction medium is severely corrosive and requires the use of special materials that are resistant to corrosion. In 1970, the Monsanto company built a device using this process, so rhodium catalyzed methylcarbonylation to produce acetic acid gradually became the dominant Monsanto process. In the late 1990s, BP successfully commercialized the Cativa catalytic method. This method uses a ruthenium catalyst and uses ([Ir (CO) I]), which is greener and more efficient than the Monsanto method.
Acetaldehyde oxidation method
Prior to Monsanto's commercial production, most acetic acid was produced by the oxidation of acetaldehyde. Although it cannot be compared with methyl carbonylation, this method is still the second method for industrial production of acetic acid. The reaction equation is as follows:
2CHCHO + O 2CHCOOH
Acetaldehyde can be produced by the oxidation of butane or light naphtha, or by hydration of ethylene.
Acetic acid low-carbon alkane liquid phase oxidation method
N-butane was used as a raw material, acetic acid was used as a solvent, and oxidation was performed with air as an oxidant in the presence of a catalyst of 170 ° C-180 ° C, 5.5 MPa and cobalt acetate. At the same time, this method can also use liquefied petroleum gas or light oil as raw materials. This method has low raw material costs, but has a long process flow, severe corrosion, and low acetic acid yield. It is limited to regions where cheap isobutane or liquefied petroleum gas raw materials are easily available.
2 CH 1 + 5 O 4 CHCOOH + 2 HO
This reaction can be carried out at the highest temperature and pressure capable of keeping butane in a liquid state. By-products include methyl ethyl ketone, ethyl acetate, formic acid and propionic acid. Because some by-products also have economic value, the reaction conditions can be adjusted so that more by-products are formed, but the separation of acetic acid and by-products increases the cost of the reaction.
Under similar conditions, using the above catalyst, acetaldehyde can be oxidized by oxygen in the air to form acetic acid:
2 CHCHO + O 2 CHCOOH
Can also be oxidized by copper hydroxide suspension:
2Cu (OH) + CHCHO CHCOOH + CuO + 2HO
Using the new catalyst, this reaction can obtain more than 95% acetic acid yield. The main by-products are ethyl acetate, formic acid and formaldehyde. Because the by-products have lower boiling points than acetic acid, they are easily removed by distillation.
Vinyl acetate oxidation
Ethylene is formed by reaction with oxygen in the presence of a catalyst (the catalyst used is palladium chloride: PdCl, copper chloride: CuCl, and manganese acetate: (CHCOO) Mn). This reaction can be seen as the oxidation of ethylene to acetaldehyde, and then by the acetaldehyde oxidation method.
Topsoe Acetate
The Topsoe method uses a single natural gas or coal as raw material. The first step: the synthesis gas generates methanol and dimethyl ether under the catalyst; the second part: methanol and dimethyl ether (both do not need purification) and CO carbonylation to generate acetic acid, this method is also called two-step method.
Acetic acid production process
BP Cativa Acetic acid BP Cativa process
BP is the world's largest supplier of acetic acid. 70% of the world's acetic acid production uses BP technology. BP launched the Cativa technology patent in 1996. The Cativa process uses a new iridium-based catalyst system and uses a variety of new additives, such as osmium, ruthenium, osmium, etc. The iridium catalyst system is more active than the rhodium catalyst, with fewer byproducts, It can be operated at low water concentration (less than 5%), which can greatly improve the traditional methanol carbonylation process, reduce production costs by up to 30%, and reduce expansion costs by 50%. In addition, as the water concentration decreases, the CO utilization efficiency increases and the steam consumption decreases.
AOPlus Celanese acetate AOPlus process
Celanese is also one of the largest acetate producers in the world. In 1978, Hurst-Celanis (now Celanese) industrialized the Monsanto acetic acid plant in Lake Clare, Texas, USA. In 1980, Celanese introduced the AOPlus (acid optimization) technology patent, which greatly improved Monsanto's process.
The AOPlus process improves the stability of rhodium catalyst by adding high concentration of inorganic iodine (mainly lithium iodide). After adding lithium iodide and methyl iodide, the water concentration in the reactor is reduced to 4% to 5%, but the carbonylation reaction rate It still maintains a high level, which greatly reduces the separation cost of the device. The change of catalyst composition enables the reactor to operate at a low water concentration (4% to 5%), which improves the yield of carbonylation reaction and the ability to separate and purify.
Use of acetic acid
Acetic acid is a bulk chemical product and is one of the most important organic acids. Mainly used in the production of vinyl acetate, acetic anhydride, acetate and cellulose acetate. Polyvinyl acetate can be used to make films and adhesives, and it is also a raw material for synthetic fiber vinylon. Acetate can make rayon and motion picture film. Acetate is an excellent solvent and is widely used in the paint industry. Acetic acid can also be used to synthesize acetic anhydride, diethyl malonate, ethyl acetoacetate, halogenated acetic acid, etc. It can also be used to make drugs such as aspirin, and it can also be used to produce acetate. It is widely used in pesticides, pharmaceuticals and dyes, photographic drugs manufacturing, textile printing and rubber industries.
In the food industry, acetic acid is used as an acidulant, flavoring agent and flavor. When manufacturing vinegar, acetic acid is diluted with water to a concentration of 4 to 5%, and various flavoring agents are added to obtain vinegar. As a sour agent, it can be appropriately diluted when used, can be used for making beverages, canned foods, such as canned tomatoes, asparagus, baby food, sardines, squid, etc., and can be used to make soft drinks, cold drinks, candy, baked goods, puddings, gum, Condiments, etc.
Acetic acid acts as a preservative. 1.5% has obvious antibacterial effect. Within 3%, it can prevent the flesh from turning green and black caused by mildew.
Acetic acid detection method
[7-16]
Method name: Glacial Acetic Acid-Determination of Glacial Acetic Acid-Neutralization Titration
Application range: This method uses the titration method to determine the content of glacial acetic acid in glacial acetic acid.
This method is suitable for glacial acetic acid.
Principle of the method: Add freshly boiled cold water and phenolphthalein indicator solution to the test sample, titrate with sodium hydroxide titration solution, and calculate the content of glacial acetic acid according to the amount of the titration solution used.
Reagent:
1. Sodium hydroxide titration solution (1mol / L)
2. Phenolphthalein indicator liquid (Phenolphthalein indicator liquid does not change color)
3. Reference potassium phthalate
4. Purple litmus solution (purple litmus solution turns red)
equipment:
Sample preparation: 1. Sodium hydroxide titration solution (1mol / L)
Preparation: Take an appropriate amount of sodium hydroxide, add water and shake to dissolve it into a saturated solution. After cooling, place it in a polyethylene plastic bottle and let it stand for several days. Take 56 mL of a clear saturated sodium hydroxide solution, add freshly boiled cold water to 1000 mL, and shake well.
Calibration: Take about 0.6g of standard potassium hydrogen phthalate dried to constant weight at 105 ° C, weigh it accurately, add 50mL of freshly boiled cold water, shake it to dissolve it as much as possible, add 2 drops of phenolphthalein indicator solution, When this solution is titrated, when the end point is reached, potassium hydrogen phthalate should be completely dissolved and titrated until the solution becomes pink. Each 1mL of sodium hydroxide titration solution (1mol / L) is equivalent to 204.2mg of potassium hydrogen phthalate. Calculate the concentration of this solution based on the consumption of this solution and the amount of potassium hydrogen phthalate taken.
Storage: Put it in a polyethylene plastic bottle and keep it in a sealed container. There are 2 holes in the plug. One glass tube is inserted into the hole. One tube is connected to the soda lime tube. One tube is used to suck out the liquid.
2. Phenolphthalein indicator liquid
Take 1 g of phenolphthalein and add 100 mL of ethanol to dissolve.
Operation steps: Take about 4mL of the test product, place it in a conical flask with a fixed weight, weigh it accurately, add 40mL of freshly boiled cold water and 3 drops of phenolphthalein indicator solution, and use sodium hydroxide titrant ) Titration. Each 1mL of sodium hydroxide titration solution (1mol / L) is equivalent to 60.05mg of CHO.
Note: "Precision weighing" means that the weighed weight should be accurate to one thousandth of the weighed weight. "Precision measurement" means that the accuracy of measuring the volume should meet the accuracy requirements of the volume pipette in national standards. [17]
Acetic Toxicology Information
Acute toxicity : LD50: 3.3 g / kg (rat oral); 1060 mg / kg (rabbit percutaneous). LC50: 5620 ppm, 1 h (mouse inhalation); 12.3 g / m3, 1 h (rat inhalation). Human oral dose of 1.47 mg / kg, the lowest poisoning amount, gastrointestinal symptoms appear; human oral dose of 20-50 g, lethal dose. 80% concentration of acetic acid can cause severe burns in guinea pig skin, 50% ~ 80% produce moderate to severe burns, less than 50% is very slight, and 5% ~ 16% concentrations have never had burns. Humans cannot tolerate more than 3 minutes at a concentration of 2 ~ 3 g / m3. The human oral lethal dose is 20 to 50 g.
Subacute and chronic toxicity : Chronic effects when the concentration of this product is about 100 mg / m3 can make workers' nasal, nasopharyngeal, eyelid and throat inflammatory reactions, and even cause bronchitis. Human inhalation (200 490) mg / m3 × (7 12) years, there are symptoms such as eyelid edema, conjunctival congestion, chronic pharyngitis, bronchitis and so on.
Mutagenicity : Microbial mutagenicity: E. coli 300 ppm (3 h). Sister chromatid exchange: 5 mmol / L of human lymphocytes.
Reproductive toxicity : The lowest oral poisoning dose (TDL0) in rats: 700 mg / kg (18 d, postpartum), which has an impact on the behavior of newborn rats. The lowest poisoning dose (TDL0) in rat testis: 400 mg / kg (1 d, male), which has an effect on male fertility index.
Health hazards : Invasion is through inhalation, ingestion, and percutaneous absorption. Irritating to nose, throat and respiratory tract after inhalation. Has a strong stimulating effect on the eyes. Skin contact, erythema appears in the light, and chemical burns in the severe. Ingestion of concentrated acetic acid can cause erosion of the mouth and digestive tract, and severe cases can be fatal due to shock.
Chronic effects : eyelid edema, conjunctival congestion, chronic pharyngitis, and bronchitis. Repeated contact over a long period of time can cause dry skin, degreasing and dermatitis.
Environmental hazards : It is harmful to the environment and can cause pollution to water bodies. [18]
Acetic acid safety and protection
Acetic acid risk
Flash point (): 39
Explosion limit (%): 4.0 17
Electrostatic effect: possible polymerization hazard
Flammability: Auto-ignition temperature: 463 ° C
Hazardous characteristics: Can react strongly with oxidants, and react violently with sodium hydroxide and potassium hydroxide. Corrosive to metals after dilution.
Higher concentrations of acetic acid are corrosive, can cause skin burns, permanent blindness to the eyes, and inflammation of the mucous membranes, so proper protection is needed. These burns or blisters do not necessarily appear immediately. In most cases, they occur within a few hours of exposure. Latex gloves are not protective, so special gloves such as nitrile rubber gloves should be worn when handling acetic acid. Concentrated acetic acid is difficult to burn in the laboratory, but when the ambient temperature reaches 39 ° C (102 ° F), it has a flammable threat. Above this temperature, acetic acid can mix with air and explode (explosion limit 4% -17% Volume concentration).
The harm of acetic acid is related to the concentration of acetic acid solution. The following table illustrates the EU classification of acetic acid solutions:
Concentration (mass) | Molar concentration | Grading | R-Phrases |
|---|
10% -25% | 1.67--4.16 mol / L | Stimulation ( Xi ) | R36 / 38 |
25%-90% | 4.1614.99 mol / L | Corrosion ( C ) | R34 |
> 90% | > 14.99 mol / L | Corrosion ( C ) | R10, R35 |
Because of the strong irritating odor and corrosive steam, the operation of acetic acid with a concentration of more than 25% should be performed under the eye mask. Dilute acetic acid solutions, such as vinegar, are harmless. However, ingesting a high concentration of acetic acid solution is harmful to human and animal health.
Acetic acid leak treatment
Pollution emission category: Z
Leak treatment: Cut off the source of fire, wear protective glasses, gas masks and acid-resistant overalls, rinse the spill with a large amount of water, let it flow into the channel, and be diluted quickly to reduce harm to the human body.
Acetic acid fire fighting method
Use mist water, dry powder, alcohol-resistant foam, carbon dioxide, and fire. Use water to keep containers in the fire cool. Use mist water to disperse the vapour, drive away the leaking liquid, and make it diluted into a non-combustible mixture. And spray the water to remove the leaked personnel.
Acetic acid first aid
Skin contact: Rinse skin with water before washing thoroughly with soap.
Eye contact: Rinse the eyes with water and then wipe them with a dry cloth. Serious cases must be sent to the hospital for treatment.
Inhalation: If inhaling vapours should remove the patient from the contaminated area, rest and keep warm.
Ingestion: Rinse mouth by mistake, give emetic to induce vomiting, and send to hospital for treatment.
Acetic acid protection
Respiratory protection: When the depth concentration in the air exceeds the standard, a gas mask should be worn.
Eye protection: Wear chemical safety protective glasses.
Hand protection: Wear rubber gloves.
Other: After work, shower and change clothes, do not bring work clothes into the living area.
Acetic acid safety information
RTECS number: AF1225000
Dangerous Goods Mark: C: Corrosive
Risk term: R10
Security term: S23
Safety term
S23Do not breathe vapour.
Do not breathe vapor.
S26In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.
After accidental contact with eyes, rinse immediately with plenty of water and seek medical advice.
S45In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.)
In case of accident or if you feel unwell, seek medical advice immediately (show the label if possible).
Risk term R10Flammable.
combustible.
R35Causes severe burns.
Causes severe burns.
Acetic acid management information
Management of Acetic Acid Operations
Closed operation to enhance ventilation. Operators must be specially trained and strictly abide by the operating procedures. It is recommended that operators wear self-absorption filtering gas masks (half-masks), chemical safety protective glasses, acid- and alkali-resistant plastic overalls, and rubber acid and alkali-resistant gloves. Away from fire and heat sources, smoking is strictly prohibited in the workplace. Use explosion-proof ventilation systems and equipment. Prevent vapors from leaking into the workplace air. Avoid contact with oxidants and alkalis. Handle with care when handling to prevent damage to packaging and containers. Equipped with the corresponding variety and quantity of fire fighting equipment and leakage emergency treatment equipment. Empty containers may be harmful residues.
Management of acetic acid storage
Store in a cool, ventilated warehouse. Keep away from fire and heat sources. The storage temperature should be kept above 16 during the freezing season to prevent freezing. Keep container tightly closed. It should be stored separately from oxidants and alkalis. Use explosion-proof lighting and ventilation facilities. Prohibit the use of spark-prone machinery and tools. The storage area should be equipped with spill emergency treatment equipment and suitable containment materials.
Management of Acetic Acid Transportation
The time limit for rail transportation of this product is to use the tanker trucks prepared by the aluminum enterprise for shipment, which must be reported to relevant authorities for approval before shipment. For non-tank railway transportation, the dangerous goods should be installed in strict accordance with the Dangerous Goods Transportation Regulations of the Ministry of Railways. The package should be complete at the time of shipment and the loading should be secure. During transportation, ensure that the container does not leak, collapse, fall, or damage. The tank (tank) truck used for transportation should have a grounding chain, and a hole partition can be installed in the tank to reduce vibration and generate static electricity. It is strictly prohibited to mix and transport with oxidants, alkalis, edible chemicals, etc. When transporting by road, follow the prescribed route and do not stop in residential areas and densely populated areas.
Management of acetic acid waste
Dispose of by incineration.
