Ethylene glycol is also known as "ethylene glycol", "1,2-ethylene glycol", or EG for short. The chemical formula is (CH2OH)2, which is the simplest diol. Ethylene glycol is a colorless, odorless, sweet-tasting liquid, which is toxic to animals. The lethal dose for humans is about 1.6 g/kg. Ethylene glycol can be miscible with water and acetone, but it is less soluble in ethers. Used as a solvent, antifreeze and raw material for synthetic polyester. Polyethylene glycol (PEG), a high polymer of ethylene glycol, is a phase transfer catalyst and is also used for cell fusion; its nitrate ester is an explosive.
Use
It is mainly used to make polyester polyester, polyester resin, moisture absorbent, plasticizer, surfactant, synthetic fiber, cosmetics and explosives, and as a solvent for dyes, inks, etc., to prepare engine antifreeze, gas dehydrating agent, It can also be used as a wetting agent for cellophane, fiber, leather, and adhesives in the production of resins. It can produce synthetic resin PET, fiber-grade PET or polyester fiber, and flake-grade PET for making mineral water bottles, etc. It can also produce alkyd resin, glyoxal, etc., and can also be used as an antifreeze. In addition to being used as an antifreeze for automobiles, it is also used for the transportation of industrial refrigeration. It is generally called a refrigerant carrier. At the same time, it can also be used as a condensing agent like water.
Glycol methyl ether series products are high-grade organic solvents with excellent performance. They can be used as solvents and diluents for printing inks, industrial cleaning agents, coatings (nitrocellulose paint, varnish, enamel), copper clad laminates, printing and dyeing, etc.; can be used for production Pesticide intermediates, pharmaceutical intermediates, and synthetic brake fluids and other chemical products raw materials; as electrolytes for electrolytic capacitors, dyes for tanning chemical fibers, etc. Used as textile auxiliaries, synthetic liquid dyes, and raw materials for desulfurization agents in the production of fertilizers and oil refining.
When ethylene glycol is used as a refrigerant, you should pay attention to:
1. Its freezing point changes with the concentration of ethylene glycol in the aqueous solution. When the concentration is below 60%, the concentration of ethylene glycol in the aqueous solution increases and the freezing point decreases, but after the concentration exceeds 60%, as the concentration of ethylene glycol increases As the concentration rises, its freezing point shows an upward trend, and the viscosity also rises with the increase in concentration. When the concentration reaches 99.9%, its freezing point rises to -13.2°C. This is an important reason why the concentrated antifreeze (antifreeze mother liquid) cannot be used directly, and it must be brought to the attention of users.
2. Ethylene glycol contains hydroxyl groups. When working at 80 degrees Celsius-90 degrees Celsius for a long time, ethylene glycol will first be oxidized to glycolic acid and then oxalic acid, namely oxalic acid (oxalic acid), which contains 2 carboxyl groups. Oxalic acid and its by-products first affect the central nervous system, then the heart, and then the kidneys. Without proper treatment, excessive intake of ethylene glycol can lead to death. Ethylene glycol oxalic acid corrodes the equipment and causes it to leak. Therefore, in the prepared antifreeze, there must be antiseptics to prevent corrosion of steel and aluminum and the formation of scale.
Water antifreeze
Ethylene glycol is a colorless and slightly viscous liquid with a boiling point of 197.4°C and a freezing point of -11.5°C. It can be mixed with water in any ratio. After mixing, as the vapor pressure of the cooling water is changed, the freezing point is significantly reduced.
The degree of reduction decreases with the increase of ethylene glycol content within a certain range.
When the content of ethylene glycol is 60%, the freezing point can be lowered to -48.3℃. When this limit is exceeded, the freezing point will increase instead.
Ethylene glycol antifreeze is prone to generate acidic substances during use, which is corrosive to metals.
Ethylene glycol is toxic, but due to its high boiling point, it will not produce vapors that can be inhaled into the body and cause poisoning.
Ethylene glycol is highly absorbent, and the storage container should be sealed to prevent overflow after absorbing water.
Since the boiling point of water is lower than that of ethylene glycol, water is evaporated during use. When the coolant is lacking, just add clean water.
This antifreeze can be recycled after use (to prevent mixing with petroleum products), after precipitation, filtering, adding water to adjust the concentration, and adding preservatives, it can continue to be used. Generally, it can be used for 3-5 years. But it needs to be filtered multiple times to prevent damage to the motor vehicle.
Many people think that the freezing point of ethylene glycol is very low. The freezing point of antifreeze is a neutralized freezing point after ethylene glycol and water are mixed in different proportions. In fact, it is not the case. After mixing, the freezing point will be changed due to the change of the vapor pressure of the cooling water. Significantly reduced.
The degree of reduction decreases with the increase of the ethylene glycol content within a certain range, but once it exceeds a certain ratio, the freezing point will increase instead.
The antifreeze liquid made of 40% ethylene glycol and 60% soft water has an antifreeze temperature of -25°C; when the antifreeze contains 50% ethylene glycol and water, the antifreeze temperature is -35°C.
Packaging, storage and transportation
Packed in galvanized iron drum, 100Kg or 200Kg per drum. The storage should be sealed, and the long-term storage should be nitrogen sealed, moisture-proof, fire-proof and freeze-proof. Store and transport in accordance with the regulations for flammable chemicals.
Health Hazards
Toxicity: Rat oral LD50=5.8ml/kg, mouse oral LD50=1.31-13.8ml/kg.
Invasion route: inhalation, ingestion, transdermal absorption.
Health hazards: There are no reports of acute or chronic poisoning of this product in China. Acute poisoning in foreign countries is mostly caused by mistaking. Inhalation poisoning is manifested by repeated episodes of fainting, nystagmus, and lymphocytosis. Acute poisoning after oral administration is divided into three stages: the first stage is mainly central nervous system symptoms, the milder may behave like ethanol poisoning, the severer will quickly develop coma and convulsions, and finally die; the second stage, the cardiopulmonary symptoms are obvious, and severe cases may have pulmonary edema , Bronchial pneumonia, heart failure; the third stage is mainly manifested in varying degrees of renal failure. The human lethal dose of this product is estimated to be 1.4ml/kg (1.56g/kg).
First aid measures Skin contact: Take off contaminated clothing and rinse with plenty of running water. Eye contact: Lift the eyelid and rinse with running water or normal saline. Seek medical attention.
Inhalation: quickly leave the scene to a place with fresh air. Keep the airway unobstructed. If breathing is difficult, give oxygen. If breathing stops, give artificial respiration immediately and seek medical attention.
Ingestion: Drink enough warm water to induce vomiting. Stomach lavage, drainage. Seek medical attention. If breathing stops, give artificial respiration immediately. Seek medical attention.
Toxicity to pets: Ethylene glycol can be obtained from antifreeze for locomotives. The ethylene glycol in antifreeze for locomotives is not a threat to humans due to the addition of bittering agents and small amounts. However, if you are not careful with pets (cats, dogs) Mixed with foods, it can cause pet poisoning and cause kidney failure.
Toxicological environment
Toxicity: It is a low-toxicity category.
Acute toxicity: LD50: 8.0～15.3g/kg (oral for mice); 5.9～13.4g/kg (oral for rats); 1.4ml/kg (oral for humans, lethal)
Subacute and chronic toxicity: 8 days after rats inhaled 12mg/m3 (continuous multiple times), the corneas of 2/15 animals were cloudy and blind; people inhaled 40% ethylene glycol mixture 9/28 people had transient fainting; people inhaled 40% The mixture of ethylene glycol was heated to 105°C and repeatedly inhaled 14/38 people with nystagmus, and 5/38 people increased lymphocytes.
Hazardous characteristics: When exposed to open flames, high heat or contact with oxidants, there is a risk of combustion and explosion. In case of high heat, the internal pressure of the container will increase and there is a danger of cracking and explosion.
Combustion (decomposition) products: carbon monoxide, carbon dioxide, water.