Monoethylene glycol or MEG is an important solvent with a chemical formula of C2H6O2, a molecular weight of 62 grams and a melting point of -12.9ºC. A polar compound in the form of a colorless, odorless liquid with a sweet taste and soluble in water. This compound is considered one of the most important commercial glycols and is used as a raw material for industrial purposes such as making polyester fibers, fabric and polyethylene terephthalate (which is used in bottle production). Its other uses include cooling, heat transfer fluid, antifreeze and hydrate inhibitor in gas lines.

Physical and chemical properties
Chemical formula C2H6O2
Colorless clear liquid appearance
Molar mass 62.07 g/mol
Melting point – 12.9 °C
Boiling point 197.3 °C
Solubility Miscible with water and soluble in most organic solvents
Density 1.1132 g/cm3
One of the most important properties of this compound is its heat transfer property. Some systems that require low, high or constant temperature usually use these materials. Materials with heat transfer properties of liquids or gases are generally divided into 3 categories:
1- Low temperature fluids: These materials are normally used in the temperature range below 32 degrees Fahrenheit (0 degrees Celsius) and up to about -148 degrees Fahrenheit (-100 degrees Celsius). Chemicals used as low temperature heat transfer fluids include salt water, hydrocarbons, and silicone oils.
2- Medium temperature: glycols such as propylene glycol (PG), ethylene glycol (EG) and 1,3 propanidol (bioglycol) are used to protect the system from freezing at temperatures below 32 degrees Fahrenheit, and by adding additives It can be used up to 350 degrees Fahrenheit.
3-High temperature fluids: These materials are usually used from 350°F to 662°F (350°C).

applications
This material is used to make the following materials:
• Heat transfer fluids
• Water based adhesives
• Latex paints and asphalt emulsions
• Electrolytic capacitors
• Leather
• Antifreeze and antifreeze additive
• Intermediate substance in chemical reaction and polymer production
• Solvent for the production of plastic, varnish, paint
• Additive to fuel, heat exchange fluids, brakes and hydraulics
• Dehydrator
• Coupling printing inks
• Textile softener
• Solvent for pigments in the finishing of textile and leather dyeing
• Raw material in the formulation of agricultural materials
• General cleaners
• Production of explosives
• Electrolytic component
• Humidifier
• Blue cover
• Preservative, rust remover and disinfectant

Properties such as durability, strength and water repellency have caused this material to be used in many industries, including the production of polyester resins, fibers and films. The physical properties of this compound allow it to find different applications as a coolant, anti-corrosion agent, dehydrating agent and chemical mediator.
It should be noted that this substance is poisonous and is not used in the food industry. Propylene glycol is used in this industry.

Benefits and limitations of use
This material is widely used in many industries due to its unique properties. Some of these properties are:
• It has water-like properties that make it miscible with many compounds
• The material is readily available and has a low price
• It has a low freezing point and a high boiling point, which is useful in many industrial uses
• It has the ability to carry good heat
• It has a long shelf life
Despite all the benefits and advantages that monoethylene glycol has, it also has some limitations, which include:
• It is highly flammable and absorbs water quickly
• In case of leakage from the car, it can cause a risk of ignition
• Improper disposal of this substance, especially in airports, can harm the environment
• Its sweet taste easily attracts children and animals, which can seriously harm health.

In the oil and gas industry, MEG is used as a thermodynamic inhibitor. MEG is added to natural gas to prevent the formation and freezing of hydrates in pipelines and prevent system corrosion.
Natural gas hydrates are ice-like solids that form when water and natural gas molecules combine. This phenomenon can occur in gas wells and secondary gas transmission pipes and cause their blockage. Water in natural gas can cause several problems for equipment. At low temperatures, water can freeze in the piping or, as is commonly the case, form hydrates with CO2 and hydrocarbons (mainly methane hydrate). However, depending on the composition of these materials, they can also be formed at high temperatures.