Combustion temperature of propylene glycol. Propylene glycol: effects on the human body

Propylene glycol is an organic substance that is colorless and odorless and has a slight sweetish taste. It is actively used for the production of various products in the chemical and food industries.

The component has low toxicity and at the same time very good viscosity. What is this substance, in what areas is it used and is it harmful to humans?

The component is widely used for the production of various cosmetics. This substance, which is present in hair washes and creams, ensures maximum penetration of active components into the layers of the epidermis.

This is a very good emollient and moisturizer; it promotes the formation of a thin film on the surface of the skin, which helps to actively retain water. This allows the skin to look healthy and radiant.

Glycol is used to make products intended for baby skin care.

It is able to retain water and very effectively moisturizes delicate baby skin, which is prone to irritation and rashes.

But if the baby’s body is prone to allergies, then after using products based on propylene glycol, peeling and redness may appear on the skin.

Therefore, if the child is inclined to do so, it is better to refuse to use any products that contain this component. Read the ingredients carefully before purchasing.

In the medical industry

The substance is used to produce various medications. It has a bactericidal effect, it is often used to obtain means for disinfecting premises and various transport equipment.

Propylene glycol is used in the production of condoms.

Due to its disinfecting effect, the substance can protect against harmful microbes during sexual intercourse.

Propylene glycol is also added to products for external use, as it actively moisturizes, helps relieve swelling, and ensures better and faster healing of burns, wounds, and ulcers.

For heating systems

The substance in question is used to produce antifreeze, which is used for heating systems. Functions performed:

• Prevents corrosive destruction of metals;
• Prevents the heating system from freezing;
• Provides dissolution of sediment with its further removal, which is formed in heating systems.
• Increases the service life of gaskets made from elements that are not made of metal.

The substance is used to produce various seasonings, sweet syrups, and food flavorings. It is also added to baked goods to keep food longer and softer. Used in brewing beer and for the production of non-alcoholic beverages.

The component is also used for the manufacture of culinary products as a thickener. The harmful properties of propylene glycol have not been proven, so it is actively used in food production.

For animals

The component is present in cattle feed to ensure that the feed lasts longer and does not spoil. It does not affect the taste characteristics of the food in any way, but improves its absorption in the animal’s body.

Propylene glycol does not have any adverse effects on the health of the animal. In the field of veterinary medicine it is used:

• As a lubricant;
• For preservation;
• As an antibacterial substance;
• For sterilization of devices.

In an electronic cigarette

The substance is used in electronic cigarettes, which have become so widespread lately. It ensures a rapid supply of nicotine to the body of a smoker. Many people are wondering how harmful this substance is to humans?

Manufacturers of electronic devices assure that propanediol is an absolutely harmless component and that it does not worsen human health.

But how are things really?

If a smoker uses an electronic device infrequently and in normal doses, then this really does not harm health in any way. If you smoke too often, the following harm can occur:

• Development of allergic reactions;
• The appearance of a feeling of soreness, dryness in the throat, in the oral cavity;
• There is a high risk of developing diseases of the respiratory system;
• The sense of smell deteriorates;
• There may often be a feeling of nasal congestion due to swelling of the nasopharynx.

Harm

In food production, the use of propylene glycol is completely safe for humans, but you can become very poisoned if you take an extremely high dose of this component. This usually occurs when glycol is accidentally ingested.

When using the component for medical purposes, you need to be aware of the danger glycol poses.

When using an intravenous overdose of a medicine with propylene glycol, disorders that are dangerous to the patient’s health may occur - hemolysis, arrhythmia, high blood pressure and even cardiac arrest.

If the concentrated product gets into the eyes, conjunctivitis may develop. If a substance that is not diluted with water gets on a person’s skin, then usually no adverse reactions occur.

But if a person is prone to developing allergic reactions, then severe itching, redness of the skin, and peeling may occur.

Glycol is used for various smoke shows, so during such shows, people nearby may experience irritation of the throat and mucous membranes. Some studies have found that propylene glycol, which is found in paint and varnish products, can provoke asthma and eczema.

conclusions

If propylene glycol is used correctly and in adequate quantities, it will not cause any harm to the body. Persons who are prone to developing allergies should be very careful when using any products containing this component.

Since allergic reactions often occur among children, you need to be especially careful when using care products containing propylene glycol.

Many ordinary people have heard the name of this unique substance more than once, but the vast majority do not quite understand its value and the urgent need for use in some situations. What kind of substance this is, why it was created and, most importantly, how this substance can help a person - we will talk in today’s article.

So, propylene glycol is usually called a colorless organic compound that is practically odorless. It is a clear liquid, somewhat viscous in consistency, which also has a slightly sweetish taste.

Today, the pharmaceutical market also offers customers several analogues of propylene glycol in various packages, these are so-called among professionals 1,2-propanediol or the same propane-1,2-diol, and, of course, α-propylene glycol, note that the data substances have nothing in common with such a substance as its isomer, called by doctors propane-1,3-diol (or β-propylene glycol).

It is important to say that propylene glycol is considered an excellent solvent for a huge number of compounds of various classes. For example, the vast majority of low molecular weight organic compounds existing in the world, especially those that contain oxygen or nitrogen, are completely mixed with this substance (without forming a residue). Such connections are usually classified as:

• Almost all monohydric alcohols (for example, methyl alcohol, ethyl alcohol, also isopropyl or n-butyl alcohol, always n-amyl alcohol and phenylethyl alcohol).
• Any ethylene and/or propylene glycols, as well as most of their esters.
• Numerous acids (including acetic, diethylacetic, valeric, oleic, etc.).
• Most aldehydes (including anise, benzoic, mustard aldehydes, salicylic, furfural, etc.) and so-called ketones (such as acetone, α-ionone, or methylisopropyl- with methylisobutyl ketone).
• Lots of esters.
• Most amines and other nitrogen-containing compounds.

The main industrial method by which it is possible to obtain propylene glycol occurs through the formation of propylene oxide. However, different manufacturers may use different processes to obtain this substance. For example, this may be a high-temperature non-catalytic process, when the production of the described substance requires temperatures from 200 ° C (or 392 ° F) and up to 220 ° C (or up to 428 ° F).

It can also be a catalytic method for obtaining the described substance, which occurs at less shocking temperatures ranging from a minimum for this process of 150 ° C (or about 302 ° F) to a maximum of 180 ° C (or up to 356 ° F). This process takes place in the presence of a so-called ion exchange resin, and sometimes in the presence of another catalyst, such as, say, a small amount of sulfuric acid, and possibly alkali.

In addition, propylene glycol, which many people need, can be isolated through the primary complete processing of substances such as glycerin and biodiesel.

Attention, an important point: you can only purchase propylene glycol from officially registered distributors, since today there are simply a terrifying number of counterfeits of this substance on the market.

Propylene glycol - this substance is deservedly considered a hygroscopic colorless liquid that contains asymmetric carbon atoms. This liquid is perfectly soluble in water, in any kind of ethanol, in diethyl alcohol, even in acetone or chloroform.

This substance is designed to fight corrosion; the liquid has fairly low volatility, and also, importantly, the lowest possible toxicity. Many will be interested that the molecular formula of ordinary propylene glycol looks like this: C3H8O2, and its molar mass is about 76.09 grams/mol, while the density of this substance is 1.036 g/cm³, and its melting point reaches -59°C.

It should be said right away that almost half, or to be more precise, about 45% of all propylene glycol produced by the world's chemical factories is usually used as some kind of chemical raw material in the production of equally important unsaturated polyester resins. And all because propylene glycol, subsequently entering into chemical reactions with mixtures of certain unsaturated resins, or maleic anhydrides, as well as with isophthalic acid, ultimately allows the formation of certain copolymers.

Such partially unsaturated polymers are usually further soldered to produce the thermoset plastics that are much needed today. In addition, propylene glycol is able to enter into the necessary reactions with propylene oxides, thereby forming so-called oligomers or polymers, which in turn are actively used in the production of numerous polyurethanes.

It cannot be said that the use of propylene glycol, unlike other similar substances, can be considered as safe as possible, which is incredibly important in the production of certain food products or numerous medications. For example, food grade (purified from impurities) propylene glycol can often be used by the food industry as a food additive with the number E1520.

By the way, this particular additive is an excellent solvent and also a preservative for many foods. Sometimes this additive can also be used in the production of tobacco products, numerous pet foods. In addition, this particular additive is one of the most basic ingredients in liquids that are used for.

Also, the use of propylene glycol is quite possible in the production of some products intended for women's personal hygiene or for their cosmetics. We are talking primarily about such products as numerous elixirs, masks, creams or lotions for the face and body. The same additive is often found in modern shampoos, hair emulsions, toothpastes, creams and even lipsticks.

Indeed, the unique property of the same propylene glycol to slightly increase or decrease the temperature of most liquids ultimately allows the manufacturer to use this substance in the composition of a wide variety of anti-icing liquids so necessary for the operation of aircraft. This substance is also included in most antifreezes intended for washing glass in cars.

In addition, anti-icing fluids, which almost always contain propylene glycol, are also urgently needed in most modern air conditioning, ventilation or heating systems of ordinary residential premises, and similar fluids are also used in many food cooling systems and other heat exchange equipment. .

And of course, it should be noted that propylene glycol may be included in some medications. For example, the most widely known drug is Diazepam, which is based on the same propylene glycol. Propylene glycol is commonly used in the pharmaceutical industry due to its unique qualities as an excellent solvent for many medicinal substances.

For example, today it is on the basis of the same propylene glycol that pharmacists around the world create a lot of oral or injectable medications that are so necessary for patients. Let us recall that the most common drugs based on propylene glycol are the previously mentioned Diazepam and, of course, Lorazepam.

Despite the fact that food-grade propylene glycol has been recognized by scientists around the world as completely non-toxic and absolutely safe to use (a substance that is not capable of causing serious health problems or significant side effects from its use), exceeding its permissible quantities during production cannot be considered beneficial for human body.

However, it should be noted that propylene glycol can cause quite serious harm to human health if its plasma concentration begins to exceed one gram per liter, which undoubtedly requires the use of an extremely high amount of medicines created on the basis of this substance and necessarily for a fairly short period of time. period.

It must be understood that real cases of poisoning with a substance such as propylene glycol, as a rule, are associated either with the inappropriate intravenous administration of its drugs, unsupervised by doctors, or with the accidental (intentional suicidal) ingestion of a fairly large amount of drugs based on propylene glycol.

Even a fairly long-term contact of a substance such as tpropylene glycol with human skin essentially cannot cause any strong irritation that is serious from a medical point of view. Moreover, even propylene glycol undiluted in liquid or water will have a truly minimal irritating effect on the mucous membranes of the eyes, nose or mouth.

Sometimes, with such exposure, the patient may experience the development of minor transient conjunctivitis, rhinitis, or seizures. In addition, propylene glycol vapor in some cases can cause some irritation of the mucous membrane of the eyes and even the membranes lining the upper respiratory tract of a person.

However, even prolonged inhalation of vapors of the described substance (propylene glycol) often does not pose any significant danger to human life or health. Only sometimes, excessively prolonged inhalation of fine mist of propylene glycol, often used for many theatrical or show productions, can cause irritation and allergic manifestations of the respiratory tract in a person.

As a rule, intravenous administration of drugs containing propylene glycol or those created on its basis in sufficiently large or excessive doses can ultimately lead to the development of hypotension, a condition such as bradycardia, as well as abnormalities of the T wave or the entire QRS complex directly on the electrocardiogram readings.

Sometimes exceeding doses of medications based on this substance leads to the development and sometimes to cardiac arrest, hyperosmolarity syndrome, so-called lactic acidosis or hemolysis.

But, according to the latest research from a Swiss university such as Karlstad, conducted in 2010, an increase in the concentration of platinum group metals, propylene glycol and some glycol ethers directly in the air of living or working premises can lead to an increased risk of developing significant respiratory and/or immune disorders.

According to the above-mentioned studies, doctors have precisely proven that too frequent inhalation of the same propylene glycol ethers can lead to the development of severe asthma, such unpleasant diseases as allergies with a sharply increased risk of complications ranging from at least 50% and up to a significant 180%.

14Jul

What is Propylene Glycol (PG)

Propylene glycol(PG) is a colorless liquid, practically odorless and has a slightly sweet taste. Traditionally, propylene glycol is extracted from raw materials coming from the petrochemical industry. However, today there are many methods for extracting this substance from renewable biological resources, such as yeast, corn, vegetable oils, and so on.

Why is Propylene Glycol needed?

Propylene glycol is An incredibly cheap and versatile substance that has many useful functions applicable in different industries.

PG perfectly absorbs and retains moisture, which is why it can be found in various moisturizers, hair styling products and similar cosmetic products. In addition, propylene glycol is an excellent emulsifier and solvent for various food colors and flavors. Combined with antifungal and antibacterial properties, it is often used in the food industry as a preservative.

What does propylene glycol contain?

Propylene glycol is an ingredient in many foods, drugs, cosmetics and other industrial and technical substances.

You'll find it in the ingredient lists of personal care products such as antiperspirants, deodorants, shaving creams, hand sanitizers, body lotions, moisturizers, conditioners, shampoos, and sunscreens. This also applies to things like paints, varnishes, polyurethane pads, plastics and tobacco products.

Recently, this ingredient, along with , is actively used in the field, as an important component for the manufacture of liquid for electronic cigarettes.

You may have heard that propylene glycol is the main ingredient in antifreeze. This is true. PG lowers the boiling point of water, which is why it is the active ingredient in antifreeze and aircraft deicing fluid. However, there are many misconceptions about propylene glycol. Due to its association with antifreeze, many believe it is a harmful ingredient. But antifreeze contains more concentrated industrial grade PG. Here we are dealing with nutritional and cosmetic qualities.

Propylene glycol - harm and safety.

Unlike the deadly ethylene glycol, propylene glycol is easy on the liver and is completely non-toxic to the human body. Approximately 45% of any propylene glycol consumed is excreted directly from the body and does not even come into contact with the liver.

Water, as a coolant, has ideal properties - high heat capacity and thermal conductivity, almost zero viscosity, insignificant thermal expansion, practically unlimited natural resources and low cost, absolute environmental safety. And the only insurmountable drawback is the low (zero) freezing temperature and, while freezing, it expands further, forming a very strong crystal lattice, the pressure of which no engineering system, no natural material can withstand.

Food and pharmaceutical production, industrial air conditioning systems and autonomous heating of buildings require maintaining a given temperature in the premises, which cannot be achieved without the use of non-freezing (low-freezing) liquids - antifreeze, refrigerants, coolants.

In recent years, aqueous solutions of glycols - ethylene glycol and propylene glycol - have been widely used as antifreeze liquids. Let's take a closer look at the thermophysical properties and characteristics of an aqueous solution of propylene glycol. An aqueous solution of propylene glycol has:

• 1) Higher density compared to water as a coolant, by 5%-8%, and the density of the solution increases with increasing concentration of propylene glycol.
• 2) Heat capacity and thermal conductivity decrease (compared to water) by up to 20% with increasing concentration of propylene glycol and decreasing operating temperature in the subzero zone.
• 3) Kinematic and dynamic viscosity is 4-5 times higher than that of water in the positive temperature zone and increases 10-15 times when the concentration increases to the practical limit of 55% and, accordingly, the crystallization temperature decreases to minus -40 °C.

The increased viscosity of an aqueous solution of propylene glycol in the zone of negative operating temperatures leads to a significant increase in hydraulic losses due to friction in pipelines and overcoming hydraulic resistance in all components of the cooling and industrial air conditioning system (see Table Nos. 1, 2, 3). Also, a significant reduction, up to 20%, in the heat capacity and thermal conductivity of a propylene glycol solution requires an increase in the rate of circulation of heat and coolant in the system or other technical solutions to ensure the transfer (reception) of the required thermal power (energy).

All these factors, as a result, will lead to special ones. exceptional situations (conditions) during the operation of engineering systems in various climatic conditions. And they should be taken into account when designing and operating heating and industrial air conditioning systems.

Table 1. Thermophysical properties of a 25% aqueous solution of propylene glycol, crystallization temperature minus - 10°C

Table 2. Thermophysical properties of a 37% aqueous solution of propylene glycol, crystallization temperature minus - 20°C

Table 3. Thermophysical properties of a 45% aqueous solution of propylene glycol, crystallization temperature minus - 30°C

Solution temperature, t°C	Density, kg/m**3	Heat capacity, Average, kJ/(kg*K)	Thermal conductivity, W/(m*K)	Dynamic viscosity, *10-3[N*s/m**2]	Kinematic viscosity, *10-6[(m**2/s]
-30°C	1066	3,45	0,397	160	150
-20°C	1062	3,49	0,396	74,3	70
-10°C	1058	3,52	0,395	31,74	30
0°C	1054	3,56	0,395	18,97	18
20°C	1044	3,62	0,394	6,264	6
40°C	1033	3,69	0,393	2,978	2,9
60°C	1015	3,76	0,392	1,624	1,6
80°C	999	3,82	0,391	1,10	1,1
100°C	984	3,89	0,390	0,807	0,82

Propylene glycol is also known as 1,2 - propylene glycol, monopropylene glycol, propanediol-1,2, Propylen Glycol, Monopropylene glycol, MPG, Propane-1,2-diol, MPG, Propane-1,2-diol, Glikol monopropylenenowy, 1,2 -dihydroxy propan, 1,2-propanediol.

Propylene glycol (propanediol) C3H6(OH)2 molecular weight 76.09.
Two isomers are known: 1,2-propylene glycol CH3CHNOCH2OH (1,2-propanediol) and 1,3-propylene glycol CH2OHCH2CH2OH.

Propylene glycol– a colorless, viscous, hygroscopic liquid, sweetish in taste and odorless.

Propylene glycol(propanediol) is a diatomic alcohol of the aliphatic series.

Boiling point 189 o C, molecular weight 76.094; viscosity at 20 o C 45.66 centipoise (cP); ignition temperature 111.1 o C, dihydric alcohol CH3CH(OH)CH2OH.

Propylene glycol completely miscible with water (dissolution occurs with the release of heat).

Propylene glycol dissolves well most low-molecular oxygen- and nitrogen-containing organic compounds such as monohydric alcohols, ethylene glycols and their ethers and other glycols, organic acids, aldehydes and ketones, esters, amines and other nitrogen-containing substances. Propylene glycol also mixes well with diethyl ether, ethylene chlorohydrin, chloroform, turpentine, acetone and many other organic solvents.

Sparingly soluble in benzene. One of the interesting properties propylene glycol is its ability to dissolve both hydrophilic and hydrophobic substances, which allows it to be used to mix substances that do not mix on their own.

With a range of connections propylene glycol forms azeotropic mixtures, i.e. such mixtures that are not separated into fractions during distillation. Forms azeotropic mixtures with aniline, (Tm=179 o C; 43% propylene glycol by weight), o-xylene (Tm=135.8 o C; 10.0%), toluene (Tm=110.5 o C; 1.5%).

Propylene glycol in the production of plastics and polymers

• Plasticizer
• Humidifier for parquet, furniture
• The basis of polyester unsaturated resins, polyurethanes

When interacting with triphenyl phosphate, phosphorus-containing compounds are formed, which are polymer stabilizers and are part of non-flammable polyurethanes. Linear polyesters obtained from propylene glycol and dicarboxylic acids containing aromatic or several methylene groups. Depending on the composition of the feedstock, the resulting polyester has hydroxyl or carboxyl groups at the ends. Of particular importance are polyesters of unsaturated acids or mixtures of saturated and unsaturated acids, which are then cross-linked with various vinyl compounds. Unsaturated polyesters are widely used for various coatings and the production of reinforced plastics, in particular fiberglass. Polyester resins with good mechanical properties at high and low temperatures, as well as high chemical activity, are obtained by interaction propylene glycol with polyhalide polyphenyls and the resulting compound - with organic acids.

Propylene glycol. Production of coolants and refrigerants.

Cooler for beer, milk, wine

Propylene glycol used for cooling beer, wine, milk and other liquids. Cooling is carried out by forced circulation, usually a 30% aqueous solution propylene glycol on coils. Advantage propylene glycol before water, ethylene glycol and a solution of salts in water is that due to non-toxicity propylene glycol The product can be used even after small leaks of propylene glycol through system leaks. Presence 0.25% propylene glycol does not affect the taste. Concentration propylene glycol 30% allows you to bring the cooler temperature to -12.8 o C; water allows you to lower the temperature only to 1.1 o C.

Propylene glycol automatically lubricates the cooling system elements.

Cooler in production

Cooling propylene glycol provides increased secondary safety in case of disruption of coolant circulation, man-made disasters, industrial accidents and personnel errors. Converting coolers to solution propylene glycol does not require modifications to the circulation system itself. When changing from water or brine to propylene glycol it is only necessary to clean the system of calcium deposits and chlorides. Proper cleaning of the system and control of the glycol solution ensures safe operation.

A reduction in energy consumption for coolant supply was also recorded.

Antifreeze for cars

Using an aqueous solution propylene glycol in cars, as a heat transfer agent from the engine to the radiator, it provides not only resistance to freezing down to –59 o C and protection of the environment during constant leaks as a result of malfunctions or regulations, but also protection of passengers, repair personnel and drivers from poisoning with ethylene glycol (more common in antifreeze toxic substance), not to mention reducing wear of moving parts due to high lubricating properties propylene glycol and increasing the service life of fixed parts due to low corrosion aggressiveness propylene glycol.

Coolant for buildings with autonomous heating systems and thermal stations

Usage propylene glycol as a coolant, it allows you to protect your home, people and animals due to secondary signs of man-made disasters and factors (fire, earthquake, accident and violation of heat supply operating rules), extends the service life of the individual heat supply system due to its low corrosiveness propylene glycol and not freezing at low temperatures. Resistance to low temperatures is especially important in the conditions of the far north and during unscheduled interruptions in the heating supply in winter, and the cost of high-quality coolant is preferable to the cost of repairing expensive equipment.
The creation of complexes with a closed thermal supply system, used, for example, in hotel country complexes, boarding houses and recreation centers, requires the use of highly reliable, environmentally friendly coolants that can withstand large energy overloads, have both high heat capacity and thermal conductivity, and high levels of anti-corrosion, durability, and heat resistance to crystallization and good lubricating properties. These are the properties that water-based coolants have. propylene glycol.

Application in air conditioning and ventilation systems

Application propylene glycol in this area provides undeniable advantages, because pour point of the pure product: from -60 to -77 o C. When water evaporates from the coolant/coolant, the system is safe while ethylene glycol freezes at 13 o C. Aqueous solutions with concentration propylene glycol 60% freezes at a temperature of about -70 o C.

In case of an emergency spill of coolant based on propylene glycol It is enough to collect it with a wet cloth, but at the same time, if ethylene glycol-containing coolant is spilled, it is recommended to change either the tiles or the wooden floor and the insulation that has absorbed the toxic ethylene glycol.