Environmental impact of deicing reagents - Студенческий научный форум

XII Международная студенческая научная конференция Студенческий научный форум - 2020

Environmental impact of deicing reagents

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Traditionally, the unexpected arrival of winter in our country causes a lot of complications. One of them is ice, dangerous for both pedestrians and motorists. Fighting him on the road is carried out using anti-icing reagents. As soon as winter comes and it comes to anti-icing reagents, pedestrians begin to complain about spoiled outerwear and shoes, and drivers remember dirty mud that is flying from under the wheels and corroded by the body.

Nowadays, anti-ice reagents are resorted to in almost all cities, both large and small. Surfactants are added to them. Because this is practically the only way to reduce the number of accidents and protect citizens from falling, and cars from collisions. Environmental pollution with anti-icing substances has a direct and indirect effect on animate and inanimate nature. That is why the issues of evaluating these funds have now become very relevant.

Anti-icing reagents (anti-icing reagents) are special products created on the basis of salts of calcium (CaCl2 - calcium chloride), magnesium (MgCl2 * 6Н2О - magnesium chloride) and sodium (NaCl2 - sodium chloride), used in the fight against ice and snowfall in winter . Hard coatings (pedestrian paths, sidewalks, carriageway) are treated with anti-icing reagents, which are prone to the formation of ice, which occurs when moisture freezes and during a snowfall. The choice of anti-icing reagents is very extensive, they are distributed both in solid and in liquid form, depending on the technology of their application and production.

Classification

Anti-icing products can be divided into:

natural: technical salt (calcium chloride, sodium chloride, magnesium chloride, etc.), ordinary building sand, fine granite crushed stone, or, as it is also called, granite crumb.

artificial: deicing reagents obtained chemically in laboratory conditions. The most popular chemical anti-icing reagents now include sodium chloride, magnesium chloride, calcium chloride and a sand-salt mixture.

Reagent Types

Anti-icing reagents are : liquid; solid; granular.

All types of anti-icing reagents have different composition and chemical characteristics, but they share one common property - lowering the melting point of snow. In snowy, slushy weather, reagents of solid types are most used, and in dry weather, with ice - liquid chemicals.

These reagents have other areas of their use:

Sodium chloride is a common table salt that we all eat. On the streets, sodium chloride is used with a low degree of purification, which may contain impurities of sand or other salts - the so-called technical salt.

Calcium Chloride is a calcium salt of hydrochloric acid registered as food supplement E509. This additive is used to preserve fruits and vegetables, to soften meat, and is used in the fermentation of dairy products (for example, in the production of cottage cheese).

Magnesium chloride is an inorganic compound that is quite common in nature. In food production, magnesium chloride acts as a hardener and thickener (E511).

Potassium acetate is a colorless or white crystals with the taste characteristics of weak alkali. In the field of food production, a solution of potassium acetate and its crystals are used as preservatives, as well as acidity regulators.

Calcium Chloride (CaCl2):

"Pros":

melts ice faster and more efficiently and prevents ice formation can be used not only during snowfall, but also before and after it as a preventive measure, penetrating into the soil, calcium improves its condition, and the consumption of this reagent and environmental load are much lower than salt.

"Minuses": short duration, an average of 3 hours; 30 percent less tire grip; causes allergies not only in humans but also in animals; corrodes metal; aggressive towards shoes made from natural materials;known for its whitening properties, changes the color of shoes

Calcium chloride (CaCl 2)

Bischofite - magnesium chloride (MgCl2 * 6H2 O):

"Pros":

effective even at low temperatures and prevents the formation of ice for several days, which significantly reduces its consumption,does not form a slippery film on the road surface when ice melts, able to absorb moisture from the environment

"Minuses": has a detrimental effect on the soil; allergic reactions in both humans and animals are possible; accumulates magnesium anions in soils and natural waters; causes paw burns in animals

Bischofite - magnesium chloride MgCl 2 * 6Н 2 О

Potassium Acetate (CH3COOC): does not lose its properties even at a temperature of -60 degrees,its duration lasts up to 3-7 days from the time of application, does not cause corrosion of metals, the adhesion coefficient during processing with this reagent remains high,mineral properties of the constituent substances fertilize the soil, does not corrode rubber and metal.

"Cons": causes allergies, expensive deicing agent, adversely affects leather shoes.

Potassium Acetate CH 3 SOOK

Sodium Chloride (NaCl):

"Pros": the cheapest way to deal with ice, instantly melts ice, does not freeze from 0 to

16 ° C and acts constantly.

"Cons": clogs water drains; pollutes the lawns pairs of sodium salts corrode the insertion of electrical wires, salt corrodes bodies, car wheels, shoes of passers-by, soil salinization occurs, green plants die.

For example, a solution of calcium chloride or sodium chloride first turns ice into water, and then the reverse chemical process occurs, hydrolysis of the salt, resulting in the formation of a poorly soluble precipitate in water. And this in turn leads not only to dirt, but also to a decrease in the coefficient of adhesion of tires to the road surface. In addition, the chemicals included in the reagents cause non-specific reactions of the skin, mucous membranes and bronchi of humans and animals. Exacerbated diseases in allergy sufferers and asthmatics.

This happens primarily because on the roads the reagents are mixed with other substances, the sources of which are a number of factors.

Firstly, automobile tires emit a significant number of chemical components (for example, carbon or sulfur), in addition, as a result of friction, small rubber particles are separated from them, which are mixed with chlorides of sodium and calcium salts.

Secondly, car bottoms are treated with anti-corrosion coatings, which also enter into a chemical reaction with anti-icing reagents. Another source of additional chemicals are washing fluids for car windows, some of which fall on the road. The fourth source of components for the chemical “cocktail” is the road surface itself.

In addition, the reagent itself - calcium chloride or sodium chloride - is not used in its pure form. Chloride serves as the basis of the reagent, to which sand or granite chips are added, in addition, the components of the reagents may contain impurities (magnesium, copper, cobalt, lead, arsenic, mercury, molybdenum). It is easy to imagine what an explosive mixture of substances that enter into active chemical reactions among themselves, gets into the soil, on our shoes, the feet of pets, as well as plants growing in the city.

Reagent control

Chemicals for the fight against ice on roads are used not only in Russia - in the USA and Canada roads are sprinkled with magnesium chloride.

However, in addition to aggressive chemical compounds, other methods of dealing with ice can also be used: for example, in Austria, Finland or Sweden, the friction method is used along with chemicals: roads are strewn with sand or stone chips. The advantage of this method is that no chemical reactions occur, and the minus is the fragility of such a coating. Sand and baby are blown off the road by the wind, carried by car wheels and pedestrian feet, and scratch shoes.

In Sweden, another method unusual for us is also used, named after the researcher TorgeiraVaa. The scientist found out:

if fine sand is mixed with hot (90–95ºC) water in a proportion of 7 to 3 and then this mixture is sprayed onto snow and ice, then the grains of sand will “melt” into the ice, thereby making the surface rough. The sand is not blown away by the wind, and the adhesion of car wheels and pedestrian shoes to the surface increases.

This treatment is enough for about a week (even with a fairly intense movement), then it must be repeated.

In Norway, they went even further - they are building heated highways. Such a radical (and expensive) method allows you to completely forget about the snow and ice on the roads. Japan also does not use any means to combat ice, including warm roads.

The Japanese went along one of the easiest ways - they simply clean the roads. Powerful and short snowfalls are characteristic of this country, therefore such a solution to the problem is quite effective.

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