Solvents is a substance that allows the dispersion of another within it. It is the dispersing medium of the Dissolution .
Summary
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- 1 Definition
- 2 General classification
- 3 In Liquid solvents we distinguish
- 1 Aqueous
- 2 Organic
- 4 Some examples of solvents
- 5 Health effects
- 1 Massive exposures
- 2 Common exposures
- 3 Exposures at home
- 4 Exposures at work
- 6 Environmental impact
- 1 Emissions to the atmosphere
- 2 Solvents affecting the ozone layer
- 7 Sources
Definition
Substance that is capable of destroying the aggregation of the Molecules of a soluble body. A broader meaning of the word is that component that is found in greater proportion in a homogeneous mixture.
General ranking
They can be solid, liquid or gaseous. Normally, only those who under normal conditions of pressure and temperature appear in a liquid state are considered as such.
In Liquid solvents we distinguish
Aqueous
The aqueous ones are used to dissolve polar substances. Its physical properties are the same as H2O and the chemical ones depend on the substances they contain. They are substances in whose molecules the distribution of the electronic cloud is asymmetric; therefore, the molecule has a positive and a negative pole separated by a certain distance. There is a permanent dipole. The classic example of an aqueous solvent is water. Low molecular mass alcohols also belong to this type.
Organic
Chemical substances, or a mixture thereof, that are capable of dissolving non-water- soluble substances and that due to their solvent properties have multiple applications in various industrial-working technologies. Those included in this group are those properly considered as solvents. In general they are substances in whose Molecules the distribution of the electronic cloud is symmetrical; therefore, these substances lack a positive and negative pole in their molecules. They cannot be considered permanent dipoles. This does not imply that some of their links are polar. Everything will depend on the geometry of its molecules. If the individual dipole moments of its bonds are compensated, the molecule will, as a whole, be apolar. Some solvents of this type are:Diethyl ether , Chloroform , Benzene, Toluene , Xylene , Ketones , Hexane , Cyclohexane , Carbon tetrachloride is the one that dissolves or will dissolve, etc. A special case is fluorinated liquids, which behave as more apolar solvents than conventional organic solvents.
Some examples of solvents
Some examples of oxygenated solvents are Alcohol , Esters , Glycolic Ethers and Ketones , including Methyl Ethyl Ketone . Examples of hydrocarbon solvents are acetone, acetonitrile, benzene, dioxane , Gasoline , Hexane , Kerosene , Methanol , Phenol, styrene, toluene, turpentine, xylene and aliphatic and aromatic hydrocarbons. Some examples of halogenated solvents are carbon tetrachloride, chlorofluorocarbons (CFCs), chlorobenzene, chloroform, ethylene dichloride, methylene chloride, perchlorethylene (tetrachlorethylene), 1,1,1-trichloroethane (methyl chloroform), and trichlorethylene.
Health effects
Massive exposures
Exposure to massive amounts of solvents can cause sudden death. Prolonged exposure to solvents can lead to blindness, cardiac arrhythmias, and kidney, liver, lung, and central nervous system injuries. Some solvents are listed as “compounds that are reasonably presumed to be carcinogenic to humans” in the Eleventh Report on Carcinogens , published by the National Toxicology Program, and can cause cancer.Some examples are acetonitrile, benzene, carbon tetrachloride, chloroform, perchlorethylene, and trichlorethylene.Exposure to glycol ethers can cause harm to the fetus, and reduce fertility in men.
Usual exposures
Regular exposure to solvents can lead to memory and hearing loss, mental illness, depression, fatigue, confusion, dizziness, feeling drunk or drugged, lack of coordination, headache, nausea, stomach pain, skin rashes, cracking or bleeding from the skin and irritation of the eyes, nose and throat. Exposure to solvent vapors can cause hoarseness, cough, lung congestion, chest tightness, and difficulty breathing. If children are exposed to high levels of solvents in the home, they may suffer from asthma.
Home exhibitions
You could be exposed to solvents by breathing them in, absorbing them through your skin, or ingesting them. At home, you could be exposed when using cleaning products, personal care products, nail polish remover, paints, rubbers, adhesives, and other household products that contain solvents. You could also be exposed if you dry-clean your clothing, which releases small amounts of perchlorethylene into the air, or if you go to a laundry where there are dry-cleaning machines.
Exposures at work
You could be exposed to solvents on the job if your job involves immersion cleaning, steam degreasing, manufacturing products that use glues and adhesives, paint removal, fuels, transfer of flammable solvents, paint, offset printing, washing in dry, carpet installation and cleaning of electronic components, auto parts, motors and circuit boards. You could be exposed if you participate in the manufacturing of soaps, printed circuit boards, semiconductors, personal care products, pharmaceuticals, or textiles. You could be exposed if you work in a hospital, factory, food processing or agricultural complex, or in a fine art restoration facility. You could also be exposed to solvents on military bases.
Environmental impact
The use of solvents is massive in all kinds of industries, which raises environmental pollution problems. In addition to their effects on human health, organic solvents, when evaporated, reach the atmosphere and intervene in the formation of tropospheric ozone, a dangerous summer pollutant that is related to allergies, asthma and respiratory diseases, as well as damage to vegetation and crops.
Emissions to the atmosphere
Emissions to the atmosphere of organic solvents reached a volume of around 600,000 tons in Spain in 1990. On the other hand, the production of used solvents, considered as toxic and dangerous waste, is estimated at 110,000 tons for 1999, three quarters of which were produced in the Autonomous Community of Catalonia (see attached graphic). The Spanish Government has ratified the Geneva Protocol (1991), which sought to reduce emissions of volatiles to the atmosphere by 30% by 1999, based on those of 1988.
Solvents that affect the ozone layer
Since some solvents deplete the ozone layer, their use and production have been progressively reduced. Some examples are CFCs, carbon tetrachloride, and 1,1,1-trichloroethane. Industries where solvents are used include dry cleaning, painting, printing, soap making, paint removal, textile manufacturing, asphalt paving, semiconductor and integrated circuit board manufacturing, printed circuit board cleaning, agriculture and food production, pesticide application, hospitals, oil painting and restoration of works of art.