English name ozone
Structure or molecular formula
O atoms form σ-bonds in sp2 hybridized orbitals. The molecular shape is V-shaped.
Relative molecular weight or atomic weight 48.00
Density gas density (0 ° C, g / L) 2.144; liquid density (-150 ° C, g / cm3 ) 1.473
Melting point (° C) (solid) -251
Boiling point (° C) (liquid) -112
Properties
Gaseous ozone thick layer With blue, with a special odor, high concentration and chlorine gas odor similar; liquid ozone dark blue, solid ozone purple-black.
Uses
Used for water disinfection and air ozonation, used as a strong oxidant in the chemical industry.
Preparation or source
The main ozone technology: electrolysis, nuclear radiation, ultraviolet, plasma and corona discharge method and so on. Widely used is the ozone generator discharge oxidizing air or pure oxygen into ozone. That is, the application of high-energy interactive current action of oxygen in the air so that oxygen molecules ionized into ozone.
Ozone is an allotropic isomer of oxygen, at room temperature, it is a blue gas with a special odor.
Molecular Formula: O3
The English word ozone is derived from the Greek word ozon, meaning "smell".
The Spanish name is Ozono
Ozone has an isosceles triangle structure, three oxygen atoms are located at the three vertices of the triangle, the top angle of 116.79 degrees.
In 1840, C.F. Scheibein of Germany found that a special odor was released during the electrolysis of dilute sulfuric acid, so he named it ozone. When the photochemistry of oxygen in the atmosphere, ozone is produced, so the ozone layer is formed at a vertical height of 15 to 25 kilometers above the ground, and its concentration is 0.2 ppm. ozone gas is obviously blue, the liquid state is dark blue, and the solid state is blue-black. It has a triangular molecular structure . Ozone is unstable, slowly decompose at room temperature, 200 ℃ when the rapid decomposition, it is stronger than the oxidizing properties of oxygen, can be oxidized to silver peroxide metal silver, lead sulfide oxidation to lead sulfate, it can also oxidize organic compounds, such as indigo will be decolorized by ozone. Ozone solubility in water is greater than oxygen, 0 ℃ and 1 × 10 Pa, a body of water can dissolve 0.494 volume of ozone. Ozone can stimulate mucous membrane, it is toxic to human body, long time in the air containing 0.1ppm ozone is not safe to breathe. The ozone layer absorbs most of the short-wavelength rays (such as ultraviolet rays) and protects human beings and other organisms. However, chlorine and nitrogen oxides contribute to the decomposition of ozone into oxygen, destroying the ozone layer and becoming one of the most important environmental issues of concern to mankind. Ozone is usually prepared from oxygen or air with the help of silent discharge, ozone generators are manufactured according to this principle. Using the difference between the boiling points of ozone and oxygen, concentrated ozone can be obtained by graded liquefaction. Ozone is a powerful bleaching agent used to bleach flour and pulp, and ozone is used to disinfect drinking water, which contains only oxygen and has no special odor. It is also used in sewage treatment.
Ozone is highly decomposable and very unstable. It is insoluble in liquid oxygen, carbon tetrachloride and so on. There is a strong oxidizing property, at room temperature can be oxidized into silver oxide, lead sulfide oxidation into lead sulfate. Ozone is many organic pigments decolorization, erosion of rubber, it is easy to oxidize organic unsaturated compounds. Ozone is extremely stable in ice, and its half-life is 2000 years.
Ozone exists mainly in the lower stratosphere 20 kilometers from the Earth's surface in the ozone layer. It absorbs short-wave ultraviolet light, which is harmful to humans, and prevents it from reaching the Earth.
In 1785, the Germans found that an odor was produced when the motor was discharged, and in 1840, the French scientist Christian Frédérique identified it as ozone.
Under ultraviolet radiation, ozone can be formed naturally from diatomic oxygen by electron emission or exposure to sunlight. Industrially, with dry air or oxygen, the use of 5 ~ 25kv AC voltage for silent discharge production. In addition, the electrolysis of dilute sulfuric acid at low temperatures, or the liquid oxygen can be heated to produce ozone.
Ozone can be used to purify the air, bleach drinking water, sterilize, treat industrial waste and as a bleaching agent.
During the summer months, surface ozone forms and accumulates in agricultural and forestry areas, especially around large cities, due to industrial and automobile emissions. Surface ozone has an erosive and damaging effect on the human body, especially on the eyes and respiratory tract. Surface ozone is also harmful to crops and forests.
Physical Properties of Ozone
Properties Data
Molecular Weight 47.99828
Boiling Point?C -111.9
Melting Point?C -193
Critical Temperature?C -5
Critical Pressure atm 92.3
Isotropic Specific Volume (90.2K) 75.7 <
Heat of generation, KJ/mol -144
Solubility in water ml/100ml 49.4
Love/hate relationship with ozone
The protective effect of the ozone layer in the atmosphere on life on earth is now well known - it absorbs most of the ultraviolet rays released by the sun, protecting plants and animals from such rays. It absorbs most of the ultraviolet rays released by the sun, saving plants and animals from the harmful effects of these rays. In order to compensate for the thinning of the ozone layer and even the hole in the ozone layer, people are trying to do everything possible, such as promoting the use of non-fluorinated refrigerants to reduce the destruction of ozone by substances such as Freon. The International Day for the Preservation of the Ozone Layer has been designated for this purpose. The resulting impression seems to be that the more protected ozone should be, the better, in fact, is not the case, if the ozone in the atmosphere, especially near the ground in the atmosphere of ozone aggregation is too much, for human beings, ozone concentration is too high instead of a scourge.
Ozone is a trace gas in the Earth's atmosphere, it is due to the atmospheric oxygen molecules by solar radiation decomposition into oxygen atoms, oxygen atoms and the surrounding oxygen molecules combined and formed, containing 3 oxygen atoms. More than 90% of the ozone in the atmosphere exists in the upper atmosphere or stratosphere, 10 to 50 kilometers from the ground, which is the atmospheric ozone layer that needs human protection. There are also a small number of ozone molecules hovering near the ground, which can still play a role in blocking ultraviolet light. However, in recent years, it has been found that the ozone concentration in the atmosphere near the ground has been increasing rapidly, which is not good.
Where is this ozone coming from? Like lead pollution, sulfides, etc., it also originates from human activities, and automobiles, fuels, petrochemicals, etc. are important sources of ozone pollution. Walking in the streets of the traffic, often see the air slightly light brown, and a pungent and irritating odor, which is usually called photochemical smog. Ozone is the main component of photochemical smog, which is not directly emitted, but transformed into, for example, nitrogen oxides emitted by automobiles, as long as the sunlight radiation and suitable meteorological conditions can generate ozone. With the increase in automobile and industrial emissions, ground-level ozone pollution has become a common phenomenon in Europe, North America, Japan and many cities in China. According to the current information available to experts, it is estimated that by 2005, the near surface atmospheric ozone layer will become the main pollutant affecting the air quality of China's northern region.
Studies have shown that ozone concentration in the air at the level of 0.012ppm - a level typical of many cities - can cause people's skin to tingle, the eyes, nasopharynx and respiratory tract to be irritated, and lung function to be affected, causing symptoms such as coughing, shortness of breath, and chest pains; ozone levels in the air increased to 0.05 ppm in the air, the number of hospital admissions rose by an average of 7% to 10%. The reason for this is that, as a strong oxidizing agent, ozone can react with almost any biological tissue. When ozone is inhaled into the respiratory tract, it reacts quickly with cells, fluids and tissues in the respiratory tract, resulting in reduced lung function and tissue damage. The dangers of ozone are even more pronounced for those who suffer from asthma, emphysema and chronic bronchitis.
By its very nature, ozone can be both helpful and harmful; it is both a God-given umbrella for mankind and, at times, a potent poison. At present, for the positive effects of ozone and human should take what measures to protect the ozone layer, people have reached **** knowledge and do a lot of work. However, for the negative effects of the ozone layer, people have been recognized, but at present, in addition to atmospheric monitoring and air pollution forecasting, there is no real practical way to solve.
The principle of ozone sterilization can be thought of as an oxidation reaction.
(1) the mechanism of ozone inactivation of bacteria:
Ozone inactivation of bacteria is always carried out very quickly. Unlike other biocides: ozone can react with the bacterial cell wall lipid double bond, penetrate into the bacterial body, the role of proteins and lipopolysaccharides, change the permeability of the cell, thus leading to bacterial death. Ozone also acts on the nuclear material in the cell, such as purines and pyrimidines in nucleic acids to destroy DNA.
(2) The inactivation mechanism of ozone on viruses:
Ozone's effect on viruses is first of all the four polypeptide chains of viral capsid proteins, and RNA is damaged, especially the proteins that form it. After the phage is oxidized by ozone, electron microscopic observation shows that its epidermis is broken into many fragments, from which a lot of ribonucleic acid is released, interfering with its adsorption to the host body.
The thoroughness of ozone sterilization is not to be doubted.
Destroying the ozone layer jeopardizes each of us.
Ultraviolet light affects human health in many ways. The human body suffers from such things as sun spots, eye diseases, changes in the immune system, photodamage reactions, and skin diseases (including skin cancer). Skin cancer is a persistent disease, and the growth of UV rays increases the risk of developing this disease. UV photons have enough energy to break double bonds. Short- and medium-wave UV rays penetrate deep into the skin, causing inflammation of the skin and damage to the body's genetic material, DNA (deoxyribonucleic acid), which causes normally growing cells to metamorphose into cancerous cells and continue to grow into whole skin cancers. It is also said that the sun's rays penetrate the top layer of the skin. Ultraviolet radiation bombards the basic units of DNA in the nuclei of skin cells, causing many of the units to dissolve into useless fragments. The repair process of these faults may become abnormal, leading to cancer. Epidemiology has confirmed that the incidence of factory non-melanoma skin cancer is strongly correlated with sun exposure. People with all types of skin are at risk of developing non-melanoma skin cancer, but the incidence is higher in light-skinned people. Animal experiments have found that in ultraviolet light, the ultraviolet B wavelength region is the wavelength region with the strongest carcinogenic effect.
It is estimated that a 1% reduction in total ozone (i.e., a 2% enhancement of UV-B) will increase the rate of underlying cellular carcinomas by about 4%. Recent studies have found that UV-B can cause changes in immune system function. Some experimental results suggest that infectious skin diseases may also be associated with UV-B enhancement resulting from ozone reduction. It is estimated that a 1 per cent reduction in total ozone would increase the incidence of skin cancer by 5-7 per cent and cataracts by 0.2-0.6 per cent. Since 1983, the incidence of skin cancer in Canada has increased by 235%, in 1991 the skin disease patients have been up to 4.7 million. The U.S. Environmental Protection Agency, said the United States in the next 50 years died of skin cancer, will be expected to increase 20 million people than in the past. Australians like to sunbathe and get a tan. Despite repeated warnings from scientists that sun exposure can lead to skin cancer, they are happy to go dark. As a result, Australians didn't wake up until the incidence of skin cancer was twice as high as anywhere else in the world. Already, skin cancer accounts for one-third of all cancers worldwide.
The United Nations Environment Programme has warned that if the Earth's ozone layer continues to shrink and thin at its current rate, the proportion of skin cancer cases worldwide will increase by 26 percent to 300,000 by the year 2000.
The United Nations Environment Programme has warned that if the ozone layer continues to shrink and thin at its current rate, the proportion of skin cancers worldwide will increase by 26 percent to 300,000 by the beginning of next century. If the ozone layer decreases by another 10 percent by the beginning of the next century, the number of cataracts worldwide could reach 1.6 million to 1.75 million people each year.
Exposure to UV rays may also induce measles, chicken pox, malaria, scarring, fungal diseases, tuberculosis, leprosy, and lymphoma.
The increase in UV rays can also cause massive deaths of marine plankton and shrimp, crab larvae, and shellfish, resulting in the extinction of some organisms. The result of UV exposure can also cause myopia in flocks of rabbits and blindness in thousands of sheep.
UV-B reduces photosynthesis by about 5% in plankton under enhanced UV-B radiation, according to experiments off the coast of Africa. Enhanced UV-B can also cause changes in freshwater ecosystems by destroying microorganisms in the water, thus reducing the self-purification of the water. Enhanced UV-B can also kill young fish, shrimp and crabs. If there is an extreme decline in the original plankton in the Antarctic Ocean, marine life as a whole will change dramatically. However, some plankton are sensitive to UV and some are not. There is a 100-fold difference in how much UV light damages the DNA of different organisms.
Severe hindrance to normal growth of various crops and trees Some plants, such as peanuts and wheat, are better protected against UV-B, while others, such as lettuce, tomatoes, soybeans and cotton, are sensitive. The United States of America University of Maryland Agricultural Biotechnology Center of Trenmola with a sun lamp on six soybean varieties for observation experiments, the results show that three of the soybean varieties are extremely sensitive to ultraviolet radiation. Specific performance, soybean leaf photosynthesis intensity decreased, resulting in yield reduction, but also make soybean seeds in protein and oil content decline. The loss of 1% of the atmospheric ozone layer, soybean production will also be reduced by 1%.
Trenmola also spent four years observing the effects of high doses of ultraviolet radiation on tree growth. The results showed that there was a significant reduction in wood accumulation, and their root growth was stunted as a result.
Adverse Disruptive Effects on Global Climate The large decrease in upper stratospheric ozone and the associated increase in lower stratospheric and upper tropospheric ozone may have adverse disruptive effects on global climate. Vertical redistribution of ozone may warm the lower atmosphere and exacerbate the greenhouse effect caused by increasing amounts of carbon dioxide.
Photochemical air pollution Excessive ultraviolet light makes polymers such as plastics susceptible to aging and decomposition, resulting in a new type of pollution - photochemical air pollution.
The molecular structure of ozone: there is a 3-center 4-electron pie bond in the center, 4 electrons are used by 3 oxygen atoms ****, and the other two black line side of the normal **** valence bond, ozone is symmetric, so it is non-polar.
But note: although the electronic formula of ozone and carbon dioxide is similar, but the molecular structure is different. Ozone is folded linear, carbon dioxide is linear. This is explained by using inorganic chemistry from college.
NASA scientists recently discovered that the giant ozone hole over Earth's Antarctica underwent a significant change in September, turning from a swirling vortex into an amoeba shape with two large ends and a small center.
Although the ozone hole appears to have shrunk in size over the past two years, scientists warn that it's too early to say that the ozone layer is "repairing itself". Paul Newman, an ozone expert at the Air and Space Agency, said rising atmospheric temperatures have caused the hole to shrink. In 2000, Antarctica's ozone hole area had once reached 2.8 million square kilometers, equivalent to the area of three continental United States; in early September 2002, the Air and Space Agency scientists estimate that the hole shrinks to 1.5 million square kilometers.
An Australian ozone research group has reported good news to the world: because of the effective implementation of environmental protection measures over the years, the ozone hole over Antarctica is shrinking, and it is expected that by 2050, this "infamous" huge hole can be completely "filled". The notorious hole is expected to be completely "filled" by 2050.
According to reports, the ozone hole over Antarctica has been one of the problems that have plagued environmentalists around the world. At its worst, the ozone hole was once as large as three Australia. Scientists have found that the main culprits of the ozone hole are chlorofluorocarbons (CFCs) in the atmosphere - an organic compound containing chlorine, fluorine and carbon (commonly known as "Freon"). "
This is the first time that we've seen this in action.)
In order to prevent further aggravation of the ozone hole and to protect the ecological environment and human health, in 1990 countries formulated the Montreal Protocol, which sets strict limits on the emissions of chlorofluorocarbons (CFCs). Now, the tireless efforts of environmental organizations over the years have finally paid off: ozone is back! Paul Fraser, an atmospheric research specialist at Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO), exclaimed, "This is big news. We've been looking forward to this day for a long time!" He said that although there are many other factors affecting the progress of the shrinking ozone hole, such as the greenhouse effect, climate change, etc., "but we have come to this conclusion after taking all the factors into account: the ozone hole over Antarctica will disappear completely in less than 50 years."
It is reported that from the 1950s onwards, with the massive popularization of refrigerators and air conditioners (the main source of HCFC production), the level of HCFCs in the atmosphere increased year by year, reaching a peak in 2000. It was only later, with the creation of new fluorine-free refrigerators, that HCFC levels began to decline significantly.
Scientists find that ozone in the soil inhibits plant growth
A joint study by European scientists found that the ozone layer is a natural barrier that protects surface organisms from the harmful effects of the sun's ultraviolet rays, but ozone in the soil is the enemy of plant growth, inhibiting the growth of a variety of plants and causing significant losses to agricultural production.
Ozone is a naturally occurring atmospheric trace colorless gas with a special odor, the vast majority of ozone exists in the stratosphere about 25 kilometers from the ground, which is often referred to as the ozone layer. The amount of ozone tends to vary with latitude, season and weather.
French researchers say that the ozone layer in the sky absorbs more than 99 percent of the sun's ultraviolet rays, providing a natural protective barrier for life on Earth, while ozone is a serious pollution when it is present in the soil. The latest research shows that the more light the place, the loss of ozone in the soil, especially for crops, the greater the loss.
The French researchers believe that the main reason for the increase in ozone content in the soil is that fossil fuels such as petroleum products produce nitrogen oxides during the combustion process, and these nitrogen oxides are floating around in the air, where some of the oxygen atoms are slowly combining with the oxygen in the air, constituting ozone composed of three oxygen atoms. They emphasized that sunlight accelerates this chemical reaction, so that ozone in the soil affects plant growth to different degrees in different climatic regions. In water treatment systems, tanks, exchange columns, and a variety of filters, membranes, and piping are constantly harboring and multiplying bacteria. While all methods of disinfection and sterilization provide the ability to remove bacteria and microorganisms, none of these methods are capable of removing all bacteria and water-soluble organic contamination in a multi-stage water treatment system. The best method currently available for continuous removal of bacteria and viruses in high-purity water systems is with ozone.
Ozone has been used in water treatment since 1905. It is superior to treating water with chlorine and removes halides from the water. The application of this method in domestic water systems is only in its infancy. Abroad, this method of disinfection has become very common, due to the fact that ozone does not produce harmful residues.
The use of ozone disinfection and the installation of ultraviolet lamps in front of the point of water to reduce ozone residues is one of the common methods of disinfection of pharmaceutical water systems, especially purified water systems.
(1) Chemical Properties and Efficacy