Ozone, the chemical molecular formula for O3, also known as three atomic oxygen, superoxygen, because of its fishy odor, it can be reduced to oxygen at room temperature. Higher specific gravity than oxygen, easily soluble in water, easy to decompose. Because ozone is composed of oxygen molecules carrying an oxygen atom, it is only a temporary state, carrying oxygen atoms in addition to oxidation, the rest of the combination of oxygen into a stable state, so ozone has no secondary pollution.
Chemical formula O3, formula quantity 47.998, an allotrope of oxygen. A pale blue gas with a fishy smell. Ozone has strong oxidation, is a stronger oxidant than oxygen, can take place at a lower temperature oxidation reaction, such as silver oxidation to silver peroxide, lead sulfide oxidation to lead sulfate, with potassium iodide reaction to iodine. Turpentine, gas, etc. can spontaneously ignite in ozone. Ozone is a strong bleaching agent in the presence of water. Unsaturated organic compounds also tend to form ozonates at low temperatures. Used as a strong oxidant, bleaching agent, fur deodorizer, air purifier, disinfection fungicide, drinking water disinfection deodorization. Ozone can be used to replace many catalytic oxidation or high temperature oxidation in chemical production to simplify the production process and improve productivity. Liquid ozone can also be used as an oxidant for rocket fuel. Exists in the atmosphere, close to the earth's surface concentration of 0.001 ~ 0.03 PPM, is generated by the oxygen in the atmosphere to absorb the sun's wavelength is less than 185nm ultraviolet rays, the ozone layer can absorb the harmful short-wave rays in the sun (below 30nm), prevent such short-wave rays from the ground, so that human beings from the damage of ultraviolet rays. [1]
Chinese name
Ozone
English name
Ozone
called
superoxide
chemical formula
O₃
molecular weight
47.9982
CAS accession number
10028-15-6
EINECS accession number
233-069-2
melting point
-192℃
boiling point
-111℃
water soluble
1 volume of water dissolved 0.494 volume Ozone
dense
2.14g/L(0°C，0.1MPa)
appearance
Blue gas at room temperature
should be used
in medicine, agriculture, catering industry, sterilization, in addition to formaldehyde and other
safety description
workplace limit value 0.15ppm
occurrence method
irradiation method, electrolysis method, radiochemical method and other
ozone,The chemical molecular formula is O3，also known as three-atomic oxygen and superoxygen, which is named for its fishy odor and can be reduced to oxygen at room temperature. Higher specific gravity than oxygen, easily soluble in water, easy to decompose. Because ozone is composed of oxygen molecules carrying an oxygen atom, it is only a temporary state, carrying oxygen atoms in addition to oxidation, the rest of the combination of oxygen into a stable state, so ozone has no secondary pollution. [2]
Liquid ozone is dark blue with a density of 1.614g/cm3（liquid，-185.4℃） and a boiling point of -111.9℃, while solid ozone is blue-black with a melting point of -192.7℃. The molecule is V-shaped and unstable. The decomposition of ozone is slow at room temperature, and it is accelerated to decompose into oxygen when the ozone is irradiated with ultraviolet light of 25nm or above 164℃ or in the presence of catalyst. [1] Under normal temperature and pressure, ozone is a gas with a critical temperature of -12.1℃ and a critical pressure of 5.31MPa. It is light blue when gaseous, dark blue when liquefied, and purple-black when solid. Gas is insoluble in water and liquid oxygen, but soluble in liquid nitrogen and lye. Liquid ozone slowly decomposes at room temperature, rapidly decomposes at high temperature, producing oxygen, and can explode when hit or friction occurs. [3]
The decomposition rate of ozone in aqueous solution is faster than that in gas phase. The half-life of ozone decomposition in water is related to temperature and pH value. As the temperature increases, the decomposition rate increases. When the temperature exceeds 100℃, the decomposition is violent; When the temperature reaches 270℃, it can be converted into oxygen immediately. The higher the pH, the faster the breakdown. It is decomposed in the air of normal temperature and pressure, and the half-life is about 15 ~ 30min. [4]
the olfactory threshold of ozone is 0.02mL/m3，If the concentration of ozone reaches 0.1mL/m3it will stimulate the mucosa, and if the concentration reaches 2mL/m3it will cause central nervous disorders. [3]
Strong oxidizing
ozone can discolor most organic pigments. Can slowly erode rubber, cork, so that organic unsaturated compounds are oxidized. Commonly used in: beverage disinfection and sterilization, air purification, bleaching, water treatment and drinking water disinfection, granary killing mold and eggs; In reaction with organic unsaturated compounds, ozonides can be formed, which can be decomposed in the presence of water, and the original unsaturated bonds can be opened to produce aldehydes, ketonesandcarboxylic acids etc.Because of ozone decomposition, it can be used as a synthetic method and determine the structure of organic matter. [3]
Ozone is one of the strongest oxidants in nature because of its strong oxidability and bactericidal properties. Its REDOX potential in water is second only to fluorine. At the same time, the product of ozone reaction is oxygen, so ozone is an efficient oxidant without secondary pollution. As a strong oxidant, its characteristics are as follows [5]：①can be used for selective oxidation, high yield of the main product; ② The oxidation temperature is low, and the oxidation ability is strong at atmospheric pressure, and it is beneficial to the oxidation of sensitive substances;③ The reaction speed is fast and can be quantitatively oxidized; ④ Easy to use and manufacture. [5]
The application of ozone is based on its strong oxidizing ability and bactericidal ability. The application of ozone according to its role classification, can be divided into: sterilization, decolorization, deodorization, deodorization and oxidation decomposition. According to its application field, it is mainly applied in the following fields: water treatment; Food processing, storage, preservation; Household appliances; Health care; Chemical oxidation. [5]
检测分析
Detection and analysis Ozone analysis mainly includes spectral analysis and electrochemical analysis. The common detection methods are iodine quantity method, indigo disulfonic acid sodium spectrophotometry, ultraviolet absorption method and chemiluminescence method. Iodimetry is commonly used in laboratories. By passing ozone into a solution of potassium iodide, iodine can be freed, and this reaction can be used for the quantitative analysis of ozone. [3]
Iodinometric method uses ozone and KI to generate I2, takes starch as indicator,titrates with sodium thiosulfate, or can use starch reagent after color development, according to the color depth, colorimetric determination at 550nm. [4]
A brief history
As early as 1785, the German physicist von Marum, experimenting with a high-powered motor, discovered that when air flows over a string of sparks, it produces a special smell, but did not investigate it. Later, in 1840, Schaubein also discovered a unique odor during electrolysis and spark discharge experiments and concluded that it was produced by a new gas, thus announcing the discovery of ozone. [6]
During World War I, ozone was first used by some German soldiers to treat skin gangrene caused by anaerobic bacteria. In 1936, the French doctor P. Ubourg first advocated injecting ozone into the rectum to treat colitis. Since then, medical researchers and medical workers have made rapid progress in the clinical application of ozone. Ozone in foreign countries, especially in Europe has a long history of more than 50 years of clinical application, after the ninety s, the application of ozone into our country, mainly applies the ozone treatment between the waist dish outstanding, scavenging free radicals, anti-aging and so on, after ozone quickly developed in clinical application and is becoming a widely used, powerful new drugs, the new method. [7]
From the early 1980s, China has begun to pay attention to the ozone disinfection of drinking water and the depth treatment of industrial wastewater, but the development is slower. In our present urban water supply, the vast majority of water plants adopt the treatment process of coagulation, precipitation, filtration and disinfection, which mainly uses chlorine gas and bleaching powder, the proportion of using ozone is very low. At the same time, the application of ozone in cooling water treatment practice is just beginning. However, due to the economic efficiency, reliability, absolute non-toxic, no secondary pollution and other advantages of ozone treatment, it can be predicted that ozone will be popularized in our country. [5]
Ozone generation methods mainly include ultraviolet irradiation method, electrolysis method, radiochemical method and dielectric barrier discharge method.
Ultraviolet irradiation
is the use of ultraviolet light irradiation dry oxygen, so that a part of the oxygen molecules are activated to dissociate into oxygen atoms, thus forming ozone.Ozone produced by ultraviolet irradiation is characterized by low concentration of ozone, the advantage is not easy to produce oxides, do not need complex conversion equipment. But UV irradiation is not suitable for mass production of ozone, only suitable for a small number of low concentration requirements of various tests, such as air disinfection, sterilization, deodorization and so on.
Electrolytic process
The technology of ozone preparation by electrolysis was established in 1840. It mainly uses low voltage direct current to electrolyze water, which produces ozone by oxidizing water at the anode-solution interface. The ozone preparation device is composed of electrolyte solution and Yin and Yang poles. Ozone precipitates at the anode, and the cathode can be divided into two types: hydrogen evolution cathode and oxygen reduction cathode. [8]Before the 1980s, electrolytes were mostly added with acid and salt electrolytes in water, with a relatively small electrolytic area, low ozone production and high operating costs. After a lot of research on plate material, electrolyte, mechanism and process of electrolysis, ozone technology by electrolysis has made great progress.Recently developed SPE (solid polymer electrolyte) electrode and metal oxidation catalytic technology, electrolyzed purified water to obtain more than 14% high concentration of ozone. Ozone produced by electrolysis has high concentration, pure composition, high solubility in water [5], no pretreatment of feed air and no nitrogen oxides; In addition, the ozone production equipment is small and light, simple structure, no noise, portable, so its application prospect is very broad. [8] Its main disadvantage is its high energy consumption. After further improvement and efforts to reduce the cost and power consumption, it may be competitive with the widely used dielectric barrier discharge method. [5]
Among the methods for preparing ozone by electrolysis, the method using lead dioxide as electrode is the main one. How to improve the efficiency of ozone production by electrolysis is the main research direction. As we know, in the electrochemical reaction, pH, temperature, current density and the types of electrode is the most critical, now there are a lot of literature reports on modification of lead dioxide electrode, such as in the lead dioxide electrode with a small amount of titanium dioxide, can greatly improve the efficiency of lead dioxide electrode current and electrical conductivity, but failed to change the lead dioxide corrosion problems; The β-type lead dioxide is more stable and affordable, and the ozone concentration can reach more than 13%, while it does not produce harmful nitrogen oxides. However, β-type lead dioxide is easy to recrystallize under high voltage and acid conditions, resulting in unstable catalytic efficiency of the anode catalytic layer. The anode and cathode catalytic layer is easy to desorption, which makes the working life of the membrane electrode very short, and even leads to short circuit in serious cases. The existing preparation technology of the membrane electrode catalytic layer is not stable, and the main reason for this problem is that the catalytic layer is not closely attached to the membrane. Based on the advantages and disadvantages of lead dioxide and SPE membrane electrode, it is necessary to study the composite membrane electrode of lead dioxide and SPE. [8]
Radiochemistry
Radiochemistry uses nuclear radiation from various sources to dissociate oxygen molecules into ozone. Two kinds of processes have been used in industrial ozone production. The first is the contact of oxygen with fission products and the thermal collision of oxygen with fission products and secondary radiation to produce ozone. Second, ozone is generated only under radiation. Because of the high cost and poor safety of using radioactive sources, this method is only suitable for some special cases and is not suitable for industrial mass production. [5]
Dielectric barrier discharge method
is also known as silent discharge method (DBD method). The corona is generated in the gas by alternating high voltage electric field, and the free energetic electrons in the corona dissociate oxygen molecules, which are aggregated into ozone molecules by collision. Dielectric barrier discharge method has the advantages of relatively low energy consumption, large ozone production per unit, dry air, oxygen or oxygen-rich gas with high concentration of oxygen can be used as the gas source, so this method is mostly used in industrial ozone synthesis. [5]
In the last century, ozone was usually produced by thermochemical methods. Although the theoretical value of ozone rate (energy utilization efficiency of ozone production) calculated by thermochemical theory is 1200g/ (kW·h), only 4% ~ 12% conversion ratio is available in practical production. The remaining energy is converted into heat and escapes, and the actual yield is far from the theoretical value. Since the 21st century, in order to improve the concentration and yield of ozone in sealed containers, so as to reduce the production cost, scientists have carried out numerous academic exchanges. [9] With the continuous theoretical research and the continuous improvement of technology, the main research directions are focused on different raw materials, related gases, different electrode forms, different reaction media, electrode materials and discharge forms. [9]
Plasma The basic principle of ozone generation in the process of plasma discharge is that in the low-temperature plasma atmosphere formed by oxygen-containing gas in the discharge reactor, free electrons of a certain energy decompose oxygen molecules into oxygen atoms, and then form ozone molecules through three-body collision reaction, and ozone decomposition reaction occurs at the same time. [9]
Ozone disinfection technology and application edit the advantages of ozone disinfection
（1）disinfection has no dead Angle, high sterilization efficiency and odor removal. During disinfection, the ozone generator produces a certain amount of ozone, which has uniform diffusion and good permeability in a relatively closed environment. It overcomes the problem of the disinfection dead Angle in ultraviolet sterilization, and achieves the purpose of all-round, rapid and efficient sterilization. In addition, because of its wide bactericidal spectrum, it can kill a variety of microorganisms such as bacterial reproductive body, spore, virus, fungus and protozoan sporulation, and can also destroy botulinum bacillus and toxin and rickettsii body etc. and also has a strong function of odor such as mildew, fishy and smelly. [2]
（2）No residue, no pollution. Ozone is produced by using the oxygen in the air. In the process of disinfection and oxidation, the excess oxygen atoms combine into molecular oxygen after 30 minutes, and there is no residual substance, which solves the problem of secondary pollution caused by the residue of disinfectant disinfection and eliminates the need for cleaning again after the end of disinfection. [2]
Disinfection
Ozone is a strong oxidant, its molecules are extremely unstable, can decompose to produce monatomic oxygen (O) and hydroxyl (OH) with strong oxidation capacity, is a unique melt-type preparation, can quickly integrate into the cell wall, damage the internal structure of bacteria, viruses and other microorganisms, has a strong killing effect on various pathogenic microorganisms. The sterilization process is a biochemical oxidation reaction. Its effects are mainly achieved through the following three forms :(1) ozone can oxidize and decompose the enzymes needed for glucose in bacteria, so that bacteria are inactivated and die; (2) Acting on nuclear substances in bacterial cells, such as purines and pyrimidines in nucleic acids, destroying their organelles, DNA and RNA, thus damaging the metabolism of bacteria and leading to the death of bacteria; (3) Ozone reacts with lipids in the bacterial cell wall, penetrates the cell membrane, invades the cell, acts on lipoproteins in the outer membrane and lipopolysaccharides in the inner membrane, and causes permeability distortion of bacteria and dissolution and death; [7]（4）Ozone acts on the four polypeptide chains of the capsid protein of the virus and damages the RNA, destroying the protein that forms it. After the phage is oxidized by ozone, its epidermis is broken into many fragments, from which a lot of ribonucleic acid is released, which interferes with its adsorption to the host. [2]
The effects of ozone are mainly concentrated in five aspects: anti-inflammation and anti-infection, pain relief, oxidation cholesterol , improvement of body immunity, and oxygen supply to ischemic tissue. But because the molecular structure of ozone is a special molecule composed of three oxygen atoms, although it has strong oxidation, but it is also very unstable, under normal temperature and pressure, it will automatically reduce to oxygen after 20 minutes. Therefore, the clinical application of ozone is now used to make, commonly used ozone generator. Its generation principle can be obtained by high-voltage discharge, corona discharge, electrochemistry, photochemistry, atomic radiation and other methods. The principle is to use high-voltage electric power or chemical reaction to make part of the oxygen in the air decompose and polymerize into ozone, which is a process of oxygen allotrope transformation. After making ozone, it can be dissolved in sterilized water, blood, body fluids, or directly acted on tissues to achieve different therapeutic purposes. [7]
The clinical application
ozone has developed from the initial treatment of colitis and skin gangrene to today's treatment of cerebral stroke, rheumatic diseases, joint diseases, disc herniation, anti-free radical anti-aging, acute and chronic hepatitis, prostatitis, chronic wounds caused by pressure ulcers, vaginitis and so on. However, the treatment effect, operation technology, promotion and application are mainly reflected in the following aspects: [7]
The treatment of disc
herniation is the most widely used in clinical practice, and the relatively mature technology is the treatment of cervical and lumbar disc herniation. Now commonly used percutaneous laser vaporization decompression combined interventional treatment of ozone, with curved needle technique under local anesthesia, during laser vaporization to constantly adjust the needle position, until the ideal location, in the laser optical fiber, two vaporization, the vaporization, to a certain concentration of 50 ug/ml) (ozone injection of intervertebral disc and vertebral side clearance with a syringe, so as to achieve anti-inflammatory, Pain relief and other effects. This method is not easy to relapse after treatment, and there are no side effects to patients. It is a new technology adopted by hospitals one after another. [7]
Treatment of viral liver disease
ozone in the treatment of acute and chronic viral hepatitis is also significant. Patient OF VIRUS virus HEPATITIS SUFFERS VIRUS TO ENCROACH AS A RESULT OF HEPATOCYTE, PRODUCE INFLAMMATORY REACTION SUCH AS OEDEMA, denATURATION, OZONE IS A KIND OF STRONG oxidANT, CAN MAKE THE RNA OF VIRUS denATURATION QUICKLY, THE METABOLISM OF BACTERIUM STOPS, ACCORDINGLY, HAVE antiINFLAMMATORY EFFECT. [7]
Ozone is used to treat viral hepatitis because it also boosts immunity and induces the production of cytokines that protect the liver. Research data also show that ozone treatment can quickly reduce the patient's body transaminase, can be yellowing, but also can reduce the level of virus in the body, inhibit virus replication, is a new treatment without toxic side effects. In 2000, ozone treatment of viral hepatitis was approved for clinical use in Europe, and in 2004, this technology was approved for clinical use in China. [7]
Treatment of ischemic and hypoxic diseases
Tylicki et al. reported that 12 hemodialysis patients with arteriosclerosis complicated with lower extremity arterial thrombosis were treated with high pressure ozone for 9 times. As a result, total cholesterol decreased by 8.34% on average, low density lipoprotein decreased by 17.9% on average, while factor VIII activity did not show significant changes. This indicates that this method does not harm the vascular endothelial system of patients, and the reduction of total cholesterol and low-density lipoprotein is conducive to the improvement of lower limb arteriosclerosis. [7]
In China, ozone has been used to treat gynecological infections, such as candida vaginitis; It has also been reported that ozone water washing combined with microwave was used to treat chronic cervicitis, ozone autoblood therapy was applied to patients with bronchial asthma and achieved good curative effect, and ozone was used to treat wound healing caused by burns, and the effect was very significant. [7]
Although ozone has been used in clinical practice for less than 50 years, it has shown its advantages in many aspects and is gradually replacing some traditional treatment methods. In 1999, Italy initiated and established the International Medical Ozone Association (IMOS) with the main purpose of promoting basic research and clinical application of ozone, and providing clinical standards for the treatment of ozone. [7]
At present, the association is working with a large number of medical workers to find new methods and directions for the clinical application of ozone. For example, in the treatment of lumbar disc herniation, multi-approach puncture approach, combination of ozone technology and collagenase technology, and double-needle technology are considered. It is believed that there will soon be more and better ozone new technology applied in clinical, for more and more patients to bring good news. From this point of view, ozone development prospects should be very broad. However, there are also contraindications in the clinical application of ozone. [7]
First, ozone cannot be absorbed directly into the lungs, because direct inhalation will cause damage to alveolar epithelial cells. Secondly, patients with faba bean disease can not be ozone blood therapy; Third, ozone treatment causes very few allergic reactions; Fourthly, in the treatment of ozone, excessive concentration and dose will cause toxic reaction. [7]
Vegetable disease control
The use of ozone to control vegetable diseases has long been studied abroad, and relevant reports have been reported in China in recent years. All air-borne diseases and most soil-borne diseases of fruit and vegetable crops such as cucumber, green pepper and eggplant can be controlled with low quality fraction of ozone produced by greenhouse plant disease ozone control equipment. Low quality fraction of ozone can effectively prevent the occurrence of cucumber downy mildew, POWdery mildew, anthracnose, leaf blight, Mosaic virus, eggplant, bean gray mold also has a preventive effect. In addition to the remarkable control effect on diseases, ozone also has the control effect on some insect pests, such as the control rate of aphids reached 63% ~ 68%. [10]
Removing Pesticide Residues from vegetables
One of the biggest concerns when eating vegetables is pesticide residues. Although agricultural administrative departments have developed many measures to reduce pesticide residues, emphasizing the rational use of pesticides, advocating the use of biological pesticides and high efficiency, low toxicity, low residue pesticides, there are still often pesticide poisoning events in vegetables. Traditional methods to remove pesticide residues include soaking and washing, soaking in alkaline water, peeling, storage, heating and so on. Dr. Pan Canping of China Agricultural University pointed out that the traditional method of water immersion can hardly remove the pesticide residues of fruits and vegetables, but the high concentration of ozone immersion can effectively remove the pesticide residues. Studies have shown that ozone can effectively degrade pesticides on bean sprouts when they are cultivated with ozone. The bean sprouts were soaked in 3mg/L ozonated water for 30min and then cultured for 8h. The pesticides on the sprouts were degraded as follows: Cremydan 100%, diazinon 76%, dichlorvos 96%. The pesticide residues of chlorothalonil, Dimethoate, trichlorfon and dichlorvos on vegetables treated with ozone reached the international permissible standard. [10]
Fresh-keeping processing vegetables
Wash and disinfect vegetables
by using the oxidation and bactericidal effects of ozone, using ozonated water to clean fruits and vegetables can not only effectively kill pathogenic bacteria and spoilage bacteria attached to the surface of vegetables, but also remove other toxic substances remaining on the surface of vegetables. It is one of the ways to maintain and improve the safety of new vegetable food. The results showed that this method could reduce the total number of bacteria on the surface of fruits and vegetables by more than 90%, especially the killing effect of Escherichia coli was particularly obvious. [10]
Fresh-cut vegetables
Western developed countries began to study and produce fresh-cut vegetables as early as the 1950s, and have now formed a complete, advanced and systematic processing system. With the rapid development of people's life and the improvement of the understanding of food safety, fresh cut vegetables have become increasingly popular in China. However, at present, the fresh-cut vegetables sold in general supermarkets are mostly processed by simple cleaning, cutting and other rough processing, and lack of advanced purification processing technology. Consumers still have concerns in their hearts, and their safety and health are still questioned. Ozone has a good killing effect on the microorganisms on the surface of vegetables, and its oxidation ability can oxidize and destroy the injured ethylene produced by fruits and vegetables, which has an ideal effect on delaying the ripening of vegetables and maintaining the fresh quality of vegetables. Recently, the application of ozone in fresh cut vegetables at home and abroad were reviewed and the research, some studies have shown that the ozone water to immerse, not only can significantly reduce the fresh cut vegetables on the surface of the microbe, improve the safety of products in the field of microbiology, also can obviously inhibit the fresh cut vegetables in the degradation of chlorophyll, has inhibitory effect on the activity of polyphenol oxidase, protect the vitamin C, But it may have a certain oxidation effect on reducing sugar. [10]
Storage of vegetables
Vegetables are still living organisms after harvesting, and respiration is one of the most important physiological activities after harvesting. If respiration is inhibited, the freshness of vegetables can be prolonged. Many experiments have shown that ozone can obviously inhibit the respiration of vegetables in storage. The principle is that vegetables release ethylene easily during storage, and ozone can be oxidized to remove ethylene, thereby slowing down the metabolism of fruits and vegetables. In addition, ozone can also destroy the foul odor of organic matter or inorganic matter, has the function of deodorization and air purification, so it can be used for the disinfection of vegetable storage environment and maintain the environment conducive to the maintenance of vegetable vitality. [10]
Desalting salted vegetables
vegetables are prone to eat too much in peak season, and not enough to eat in off-season. People usually make some vegetables into pickles and salted vegetables. Such as pickled mustard, snow vegetables, radish and so on are the main pickled vegetables, in the curing process, generally use 8% to 15%, or even higher concentration of salt for curing, resulting in too salty taste, can not be eaten directly, and may even appear salt poisoning. Therefore, salted vegetables need to be eaten after desalting. The traditional desalting method uses tap water to soak. After desalting, microorganisms proliferate in large numbers, especially in summer, which is prone to long film, flowers and soft. Ozone has the characteristics of killing a variety of microorganisms, studies have shown that the use of ozone immersion for desalination of salted vegetables, compared with water immersion treatment of salted vegetables, the number of microorganisms significantly decreased. [10]
