Common ozone data
1, ozone generator size is the number of the ozone production according to the divided. Ozone production unit is mg / h or g / h (mg / h or g / h), i.e., the ozone generator one hour the number of weight units of the ozone can be generated.
2, the ozone concentration in the air units are ppm or mg / m3; concentration of ozone in water units are ppm or mg / L. Conversion: When in the air 1ppm = 2 mg / m3; in the water, 1ppm = 1mg / L.
3, ozone in the atmosphere reaches a certain concentration will cause environmental pollution. China provides: In the environment, the ozone concentration over living 0.1mg / m3 constitutes air pollution; in the workplace, when ozone concentrations exceed 0.2mg / m3 constitutes pollution.
4, the concentration of ozone in the air 0.01-0.02mg / m3, olfactory person can know.
5, when the food plants, cosmetics factory, workshops, warehouses and other places for disinfection, ozone concentrations in the air should reach 10-20 mg / m3, and to closed for 30 minutes. When people can not be disinfected at the scene.
6, under atmospheric mixing conditions, bottled pure water with ozone disinfection, usually 1m3 / h of water required to use 3g ozone and ozone concentration in water demand ≥0.3mg / L; when ozone disinfection for bottled mineral water, usually 1m3 / h water 6g need to use ozone and ozone concentration in water demand ≥0.5mg / L.
Ozone is a special smell irritating unstable gas, the molecular structure shown in FIG. It photochemical synthesis within the Earth in the stratosphere, but on the ground plane exists only in very low concentrations.
1.1 General physical properties
At room temperature, the ozone gas is blue, but at room temperature, the blue is not obvious, unless the gas is relatively thick. The main physical properties of ozone are shown in Table 1-1, the liquid density and vapor pressure are shown in Table 1-2.
The physical properties of pure ozone 1-1
Melting point (760mmHg) / ℃ -192.5 ± 0.4 gas density (0 ℃) / (g / L) 2.144
Boiling point (760mmHg) / ℃ -111.9 ± 0.3 heat of evaporation (-112 ℃) / (J / L) 316.8
The critical temperature / ℃ -12.1 critical density / (g / ml) 0.437
Critical Pressure / atm 54.6 solid ozone density (77.4K) / (g / cm 3) 1.728
Critical volume (cm 3 / mol) 111 liquid heat capacity (90 ~ 105K) / (cal / k) 0.425 + 0.0014 × (T-9)
Viscosity liquid ozone 77.6K (Pa • s)
90.2K (Pa • s) 0.00417
0.00156 heat of vaporization
-183 ℃ 14277
Surface tension (cyn / cm) ①
38.4 generate heat
Ideal gas (0k) 142.98
Isotonic hematocrit (90.2K) 75.7 free energy (gas, 298.15k) 162.82
Dielectric constant (liquid 90.2k) 4.79 dipole / Debye (Debye) 0.55
Magnetic susceptibility (cm-gs units) of the gas / liquid 0.002 × 10 -6
①1dyn = 10 -3 N / m; 1atm = 101.325Pa; 1cal = 4.18J.
Table 1-2 ozone liquid density and vapor pressure
Temperature / ℃ liquid density
/ (G / cm 3) the vapor pressure of the liquid
/ MmHg temperature / ℃ liquid density / (g / cm3) of liquid vapor pressure
74.2 0.11 1.442 1.574 -183 -140
1.566 0.21 1.410 190 -180 -130
1.535 1.41 1.318 427 -170 -120
1.504 6.75 1.347 865 -160 -110
-150 -100 24.3 1.473 1.316 1605
1.2 ozone solubility
Ozone slightly soluble in water, the standard pressure and temperature (STP), the solubility of oxygen than 13 times (see Table 1-3), 25 times larger than the air.
Table 1-3 ozone solubility in water (a gas partial pressure of 10 5 Pa) / (ml / L)
Gas density (g / L) Temperature / ℃
O 2 1.492 49.3 38.4 31.4 26.7
O 3 2.143 641 520 368 233
Air 28.8 23.6 18.7 16.1 1.2928
Ozone was introduced into distilled water, can be measured at different temperatures and different pressures of ozone solubility in water. Figure 2-2 is at a pressure of 1atm, pure ozone solubility curve in the water and temperature. Known from Figure 2-2, when the temperature is 0 ℃, pure ozone solubility in water of up to 2.858 × 10 -2 mol / L (1372mg / L).
Ozone and other gases, as consistent with the solubility in water Henry's law, i.e., at a certain temperature, any gas dissolved in the liquid of known mass, is proportional to the partial pressure of the gas acting on the liquid, and the size of Henry's constant is only a function of temperature, independent of concentration.
C = K H P (1-1)
Where C - solubility of ozone in water, mg / L;
P - ozone partial pressure of ozone in air, kPa;
KH - Henry's constant, mg / (L • kPa).
From the formula (1-1) known, due to the actual production are mostly used in ozonized air, its partial pressure of ozone is very small, so the solubility of ozone is far less than the data in Table 1-3. For example, using air as a raw material of production of ozone generator ozonized air, ozone only from 0.6% to 1.2% (by volume). According to the gas equation and Dalton's law known ozone ozone partial pressure only 0.6% -1.2% of the air pressure. Thus, when the water temperature is 25 ℃, the ozonized air added to this water, and the solubility of ozone only (0.625 ~ 1.458) × 10 -4 mol / L (3 ~ 7mg / L).
Table 1-4 low concentrations of ozone in water solubility / (mg / L)
Gas mass percentage content /% Temperature / ℃
1 8.31 7.39 4.29 3.53 6.5 5.6 2.7
1.5 8.4 6.43 5.09 9.75 12.47 11.09 4.04
2 16.64 17.79 11.19 8.57 7.05 5.39 13
3 24.92 22.18 19.5 16.79 12.86 10.58 8.09
In general water treatment, ozone concentration is low, the solubility in water is not so big. At lower concentrations, the solubility of ozone in water is basically satisfy Henry's law. Low concentrations of ozone in water solubility in Table 1-4.
Second, the chemical properties of ozone
1. The chemical properties of ozone is very unstable in air and water will slowly break down into oxygen, the reaction is:
2O3 → 3O2 + 285kJ (1-2)
Due to release a lot of heat decomposition, so when its content is more than 25%, it is easy to explode. But generally ozonation ozone content in the air is hard to over 10% in the long historical process of ozone for drinking water treatment, and yet none of oxygen explosion case.
Content of 1% or less of ozone decomposition in air at normal temperature and pressure of the half-life of about 16h. With increasing temperature, the decomposition speed, temperature exceeds 100 ℃, decomposition is very intense, high temperature reached 270 ℃, which can be converted immediately into oxygen. The decomposition of ozone in the water faster than the speed of the air more. In an aqueous solution containing impurities quickly revert to the formation of ozone in its oxygen. Ozone water concentration of 6.25 × 10 -5 mol / L (3mg / l), the half-life of 5 ~ 30min, but decompose slowly in pure water, such as distilled water or tap water in the half-life is approximately 20min (20 ℃), but in double distilled water, after 85min after only 10 percent of ozone decomposition, if the water temperature is close to 0 ℃, ozone will become more stable.
Ozone with the water temperature and increase the PH value of the decomposition rate is accelerated in the water, the relationship between Figures 1-3 is PH = 7, the water temperature and decomposition rate, Figure 1-4 is 20 ℃, the relationship between PH and the decomposition rate.
In order to improve the utilization of ozone, the ozone decomposition treatment process requires more slowly, but in order to reduce ozone pollution on the environment, the exhaust gas after-treatment is required ozone decomposition faster.
2. ozone oxidation
Ozone was strong oxidation, the oxidation-reduction potential after F 2, in its application mainly use this feature. Seen from Table 1-5.
From Table 1-5, in addition to the standard electrode potential lower than that of ozone than fluorine, are higher than oxygen, chlorine, potassium permanganate, chlorine dioxide and other oxidants. Ozone is commonly described in the oxidation capacity of the strongest oxidants. Meanwhile, after the reaction product of ozone is oxygen, ozone is a highly efficient so no secondary pollution oxidant.
Table 1-5 Comparison of redox potential
Name Formula standard electrode potential / mv Name Formula standard electrode potential / mv
F2 2.87 fluorine chlorine dioxide ClO 2 1.50
Ozone O3 2.07 chlorine Cl 2 1.36
Oxygen, hydrogen peroxide H2O2 1.78 O 2 1.23
Potassium permanganate MnO4 - 1.67
3. ozone oxidation reaction
oxidation of a, and inorganics
⑴ reaction of ozone with ferrous
⑵ the reaction of ozone with Mn2 +
⑶ reaction of ozone with sulfides
⑷ reaction of ozone with sulfur cyanide
⑸ reaction of ozone with cyanide
The overall reaction is:
The reaction of ozone with chlorine ⑹
Reaction b, ozone and an organic substance
Ozone reacts with organic matter in water is extremely complex, only recognized by the following reaction of several listed for reference.
⑴ reaction of ozone with the ozone olefinic compound easily reacts with the olefin compound having a double-stranded, the reaction course is described as follows:
Wherein G represents OH, OCH3, OCCH3, etc. group. The final reaction product may be monomeric, polymeric, or staggered mixture ozonide. Ozonide decomposed into aldehydes and acids.
The reaction of ozone and the reaction of aromatic compounds and aromatic compounds ⑵ ozone slower, in the series benzene <naphthalene <phenanthrene <pyrene <anthracene, which increases the reaction rate constant. Its
⑶ reaction to nucleoprotein (amino acids) Department
⑷ oxidation of organic ammonia
Ozone in the oxidation mixture is the following sequence
Alkenes> amines> phenol> polycyclic aromatic hydrocarbons> alcohol> aldehyde> paraffins
c, ozone toxicity and corrosiveness
Ozone is harmful gases when the concentration of 6.25 × 10 -6 mol / L (0.3mg / m3), eye, nose and throat irritation feeling; concentrations (6.25-62.5) × 10 -5 mol / L (3 ~ 30mg / m3), the headache and respiratory paresis embolism; ozone concentration of 3.125 × 10 -4 ~ 1.25 × 10 -3 mol / L (15 ~ 60mg / m 3) when it is hazardous to your health. Its toxicity and contact time are also relevant, for example, long-term exposure 1.748 × 10 -7 mol / L (4ppm) less ozone will cause permanent heart disorders, but the contact is not more than 20ppm or less ozone 2h, the human body without permanent harm. Therefore, the ozone concentration allowable value set at 4.46 × 10 -9 mol / L (0.1ppm) 8h. Due to a very strong odor of ozone concentration of 4.46 × 10 -9 mol / L (0.1ppm), people feel that, therefore, the use of ozone has been 100 years of history in the world, and have not found a case of lead poisoning due to ozone reported death.
Ozone has a strong oxidation resistance, in addition to gold and platinum, the ozone air almost all of the metal has a corrosive effect. Aluminum, zinc, lead and ozone exposure are strongly oxidized, but largely unaffected by ozone-containing ferrochrome alloy corrosion. Based on this, the production often containing 25% Cr ferrochromium alloys (stainless steel) to manufacture equipment and filling equipment in direct contact with ozone ozone components.
Ozone non-metallic materials also have a strong corrosive effect, the use of PVC Plates was fairly stable, the use soon see loose, filling cracks and perforations in the ozone equipment even elsewhere. Ozone generation equipment and metering devices, not for ordinary rubber sealing material must be corrosion-resistant and strong acid-resistant silicone rubber or rubber.
The physical properties of ozone
Under normal temperature and pressure, lower concentration of ozone is a colorless gas. When the concentration of 15%, showing a pale blue. Ozone can be dissolved in water, at ambient temperature and pressure the solubility of ozone in water is about 13 times higher than that of oxygen, 25 times higher than air. But the stability of the aqueous solution of ozone greatly influenced by the impurities contained in the water, particularly the presence of metal ions, ozone can be quickly decomposed into oxygen, slow decomposition in pure water.
Ozone density is 2.14g • l (0 ° C, 0.1MP). Boiling point is -111 ° C, the melting point is -192 ° C. The molecular structure of ozone is unstable, it is easier to self-decomposition in the air than in water. The main physical properties of ozone are shown in Table 1-1. Ozone in the water solubility of different temperatures are shown in Table 1-2. Although the solubility of ozone in water is 10 times larger than that of oxygen, but practically its solubility is very small, because he comply with Henry's law, the partial pressure and the total pressure is proportional to its solubility and System. Ozone content in the air is very low, so the partial pressure is very low, it will force the water to escape from the water and ozone air interface, so that the water is always in decreasing ozone concentration state.
Table 1: The main physical properties of ozone
Item Value Item Value
47.99828 molecular viscosity (liquid), Mpa • S at 90.2 when 1.56
Melting point, ° C -192.7 + (-) 0.2 surface tension, Mn / m when at 77.2K 43.8
Boiling point, ° C -111.9 + (-) 0.3 surface tension, Mn / m when at 90.2K 38.4
Critical state (temperature) / ° C -12.1 + (-) 0.1 isotonic hematocrit (90.2K) 75.7
Critical state (pressure) / Mpa 5.46 dielectric constant (liquid, 90.2K), F / m 4.79
Critical state (volume) / (cm3 / mol) 147.1 dipole moment, C • m (D) 1.84 * 10 (0.55)
Critical state (density) / (g / cm3) 0.437 heat capacity (liquid, 90-150K), F / m 1.778 + 0.0059 (T-90)
Density gaseous (0 ° C, 0.1Mpa) / (g / l) 2.144 molar heat of vaporization, while at 161.1K 14277
Density liquid (90K) / (g / cm3) 1.571 molar heat of vaporization, while at 90K 15282
Density solid state (77.4K) / (g / cm3) 1.728 mole generate heat, KJ / mol -144
Viscosity (liquid), Mpa • S at the 77.6K 4.17
Table 2: Solubility of ozone in water
Temperature, ° C Solubility, g / l
Chemical properties of ozone
Ozone is very unstable at room temperature can be broken down into oxygen. Ozone, chlorine dioxide and hydrogen oxidation potential (redox potential) are 2.07,1.36,1.28 volts, visible ozone oxidation in the treated water is one of the strongest forces. Ozone oxidation leads to unsaturated organic molecules rupture. Ozone molecules in the organic molecules of the double bond, generating ozonides. Ozonide produces spontaneous splitting one carboxyl group, and zwitterionic compounds with acidic and basic groups, which are unstable, decompose into acid and aldehyde.
Ozone and inorganic reactions
In addition to platinum, gold, iridium, fluorine, ozone can react with almost all the elements in the periodic table. Ozone with K, Na reacts oxide or peroxide, in the ozonide radical anion O3 substantially. Ozone may be a transition metal oxide to a higher or highest oxidation state, to form a more insoluble oxides, people often take advantage of this nature of the wastewater Fe2 +, Mn2 +, and Pb, Ag, Cd, Hg, Ni and other heavy metal ions are removed. In addition, fuel is burned in the ozone is more violent than the combustion in oxygen, obtained higher temperatures.
The reaction of ozone with organic matter
Ozone and organic compounds react in three different ways: First, the general chemical reaction; the second is to generate peroxide; ozone decomposition occurs three or generate ozonide. After the harmful substances such as xylene reacts with ozone to form harmless water and carbon dioxide. Refers to the so-called ozone decomposition reaction with ozone in a polar organic compound, an organic compound is reacted in the original position of the double bond, the molecule is split into two. Because ozone is a strong oxidizing power, not only sterilization, but also remove the water taste and color and other organic matter, which is its advantage, but its spontaneous decomposition, performance instability, can only be used with the production, unsuitable storage and transport, which is its shortcomings. Of course, if the purified water and clean air from the point of view, due to its rapid decomposition without the presence of residual material, and can be said to be a major advantage of ozone.
Humus reaction of ozone with water
Humic acid structure contains a lot of cavities, they trapped or fixed organic molecules. Such as humus can interact with the metal and pesticide. They also may contain trapped in the polymerized network star volatile aromatic compound. These compounds may be released during chemical oxidation, resulting in an increase or increase the toxicity of the TOC. Therefore, to achieve the supply of people to clean, safe drinking water purposes, to remove the raw water humus is very necessary and important.
4. The use of ozone
With the intensification and improvement of water quality standard water pollution, for the lack of conventional treatment processes, ozone technology is becoming a cause for concern, and gradually applied. The main effect of ozone are: disinfection, oxidation of organic matter, odor and color removal, to remove particles. All aspects of data show that China's current use of ozone technology is mainly applied in drinking water disinfection, swimming pool water disinfection, medical industry, has not been widely used.
The main application areas of ozone
Disinfection of drinking water; bottled, bottled purified water, mineral water disinfection of drinking water; water treatment tank tower roof
Advanced treatment of urban sewage treatment of urban sewage treatment plant
Entertainment swimming pool water disinfection; place of air purification, disinfection environment
Medical Professions ward, operating room air disinfection, sterilization of medical equipment, medical sterilization wastewater disinfection, disinfection of clothing
Chemical industrial waste water, waste gas treatment; can rapidly decompose cyanide wastewater chromium salts, phenol; organic dye decolorization
Ozone disinfection washing appliance industry, ozone washing machines, Ozone Sterilizer, Ozone dishwasher
At standard temperature and pressure, the solubility of ozone is 13 times more oxygen.
From Henry's law can be concluded: To improve the solubility of ozone in water, must be increased in the entire ozone gas partial pressure in the gas source, i.e., increase the concentration of the ozone source, the source is not enough if the concentration of ozone, and then a long processing time, the ozone concentration in water not to mention too high (due to the concentration of equilibrium has been reached).
From the above discussion, it can be concluded:
1, in order to ensure the sterilization effect, we must ensure that a certain concentration of ozone in water and processing time.
2, in order to ensure a certain concentration of ozone in water would need to ensure that:
a. The concentration of ozone source.
b. Certain temperatures.
c. The water temperature is not too high.
d. Ozone gas into the water the specific surface area as large as possible, so that the ozone contact with water more opportunities.
General water quality of drinking water disinfection application experience at home and abroad based on the parameters recommended for: aqueous ozone concentration O.4mg / L, contact time of 4 minutes, the CT value of 1.6. Ozone dosage 1-2mg / L, the water temperature is preferably below 25 ℃. Former Soviet Union, the ozone concentration in drinking water standard of not less than O.3mg / L. Our bottled water industry recommended filling the water bottle when the ozone concentration 0.3mg / L. Second, the current three common contact means before its effects already mentioned the fundamental purpose of the section is to ensure that the contact means ozone in water solubility as large as possible, For this purpose, it is required to make ozone gas and water contact surface as large as possible, there is sufficient contact time, and thus the contact means of the basic requirements are:
1, to ensure optimal ozone absorption.
2, when the contact means work, control of process parameters is easy, stable, good security.
3, energy (stirring or conveying water, gas power required) minimum.
4, has the largest production capacity with minimal volume.
5, the structure is simple, inexpensive materials, low manufacturing and maintenance costs.
Contact devices commonly used in three ways: a bubble column, or cell: water injector (venturi) and fixed spiral mixer (alone or in combination): blender or screw pump: there are two or more series to use, as outlined below : l, bubbling: Large water bubbler tank, water is commonly used small bubble column, it requires a small bubbler (several microns to several tens micron pore size) of the aperture to increase the specific surface area of ozone, and require uniform pore size distribution of gas to the water, gas full access, especially when using multiple bubbling pool cloth scrubber, but generally require air from the surface to the cloth surface, the depth of not less than 4-5m, in order to facilitate gas, full contact with water.
Common ozone data