CN1569240A - Device for catalytic purifying air and water by vaccum ultraviolet light action - Google Patents
Device for catalytic purifying air and water by vaccum ultraviolet light action Download PDFInfo
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- CN1569240A CN1569240A CNA031497853A CN03149785A CN1569240A CN 1569240 A CN1569240 A CN 1569240A CN A031497853 A CNA031497853 A CN A031497853A CN 03149785 A CN03149785 A CN 03149785A CN 1569240 A CN1569240 A CN 1569240A
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Abstract
The invention discloses a device for catalytic purifying air and water by vacuum ultraviolet light. The device comprises a low pressure mercury lamp capable of emitting 185 nm ultraviolet and a photocatalyst, a filter screen and a fan, a reactor also can be included. It combines the functions of vacuum ultraviolet photolysis and photocatalyst. Thus it has a more rapid reaction velocity than that of the sole vacuum ultraviolet photolysis or single photocatalyst, a better purification effect under the same energy consumption. Therefore it improves the efficiency and lowers the cost. The device can be used for purification of air and water, in particular for purification of indoor air and drinking water.
Description
Technical Field
The invention relates to a device for purifying air and water, in particular to a device for purifying air and water by vacuum ultraviolet light catalysis.
Background
The pollutants such as particulate matters, pathogenic microorganisms, volatile organic compounds and the like in the indoor air are harmful to the health of people. The currently adopted indoor air purification methods mainly comprise filtration, adsorption, electrostatic dust removal, ozone oxidation disinfection, negative oxygen ion, photocatalysis and the like.
The filtering method can effectively remove particulate matters, smoke, dust and the like. The high-efficiency filter material (HEPA) has the characteristics of high temperature resistance, corrosion resistance, water resistance and mildew resistance, can effectively trap inhalable particles, smoke, dust, bacteria and the like with the particle size of more than 0.3 mu m, and has the filter efficiency of more than 99.97 percent. However, the HEPA filtration method has a disadvantage in that volatile organic compounds in the air cannot be removed. The high-voltage electrostatic dust collector can ionize and adsorb pollutants in air, and the dust collection efficiency mainly depends on the electric field intensity, the size of dust particles, the air flow speed and the retention time of the dust particles in a dust collection section.
The adsorption method is a widely applied indoor air purification method at present, and has the characteristics of broad spectrum and high efficiency. The main disadvantage of the adsorption method is that the adsorption saturation is caused, and the porous adsorption material needs to be replaced periodically. The air quantity and the concentration of harmful substances directly influence the service life and the adsorption efficiency of the air quantity and the concentration of the harmful substances.
The ozone oxidation method can effectively disinfect, deodorize and degrade organic matters, but ozone has high toxicity, people can not enter the site in the ozone disinfection process, the ozone with higher concentration (more than 1ppm) can easily cause uncomfortable feelings such as cough and the like, and the ozone with higher concentration brings more serious harm to human health, so that the pure ozone type air purifier has no application value. The U.S. environmental protection agency has mandated the prohibition of ozone generators as air purification equipment. In addition, ozone oxidation is selective and does not degrade many volatile organics (e.g., toluene).
The photocatalysis method is a new technology developed in the 70 s of the 20 th century, can remove organic pollutants in water and air, and has the functions of sterilization and disinfection. The photocatalytic technique generally utilizes an ultraviolet light source (e.g., a low-pressure mercury lamp emitting 254nm ultraviolet light, or 365nm violet light)External black-light lamp, etc.) irradiated with a semiconductor catalyst having photocatalytic activity, such as titanium dioxide (TiO)2) Zinc oxide (ZnO), tungsten trioxide (WO)3) And the valence band electrons of the semiconductor catalyst are excited by ultraviolet light and then jump to the conduction band, an electron with strong reducing capability is generated in the conduction band, and a hole with strong oxidizing capability is generated in the valence band.
The ultraviolet light excites the cavity generatedby the semiconductor and the hydroxyl radical formed after the cavity is transferred to the surface of the semiconductor and captured by water or hydroxyl, so that the ultraviolet light has strong oxidizing capability, can oxidize and degrade most pollutants in air and water, such as volatile organic compounds, disinfection byproducts, endocrine disruptors and other organic pollutants, and can kill various bacteria, viruses and the like, thereby playing a role in purifying air and water. Unlike activated carbon adsorption, it is not a simple technique to convert contaminants from one phase to another or to concentrate them, but rather a purification technique that can completely remove the contaminants while also providing a germicidal effect. However, the activity of the existing photocatalyst is not high, the efficiency of purifying air and water by photocatalysis is low, the treatment time is long, the energy consumption is high, and meanwhile, the condition of catalyst deactivation can also occur. Therefore, how to improve the efficiency of photocatalysis, improve the economy of photocatalysis technology, and simultaneously avoid the inactivation of the photocatalyst is a problem to be solved in the practical application of photocatalysis.
Vacuum ultraviolet light is ultraviolet light with the wavelength below 200nm, and two vacuum ultraviolet light sources are common: one is a low-pressure mercury lamp which emits vacuum ultraviolet rays of 185nm in addition to far ultraviolet rays of 253.7 nm; another is an excimer light source, for example, a xenon excimer light source can emit vacuum ultraviolet light at 172 nm. Since 185nm vacuum ultraviolet rays may cause damage by photolysis of oxygen in the air to generate ozone, a low-pressure mercury lamp emitting no 185nm is generally used as a photocatalytic light source, and for example, a low-pressure mercury lamp emitting no 185nm ultraviolet rays can be made by doping titanium dioxide into quartz used as a lamp tube.
When a low-pressure mercury lamp capable of emitting 185nm ultraviolet light is used as a light source, the main light emitted from the lamp is 253.7nm ultraviolet light with a small amount of 185nm ultraviolet light. When air and water are irradiated with 185nm ultraviolet light, the following effects occur:
(1) directly photolyze pollutants in air and water or kill pathogenic microorganisms. However, since the 185nm vacuum ultraviolet light emitted by low pressure mercury lamps is relatively weak, this effect is very limited and contributes little to the degradation of contaminants.
(2) Photolysis of water molecules and oxygen to form hydroxyl radicals (OH ·) by the following reaction:
in water, since the content of oxygen is relatively small compared to water, vacuum ultraviolet rays are primarily absorbed by water at the beginning, and the water is decomposed to generate hydroxyl radicals (OH ·) having strong oxidizing properties. In air, the concentration of water vapor is much lower than that of oxygen, so the pathway of oxygen photolysis to form hydroxyl groups is more important. Since water and oxygen have strong absorption of 185nm ultraviolet rays, 185nm ultraviolet rays are totally absorbed in a short optical path. The water and oxygen molecules are photolyzed to form hydroxyl radicals and active oxygen atoms, which can degrade pollutants quickly and effectively.
If the oxygen atoms generated by the photolysis of oxygen do not completely react with the pollutants or water, the oxygen atoms react with the pollutants or water to generate ozone:
excessive ozone generation is detrimental and undesirable.
Summary of the invention
The invention aims to provide a device for purifying air and water by vacuum ultraviolet light catalysis, which can more economically and effectively remove pollutants in the air and the water.
The device for purifying air and water by vacuum ultraviolet light catalysis comprises a low-pressure mercury lamp capable of emitting 185nm ultraviolet rays and a photocatalyst.
In order to make the purifying device more effective, the device also comprises a filter screen and a fan, and also comprises a reactor.
Among them, the photocatalyst may be a semiconductor catalyst having photocatalytic activity, such as titanium dioxide, zinc oxide, tungsten trioxide, or the like. The photocatalyst can be made into a net-shaped or plate-shaped catalyst form, and can be fixed on the inner wall of the reactor or coated on a metal sheet close to the inner wall of the reactor.
The device for purifying air and water by vacuum ultraviolet light catalysis uses a low-pressure mercury lamp capable of emitting 185nm ultraviolet rays as a light source for photocatalysis, the main light rays emitted by the lamp are 253.7nm ultraviolet rays and a small amount of 185nm ultraviolet rays, and the device has the following advantages when being used together with a photocatalyst:
(1) ultraviolet rays with the wavelength of 253.7nm can be used as a light source of the photocatalyst to generate photocatalysis without an additional light source; whereas 185nm vacuum ultraviolet light is absorbed over a short distance and does not generally strike the photocatalyst surface and therefore is not generally a source of light for photocatalysis.
(2) Ozone generated by the photolysis of 185nm vacuum ultraviolet can be used as an electron capture agent in the photocatalytic process, so that the efficiency of the photocatalytic reaction is improved. In air, the presence of the photocatalyst may also serve to reduce the concentration of ozone.
(3)185nm vacuum ultraviolet can directly degrade pollutants and degrade pollutants by photolyzing hydroxyl radicals generated by water or oxygen.
The invention skillfully combines the functions of vacuum ultraviolet photolysis and photocatalysis, namely, the vacuum ultraviolet photolysis and photocatalysis are realized in the reaction process, the vacuum ultraviolet excites the ozone generated by air and water, the photocatalysis is promoted, the defect of single reaction is avoided or reduced, namely, a large amount of ozone is generated by the vacuum ultraviolet photolysis and the reaction rate of photocatalysis is low. Meanwhile, the device is not the superposition of simple vacuum ultraviolet photolysis and photocatalysis, has higher reaction speed than the single vacuum ultraviolet photolysis and photocatalysis, has better purification effect under the same energy consumption, and can improve the efficiency and reduce the cost. The device can be used for purifying air and water, particularly indoor air and drinking water, can remove various organic pollutants and pathogenic microorganisms in the air and the water, and has important practical application value.
Drawings
FIG. 1 is a flow chart of a vacuum ultraviolet light catalytic air purification device
FIG. 2 is a flow chart of a vacuum ultraviolet light catalytic air purification device
FIG. 3 is a graph showing the relationship between the n-hexane degradation rate and the concentration in air
FIG. 4 is a graph showing the degradation rate of n-hexane in air as a function of time
FIG. 5 is a graph showing the relationship between the degradation rate and concentration of toluene in air
FIG. 6 is a graph showing the degradation rate of toluene in air versus time
Detailed Description
Example 1: vacuum ultraviolet light catalytic air purifier
The device for purifying air by vacuum ultraviolet light catalysis of the invention is shown in figure 1 and comprises a filter device 1, a mesh catalyst titanium dioxide 2, a low-pressure mercury lamp 3 emitting 185nm ultraviolet light, a mesh catalyst titanium dioxide 4 and a fan 5. The fan 5 extracts the air to be purified, firstly, the particulate matters in the air are removed through the filtering device 1, and the air reaches the low-pressure mercury lamp 3 after being subjected to catalytic purification by the mesh-shaped catalyst titanium dioxide 3 to be subjected to ultraviolet photolysis, so that the ozone is also an ozone generation layer, the ozone generated by vacuum ultraviolet photolysis is removed through catalytic purification by the mesh-shaped catalyst titanium dioxide 4, and meanwhile, organic pollutants and pathogenic microorganisms in the air are also removed, so that the air purifying effect is achieved.
Example 2: vacuum ultraviolet light catalytic air purifier
The device for purifying air by vacuum ultraviolet light catalysis of the invention is shown in figure 2 and comprises a filter device 1, a fan 2, a low-pressure mercury lamp 3 emitting 185nm ultraviolet light and a plate-shaped photocatalyst tungsten trioxide 4. The fan 2 extracts air to be purified, firstly passes through the filtering device 1, removes particles in the air, reaches the low-pressure mercury lamp 3 through the fan, carries out ultraviolet photolysis, and the ozone generation layer is the catalytic purification of the plate-shaped catalyst tungsten trioxide, removes ozone generated by vacuum ultraviolet photolysis, and simultaneously removes organic pollutants and pathogenic microorganisms in the air, thereby achieving the effect of purifying the air.
Example 3 degradation of n-Hexane in air by the apparatus of the invention
N-hexane is a typical volatile organic compound in indoor air and is recommended as a model pollutant for testing indoor air purifiers. The normal hexane is degraded in a cylindrical device with the volume of 1.44 liters, a 15W low-pressure mercury lamp capable of emitting 185nm ultraviolet rays is arranged in the center of a cylindrical reactor, an aluminum sheet loaded with a titanium dioxide photocatalyst is arranged close to the inner wall of the cylindrical reactor, air containing normal hexane flows in from one end of the reactor, and treated gas flows out from the other end. When the vacuum ultraviolet photolysis is carried out, the aluminum sheet loaded with the titanium dioxide is not placed; when the photocatalytic degradation is carried out, a 15W low-pressure mercury lamp which does not emit light at 185nm is used as a light source for photocatalysis. Under various conditions, the effect of vacuum ultraviolet light catalytic degradation of n-hexane is far better than that of vacuum ultraviolet light degradation and photocatalysis.
As shown in FIG. 3, under the conditions of a flow rate of 12L/min and a relative humidity of 35% air, no matter whether the n-hexane concentration is high or low,the removal rate of the n-hexane by vacuum ultraviolet light catalysis is about 15-20 percentage points higher than that of vacuum ultraviolet light decomposition, and 18-25 percentage points higher than that of the photocatalysis.
Under the conditions of normal hexane concentration of about 3ppm and relative humidity of 35%, the removal rate of normal hexane by vacuum ultraviolet light catalysis is about 7-12% higher than that of vacuum ultraviolet light photolysis and about 15-20% higher than that of photocatalysis, and the results are shown in fig. 4.
Example 4: the device of the invention is used for degrading toluene in air
Toluene is a common contaminant in indoor air and is one of the model contaminants for testing the performance of air purifiers. The degradation of toluene was carried out in a 1.44 liter cylindrical apparatus, a 15W low pressure mercury lamp emitting 185nm ultraviolet was placed in the center of the cylindrical reactor, an aluminum sheet carrying a titanium dioxide photocatalyst was placed against the inner wall of the cylindrical reactor, toluene-containing air flowed in from one end of the reactor, and the treated gas flowed out from the other end. When the vacuum ultraviolet photolysis is carried out, the aluminum sheet loaded with the titanium dioxide is not placed; when the photocatalytic degradation is carried out, a 15W low-pressure mercury lamp which does not emit light at 185nm is used as a light source for photocatalysis. Under various conditions, the effect of the vacuum ultraviolet light catalytic degradation of toluene is far better than that of the vacuum ultraviolet light degradation and photocatalysis.
At a flow rate of 12L (i.e., a treatment time of 7.2s) and a relative humidity of 35%, the vacuum uv-photocatalytic treatment has a high removal rate of toluene with various concentrations, for example, a removal rateof 63% for toluene with an initial concentration of 0.55ppm, while the photocatalytic treatment has only 34%. The removal rate of the vacuum ultraviolet photocatalysis toluene under other concentrations is 25-30 percentage points higher than that of photocatalysis. Vacuum ultraviolet photocatalysis also has higher removal rate than vacuum ultraviolet photolysis, which is 4-25 percentage points higher. The results are shown in FIG. 5.
When the toluene content is 1ppm and the relative humidity is 35%, the vacuum ultraviolet light catalysis has higher removal rate of the toluene in shorter treatment time. For example, the removal rate in the treatment of 4.6s was 37%, the removal rate in the treatment of 5.4s was 49%, and the removal rate in the treatment of 17.3s was 75.6%. The removal rates after vacuum ultraviolet and photocatalytic treatment for 4.6s are respectively 18.7 percent and 15.2 percent; the removal rates after 17.3s of treatment were 65.5% and 65.1%, respectively, which were much lower than those of vacuum ultraviolet photocatalysis. Because the indoor air purification is carried out under the condition of very large flow (namely very short treatment time), the advantages of the vacuum ultraviolet light catalysis under the condition of large flow are more obvious. The results are shown in FIG. 6.
Example 5: the device of the invention is used for purifying pollutants in water
The device for purifying water by vacuum ultraviolet light catalysis is shown in figure 7. Comprises a reactor 1, a low-pressure mercury lamp 2 with a quartz sleeve and emitting 185nm ultraviolet light, a photocatalyst coated on the inner wall of the reactor or a metal foil 3 coated with the photocatalyst and arranged close to the inner wall of the reactor. The effect of purifying pollutants in water by vacuum ultraviolet light catalysis was tested in a cylindrical reactor with a volume of 0.8L. The low-pressure mercury lamp with the quartz sleeve is placed in the middle of the reactor, the catalyst is fixed on the inner wall of the reactor, or the catalyst is coated on the metal sheet, and the metal sheet is placed to be close to the inner wall of the reactor. When the vacuum ultraviolet light catalytic degradation is carried out, a 15W low-pressure mercury lamp capable of emitting 185nm ultraviolet light is used as a light source; when vacuum ultraviolet photolysis is carried out, a 15W low-pressure mercury lamp capable of emitting 185nm ultraviolet light is still used as a light source without a catalyst; when photocatalytic degradation is carried out, a low-pressure mercury lamp which cannot emit 185nm ultraviolet light is used as a light source.
The degradation of various pollutants such as 4-chlorophenol, 2, 4-dichlorophenol, p-nitrophenol, hydroquinone, 4-chlorobenzoic acid and the like is tested, vacuum ultraviolet photocatalysis has better degradation effect than photocatalysis and vacuum ultraviolet degradation, and the reaction rate can be accelerated. For example, for 4-chlorophenol, the first order reaction rate constant of vacuum ultraviolet light catalytic degradation is 1.183min-1And the vacuum ultraviolet photolysis and the photocatalysis are respectively 0.815min-1And 0.677min-1Respectively increased by 45% and 75%; the vacuum ultraviolet light catalytic reaction rate constant of the 2, 4-dichlorophenol is 0.7229min-1While the photocatalysis is only 0.0669min-1The improvement is 9.8 times; the reaction rate of hydroquinone vacuum ultraviolet light catalysis is 6 times of that of photocatalysis, and is improved by 30 percent compared with vacuum ultraviolet photolysis; the vacuum ultraviolet light catalytic reaction rate constant of the 4-chlorobenzoic acid is improved by 50 percent compared with the vacuum ultraviolet light photolysis rate constant. The results are shown in Table 1.
TABLE 1 first order reaction Rate constants (l/min) for vacuum ultraviolet photocatalytic degradation of contaminants
| Contaminants | Vacuum ultraviolet light catalysis | Vacuum ultraviolet photolysis | Photocatalysis |
| 4-chlorophenol | 1.183 | 0.815 | 0.677 |
| 2, 4-dichlorophenol | 0.7229 | - | 0.0669 |
| Hydroquinone | 0.606 | 0.466 | 0.099 |
| 4-Chlorobenzenecarboxylic acid | 0.725 | 0.484 | - |
Claims (8)
1. A device for purifying air and water by vacuum ultraviolet light catalysis comprises a low-pressure mercury lamp capable of emitting 185nm ultraviolet rays and a photocatalyst.
2. The apparatus of claim 1, wherein: the device also comprises a filtering device and a fan.
3. The apparatus of claim 1, wherein: the apparatus also includes a reactor.
4. The apparatus of claim 1, 2 or 3, wherein: the photocatalyst is a semiconductor catalyst having photocatalytic activity.
5. The apparatus of claim 4, wherein: the photocatalyst is titanium dioxide, zinc oxide or tungsten trioxide.
6. The apparatus of claim 4, wherein: the photocatalyst is made into a net-shaped or plate-shaped form.
7. The apparatus of claim 4, wherein: the photocatalyst is fixed on the inner wall of the reactor.
8. The apparatus of claim 4, wherein: the photocatalyst is coated on a metal sheet which is tightly attached to the inner wall of the reactor.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB031497853A CN1304059C (en) | 2003-08-06 | 2003-08-06 | Device for catalytic purifying air and water by vaccum ultraviolet light action |
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| Application Number | Priority Date | Filing Date | Title |
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| CNB031497853A CN1304059C (en) | 2003-08-06 | 2003-08-06 | Device for catalytic purifying air and water by vaccum ultraviolet light action |
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| CN1569240A true CN1569240A (en) | 2005-01-26 |
| CN1304059C CN1304059C (en) | 2007-03-14 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102188907A (en) * | 2010-03-18 | 2011-09-21 | 清华大学 | Device for removing harmful substance and air cleaning device by utilizing device for removing harmful substance to clean air |
| CN102908883A (en) * | 2012-09-27 | 2013-02-06 | 北京大学 | Method for simultaneously desulfurizing and denitrating flue gas |
| CN103945872A (en) * | 2011-11-18 | 2014-07-23 | 高爽工业公司 | System and method for generation of active species in a media by uv radiation |
| CN104534569A (en) * | 2014-12-24 | 2015-04-22 | 广东顺德盈派电器科技有限公司 | Sterilizing device |
| CN107469103A (en) * | 2017-09-19 | 2017-12-15 | 何丽娟 | A kind of Medical ultraviolet rotates disinfect box |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2367495B (en) * | 1999-07-19 | 2004-06-16 | Mitsui Shipbuilding Eng | Method and apparatus for purifying oxygen containing gas |
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2003
- 2003-08-06 CN CNB031497853A patent/CN1304059C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102188907A (en) * | 2010-03-18 | 2011-09-21 | 清华大学 | Device for removing harmful substance and air cleaning device by utilizing device for removing harmful substance to clean air |
| CN103945872A (en) * | 2011-11-18 | 2014-07-23 | 高爽工业公司 | System and method for generation of active species in a media by uv radiation |
| CN102908883A (en) * | 2012-09-27 | 2013-02-06 | 北京大学 | Method for simultaneously desulfurizing and denitrating flue gas |
| CN104534569A (en) * | 2014-12-24 | 2015-04-22 | 广东顺德盈派电器科技有限公司 | Sterilizing device |
| CN107469103A (en) * | 2017-09-19 | 2017-12-15 | 何丽娟 | A kind of Medical ultraviolet rotates disinfect box |
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| CN1304059C (en) | 2007-03-14 |
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