Ozone is also known as triple oxygen, molecular formula for O3, molecular weight of 48.00.
I. Physical and chemical properties: ozone at room temperature for the blue explosive gas, there is a peculiar smell for the strongest known oxidant, density of 1.658 (air = 1). Ozone gas can be liquid after cold treatment, its liquid density of 1.71, boiling point of -112.3 ℃, solubility in water is higher than oxygen, but because of the partial pressure is low, so in the usual use of temperature and pressure, can only get a few milligrams per liter of the solution, ozone-containing solution, warm will explode. The stability of ozone is extremely poor, at room temperature can decompose itself into oxygen, at a high temperature of 270 ℃ can be immediately converted to oxygen. 1% aqueous solution at room temperature in the atmosphere half-life of 16 minutes, so the ozone can not be like other industrial gases can be stored in bottles, generally on-site production, and immediate use.
Two, sterilization: ozone is a broad-spectrum bactericide, can kill bacterial propagules and spores, viruses, fungi, etc., and can destroy botulinum toxin. Ozone sterilization in water faster than chlorine.
Three, factors affecting the sterilization effect:
①PH: disinfection of aqueous ozone solution, if the PH increases, the required concentration must be increased.
② humidity: disinfection with ozone fumigation, high relative humidity is good, low effect is poor, almost no bactericidal effect on dry bacteria.
③ Temperature: lower temperature is conducive to the dissolution of ozone, can enhance its disinfection, even at 0 ℃ can maintain a good sterilization effect, such as water temperature of 4-6 ℃, ozone sterilization dosage of 100, water temperature of 10-21 ℃, 160, water temperature 36-38 ℃, then 320. When it is 320, organic matter can reduce its bactericidal effect.
Four, toxicity: ozone concentration in the air up to 0.01-0.02mg / L can be smelled: concentration of 1mg / L, can cause accelerated respiration, change, chest tightness and other symptoms, in the 2.5-5mg / L, can cause accelerated pulse rate, fatigue, headache, stay for 1 hour can occur emphysema, or even death, the operation of the site air permissible threshold limit of 0.2mg / m3.
Fifth, corrosive: ozone is a strong oxidant, can damage a variety of items, the higher the concentration of the more serious damage to the items, can make the copper appear green rust spots, especially the aging of rubber, color darkening, elasticity is reduced, so that brittle, broken, so that the fabric bleaching and discoloration.
Sixth, stability: ozone stability is very poor, room temperature can decompose itself into oxygen, stop occurring, ventilation 30-60 minutes after the concentration of the same level as the atmosphere.
Seven, the scope of use: in terms of disinfection, the use of ozone are mainly the following:
1, liquid disinfection: drinking water, industrial sewage and beverage water purification and disinfection.
2, object surface disinfection, eating utensils, hairdressing tools, food processing equipment, clothing, coins, tickets, etc. put in a closed box disinfection.
3, antiseptic preservation: vegetables, fruits, eggs, fish, meat, dried and fresh souvenirs, aquatic products processing, storage and refrigeration.
Eight, the use of methods:
1 liquid disinfection: ozone disinfection of drinking water, the amount depends on the quality of water, should be determined by the experiment to determine the exact value of the cleaner water, generally should be added to the ozone 0.5-1 mg / L, the role of the 5-10 minutes, the water to maintain the ozone concentration of 0.1-0.5 mg / L; for the more serious contamination of drinking water, the ozone dosage can be increased to 3 -6 mg / L. For sewage, the ozone concentration can be increased to 0.1-0.5 mg / L. -For sewage treatment, the concentration of ozone used in sewage is 100-200 mg/L, the role of 30 minutes, in most cases, can kill or destroy all the microorganisms and their toxins, and can improve water quality. The longer the action time, the better the effect.
2, disinfection of air: the air of the dense space with 5-10 mg/ m3 concentration of ozone role for 30 minutes.
Nine, note: because the ozone is a strong oxidant, the damage to the goods is greater, rarely used as a fumigation disinfection, the provisions of the atmosphere allows 0.2 mg / m3, so disinfection should be carried out under unoccupied conditions.
Ten, content determination: in a 500ml conical glass bottle with stopper, add 350ml distilled water and 20ml 20% KI solution, in the exhaust pipe shunt ozone gas 2L into the conical bottle, and then drop 5ml of concentration of 3mol/L H2SO4 solution, after 5 minutes of resting with 0.1000mol/L Na2S2O3 titration, the reaction to a light yellow color, when added. 1ml of 0.5% starch indicator, titrate until colorless, calculate the amount consumed, each milliliter of mol/l of Na2S2O3 solution is equivalent to 48.00mg of O3.
O3 concentration (mg/liter)=M×V×48×1000/2×2×100=12MV
In the formula: M=g molecules of concentration,, it should be calibrated to the fourth decimal place; V = number of milliliters consumed.
When the O3 concentration is high, you can take 1 liter of ozonated gas, then the formula for the O3 concentration (mg / liter) = 24MV.
Air sterilization and disinfection technology
Ozone: the use of air or pure oxygen through the corona discharge method (commonly used) or electrolysis method to obtain. Currently commonly used in sewage treatment and indoor air purifiers, effective sterilization time of about 30min. A certain concentration range is favorable to human health, more than a certain concentration is unfavorable to the human body.
Ultraviolet light: wavelength 200-300nm, easy to penetrate clean water and air, for air and object surface sterilization. Currently often made into ultraviolet sterilization lamp, now widely used in hospitals for indoor purification. Effective sterilization time in more than 2 hours, while the human body has side effects.
Photocatalyst: the light will activate the surface of titanium oxide, generating electrons e and positive holes. The electrons will restore the oxygen in the air, and the positive holes will oxidize and decompose the adsorbed substances on the surface, realizing air purification, antifouling and antibacterial. At present, it is commonly used in outdoor and object surface antibacterial antifouling treatment.
Plasma: the use of corona discharge or electric field glow discharge will be the components of the air into a plasma treatment, destroying the microstructure of microorganisms, to achieve the sterilization and disinfection of air. At present there is a combination of ionization dust collector with electrostatic dust removal, commonly used in indoor purification machine, it should be said that at present the relevant domestic product technology is not complete.
Antimicrobial agent material: At present, there are many filter manufacturers launched with antibacterial agent or antibacterial agent filter, from the material to inhibit the propagation of microbial reproduction, take a certain effect of purification. Some filter materials treated with anti-microbial agents have a certain sterilizing and disinfecting effect. Such as enzyme filters.
Nanotechnology: antimicrobial capacity of the metal ions, can make its periphery can produce sterilization of the activated oxygen, and can penetrate into the bacterial cells to kill bacteria, so as to play a multiple strong sterilization effect. When the bacteria are killed, the metal ions and free from the bacterial body, repeat the sterilization function, which is its incomparable long-lasting. At present, there are many domestic manufacturers in this area, the product can be used for plastics, fibers, rubber, wood, paper, paint, resin, etc., which is mainly used for plastics and fibers.
Dry heat and moist heat sterilization, although both the use of heat sterilization, but because of its own nature and the conduction medium is different, so the characteristics of its sterilization are not the same (Table 1).
Table 1 dry heat sterilization and moist heat sterilization comparison
Dry heat moist heat
Effect on the object
Applicable objects
Acting temperature
Acting time
Bactericidal ability Air
Scorch
Metal, glass, and other items that do not fear the coking objects
High (160-400 ℃)
Acting time
Acting time
Bactericidal capacity 160-400°C)
Long (1-5 hours)
Worse Water and steam
Moisture (leather damage)
Cotton fabrics, water, liquids, and other items that do not tolerate heat and moisture
Low (60-134°C)
Short (4-60 minutes)
Stronger
Moist heat and dry heat have their own characteristics, and it is difficult to completely replace each other, but in general, moist heat disinfection is better than dry heat, so the use of common. Wet heat is better than dry heat disinfection effect for three reasons: ① protein in the water more easily denatured, more water, the more easily solidified; ② wet heat penetration, fast conduction. ③ steam with latent heat, when the steam and sterilized items in contact, can be condensed into water and release latent heat, so that the humidity rises rapidly, to strengthen the sterilization effect.
Moist heat using air and water vapor, fast thermal conductivity, strong penetration, can penetrate into the bacteria, so that the bacterial cell membrane expansion rupture, outflow of plasma, heat solidification and denaturation. At the same time, steam has latent heat, can rapidly increase the temperature of the sterilized items, to enhance the sterilization effect. Dry heat is the relative humidity in 20% below the high heat, heat conduction by the air, the speed is slower, must increase the temperature and appropriate extension of disinfection time, in order to achieve the purpose of sterilization. So in the same temperature conditions wet heat than dry heat sterilization effect is good.
Do not use UV sterilization lamps
I recently saw a number of shopping malls in some of the use of ultraviolet lamp counter. I asked the saleswoman: "The old so lighted line?" She said: "This is not a fly." Obviously, it is not enough to recognize the ultraviolet sterilization.
Ultraviolet radiation is a good method of physical sterilization. Especially for air disinfection, simple and easy. But it can only kill the surface of the object bacteria and influenza virus. Hospitals also use it to cure rickets, malnutrition, anemia, katydid rhinitis, laryngitis, bronchitis and so on. However, the dosage should not be too large and the time should not be too long. It should be supervised by a person. Otherwise it will also cause harm to the human body. Clinical often encountered ultraviolet-induced conjunctivitis, light source dermatitis, photosensitive vomiting and so on, so that mall is often open ultraviolet light is not right.
Ultraviolet lamps are generally used at home with 15-watt lamps at a relative temperature of 60% irradiation for 20 minutes. General calculation to 1 cubic meter 1 watt old projection. If the house is large lamp small, can be appropriate to extend the irradiation time, but shall not exceed 1 hour.
Use three points of attention: First, hanging lamps to the vertical ground, the height should not exceed 3 meters. Irradiated items: clothing, bedding to 1-1.5 meters for good. Second, indoor disinfection corners should not have things to cover, the lamp should be dusted regularly. Third, the kitchen, toilet use the lamp to be directed at the disinfection of the object, turn on the light after the personnel to leave, to turn off the light regularly. (Harbin First Hospital Yang Guojun)
A, irradiation sterilization
γ-ray irradiation sterilization has gradually replaced the original method of steaming, high temperature and high pressure sterilization method, drug fumigation sterilization method, widely used in the sterilization of medical equipment.
Characteristics of irradiation sterilization:
1, r-ray has a strong penetrating ability, the treated material can be pre-packaged into boxes, sealed, so that it becomes a package that can not pass through the bacterial, so that after radiation sterilization, their shelf-life is almost unlimited;
2, irradiation sterilization will not cause a significant increase in the temperature of the irradiated material, is a cold It is a cold sterilization method, which is the only best sterilization method for heat-sensitive medicines;
3. The sterilization is thorough and the processing quality can be guaranteed; the processing speed is fast and the processing cost is low.
Processing range:
Surgical instruments, surgical gowns, surgical caps, masks and other surgical appliances; syringes, blood transfusion apparatus, plasma separator, blood perfusion apparatus, cardiac blood catheter, negative pressure drainage bottles, urinary catheters, bone marrow needles, and other medical equipment; gauze tablets, gauze pads, haemostatic gauze, skimming cotton balls, maternity sanitary napkins and other dressings; plastic culture plates, humidifiers, packaging bottles, Medical supplies such as spray nozzles, bottle cap sets, etc. r-ray irradiation sterilization is carried out at room temperature and long pressure, and it is the most ideal sterilization method for cosmetics that are not resistant to high temperature. Talcum powder, mother-of-pearl powder, foundation, make-up box, make-up brushes, brushes, traditional Chinese medicine masks, various creams and so on are suitable for irradiation sterilization.
In addition, more and more daily necessities, etc. also use irradiation sterilization method. For example, toilet paper, sanitary napkins, children, elderly patients with diapers, shower gel, etc., dried flowers, scented bags, feather jewelry, wooden handicrafts, etc., livestock and poultry feed, pet feed, etc..
Glass, pearls, gemstones and other decorative items, crafts and artwork coloring, the use of radiation method also shows the advantages of other methods incomparable.
Two, food irradiation
Food irradiation is the use of γ-ray irradiation of food to inhibit germination, insecticidal sterilization, extend the shelf life and detection of disease treatment, so as to achieve the purpose of preserving food.
Thoroughly sterilized by irradiation of food is conducive to the health of safe food, especially raw seafood, wild animals with a variety of disease-causing bacteria, the use of irradiation disinfection will be the most thorough elimination of a variety of viruses is an effective method.
Features of food irradiation preservation:
1, food irradiation sterilization process does not change the temperature of the food itself, and will not change the taste and nutritional value of the food itself.
2, after irradiation of vegetables and fruits, can keep fresh and extend the shelf life of several months.
3, finished food products can be packaged into boxes irradiation sterilization, to avoid secondary pollution, but also to reduce or avoid the use of preservatives and other toxic and harmful substances.
Processing range:
Dehydrated vegetables, seasonings, soups, frozen aquatic products, grain and fruit, cookies, preserved meat, moon cakes, potatoes, garlic, ginger and so on.
Third, radiation chemical
Domestic and foreign radiation chemical method has been successfully developed many new polymer materials, they have excellent performance, widely used in high-temperature flame-retardant wires and cables, heat-shrinkable tubes, high-temperature hot water pipes, adhesives, tires, biomedical materials and other aspects.
Processing range:
1, radiation cross-linked polyethylene
2, heat-shrinkable materials
3, foam, water-absorbent materials
4, high-strength medical silicone rubber, etc.
5, polymer composites, nano-materials preparation, etc.