1, Introduction
Chlorofluorocarbons, also known as chlorofluorocarbons, are organic substances containing only chlorine, fluorine and carbon, including trichlorofluoromethane, dichlorodifluoromethane and dichlorotetrafluoroethane. At room temperature, chlorofluorocarbons are volatile (high vapor pressure, low boiling point), chemically stable, nonflammable and nontoxic.
HCFCs belong to volatile organic compounds. The process from gas to liquid and from liquid to gas is easy to realize. In addition, it has the characteristics of high density, low viscosity, low surface tension and low refractive index.
2. Preparation and characterization
Like the preparation of other halogenated hydrocarbons, chlorofluorocarbons can be prepared from alkanes by halogenation reaction (belonging to free radical reaction), and fluorine atoms and chlorine atoms replace hydrogen atoms. The product can be characterized by spectrophotometry, gas chromatography and mass spectrometry.
3. Influence
Once chlorofluorocarbons enter the atmosphere, they will accumulate and consume ozone in the stratosphere, resulting in ozone holes. This is because ultraviolet rays from the sun will decompose chlorofluorocarbons in the stratosphere and generate free chlorine atoms, which will react with ozone and convert ozone into oxygen.
Application of ozone oxidation technology;
1, coagulation-ozone oxidation technology
In coagulation-ozone oxidation technology, ozone can change the properties of suspended solids in water, thus changing the removal effect of coagulation operation unit. This method can make the suspended particles in water bigger and the dissolved organic matter into miscible colloidal particles, thus reducing the dosage of coagulant and the consumption of chemical agents.
2. Ozone biochemical method
In recent years, there are many patent reports on the treatment of wastewater by this method. Ozone is used to pretreat wastewater, which destroys refractory organic matter in water and improves biodegradability, and then activated carbon biofilter is used for further treatment. This technology makes full use of the strong oxidation of ozone and the cost advantage of biofilter, and the combined treatment effect is good.
3. Combined oxidation of ozone and hydrogen peroxide
Ozone-hydrogen peroxide system is an advanced oxidation method for sewage treatment. The synergistic effect of ozone and hydrogen peroxide can produce hydroxyl radicals with strong oxidation, which can effectively remove organic pollutants in water. In addition, ozone-hydrogen peroxide process is also very effective for removing organic pollutants from natural water.