REVIEW: Photo-oxygen purification equipment is mainly used for the purification and odor elimination of harmful exhaust gases in the production processes of food, medicine, chemical industry, sewage, garbage, plastic, spraying, paper making, tires and so on. Photochemical and photocatalytic oxidation method is currently a more advanced oxidation technology. The so-called photocatalytic reaction, is the role of light under the chemical reaction. Photochemical reactions require molecules to absorb electromagnetic radiation of specific wavelengths, excited to produce molecular excited states, and then react chemically to generate new species or become intermediate chemical products that initiate thermal reactions. The activation energy of photochemical reaction is derived from the energy of photons, and the photoelectric conversion and photochemical conversion in the utilization of solar energy have been very active research fields.
Photocatalytic oxidation technology uses photo-induced oxidation of O2, H2O2 and other oxidants combined with optical radiation. The main light used for UV light, including uv-H2O2, uv-O2 and other processes can be used for sewage treatment CHCl3, CCl4, PCBs and other refractory substances. In addition, there is a synergistic effect between ultraviolet light and iron ions in the Fenton system with UV light, which greatly accelerates the rate of hydroxyl radical decomposition by H2O2 and promotes the oxidative removal of organic compounds.
Nature has a very powerful self-healing function, such as exhaust emissions in the atmosphere, after a period of time the exhaust material will be slowly decomposed, the most important of which is the occurrence of photochemical reactions. Exhaust gases, through the absorption of photons or other particles of energy, make chemical bonds break to form free-form atoms, and then undergo a series of redox reactions to ultimately produce simple substances such as H 2 O and CO 2.
After a long period of research, it has been found that when a chemical substance absorbs energy (such as thermal energy, photon energy, etc.), its chemical properties can be made more active or even cracked. When absorbed energy is greater than the chemical bond energy, you can make the chemical bond fracture, the formation of free energy with atoms or groups. In the wavelength range of 154nm-184.9nm (1200KJ / mol-600KJ / mol) under the action of high-energy ultraviolet rays, on the one hand the oxygen in the air is cracked and then combined to produce ozone; the other hand, the chemical bonds of pollutants rupture to form a free state Atoms or groups; simultaneous generation of ozone involved in the reaction process, the final exhaust gas was cracked into simple and stable compounds such as CO2, H2O, N2 and so on.
Due to the same nature as the combustion of organic waste gas, both molecules are fragmented by the energy absorbed by the molecule (the heat energy absorbed by the combustion and the photon energy absorbed by photolysis), and then the simple substance is oxidized and the reaction temperature of photolysis is normal temperature, Call it "cold burning."
Discover history and genre
Ultraviolet light is the general term for the wavelength of the electromagnetic spectrum from 10nm to 400nm, can not cause people's vision. In 1801, German physicist Ritter discovered that ultraviolet rays were found in the outer part of the violet end of daylight spectrum to make photographic negatives contain silver bromide.
The scope of the UV spectrum in the draft international standard limiting the irradiance of solar radiation is divided as follows:
use
Photovoltaic oxygen purification equipment is mainly used for the purification and odor elimination of harmful exhaust gases in the production processes of food, medicine, chemical industry, sewage, garbage, plastic, spraying, paper making and tire.
Photo-catalytic technology of oxygen gas treatment briefly principle
Used in industrial waste gas treatment UV wavelength of 154nm-254nm, the shorter the wavelength the greater the energy. In this wavelength region, the "kill" space is also small due to the relatively short wavelength of 154 nm-185 nm. While 185nm-254nm, although the wavelength is longer but the scope of the killing space is relatively large.
Exhaust gas photolysis oxidation mechanism consists of two processes:
1. In the process of generating high-energy ion population, a certain amount of harmful gas molecules by high energy, itself breaks down into simple substance or into harmless substances.
2. Ion groups containing a large number of high-energy particles and highly reactive free radicals interact with macromolecular gases such as benzene, toluene and the like, opening the chemical bonds within their molecules and converting them into harmless small molecules. The new eco-oxygen ions have a strong oxidation, it can effectively oxidize and decompose organic matter not controlled by negative ions. Excess oxygen ions (positive), which react with the exhaust gas, can quickly combine with oxygen ions (negative) to form neutral oxygen and thus will not adversely affect equipment and the environment.
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