Advanced oxidation technology is also called as the depth of oxidation technology, to produce a strong oxidation ability of hydroxyl radical (• OH) as the characteristic, the high temperature and high pressure, electricity, sound and light irradiation, catalysts, reaction conditions such as the macromolecular refractory organics oxidation into the low-toxic and non-toxic small molecules.According to different ways and reaction conditions, free radicals can be divided into photochemical oxidation, catalytic wet oxidation, acoustic chemical oxidation, ozone oxidation, electrochemical oxidation and Fenton oxidation.
Oxidation is the chemical process of REDOX of organic or inorganic substances using oxidants.There are many kinds of oxidants, such as hydrogen peroxide, potassium permanganate, potassium dichromate, chlorine dioxide, etc.The most significant characteristic of the advanced oxidation method is hydroxyl radical •OH is the main oxidant that reacts with organic matter.
Hydroxyl radical is a powerful chemical oxidant, and its oxidation potential is 3.06 times higher than that of normal oxidants (such as ozone 2.07, chlorine gas 1.36, hydrogen peroxide 1.77).
In the reaction, the generation of organic • OH free radical chain reaction can continue to • OH, or through organic peroxide radicals generated after oxidizing decomposition reaction until further degradation for the final product of CO2 and H2O, so as to achieve the goal of the oxidative decomposition of organic matter.Advanced oxidation can be divided into many types, such as hydrogen peroxide as the main oxidation method, such as Fenton oxidation method.Under the action of catalyst, H2O2 and ferrite can generate two active hydroxyl radicals, which can effectively oxidize organic compounds.
Other oxidation methods include titanium dioxide oxidation and wet oxidation.
LBOZONE would like to share more about the advanced ozone oxidation methods .It has important in guiding universities testing and institutes researches . The reaction mechanism of ozone with pollutants includes direct reaction (direct reaction of ozone with organic matter) and indirect reaction (ozone decomposition produces •OH, •OH with organic matter for oxidation reaction).The direct reaction of O3 has strong selectivity, which is to destroy the double bond structure of organic compounds.Indirect reaction in general is not selective, O3 formation in the water, OH basically has the following three ways: under the condition of alkaline decomposition generated • OH, under the influence of uv light generated • OH and generated under the metal catalyst, OH.
Ozone oxidation can be realized mainly through direct reaction and indirect reaction. direct reaction refers to the ozone react with organic matter directly, this way has strong selectivity, usually attack has the double bond of organic matter, usually of unsaturated fatty hydrocarbon and aromatic hydrocarbon compounds is effective;Indirect reaction refers to the decomposition of ozone into •OH, and the oxidation of organic materials through •OH is not selective.
Although ozone oxidation method has strong ability of decoloring and removing organic pollutants, but the method of the operation cost is higher, selective oxidation of organic matter in low dose and short period of time can't completely mineralization of pollutants, and the decomposition of the generated intermediate prevents ozone oxidation process.It can be seen that ozone oxidation method is still very limited in the treatment of landfill leachate.
The O3/H2O2 process has been studied in Japan since the late 1970s to treat high concentration organic wastewater, while in the United States, it was used to treat volatile organic compounds in urban sewage in the 1980s.
LBOZONE used this process, treatment of electroplating wastewater, achieve a very good effect.It was found by some users that use only to treat wastewater,maybe the initial effect is not obvious, but it will shows up later.It’s because there are many oxidizable substances in waste water, and ozone will preferentially react with substances that react easier and more quickly, while the other substances cannot achieve the purpose of treatment.
And hydroxyl radical • OH differ with different organic material reaction rate constant is small, the hydroxyl free radical is a selective small antioxidant, when there is a variety of water pollutants, there will not be a kind of material degradation and another is almost the same.Therefore this is the reason of using advanced oxidation method can achieve twice the result with half of effort,
Advanced oxidation requires oxygen gas as air source of ozone generator. The ozone outlet best concentration is 100-200mg/L.In order to improve the oxidation effect, it is recommended to use the high efficiency ozone gas-liquid mixing device.
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