Ozone based Advanced Oxidation Processes (O3 AOPs) are efficient water treatment and air purification technologies that generate highly oxidizing hydroxyl radicals (· OH) through the synergistic effect of ozone (O3) and other oxidants or catalysts, thereby efficiently degrading organic pollutants, sterilizing and disinfecting, and removing odors. Due to its fast reaction rate, wide applicability, and no secondary pollution, advanced ozone oxidation technology has been widely used in environmental treatment, industrial wastewater treatment, drinking water purification, and other fields.

Basic principles of advanced ozone oxidation

Ozone (O3) is a strong oxidant with a redox potential (2.07 V) second only to fluorine (2.87 V) and hydroxyl radicals (2.80 V). However, ozone has limited oxidation efficiency for certain recalcitrant organic compounds when acting alone, so it is often combined with other technologies to form advanced oxidation systems and improve reaction efficiency.

Direct ozone oxidation

Ozone molecules can directly react with organic compounds, mainly attacking compounds containing double bonds, aromatic rings, or electron rich groups, such as:

Alkenes, phenols, dyes, etc. are easily oxidized by ozone.

The reaction mechanism includes electrophilic addition, cycloaddition, and hydrogen extraction.

Indirect oxidation of hydroxyl radicals (· OH)

Ozone can decompose to produce hydroxyl radicals (· OH) under specific conditions (such as alkaline environment, UV irradiation, and the presence of catalysts), with stronger oxidation ability (oxidation potential 2.80 V), and can almost indiscriminately degrade the vast majority of organic matter:

O3 + OH? ·OH + O2? (Under alkaline conditions)

O3+H2O+UV 2 · OH+O2 (photocatalytic ozonation)

O3+catalyst (such as Fe2? 、 TiO? ）·OH (catalytic ozonation)

The main technologies of advanced ozone oxidation

According to different reaction conditions, advanced ozone oxidation technology can be divided into the following categories:

Ozone/Hydrogen Peroxide (O3/H2O2)

Hydrogen peroxide (H2O2) can promote the decomposition of ozone to generate · OH:

O_3 + H_2O_2 ·OH + O_2 + HO_2·

Suitable for treating recalcitrant organic compounds such as pesticide and pharmaceutical wastewater.

Ozone/Ultraviolet (O3/UV)

Ultraviolet light (UV) stimulates ozone decomposition, increasing the yield of · OH:

O3+UV O2+O (^ 1D) \ \ quad (\ \ text {excited state oxygen atom})

O(^1D) + H_2O 2·OH

Commonly used for deep treatment of printing and dyeing wastewater and pharmaceutical wastewater.

Ozone/catalyst (catalytic ozone oxidation)

Homogeneous catalysis (such as Fe2? 、 Mn2? ）：

O_3 + Fe^{2+} Fe^{3+} + ·OH + O_2

Heterogeneous catalysis (such as activated carbon, TiO?)? 、 MnO? ）：

Catalysts provide active sites to promote ozone decomposition.

Suitable for the removal of low concentration organic pollutants.

Ozone/Ultrasound (O3/US)

Ultrasonic cavitation effect promotes ozone mass transfer and generates additional · OH:

H_2O + US ·OH + H

Suitable for pretreatment of high concentration organic wastewater.

Application of advanced ozone oxidation

water treatment

Drinking water purification: removing trace organic matter (such as pesticides, endocrine disruptors) and disinfection by-products precursors.

Industrial wastewater treatment:

Dyeing wastewater decolorization and degradation of benzene derivatives.

Removal of phenols and polycyclic aromatic hydrocarbons (PAHs) from petrochemical wastewater.

Degradation of antibiotic residues in pharmaceutical wastewater.

Advanced treatment of municipal sewage: combined with biological treatment to improve effluent quality.

air purification

VOCs (volatile organic compounds) treatment: degradation of formaldehyde, benzene derivatives, etc.

Odor gas treatment: decompose hydrogen sulfide, ammonia, etc.

Other fields

Food industry: Cleaning and disinfecting fruits and vegetables, extending their shelf life.

Medical disinfection: sterilization of surgical instruments and medical wastewater.

Advantages and challenges of advanced ozone oxidation

advantage

Efficient degradation: · OH can quickly mineralize organic matter into CO? And H? O.

Broad spectrum applicability: capable of treating various difficult to degrade pollutants.

Environmentally friendly: No secondary pollution, ozone can decompose into oxygen on its own.

challenge

High operating costs: Ozone generators consume a significant amount of energy.

Selective oxidation: Some pollutants require optimization of reaction conditions.

The risk of by-products, such as the generation of bromate (BrO??), needs to be controlled.

Future Development Trends

1. Coupling other technologies such as membrane separation and biological treatment to improve economic efficiency.

2. Development of new catalysts: Improve ozone utilization efficiency and · OH yield.

3. Intelligent control: Optimize ozone dosage and reduce energy consumption.

Ozone advanced oxidation technology has become an important method in the fields of water treatment and air purification due to its strong oxidation ability and environmentally friendly characteristics. With the development of catalytic materials, reactor design, and intelligent control technology, its application prospects will be even broader. Future research should focus on reducing costs and improving efficiency to promote the large-scale application of this technology.

References (specific references can be supplemented as needed)

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