The basics of oxidants in water treatment. Part A: OH radical reactions

2007 ◽  
Vol 55 (12) ◽  
pp. 19-23 ◽  
Author(s):  
C. von Sonntag
Keyword(s):  
Water Treatment ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
Radical Reactions ◽  
Oh Radicals ◽  
Oh Radical ◽  
Oxidation Processes

The Advanced Oxidation Processes (AOPs) are based on the reactions of the highly reactive •OH radicals. The formation of •OH by the various AOPs and their ensuing reactions are reviewed.

scholarly journals Ultrafine bubbles as an augmenting agent for ozone-based advanced oxidation

2021 ◽  
Author(s):  
Tatek Temesgen ◽  
Mooyoung Han
Keyword(s):  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
Negative Influence ◽  
Oh Radicals ◽  
Oh Radical ◽  
Oxidation Processes ◽  
Acidic Conditions ◽  
Ph Conditions ◽  
First Time ◽  
Influence Of Ph

Abstract In this study, the influence of nanobubbles (NBs) application in ozone (O3) based advanced oxidation processes (AOP) is investigated. The results demonstrate the potential of NBs application to O3 – based AOP. It was observed that NBs suppress the negative influence of pH and operating temperatures on the efficiency of ozonation. In addition, the application of NBs tends to improve the solubility of O3 and the rate of mass transfer under the influence of a broad range of temperature and pH conditions. The results of this research indicate that application of NBs minimized the reduction in concentration of dissolved O3 with an increase in temperature. Furthermore, application of NBs highly improved the OH radical formation in acidic conditions. The results of this research depicted for first time that the application of NBs strongly encourages the initiation of reactions involving OH radicals. It was found by this research that NBs can boost the concentration of OH radicals up to 3.5 fold compared to equivalent MB supported ozonation systems. This is assumed to improve the efficiency of currently existing conventional bubble supported O3 – based AOP systems.

Inter-calibration of OH radical sources and water quality parameters

1997 ◽  
Vol 35 (4) ◽  
pp. 1-8 ◽  
Author(s):  
Jürg Hoigné
Keyword(s):  
Water Quality ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Oh Radicals ◽  
Oh Radical ◽  
Natural Systems ◽  
Oxidation Processes

OH radicals are the key oxidants that control most Advanced Oxidation Processes (AOPs) currently applied in water technology and that also occur in some natural systems such as cloud waters. The efficiencies of the various OH radical sources can be experimentally quantified and compared when they are calibrated by following the oxidation of inter-calibrated reference compounds that react during the process only with OH radicals. To apply and generalize the results, however, water quality parameters controlling the lifetime of OH radicals via OH-scavenging reactions by pollutants and further solutes must also be quantified by methods that allow for calibrations.

Advanced oxidation processes: mechanistic aspects

2008 ◽  
Vol 58 (5) ◽  
pp. 1015-1021 ◽  
Author(s):  
C. von Sonntag
Keyword(s):  
Activated Carbon ◽  
Fenton Reaction ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
Oh Radicals ◽  
Oh Radical ◽  
Reactive Intermediate ◽  
Oxidation Processes ◽  
Water Matrix ◽  
Vacuum Uv

The reactive intermediate in Advanced Oxidation Processes (AOPs) is the •OH radical. It may be generated by various approaches such as the Fenton reaction (Fe2 + /H2O2), photo-Fenton reaction (Fe3 + /H2O2/hν), UV/H2O2, peroxone reaction (O3/H2O2), O3/UV, O3/activated carbon, O3/dissolved organic carbon (DOC) of water matrix, ionizing radiation, vacuum UV, and ultrasound. The underlying reactions and •OH formation efficiencies are discussed. The key reactions of •OH radicals also addressed in this review.

Advanced Oxidation Processes for Wastewater Remediation: Fundamental Concepts to Recent Advances

2021 ◽  
pp. 37-86
Keyword(s):  
Water Treatment ◽  
Organic Pollutants ◽  
Large Scale ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
Oxidation Potential ◽  
Wastewater Remediation ◽  
Oxidation Processes ◽  
Sludge Disposal ◽  
Different Types

Industrialization and modernization in recent times have led to a water crisis across the world. Conventional methods of water treatment like physical, chemical and biological methods which comprise of many commonly used techniques like membrane separation, adsorption, chemical treatment etc. have been in use for many decades. However, problems like sludge disposal, high operating costs etc. have led to increased focus on Advanced Oxidation Processes (AOPs) as alternative treatment methods. AOPs basically involve reactions relying on the high oxidation potential of the hydroxyl (OH•) free radical. They have the potential to efficiently treat various toxic, organic pollutants and complete degradation of contaminants (mineralization) of emerging concern. Many different types of homogenous as well as heterogenous AOPs have been studied viz: UV/H2O2, Fenton, Photo-Fenton, Sonolysis, Photocatalysis etc. for treatment of a wide variety of organic pollutants. Different AOPs are suitable for different types of wastewater and hence proper selection of the right technique for a particular type of pollutant is required. The inherent advantages offered by AOPs like elimination of sludge disposal problems, operability under mild conditions, ability to harness sunlight, non selective nature (ability to degrade all organic and microbial contamination) etc. have made it one of the most actively researched areas in recent times for wastewater treatment. Despite the benefits and intense research, commercial applicability of AOPs as a practical technique for treating wastewater on a large scale is still far from satisfactory. Nevertheless, positive results in lab scale and pilot plant studies make them a promising water treatment technique for the future. In the present chapter, an attempt has been made to discuss all aspects of AOPs beginning with the fundamental concepts, classification, underlying mechanism, comparison, commercialization to the latest developments in AOPs.

Advanced Oxidation Processes for Wastewater Remediation: Fundamental Concepts to Recent Advances

2021 ◽  
pp. 37-86
Keyword(s):  
Water Treatment ◽  
Organic Pollutants ◽  
Large Scale ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
Oxidation Potential ◽  
Wastewater Remediation ◽  
Oxidation Processes ◽  
Sludge Disposal ◽  
Different Types

Industrialization and modernization in recent times have led to a water crisis across the world. Conventional methods of water treatment like physical, chemical and biological methods which comprise of many commonly used techniques like membrane separation, adsorption, chemical treatment etc. have been in use for many decades. However, problems like sludge disposal, high operating costs etc. have led to increased focus on Advanced Oxidation Processes (AOPs) as alternative treatment methods. AOPs basically involve reactions relying on the high oxidation potential of the hydroxyl (OH•) free radical. They have the potential to efficiently treat various toxic, organic pollutants and complete degradation of contaminants (mineralization) of emerging concern. Many different types of homogenous as well as heterogenous AOPs have been studied viz: UV/H2O2, Fenton, Photo-Fenton, Sonolysis, Photocatalysis etc. for treatment of a wide variety of organic pollutants. Different AOPs are suitable for different types of wastewater and hence proper selection of the right technique for a particular type of pollutant is required. The inherent advantages offered by AOPs like elimination of sludge disposal problems, operability under mild conditions, ability to harness sunlight, non selective nature (ability to degrade all organic and microbial contamination) etc. have made it one of the most actively researched areas in recent times for wastewater treatment. Despite the benefits and intense research, commercial applicability of AOPs as a practical technique for treating wastewater on a large scale is still far from satisfactory. Nevertheless, positive results in lab scale and pilot plant studies make them a promising water treatment technique for the future. In the present chapter, an attempt has been made to discuss all aspects of AOPs beginning with the fundamental concepts, classification, underlying mechanism, comparison, commercialization to the latest developments in AOPs.

Combination of advanced oxidation processes and gas absorption for the treatment of chlorinated solvents in waste gases

2001 ◽  
Vol 44 (9) ◽  
pp. 173-180 ◽  
Author(s):  
J. Dewulf ◽  
H. Van Langenhove ◽  
E. De Smedt ◽  
S. Geuens
Keyword(s):  
Advanced Oxidation Processes ◽  
Bubble Column ◽  
Chlorinated Solvents ◽  
Advanced Oxidation ◽  
Chemical Oxidation ◽  
Chloride Ions ◽  
Gas Absorption ◽  
Oh Radicals ◽  
Chlorinated Organic Compounds ◽  
Oxidation Processes

Treatment of chlorinated organic compounds in waste gases is difficult because of several reasons: these compounds are dioxin precursors when incinerated, and also biological treatment is difficult because of a limited number of suitable microbial degradation pathways. On the other hand, since the 1990s, a new generation of chemical oxidation techniques has been introduced in water treatment. Advanced Oxidation Processes (AOPs) are based on a combination of UV/H2O2, UV/O3 or H2O2/O3. The combinations result in the generation of OH-radicals, which subsequently attack the organic pollutants. In this work, the treatment of a gas stream (240 L/h) loaded with 20-40 ppmv trichloroethylene (TCE) is presented. Therefore, a combination of an absorption process in a bubble column with a liquid H2O2/O3 initiated oxidation, was investigated. Removal efficiencies, depending on the dosed H2O2 and O3, up to 94% were found. The production of chloride ions was investigated: the Cl-atoms from the removed TCE could be found back as chloride ions. Next to the experimental work, attention was paid to the mechanisms taking place in the proposed concept. Here, a simulation model was developed, considering gas/liquid mass transfer of TCE and ozone, axial liquid dispersion, advective gas and liquid transport and about 29 chemical reaction steps. The modelling allowed a better understanding of the technique and gives insight in its possibilities and limitations. Finally, it can be concluded that the proposed technique shows interesting perspectives: it is able to transform chlorine in chlorinated solvents into chloride ions effectively at ambient temperature conditions.

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