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.

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.

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.

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.

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.

scholarly journals Kinetics and Mechanistic Studies of Photochemical and Oxidative Stability of Galaxolide

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1813
Author(s):  
Aneta Sokol ◽  
Artur Ratkiewicz ◽  
Iwona Tomaszewska ◽  
Joanna Karpinska
Keyword(s):  
Advanced Oxidation Processes ◽  
Degradation Products ◽  
Advanced Oxidation ◽  
Degradation Process ◽  
Oh Radicals ◽  
Direct Photolysis ◽  
Oxidation Processes ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
Oxidative Agents

Studies on kinetics of galaxolide (HHCB) degradation under influence of UV, simulated sunlight and some advanced oxidation processes (H2O2, UV/H2O2, and Vis/H2O2) were conducted. Galaxolide appeared to be a photolabile compound. The first-order kinetics model was assumed for all studied processes. It was observed that basic pH favored HHCB degradation. The influence of natural matrices (river water and artificial sweat) on direct photolysis of HHCB was examined. It was stated that the process of the photodegradation proceeded slower at the presence of each matrix. HHCB lactone was identified using the GC-MS technique. The recorded chromatograms showed that apart from the lactone, other degradation products were formed that we could not identify. In order to deeper understand the HHCB degradation process, DFT calculations were performed. The results pointed out that OH radicals play a key role in HHCB decomposition, which mainly proceeds via H abstractions as well as OH additions. It follows from the calculations that the visible light is sufficient to initiate the advanced oxidation processes (AOPs) under the oxidative conditions, whereas UV irradiation is needed to start decay with no oxidative agents.

Advanced oxidation technologies for the degradation of pesticides in ground water and surface water

2002 ◽  
Vol 2 (1) ◽  
pp. 129-138 ◽  
Author(s):  
G.F. Ijpelaar ◽  
M. Groenendijk ◽  
R. Hopman ◽  
Joop C. Kruithof
Keyword(s):  
Water Quality ◽  
Water Treatment ◽  
Surface Water ◽  
Advanced Oxidation Processes ◽  
Nitrate Concentration ◽  
Advanced Oxidation ◽  
Fenton Process ◽  
Practical Application ◽  
Oxidation Processes ◽  
By Products

An overview of the Advanced Oxidation Processes (AOP) studied for the degradation of pesticides combined with the formation of by-products is presented. It was found that the degree of conversion of pesticides is about the same with the Fenton process and UV/H2O2 within the margin of practical application, but slightly different with ozone/H2O2. Bentazone is readily degraded by the latter process, but more persistent during water treatment with the Fenton process and UV/H2O2, whilst atrazine is difficult to convert with all of these processes. Although bromate formation cannot be avoided completely with ozone/H2O2, it can be realized with the Fenton process and UV/H2O2. Upon degradation of pesticides with UV/H2O2 nitrite is produced, the amount depending on the water quality with respect to the nitrate concentration. Based on the a-selective nature of the hydroxyl radical AOC is formed out of DOC, which indicates that ozone/H2O2, the Fenton process as well as UV/H2O2 should be applicable for the development of biological GAC filtration.

scholarly journals Advanced Oxidation Processes Coupled with Nanomaterials for Water Treatment

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2045
Author(s):  
Inês M. F. Cardoso ◽  
Rita M. F. Cardoso ◽  
Joaquim C. G. Esteves da Silva
Keyword(s):  
Water Quality ◽  
Water Treatment ◽  
Advanced Oxidation Processes ◽  
Tap Water ◽  
Water Quality Management ◽  
Advanced Oxidation ◽  
Active Role ◽  
Water Contaminants ◽  
Ongoing Research ◽  
Oxidation Processes

Water quality management will be a priority issue in the near future. Indeed, due to scarcity and/or contamination of the water, regulatory frameworks will be increasingly strict to reduce environmental impacts of wastewater and to allow water to be reused. Moreover, drinking water quality standards must be improved in order to account for the emerging pollutants that are being detected in tap water. These tasks can only be achieved if new improved and sustainable water treatment technologies are developed. Nanomaterials are improving the ongoing research on advanced oxidation processes (AOPs). This work reviews the most important AOPs, namely: persulfate, chlorine and NH2Cl based processes, UV/H2O2, Fenton processes, ozone, and heterogeneous photocatalytic processes. A critical review of the current coupling of nanomaterials to some of these AOPs is presented. Besides the active role of the nanomaterials in the degradation of water contaminants/pollutants in the AOPs, the relevance of their adsorbent/absorbent function in these processes is also discussed.

Sign in / Sign up

Export Citation Format

Share Document