Radical Reactions and Their Application for Water Treatment

2020 ◽  
pp. 203-219
Author(s):  
Pavel Hrabák ◽  
Stanisław Wacławek
Keyword(s):  
Water Treatment ◽  
Radical Reactions

Anisole nitration during gamma-irradiation of aqueous nitrite and nitrate solutions: free radical versus ionic mechanisms

2010 ◽  
Vol 7 (2) ◽  
pp. 183 ◽  
Author(s):  
Gracy Elias ◽  
Bruce J. Mincher ◽  
Stephen P. Mezyk ◽  
Thomas D. Cullen ◽  
Leigh R. Martin
Keyword(s):  
Free Radical ◽  
Water Treatment ◽  
Condensed Phase ◽  
Aromatic Compounds ◽  
Nitrous Acid ◽  
Radical Reactions ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Beam Irradiation ◽  
Free Radical Reactions

Environmental context. The nitration of aromatic compounds is an important source of toxic, carcinogenic, and mutagenic species in the atmosphere. Gas phase nitration typically occurs by free radical reactions. Condensed-phase free radical reactions may also be relevant in fog and cloud water in polluted areas, in urban aerosols with low pH, in water treatment using advanced oxidation processes such as e-beam irradiation, and in nuclear waste treatment applications. This paper discusses research towards an improved understanding of nitration of aromatic compounds in the condensed phase under conditions conducive to free radical formation. Abstract. In the irradiated, acidic condensed phase, radiation-enhanced nitrous acid-catalysed, nitrosonium ion, electrophilic aromatic substitution followed by oxidation reactions dominated over radical addition reactions for anisole. This ionic mechanism would predominate in urban atmospheric aerosols and nuclear fuel dissolutions. Irradiated neutral nitrate anisole solutions were dominated by mixed nitrosonium/nitronium ion electrophilic aromatic substitution reactions, but with lower product yields. Solutions such as these might be encountered in water treatment by e-beam irradiation. Irradiation of neutral nitrite anisole solutions resulted in a statistical substitution pattern for nitroanisole products, suggesting non-electrophilic free radical reactions involving the •NO2 radical. Although often proposed as an atmospheric nitrating agent, NO2 radical is unlikely to have an important effect in the acidic condensed phase in the presence of more reactive, competing species such as nitrous acid.

Recent advances in structure and reactivity of dissolved organic matter in natural waters

2008 ◽  
Vol 8 (6) ◽  
pp. 615-623 ◽  
Author(s):  
William J. Cooper ◽  
Weihua Song ◽  
Michael Gonsior ◽  
Daina Kalnina ◽  
Barrie M. Peake ◽  
...  
Keyword(s):  
Organic Matter ◽  
Free Radical ◽  
Water Treatment ◽  
Dissolved Organic Matter ◽  
Carbon Cycling ◽  
Natural Waters ◽  
Anthropogenic Sources ◽  
Radical Reactions ◽  
Detailed Knowledge ◽  
Free Radical Reactions

The goal of our research is to better understand the structure and reactivity of natural dissolved organic matter (DOM) in aquatic environments. A more detailed knowledge of these DOM characteristics would lead to a better understanding of carbon cycling in natural waters and processes associated with water treatment using free radical chemistry. Our specific interest in DOM in natural waters is several-fold: 1) the photochemical formation of reactive oxygen species, 2) photobleaching of the DOM in coastal oceans, and 3) using chromophoric DOM (CDOM) as a tracer of water masses and in carbon cycling. Our interest in water treatment is that DOM is the major sink of hydroxyl radicals employed in advanced oxidation processes for the destruction of pollutants and thus adversely affects the efficiency of the process. We are using the techniques of radiation chemistry to explore the fundamental free radical and redox chemistry of DOM. We have initiated a study of the free radical reactions of DOM using isolated fractions of Suwannee River fulvic and humic acids and isolates from various anthropogenic sources. We are also investigating the use of model compounds in an attempt to understand the free radical transients formed from DOM either as a result of free radical reactions or photochemical reactions.

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.

To the issue of water treatment by hydrocyclone on the systems of the combined irrigation

2020 ◽  
Vol 0 (2) ◽  
pp. 21-25
Author(s):  
Nikolay Dubenok ◽  
Andrey Novikov ◽  
Sergei Borodychev ◽  
Maria Lamskova
Keyword(s):  
Water Treatment ◽  
Organic Compounds ◽  
Irrigation Water ◽  
Irrigation System ◽  
Petroleum Products ◽  
Cylindrical Part ◽  
Agricultural Landscapes ◽  
Treatment Unit ◽  
Drain Pipe ◽  
Irrigation Network

At the stage of water treatment for irrigation systems, the efficiency capture coarse and fine mechanical impurities, as well as oil products and organic compounds affects the reliability of the equipment of the irrigation network and the safety of energy exchange processes in irrigated agricultural landscapes. The violation of work irrigation system can cause disruptions in irrigation schedules of agricultural crops, crop shortages, degradation phenomena on the soil and ecological tension. For the combined irrigation system, a water treatment unit has been developed, representing a hydrocyclone apparatus with a pipe filter in the case. For the capacity of 250 m3/h the main geometrical dimensions of hydrocyclone have been calculated. To organize the capture petroleum products and organic compounds, it has been proposed a modernization of a hydrocyclone unit, consisting in dividing the cylindrical part of the apparatus into two section. The first is section is for input irrigation water, the second one is for additional drainage of clarified irrigation water after sorption purification by the filter, placed on the disk and installed coaxially with the drain pipe and the pipe filter.

Simple improvements for emergency batch water treatment

Waterlines ◽  
2007 ◽  
Vol 26 (1) ◽  
pp. 17-19 ◽  
Author(s):  
Caetano Dorea
Keyword(s):  
Water Treatment

Bulk water treatment unit performance: For the cameras or the community?

Waterlines ◽  
2012 ◽  
Vol 31 (1-2) ◽  
pp. 53-66 ◽  
Author(s):  
Richard Luff ◽  
Caetano Dorea
Keyword(s):  
Water Treatment ◽  
Bulk Water ◽  
Treatment Unit ◽  
Unit Performance
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