Fenton agent

To enhance the remediation of CAHs, the EK process coupled to other technologies has been developed. For instance, the EK process was used to transport Fenton agents for the remediation of TCE-contaminated soils (Yang and Liu, 2001). EK-... 

Lee and Chu also reported that the addition of Fenton agent or hydrogen peroxide to the degradation medium would retard the well-known adverse effect of the conventional y-irradiation sterilization of synthetic absorbable sutures [Lee et al., 1996a]. They found that these y-irradiated sutures retained better tensile breaking strength in the Fenton medium than in the regular buffer media. Chu et al. postulated that the y-irradiation induced a-carbon radicals in these sutures react with the hydroxyl radicals from... 

Oxidation. Oxidation is one of the main chemical methods to treat and decompose dyes in wastewater. The oxidation agents used ate chlorine, bleach, ozone, hydrogen peroxide, Fenton s reagent, and potassium permanganate. 

Heterocyclic compounds have in most cases been hydroxylated by modified forms of Fenton s reagent. For instance, EDTA or pyrophosphate have been added to the system to complex the ferrous ions. It has been shown in the reactions of bcnzenoid compounds, however, that addition of complexing agents does not affect the distribution of isomers obtained by Fenton s reagent,and therefore the hydroxyl radical must still be the hydroxylating species. 

The Tf- CF system is preferred over Fenton s reagent because Ti4 is a less powerful oxidizing agent than Fc5+ and the above mentioned pathway and other side reactions are therefore of less consequence.252 Much of the discussion on redox initiation in Section 3.3.2.6.1 is also relevant to hydrogen peroxide. 

Humans Hydrogen peroxide has been used as an enema or as a cleaning agent for endoscopes and may cause mucosal damage when applied to the surface of the gut wall. Hydrogen peroxide enteritis can mimic an acute ulcerative, ischaemic or pseudomembranous colitis, and ranges from a reversible, clinically inapparent process to an acute, toxic fulminant colitis associated with perforation and death (Bilotta and Waye, 1989). It is conceivable that anecdotal reports of exacerbation of IBD by iron supplementation (Kawai et al. 1992) are mediated by hydroxyl radical production by the Fenton reaction. 

The antiulcer agent rebamipide ((2-(4-chlorobenzoy-lamino)-3-[2(lH)-quinolinon-4-yl]propionic acid) dose-dependently decreased hydroxyl radical signal generated by the Fenton reaction in an e.s.r. study. Rebamipide is active as a hydroxyl radical scavenger and inhibitor of superoxide production by neutrophils (Yoshikawa etal., 1993). 

The mixture is known as Fenton s reagent, and the effective oxidising agent in the system is the hydroxyl radical, HO. This is particularly good as an abstractor of H, and can be used either to generate the resultant radical, e.g. (30), for further study, or, in some cases prepara-tively through the latter s dimerisation, e.g. (31) ... 

Using Volatile Anaesthetic Agents. Dr. P. Fenton, Update in Anaesthesia, Practical Procedures, Issue 5,1995, http //www.nda.ox.ac.uk/wfsa/html/u05/u05 007.htm... 

Thus, superoxide itself is obviously too inert to be a direct initiator of lipid peroxidation. However, it may be converted into some reactive species in superoxide-dependent oxidative processes. It has been suggested that superoxide can initiate lipid peroxidation by reducing ferric into ferrous iron, which is able to catalyze the formation of free hydroxyl radicals via the Fenton reaction. The possibility of hydroxyl-initiated lipid peroxidation was considered in earlier studies. For example, Lai and Piette [8] identified hydroxyl radicals in NADPH-dependent microsomal lipid peroxidation by EPR spectroscopy using the spin-trapping agents DMPO and phenyl-tcrt-butylnitrone. They proposed that hydroxyl radicals are generated by the Fenton reaction between ferrous ions and hydrogen peroxide formed by the dismutation of superoxide. Later on, the formation of hydroxyl radicals was shown in the oxidation of NADPH catalyzed by microsomal NADPH-cytochrome P-450 reductase [9,10]. 

Fenton s reagent chemistry has been used for the direct self-bonding of wood particles. Indirect methods, involving the use of surface-activated fibres in combination with other bonding agents such as furfural and lignosulphonates, have also been studied (Philippou, 1982 Philippou etal, 1982). Since the use of Fenton s reagent requires the presence of... 

Moura, FCC Araujo, MH Costa, RCC Fabris, JD Ardisson, JD Macedo, WAA Lago, RM. Efficient use of Fe metal as an electron transfer agent in a heterogeneous Fenton system based on Fe°/Fc304 composites. 

Various attempts have been made to measure the formation of peroxides in isolated proteins and low density lipoproteins upon exposure to various oxidizing agents including ionizing radiation, transition metals involved in Fenton reaction, peroxyl radicals, photosensitizers and enzymatic oxidative systems (for reviews see References 195, 234 and 241). 

Another function of ascorbic add is to generate Fe(II) from Fe (III), which is part of the Haber-Weiss-Fenton Reaction (77). In that reaction, peroxide is reduced to the hydroxyl radical, HO, an extremely powerful oxidizing agent. It should also be noted that ascorbic acid can chelate metals 18 and will promote the carbohydrate-amine browning reaction (79-20). 

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