Destruction oxidative

U.S. Environmental Protection Agency, Emerging Technology Summary Easer Induced Photochemical Oxidative destruction of Toxic Organics in Eeachates and Groundwaters, EPA/540/SR-92/080, Cincinnati, Ohio, 1993. 

Corrosion (from Latin corrodere, gnaw to pieces ) of metals is the spontaneous chemical (oxidative) destruction of metals under the elfect of their environment. Most often it follows an electrochemical mechanism, where anodic dissolution (oxidation) of the metal and cathodic reduction of an oxidizing agent occur as coupled reactions. Sometimes a chemical mechanism is observed. 

The high reactivity of the radicals OH and HO is well known it brings about the oxidative destruction of the binder, which we call the photocatalytic oxidation cycle" (POC). It is a cycle in which water and oxygen are constantly being consumed to destroy the binder. 

SG Voronina. The Kinetics, Reactivity and Peculiarities of Mechanism of Oxidative Destruction of Esters. Ph.D. Thesis, Kemerovo State University, Kemerovo, 1991, pp. 3-18 [in Russian]. 

Investigations into the molecular weight distribution showed that C—C bond break down randomly [126]. Thus, in the PS oxidized at 473 K, the ratio Mw/A/n initially increased from 1.06 to 1.50 (in this case, Mn decreased from 400,000 to 90,000) and remained virtually unchanged during further oxidation. The situation was different with PE residual oxygen at concentrations as low as 0.3% promoted the destruction of this polymer [127]. Moreover, anaerobic conditions at 588 K induced cross-linking processes in PE, while in the presence of 0.34% 02 the destructive processes became predominant. The decrease in Mn at 628 K under anaerobic conditions was not accompanied by changes in the ratio Mw/Mn 3. Conversely, this ratio increased in the course of the oxidative destruction of PE. 

Alkoxyl radicals can result from the isomerization of peroxyl radicals of oxidized PP (see above 13.1.6). If alkoxyl radicals cause polymer destruction, then, as they are produced from alkyl radicals, their accumulation and quasistationary concentration must decrease with increasing p02. However, despite varying p02, vs = const, in the oxidized PE and PP and, therefore, alkoxyl radicals essentially do not contribute to the oxidative destruction of polymers. At moderate temperatures, alkoxyl radicals eliminate hydrogen atoms from PH more rapidly than they undergo degradation. 

This reaction is very exothermic (A// —180 to —200kJ mol-1) and, therefore, seems to be very probable from the thermochemical point of estimation. The pre-exponential factor is expected to be low due to the concentration of the energy on three bonds at the moment of TS formation (see Chapter 3). To demonstrate that this reaction is responsible for the oxidative destruction of polymers, PP and PE were oxidized in chlorobenzene with an initiator and analyzed for the rates of oxidation, destruction (viscosimetrically), and double bond formation (by the reaction with ozone) [131]. It was found that (i) polymer degradation and formation of double bonds occur concurrently with oxidation (ii) the rates of all three processes are proportional to v 1/2, (iii) independent of p02, and (iv) vs = vdbf in PE and vs = 1.6vdbf in PP (vdbf is the rate of double bond formation). Thus, the rates of destruction and formation of double bonds, as well as the kinetic parameters of these reactions, are close, which corroborates with the proposed mechanism of polymer destruction. Therefore, the rate of peroxyl macromolecules degradation obeys the kinetic equation ... 

Table 22. Comparison of the various chemical processes vs electrochemical oxidative destruction for the destruction of organic compounds [288]...

During the last two decades an increasing interest in the application of Advanced Oxidation Processes (AOPs) is observed. These processes are applied for the oxidation of toxic organic pollutants present in wastewater or in surface water that is used for the production of drinking water. The process of oxidation is mainly based on the oxidative destruction by radicals of which the hydroxyl radical (OH ) is the most powerful one. Most important AOPs are ... 

Brabbs and Brokaw [22] were among the first who suggested the main oxidation destruction path of methyl radicals to be... 

Taylor, H. and O Leary, R. A study of uranium oxide based catalysts for the oxidative destruction of short chain alkanes, Appl. Catal, B Environmental, 2000, Volume 25, Issues 2-3, 137-149. 

CIS-[Ru(H20)2(dinso) ] is made from as-RuClj(dmso) and Ag(BF ) in aq. EtOH. The system c/s-[Ru(H20)j(dmso) ] Vaq. Na(ClO) or TBHP/CH Cl oxidised alkanes such as adamantane, cyclo-octane, -heptane and -hexane to the corresponding alcohols and ketones as did [Ru(Hj0) PWjj(0)3g ] . A free-radical mechanism may be involved for the TBHP oxidations, but those with (C10) probably involve oxoruthenate(VI) or oxoruthenate(IV) intermediates [823], The oxidative destruction of a-chlorinated alkenes by CM-[Ru(HjO)2(dmso) ] Vaq. Oxone /Me(CH3) jN(HSO ) MCj to carboxylic acids and ultimately to CO and HCl was reported [946],... 

Oxidative destruction of a-chlorinated alkenes by cA-[Ru(H30)3(dmso) ] Vaq. Oxone /Me(CH2)jjN(HSO )Me3 gave carboxylic acids and ultimately CO and HCl forperchoroethylene, trichloroethylene, cA-l,2-dichloroethylene, 1,1-dichloropropene,... 

For oxidative destruction of alkenes, e.g. oxidation of an alkene by RuO with concomitant cleavage of phenyl rings cf above, 3.2.2.1, Fig. 3.18 [206]. 

The importance of cell death mediated by oxidative damage has led to the popularity of antioxidants as potential therapeutics. A variety of naturally occurring (vitamin C, vitamin E) and synthetic (lazaroids) antioxidants have been smdied as possible remedies for a wide variety of ailments. Large doses of vitamin E have been studied as a putative therapy in Alzheimer s disease, functioning through the inhibition of amyloid-induced oxidative destruction of neuronal membranes within the brain. 

Fume-Off. The oxidative destruction of byproducts in nitration reactions Ref Coll, "Summary Report of Div 8 NDRC", Vol 1(1946), p 153... 

Various polymers may differ greatly in their susceptibility to oxidative destruction at elevated temperatures, however, the difference becomes smaller. For instance, the rates of destruction of PIB and PS at 373 differ by two orders of magnitude, and by only a factor of three to four at 423 [37]. 

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