Oxidation of organic materials

Silver sulfate has been described as a catalyst for the reduction of aromatic hydrocarbons to cyclohexane derivatives (69). It is also a catalyst for oxidation reactions, and as such has long been recommended for the oxidation of organic materials during the deterrnination of the COD of wastewater samples (70,71) (see WASTES, INDUSTRIAL WATER, INDUSTRIAL WATERTTEATI NT). 

These equations are based on the thermodynamically stable species. Further research is needed to clarify the actual intermediate formed during overcharge. In reahty, the oxygen cycle can not be fully balanced because of other side reactions, that include gtid corrosion, formation of residual lead oxides in the positive electrode, and oxidation of organic materials in the cell. As a result, some gases, primarily hydrogen and carbon dioxide (53), are vented. 

Ca.ta.lystInhibition. A number of potential appHcations for catalytic oxidation of organic materials have resulted in serious odor or eye... 

In normal battery operation several electrochemical reactions occur on the nickel hydroxide electrode. These are the redox reactions of the active material, oxygen evolution, and in the case of nickel-hydrogen and nickel-metal hydride batteries, hydrogen oxidation. In addition there are parasitic reactions such as the corrosion of nickel current collector materials and the oxidation of organic materials from separators. The initial reaction in the corrosion process is the conversion of Ni to Ni(OH)2. 

When the temperature of a carbonate reservoir that is saturated with high-viscosity oil and water increases to 200° C or more, chemical reactions occur in the formation, resulting in the formation of considerable amounts of CO2. The generation of CO2 during thermal stimulation of a carbonate reservoir results from the dealkylation of aromatic hydrocarbons in the presence of water vapor, catalytic conversion of hydrocarbons by water vapor, and oxidation of organic materials. Clay material and metals of variable valence (e.g., nickel, cobalt, iron) in the carbonate rock can serve as the catalyst. An optimal amount of CO2 exists for which maximal oil recovery is achieved [1538]. The performance of a steamflooding process can be improved by the addition of CO2 or methane [1216]. 

Because of the invalidity of the classical procedure, several workers have attempted to devise a method that is free from interference by chloride. Chloride interference can be eliminated by preventing the concurrent oxidation of organic material and chloride. This can be effected in two ways - either by leaving the chloride in the test mixture but preventing its oxidation, or by removing the chloride prior to the chemical oxygen demand test. 

An interesting version of electrochemical oxidation is available in the photocatalytic oxidation of organic materials on semiconductor surfaces, for example on Ti02 or CdS (for a review, see Fox, 1991). When light of a suitable wavelength is allowed to impinge on such a surface, electrons in the valence band are excited to the conduction band, and a potential difference, equal to the band gap, is set up between the two levels. The holes in the valence band will thus be capable of extracting electrons from an external substrate. 

Matthews, R.W. Photo-oxidation of organic material in aqueous suspensions of titanium dioxide. Water Res., 20(5) 569-578, 1986. 

For the oxidation of organic materials with air or pure oxygen a variety of techniques has been established which produce very good results. Dry ashing, however, although... 

Another application of carbon isotopes in foraminifera is to distinguish distinct water masses and to trace deep water circulation (Bender and Keigwin 1979 Duplessy et al. 1988). Since dissolved carbonate in the deeper waters becomes iso-topically lighter with time and depths in the area of their formation due to the increasing oxidation of organic material, comparison of sites of similar paleodepth in different areas can be used to trace the circulation of deep waters as they move from their sources. Such a reconstruction can be carried out by analyzing 8 C-values of well-dated foraminifera. 

SCWO promises rapid, efficient oxidation of organic materials in aqueous media without generation of products of incomplete combustion (PICs), particulate material, or oxides of nitrogen and sulfur. 

The principle of supercritical wet oxidation can be applied to several areas, including municipal waste treatment, chemical waste treatment, polymeric waste treatment, and the treatment of mildly radioactive waste. Since the basic principle of wet oxidation involves the rapid oxidation of organic material, any substance which is mildly oxidative can be subjected to this process. With such high temperature operation, the remaining fraction of inorganic material can be simply precipitated as a salt and then easily collected from the bottom of the oxidation vessel. 

Respiration is a broad term for the oxidation of organic materials to carbon dioxide. When the electron acceptor is not oxygen they are called anaerobic respirations. Table S.I4 illustrates possible types of respiration. Nitrate, sulphate and carbon dioxide are significant electron acceptors in anaerobic respiration and many are of environmental significance. 

Titanium dioxide is widely used in the production of plastics, enamels, artificial fibers, electronic materials, and rubber (Hadjiivanov and Klissur-ski, 1996). Its ability to photocatalyze the oxidation of organic materials has been known for years in the paint industry. For this reason, TiOz is used as a white paint pigment (Stafford et al., 1996). TiOz is also known as an excellent catalyst for semiconductor photocatalysis due to its nonselectivity for environmental engineering applications it is nontoxic, insoluble,... 

The slow oxidation of organic materials that are exposed to oxygen in the atmosphere is termed autoxidation. A simple example of this reaction is provided by the following equation ... 

The body heat of all animals is furnished by oxidation. This heat requires that animals have cooling systems. Slow oxidation of organic materials, many that could otherwise cause disease, occurs in nature. Waters and streams are automatically... 

Goulden, P. and D. Anthony (1978). Kinetics of uncatalyzed peroxydisulfate oxidation of organic materials in fresh water. Anal. Chem. 50, 953-958. 

OXIDATION OF ORGANIC MATERIAL IN SUPERCRITICAL WATER AND CARBON DIOXIDE... 

The energy required to keep the human body warm and to cany on the c hemical and physical processes involved in life is obtained from the oxidation of organic material derived from or contained in the... 

Manufacture of basic chromium sulfates from solutions obtained in the dichrorinate oxidation of organic materials such as montan waxes or anthracene... 

Because UV radiation disinfection provides no disinfecting residual, a secondary disinfectant is needed. Very little oxidation of organic materials occurs with typical UV radiation systems used for drinking water disinfection consequently, if oxidation is required (for iron, manganese, sulfide, nitrate, etc.), a strong oxidizing agent may be... 

UV hulhs that produce radiation at 184.9 nm generate some quantities of ozone, which, in turn, can provide some oxidation of organic materials. The comhination of UV radiation and ozone produces the hydroxyl free radical, which is a more powerful oxidizing agent than is ozone itself. The 184.9 nm wavelength radiation is not as effective for UV disinfection as the 254 nm wavelength, except by the amount of ozone generated, which will provide some CT value. 

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