Oxidizable Compounds

Oxidizers do not discriminate among compounds and are capable of reacting with any oxidizable compounds in a waste stream. Oxidation is used either to degrade a compound completely or quite often, to degrade a compound partially to a less toxic form or intermediate that can be discharged or if needed, treated further by another process. 

Nevertheless, an anaerobic system may be the method of choice under certain conditions (/) contamination with compounds that degrade only or better under anaerobic conditions, (2) low yield aquifers that make pump and treat methods or oxygen and nutrient distribution impractical, (J) mixed waste contamination where oxidizable compounds drive reductive dehalogenation of chlorinated compounds, or (4) deep aquifers that make oxygen and nutrient distribution mote difficult and cosdy. 

Even very small amounts of transition-metal ions like cobalt, nickel, and copper cause rapid decomposition. They form reactive intermediates that can decrease the stabiUty of oxidizable compounds in the bleach solution and increase the damage to substrates. Hypochlorite is also decomposed by uv light (24,25). Acidic solutions also lose available chlorine by the reverse of equations 1 and 2. 

The limited anodic potential range of mercury electrodes has precluded their utility for monitoring oxidizable compounds. Accordingly, solid electrodes with extended anodic potential windows have attracted considerable analytical interest. Of the many different solid materials that can be used as working electrodes, the most often used are carbon, platinum, and gold. Silver, nickel, and copper can also be used for specific applications. A monograph by Adams (17) is highly recommended for a detailed description of solid-electrode electrochemistry. 

Acetylchloride is a trapping agent that allows the reaction to go completion, transforming the product into a less oxidizable compound.The results of other reactions between indole (57) and substituted cyclohexa-1,3-dienes show that the photo-induced Diels-Alder reaction is almost completely regioselective. In the absence of 59 the cycloaddition did not occur the presence of [2+2] adducts was never detected. Experimental data support the mechanism illustrated in Scheme 4.14. The intermediate 57a, originated from bond formation between the indole cation radical and 58, undergoes a back-electron transfer to form the adduct 60 trapped by acetyl chloride. 

In the absence of any oxidizable compound, the net reaction is the Fe-catalyzed decomposition of H2O2 (Reaction 6.8). This reaction also occurs when a target... 

Another intermediate of the photolysis of TiO was observed in experiments with platinized particles (in the absence of polyvinyl alcohol). The spectrum shown in Fig. 22 is prraent immediately after the laser flash. The signal decays as shown by the inset in the figure. The rate of decay is not influenced by oxygen but is increased by oxidizable compounds such as Br ions in the solution. The broad absorption band in Fig. 22 with a maximum at 430 nm was attributed to trapped positive holes. Chemically, a trapped hole is an 0 radical anion. In homogeneous aqueous solution, 0 ... 

In contrast to a variety of oxidizable compounds, only a few examples for the detection of strong oxidants with transition metal hexacyanoferrates were shown. Among them, hydrogen peroxide is discussed in the following section. Except for H202, the reduction of carbon dioxide [91] and persulfate [92] by Prussian blue-modified electrode was shown. The detection of the latter is important in cosmetics. It should be noted that the reduction of Prussian blue to Prussian white occurs at the lowest redox potential as can be found in transition metal hexacyanoferrates. 

In many industrial areas, antioxidants play a significant role in the context of stability improvement of easily oxidizable compounds. There is a considerable interest in antioxidants as bioactive components of food and as nutritional agents with a role in the maintenance of health and in disease prevention. 

One of the oldest methods of superoxide detection is the oxidation of epinephrine [72]. This method has the typical disadvantages of oxidizable compounds due to the possibility of the nonsuperoxide-mediated oxidation of epinephrine. Still, SOD-inhibitable epinephrine oxidation might be used as a superoxide assay [72]. 

In addition to the many enzyme systems available, there are with each a series of chromogenic substrate solutions that can be used to create different colors and locations of reaction products. For the peroxidase system, there are numerous oxidizable compounds that precipitate as a permanent color. The most common and still widely used is 3,3 diaminobenzidine tetrahydro-chloride (DAB). This compound precipitates to a golden brown color when in solution with peroxidase and hydrogen peroxide. This brown color has many subtleties and readily stands out in a tissue section. With practice, it is possible to differentiate specific from nonspecific staining patterns just by examining the characteristics of the precipitated pigment. This material is also insoluble in alcohol and xylene, and therefore the tissue may be routinely dehydrated and cleared without loss of chromogen. 

Calcium nitrate is a strong oxidizing agent. Mixing with organic substances such as fuel oil or hydrocarbons or other oxidizable compounds can cause explosion. 

Liquid chromatography with electrochemical detection (LCEC) is in widespread use for the trace determination of easily oxidizable and reducible organic compounds. Detection limits at the 0.1-pmol level have been achieved for a number of oxidizable compounds. Due to problems with dissolved oxygen and electrode stability, the practical limit of detection for easily reducible substances is currently about 10-fold less favorable. As with all detectors, such statements of the minimum detectable quantity must be considered only with the proverbial grain of salt. Detector performance varies widely with the analyte and the chromatographic conditions. For example, the use of 100- m-diameter flow systems can bring attomole detection limits within reach, but today this is not a practical reality. 

The oxidation detector for the fluorimetric analysis of carbohydrates in effluents from liquid chromatography columns provides a sensitive method of analysis in blood and urine [110]. The principle involves the reduction of cerium(IV) to cerium(III) by oxidizable compounds such as organic acids and many carbohydrates. The fluorescence... 

Aromatic amines, molecules containing one or more aromatic rings bearing a primary or substituted amine function, constitute a second important class of electrochemically oxidizable compounds. Several specific reports dealing with the determination of aromatic amines by LCEC have recently appeared. 

The oxidizable compounds A, B, and C display the following hydrodynamic voltammograms ... 

A considerable amount of work has been published dealing with the electro-oxidation of organics at Ni anodes in aqueous base [548-552], These reactions have generally been dehydrogenations, e.g. primary alcohols to aldehydes, secondary alcohols to ketones and primary amines to nitriles. The reactions occur on a relatively thick layer of oxide on the Ni anodes. Pletcher and co-workers [529, 548, 549] observed that most of the oxidizable compounds were found to oxidize at the same potential and this potential coincided with that at which the surface of the Ni became oxidized. A typical cyclic voltammogram recorded at Ni in dilute KOH in the presence and absence of n-propylamine is shown in Fig. 23. It can be seen that addition of n-propylamine results in an oxidation wave being observed which is... 

Strong oxidizing agents React violently with easily oxidizable compounds such as some organic solvents... 

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