Peroxydisulfate concentration

The effects of peroxydisulfate concentration, of pH, of time of irradiation and of added radical scavengers on the rate of decomposition of peroxydisulfuric acid, in the 60Co y-radiolysis of this compound are reported. In dilute H2SOj, solutions, the rate of S2Os2 decomposition is very small. G(-S20g2 ) decreases with pH and, at constant acidity, increases with [K2S208]. It is inferred that SOradicals compete with peroxydisulfate for reaction with H02. The reactions... 

The Effects of pH and of Time of Irradiation. In Figure 1 are given the results obtained in the radiolysis of a 10-4M K2S208 solution in water. It is seen that the initial rate of decomposition of peroxydisulfate is very high its value, inferred from the tangent to the curve at time zero, is about 6.0. The H202 yield is zero for the small doses but it increases as the peroxydisulfate concentration diminishes and, once the... 

Figure 3. Molecular yields of H202 and H2SO- and decomposition yield of S2 0 82 ions vs. peroxydisulfate concentration in aerated 0.4M H230h solutions...

Photolysis or thermolysis of persulfate ion (41) (also called peroxydisulfate) results in hoinolysis of the 0-0 bond and formation of two sulfate radical anions. The thermal reaction in aqueous media has been widely studied."51 232 The rate of decomposition is a complex function of pH, ionic strength, and concentration. Initiator efficiencies for persulfate in emulsion polymerization are low (0.1-0.3) and depend upon reaction conditions (Le. temperature, initiator concentration)."33... 

The first Ag(II) compound to be isolated in the solid state was tetra-kis(pyridine)silver(2 +) peroxydisulfate.13,14 Its stability can be attributed to its insolubility, the coordination of the Ag(II) ion, and the presence of an anion with an element in a high oxidation state. It can be prepared conveniently, rapidly, and in high yield by reaction of a solution containing silver nitrate and pyridine with a solution of potassium peroxydisulfate. The corresponding, but less stable, nitrate can be prepared by the electrolytic oxidation of silver nitrate in concentrated aqueous pyridine.15... 

A half-order dependence on hydrogen ion concentration has been observed in the Ag(I)-catalysed oxidation of some alkyl mandalates with peroxydisulfate. A free radical mechanism has been suggested.125... 

Concentrated HCI Manganese (II) sulfate + phosphoric acid Chlorine dioxide gas evolved, imparts yellow color to acid Violet coloration due to diphosphatomanganate formation peroxydisulfate nitrates, bromates, iodates, and periodates react similarly... 

A procedure was developed for the determination of total and labile Cu and Fe in river surface water. It involved simultaneous solvent extraction of the metals as diethyldithio-carbamates (ddc) and tfac complexes. The complexes were extracted by isobutyl methyl ketone (ibmk) and the solution subjected to flame atomic absorption spectrometry. Variables such as pH, metal complex concentration, reaction time, ibmk volume and extraction time were optimized. Prior to the solvent extraction a microwave-assisted peroxydisulfate oxidation was used to break down the metallorganic matter complexes in the river surface waters . Trifluoroacetylacetone was used as a chelation agent for the extraction and quantitative determination of total Cr in sea water. The chelation reaction was conducted in a single aqueous phase medium. Both headspace and liquid phase extractions were studied and various detection techniques, such as capillary GC-ECD, EI-MS (electron-impact MS) and ICP-MS, were tested and compared. The LOD was 11-15 ngL Cr for all the systems examined. The method provided accurate results with EI-MS and ICP-MS, while significant bias was experienced with ECD °. ... 

Quinazoline is quantitatively converted into 2- ert-butylquinazolin-4(3//)-one by treating it in aqueous solution with an excess of pivalic acid and ammonium peroxydisulfate at pH 0-1 in the presence of a catalytic amount of silver nitrate. At pH 5 where the concentration of a covalent hydrate is too small to influence the course of the reaction, it is converted into a mixture of 2-rcrr-butylquinazoline, 4-rc-Tr-butylquinazoline, and 2,4-di-to7-butylquinazoline in a ratio of 4 3 2. ° ... 

Kolthoff and Carr used the suppressing effect of bromide to permit the determination of peroxydisulfate even in the presence of organic matter. The optimum bromide concentration was of the order of IM ferroin served as the indicator for the back titration, which was carried out with Ce(IV) in 0.5 M H2SO4. 

NaOCl or in 7 M KOH with peroxydisulfate. The dissolution of this precipitate in sulfuric or nitric acid leads to a mixture of Am , Am, and Am . Am02(0H)2 has been suggested to precipitate in slightly basic concentrated NaCl solutions under inert atmosphere, but it also has not yet been characterized. ... 

Many of the classic partitioning processes rely on the formation of Am" to facilitate separation from trivalent lanthanides or heavier trivalent actinides. Americium(VI) can be prepared in basic aqueous solutions from Am using powerful oxidants, such as peroxydisulfate, and from Am using weaker oxidants, such as Ce. It can be precipitated from solution as a carbonate by electrolytic or ozone oxidation of concentrated carbonate solutions of Am or Am, or solubilized by dissolution of sodium americyl(VI) acetate. These oxidations and the resulting coordination compounds have been used for relatively large scale processing. For examples, Stephanou et found that Cm could be separated from Am by oxidizing the latter to Am with... 

Nitro-2-nitrosotoluene 193 4-Nitro-o-toluidine (NH2 = 1) (50 g, 0.33 mole) is treated with an ice-cold mixture of concentrated sulfuric acid (200 ml) and water (50 ml). The whole is stirred at room temperature. Meanwhile Caro s acid is prepared as follows potassium peroxydisulfate (300 g) is stirred into ice-cold sulfuric acid (d 1.84 175 ml), and the mixture is treated with ice (800 g) and water (300 ml) and vigorously stirred. This solution of Caro s acid is added, with stirring, to the suspension of nitrotoluidine, stirring is continued for a further 2 h at 40°, and then more powdered potassium peroxydisulfate (100 g) is added in one portion. The mixture is stirred at 40° for yet a further 2 h, then diluted with water (to 41). The precipitate is filtered off and washed with water, and the 5-nitro-2-nitrosotoluene is purified by distillation in steam, the yield being 30-39 g. 

The purification of the water has been previously described (10). With the exception of the arsenious oxide (from Carlo Erba, Italy), the chemicals used were Merck analytical products. The peroxymonosul-fate samples were obtained from hydrolysis of potassium peroxydisulfate solutions a 10"2M K2S208 solution in 1M sulfuric acid was heated at 60 °C. for 75 minutes and let cool overnight inside the thermostated bath (an ultrathermostat Colora was used). Under these conditions, the peroxydisulfate remaining in the solution, as well as the hydrogen peroxide formed in the simultaneous hydrolysis of the Caro s acid, are small when compared with the resulting peroxymonosulfate concentration. 

The difference in the rates of decomposition of the peroxydisulfate in water and in acid solutions results, therefore, from the existence a competition between S2082" and sulfate radicals for reaction with H02, this competition being evidenced by the rapid decay of G( —S2082") with the dose, in the aqueous solution, its decay with the pH and its increase as [K2S208] increases at constant sulfuric acid concentration. 

Prepare a solution of peroxymonosulfuric acid, H2SO5, by mixing a little ice-cold concentrated sulfuric acid with potassium peroxydisulfate, keeping the mixture ice-cold for a minute, and then diluting with water. Repeat, with this solution, the tests given above. 

When an enantiomer of CSA is used in the polymerization, such as R-CSA, it is possible to create chiral polyaniline nanofibers. Figure 7.20 shows the circular dichroism (CD) spectrum of a water dispersion of as-prepared R-CSA doped polyaniline nanofibers. The positive peak at 450 nm is characteristic of chiral polyaniline [66-70], and is consistent with water s effect on the direction of the CD signals previously observed [71]. The peak at 290 nm is due to excess R-CSA in the dispersion. Recently, Wang et al. discovered that highly chiral polyaniline nanofibers can be produced by incremental addition of the oxidant, ammonium peroxydisulfate, into aniline solution with aniline oligomers and concentrated chiral dopants (>5 M R- or S-CSA) [72]. Chiral polyaniline nanofibers are very interesting for chiral recognition studies [68]. 

In order to determine the TP concentration in water, the digestion process must involve both oxidative and hydrolytic processes in order to hydrolyze P-O-P linkages (e.g., polyphosphates) and oxidize phosphoesters and C-P compounds to inorganic phosphate. For example, in an online TP digestion system, which involves both thermal digestion and UV photooxidation, it is necessary to use a mixture of sulfuric acid and peroxydisulfate in order to obtain high recoveries of both organic and condensed phosphorus. 

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