Oxidants persulphate

H0S(0)200S(0)20H. Dibasic acid formed as salts by electrolysis of sulphates at low temperatures and high current density. The acid and persulphates are strong oxidizing agents ( "[S20a] to S04 -t-2 01 volts in acid) but the reactions are often slow. Compare permonosulphuric acid. 

Siher(Il) oxide, AgO, is a black solid, Ag Ag 02, obtained by anodic or persulphate oxidation of an AgNOs solution. Continued anodic oxidation gives impure Ag203. Argentates, e.g. K.AgO, containing silver(I) are known. 

The well-known reaction of Ni(II) with dimethylglyoxime (H Dm) in alkaline medium under the influence of such oxidants as persulphate and iodine is widely used for the photometric determination of nickel. The red product (RP) of this reaction is used for this purpose. However, the nature of this red compound has not been defined yet. Using of peroxyacids makes it possible to obtain additional data concerning the conditions and mechanism of generation of RP as well as to improve the metrological pai ameters of the method. 

In aqueous solutions the persulphate ion is known as a strong oxidizing agent, either alone or with activators. Thus, it has been extensively used as the initiator of vinyl polymerization [43-47]. However, only later, Kulkarni et al. [48] reported the graft copolymerization of AN onto cellulose using the Na2S203/K2S20s redox system. 

Discussion. Chromium (III) salts are oxidised to dichromate by boiling with excess of a persulphate solution in the presence of a little silver nitrate (catalyst). The excess of persulphate remaining after the oxidation is complete is destroyed by boiling the solution for a short time. The dichromate content of the resultant solution is determined by the addition of excess of a standard iron(II) solution and titration of the excess of the latter with standard 0.02 M potassium dichromate. 

An excess of a standard solution of iron(II) must therefore be added and the excess back-titrated with standard cerium(IV) sulphate solution. Erratic results are obtained, depending upon the exact experimental conditions, because of induced reactions leading to oxidation by air of iron(II) ion or to decomposition of the persulphate these induced reactions are inhibited by bromide ion in concentrations not exceeding 1M and, under these conditions, the determination may be carried out in the presence of organic matter. 

The longest established silver(III) complexes are the red to brown bi-guanides, like the ethylene bis(biguanide) shown in Figure 4.14 persulphate oxidation of Ag+ in the presence of this ligand gives a silver(III) complex with essentially square planar coordination. 

Peroxomonosulphate and peroxodisulphate have also been used to oxidize sulphoxides to sulphones in good yields at room temperature. Potassium persulphate (KHS05) readily oxidizes a range of sulphoxides to sulphones at 0°C in yields greater than 90%, in the presence of hydroxy, keto and alkene groups82-84. The mechanism is similar to that observed for other peroxy species, as discussed above. Peroxomonosulphate oxidation has been used as an analytical procedure for the estimation of dimethyl sulphoxide84. 

The oxidation of oxalic acid by mercuric chloride to give CO2 and mercurous chloride is a classic example of an induced reaction. This reaction is extremely slow unless small quantities of chromic acid and manganous ions are added, whereon facile reduction takes place Addition of permanganate or persulphate and some reducing agents is also effective and the oxidation proceeds readily under photo- or X-irradiation (Eder s reaction). The large quantum yield points to a chain mechanism , which could also function with an inducing oxidant, viz. 

Both Ag(ll) and Ag(III) have been considered to be the active species in the Ag(I)-catalysed oxidation of many compounds by persulphate ion. Salts of Ag(III) have been prepared but only a single kinetic study (of the decomposition of water by the ethylene dibiguanide nitrate) has been reported (p. 366). 

Oxidations by persulphate ion have been reviewed by House . Silver-ion catalysed reactions normally obey the rate expression... 

Since all the oxidations follow the same basic kinetics and involve an oxidising metal ion in trace quantities, the details are not reiterated here. The simple oxidation of Ag(I) by persulphate is discussed on p. 475. 

The field of reduction is much less well charted than that of oxidation but a substantial literature exists nonetheless and is growing rapidly. Reductions are conveniently classified into (/) those involving and initial electron acceptance by the substrate (possibly followed by rapid protonation) and ( ) those involving electron acceptance concerted with, or followed very rapidly by, homolysis of the substrate the latter includes the important Fenton and silver-persulphate reactions, as well as reductions of halogens, hydrazine and possibly NO3 and NOJ. 

The reduction by Ag" is the most widely investigated example although in recent years several other reductants have been used. The series of oxidations effected by the Ag -SjOg couple are referred to in the section on Ag(II) and Ag(III). In general the rate of disappearance of persulphate is independent of the concentration and, to some extent, the nature of the substrate, viz. 

The oxidations by persulphate of certain complexes of Ag(I) to stable forms of Ag(II) or Ag(III) have recently been examined . Bipyridyl (bipy) and ethylene-bisbiguanide (enbig) were selected as ligands. The stoichiometry of the oxidation... 

The oxidation of Ag(enbig) to Ag(enbig) is less straightforward, comprising two consecutive stages each of which is first-order in both metal ion and persulphate. The rate data for the steps are... 

The two steps are considered to be an oxidation of Ag(I) to Ag(II) followed by an oxidation of the latter to Ag(III). The stoichiometry is unexpected in that one Ag(I) species consumes two persulphate ions. The release of -804 would be expected to result in oxidation of further Ag(enbig) the existence of two stages rules out a two-equivalent oxidation directly to Ag(enbig). ... 

Cu(II) also catalyses the persulphate oxidation of numerous substrates, for example that of oxalate-ion with a rate law ... 

The reduction of persulphate by tris-[a-(2-pyridyl)-benzylideneaniline] iron(II) is, by contrast, independent of persulphate ion concentration , and the rates of reaction of several ring-substituted complexes of this type correspond exactly to the rates of acid-catalysed separation of one ligand. Clearly oxidation of the ligand... 

The reduction of persulphate by stannous ions is strongly affected by dissolved oxygen The anaerobic oxidation is first-order in both oxidant and reduc-tant with E 11.9 kcal.mole and AS = —19.4 eu . 

In the absence of oxygen the addition of arsenic(Iir) has only a slight effect on the rate of reduction of peroxydisulphate. In the presence of air the rate of reduction of persulphate increases nearly fortyfold (Table 12). The oxidation of arsenic(III) by SO4 from reaction (62) is not a chain process, thus it need not be considered in the iron(III)- and copper(II)-catalyzed reaction between peroxydisulphate and arsenic(III). 

An account of a serious warehouse explosion (15 dead, 141 injured). The two principal detonations were mostly due to ammonium nitrate, of which some hundred tonnes had been present, but the initiating fire was first observed in ammonium persulfate. This had been promiscuously stored alongside potassium permanganate, matches, potassium nitrate and sodium sulphide (or possibly sulphite), inter alia. None of these would improve the safety of ammonium persulfate. It was shown that the persulphate gives an immediate exothermic reaction with the sulphide. This was ascribed as the ultimate initiation. It was concluded that oxidants and... 

Starting natural graphite from Zavalie deposit in, Ukraine was chemically intercalated in sulfuric acid. Potassium persulphate was used as an oxidizer. Thermal expansion of graphite was performed at 900°C [3], Carbon content in the experimental samples was of about 99.0%. 

A3 AIBN c Cp DLS DLVO DSC EO GMA HS-DSC KPS LCST Osmotic third virial coefficient 2,2 -Azobis(isobutyronitrile) Polymer concentration Partial heat capacity Dynamic light scattering Derjaguin-Landau-Verwey-Overbeek Differential scanning calorimetry Ethylene oxide Glycidylmethacrylate High-sensitivity differential scanning calorimetry Potassium persulphate Lower critical solution temperature... 

VCL N-vinylcaprolactam, SDS sodium dodecyl sulphate, MACUE042 polyethylene oxide)42 undecyl a-methacrylate, KPS potassium persulphate, VA-086 2,2 -azobis [ 2-methyl-N-(2-hydroxye thyl) propionamide ]... 

Organogermanium compounds can be mineralized by wet oxidative digestion for 4 h at 70°C, in aqueous potassium persulphate, at pH 12. After dilution to an adequate concentration germanium can be determined by ICP-AES (inductively coupled plasma atomic emission spectrometry)9. 

As mentioned above, many variants of the Dohrmann total organic carbon analyser are available, ranging from low-cost non-automated analysers based on sample combustion in a platinum boat (DC8JA) or using persulphate oxidation/ultraviolet irradiation (DC 88) to top-of-range fully automated and computerized systems based on combustion in a ceramic tube (DC 90) or combined simultaneous persulphate-ultraviolet oxidation (DC 180). Only one of these systems, the DC 180, is discussed below in any detail. 

In the reactor combined UV persulphate oxidation ensures quantitative total organic carbon recovery. The resulting carbon dioxide with entrained water goes through a gas/liquid separator, a water trap and drier before it... 

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