Peroxodisulfate Ion Research Articles

Elucidation of the Mechanism of Reaction between S2O82–, Selenite and Mn2+ in Aqueous Solution and Limestone-Gypsum FGD Liquor

The mechanism of reaction between peroxodisulfate ion (S2O8(2-)), selenite (Se(IV)O3(2-)) and Mn(2+) as an inhibitor of selenite oxidation was studied using aqueous solutions composed of commercial reagents, as well as limestone-gypsum flue gas desulfurization (FGD) liquors sampled from coal fired power plants. The oxidation of selenite to selenate (Se(VI)O4(2-)) is promoted by the sulfate ion radical (SO4(-)) which results from decomposition of S2O8(2-). In the presence of Mn(2+), selenite oxidation was prevented due to the difference in rates of reaction with SO4(-). The ratio of the oxidation rate constants of selenite and Mn(2+) with SO4(-) was determined over a temperature range of 40-60 °C, and was found to be little influenced by the various coexisting components in FGD liquors.

Speciation and oxidation reaction analysis of selenium in aqueous solution using X-ray absorption spectroscopy for management of trace element in FGD liquor

Batch and in situ X-ray absorption spectroscopy (XAS) analysis were applied to the identification of selenium in aqueous solution containing selenite (Se(IV)O32-) and selenate (Se(VI)O42-) ranging from 10 to 1000mg-Se/L, respectively. Se K-edge XANES spectra were detected by means of a multi-channel silicon drift detector (SDD). Furthermore, the oxidation state of selenium was identified by measuring the energy of X-ray absorption, and the local structure around selenium atom was determined by analyzing the EXAFS. The Se K-edge XANES spectrum of selenite was gradually shifted to that of selenate in the presence of peroxodisulfate ion (S2O82-) which was the dominant oxidizing agent in wet flue gas desulfurization (FGD) liquor and had a subsequent effect on the selenium oxidation in the liquid phase. Concentrations of selenite and selenate calculated by linear fitting analysis of the XANES spectra were in good agreement with the results of quantitative analysis for selenite and selenate by ICP-AES.

ペルオキソ二硫酸アンモニウム溶液を用いた銅のエッチングレートに結晶構造が及ぼす影響

e in uence of crystallographic structure on the etching rate of copper was studied in 1 mol/dm ammonium peroxodisulfate solution using a scanning probe microscope (SPM), electron back scatter di raction patterns (EBSD), and corrosion potential measurements. e (001), (101), and (111) faces etched at slower rates than the (327) and (425) faces, which have higher Miller indices. e etching rate of the (001) or (101) oriented polycrystalline copper was approximately half that for the oriented polycrystalline copper with higher indices. e polycrystalline copper etched at highly rate showed a relatively noble corrosion potential. It was suggested that the etching rate of polycrystalline copper was controlled by the mean value of the reduction kinetics of the peroxodisulfate ion on each of the grain surfaces.

The Coordination Behaviour of the Peroxodisulfate Anion with Group XII Metal Ions: [Zn(H2O)(C12H8N2)2(S2O8)]·H2O and Related Compounds

The title compound is monomeric with a Zn(II) hexacoordinated center. The coordination sphere is formed by four nitrogens from two phenanthroline molecules, one oxygen from a monodentate peroxodisulfate ion, and one oxygen from a water molecule. A non-coordinated water molecule completes the formula with an important role in the stabilization of the structure through the formation of two OHW–H···Opds bridges (acting as a donor) and one OCW–H···OHW bridge where it is an acceptor group (HW: hydration water; pds: peroxodisulfato; CW: coordinated water). The compound is triclinic, space group P-1 with a = 8.763 (3) A, b = 9.068 (3) A, c = 17.531 (6) A, α = 96.48 (2)°, β = 103.94 (3)°, γ = 104.57 (3)°, V = 1286.0 (7) A3 and Z = 2. The structure was solved by direct methods with a conventional R (on F) = 0.050 for 4534 reflections with Fo > 4σ(Fo). The compound is isomorphous with the Cd analogue (in Harvey et al. Aust J Chem 54:307, 2001). An eventual dependence of conformation and coordination mode of the peroxodisulfate anion on the ancillary organic ligand taking part in the coordination compounds analyzed is discussed. The crystal structure of [Zn(H2O)(C12H8N2)2(S2O8)]·H2O is reported. In addition, similarities in conformation and coordination mode of the peroxodisulfato anion in hybrid (organic–inorganic) complexes of group XII metal ions containing similar organic ligands are discussed.

Effect of oxidizing agents on selenate formation in a wet FGD

In a coal combustion process, a considerable amount of selenium is captured in the wet FGD, where it is oxidized from selenite ( Se ( IV ) O 3 2 - ) to selenate ( Se ( VI ) O 4 2 - ) , which is difficult to remove. Diethyl-p-phenylene-diammonium (DPD) absorptiometric analysis and ion chromatography identified peroxodisulfate ion ( S 2 O 8 2 - ) as the dominant oxidizing agent in the FGD liquor. Selenite was easily oxidized to selenate in the presence of S 2 O 8 2 - and the oxidation was accelerated as the temperature increased. Addition of Mn 2+ ion was found to be effective in controlling selenate formation. When Mn 2+ ion was added, S 2 O 8 2 - oxidized not selenite to selenate but rather Mn 2+ to MnO 2, which captured some dissolved selenite.

Reaction of hydrogen peroxide with coordinated superoxide in [(NH3)5CoIII(μ-O2)CoIII(NH3)5]5+: a mechanistic study

In aqueous acetate buffer media, hydrogen peroxide reduces the bridging superoxide in [(NH3)5CoIII(micro-O2)CoIII(NH3)5]5+ (1) to the corresponding peroxide in the complex, [(NH3)5CoIII(micro-O2H)CoIII(NH2)(NH3)4]4+ (2), itself being oxidized to HO2*. The complex 2 thus produced decomposes rapidly to the final products, CoII, NH3, etc. instead of reacting with a second molecule of hydrogen peroxide. In the presence of excess [H2O2] over (1), the reaction obeyed first-order kinetics and exhibited inverse proton dependence. [(NH3)5CoIII(micro-O2)CoIII((NH2)(NH3)4]4+ (3), a conjugate base of 1, seems to be the kinetically reactive species and the cause for the observed inverse proton dependence. Kinetics is little affected when one of the hydrogen atoms from hydrogen peroxide is replaced with an alkyl group, as in tert-butyl hydroperoxide. But replacement of both the H atoms with alkyl groups halts the reaction as seen with di-tert-butyl peroxides, and peroxodisulfate ion. The reaction rate with hydrogen peroxide significantly decreases with increasing proportion of D2O replacing water in the solvent and the rate-limiting step seems to be an H-atom transfer.

A time-resolved photoacoustic calorimetry study for the determination of the partial volume and formation enthalpy of the [formula omitted] aqueous radical

Photoacoustic calorimetry was applied to the photolysis at 266 nm of aqueous peroxodisulfate ion in the presence of bisulfite. A time-resolved analysis of the signals at variable temperature (282–295 K) yields the heat of formation (−530 kJ mol −1) and the partial molal volume (50 mL mol −1) of aqueous sulfite radical. The ca. 11 mL mol −1 difference between the experimental molal volumes of SO 3 - and the parent closed shell ion with similar intrinsic size SO 3H −, indicates a diverse rearrangement of the solvent molecules around each species, probably as a result of the dissimilar electronic distribution.

Electrochemical combustion of herbicide mecoprop in aqueous medium using a flow reactor with a boron-doped diamond anode

The anodic oxidation of 1.8 l of solutions with mecoprop (2-(4-chloro-2-methylphenoxy)-propionic acid or MCPP) up to 0.64 g l −1 in Na 2SO 4 as background electrolyte within the pH range 2.0–12.0 has been studied using a flow plant containing a one-compartment filter-press electrolytic reactor with a boron-doped diamond (BDD) anode and a stainless steel cathode, both of 20-cm 2 area. Electrolyses carried out in batch under steady conditions and operating at constant current density between 50 and 150 mA cm −2 always yield complete mineralization due to the great concentration of hydroxyl radical generated at the BDD anode. The degradation rate is practically independent of pH and Na 2SO 4 concentration, but it becomes faster with increasing MCPP concentration, current density, temperature and liquid flow rate. The effect of these parameters on current efficiency and energy cost has also been investigated. Generated weak oxidants such as H 2O 2 and peroxodisulfate ion have little influence on the mineralization process. The kinetics for the herbicide decay follows a pseudo first-order reaction with a higher rate constant when current density increases. Aromatic products such as 4-chloro- o-cresol, 2-methylhydroquinone and 2-methyl- p-benzoquinone, and generated carboxylic acids such as maleic, fumaric, lactic, pyruvic, tartronic, acetic and oxalic, have been identified as intermediates by chromatographic techniques. The initial chlorine is completely released in the form of chloride ion, which is slowly oxidized to Cl 2 at the BDD anode. A reaction pathway for MCPP mineralization involving all products detected is proposed.

Flow injection spectrophotometric determination of fosfestrol, following on-line thermal induced digestion and using an orthophosphate calibration graph

A novel flow injection (FI) system for the spectrophotometric determination of diethyl stilbestrol diphosphate (fosfestrol) in pharmaceutical formulations is described. On-line thermal induced digestion of the analyte by peroxodisulfate ion was performed and the orthophosphate ion generated was determined spectrophotometrically ( λ max=690 nm) using a molybdenum blue based FI approach. As the achieved conversion of the analyte was quantitative, an orthophosphate calibration graph can be used for its determination as well. The chemical and FI variables affecting the digestion were investigated. A linear calibration graph was obtained in the range 5.0×10 −7–1.0×10 −4 mol l −1 fosfestrol. The relative standard deviation was very good ( s r=0.8% at 5.0×10 −5 mol l −1 fosfestrol, n=12) and the 3 σ detection limit was 2.5×10 −7 mol l −1. The sampling rate was 60 injections h −1. The average accuracies for the determination of the analyte in a pharmaceutical formulation evaluated by comparison of the results with those obtained by the supplier (Asta Medica) and the method recommended by the US Pharmacopoeia were also very good ( e r of +0.8 and −0.3%, respectively). Average recoveries of known amounts of the analyte ranging between 97.9 and 100.8% were also obtained.

Electron Transfer Reactions Between Peroxodisulfate-and Iron(II) and Nickel(II)-oxime-imine Complexes--a Kinetic Study

The kinetics of the oxidation of complexes, [Fe(H 2 L) 2+ and [Ni(HL')] 2+ (H 2 L u = u 3,14-dimethyl-4,7,10,13-tetraazadeca-3,13-diene-2,5-dione-dioxime, (I)) and HL'=15-amino-3-methyl-4,7,10,13-tetraazapentadec-3-ene-2-one-oxime, (II)) by peroxodisulfate ion was studied spectrophotometrically under pseudo-first-order conditions keeping the complexes as minor components, within the pH range 3.0-7.93 at I =0.20 u mol u dm m 3 (NaClO 4 ) for the former and I =0.25 u mol u dm m 3 for the latter complex at 303 u K. At a particular pH, plots of k obs vs. [S 2 O 8 2 m ] yield ascending curves with decreasing slope values for both the reactions, and the general rate law: d/d t [complex]=2 kQ [S 2 O 8 2 m ]/(1+ Q [S 2 O 8 2 m ]) is followed. A pre-equilibrium ion-pair formation between the reactants prior to electron transfer is proposed. A plot of m [log( k 12 / W 12 ) m 1/2 u log u k 22 ] vs. 1/2 u log( K 12 f 12 ) for such reactions yields a straight line with slope m (0.73 - 0.10) which deviates significantl...

Initial state versus transition state solvation effects on the kinetics of oxidation of nickel(II) dioxocyclam by peroxodisulfate

The kinetics of oxidation of 1,4,8,11-tetraazacyclotetradecane-5,7-diamidonickel(II) (‘nickel dioxocyclam’) by peroxodisulfate have been measured in a range of binary aqueous solvent mixtures. Reaction rates are retarded by the presence of organic co-solvents, indicative of destabilization of the transition state (TS) relative to the initial state (IS) in the binary aqueous mixtures. Thus the TS is more hydrophilic than the IS. From solubility measurements of the nickel(II) macrocycle, the transfer chemical potential of the IS of the reaction has been estimated and compared with that of the TS. The transfer potential of the IS is dominated by the solvation of the peroxodisulfate ion.

Analysis of Hydroxyl Radical Generated in Electrolyzed Strong Acid Aqueous Solution by Electron Spin Resonance Spectroscopy.

電解助剤を添加した水の電気分解によつて得られる強酸性電解生成水溶液中の活性酸素種であるヒドロキシルラジカルの解析を,ESRを用いて行つた.2種のスピソトラップ剤[5,5-ジメチル-1-ビロリン1-オキシド(DMPO)およびN-[(1-オキシド-4-ピリジニオ)メチレン]-t-ブチルアミンN-オキシド]のヒドロキシルラジカル付加体をそれぞれ観測することができ,強酸性電解生成水溶液からヒドロキシルラジカルが生成することを確認した.電解後冷暗所に10日程度保存しても生成するヒドロキシルラジカル量は変化せず,安定していた.また,塩化ナトリウムに代わって硫酸ナトリウムを電解助剤として使用した場合にもヒドロキシルラジカルが生成し,スピン付加物DMPO-OHの量が測定時間とともに増加することがわかった.強酸性電解生成水溶液中にはヒドロキシルラジカルが存在するのではなく,その前駆体が存在しており,それはペルオキソニ硫酸イオンであると推定される,電解助剤に塩化ナトリウムを用いた通常の強酸性電解生成水溶液においても,電流密度および使用水中の硫酸イオン濃度を調整することにより,生成するヒドロキシルラジカル量を捌御できることが示唆された.

ChemInform Abstract: Oxidation of Nucleic Acid Related Compounds by the Peroxodisulfate Ion.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Oxidation of Nucleic Acid Related Compounds by the Peroxodisulfate Ion

Abstract The treatment of nucleic acid bases, nucleosides, and nucleotides with peroxodisulfate ion in a phosphate buffer solution at pH 7.0 or water at 70—75 °C was investigated. The reaction of thymine and 5-methylcytosine nucleosides and nucleotides resulted in the oxidation of the 5-methyl groups. The oxidation products from 1,3-dimethyluracils and the time-course of the reaction of uracils led to two plausible reaction mechanisms for the oxidation of uracils.

ChemInform Abstract: Stoichiometry, Kinetics and Mechanism of the Silver(I) Catalyzed Oxidation of Hyponitrous Acid with Peroxodisulfate Ion in Acid Perchlorate Solutions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Kinetic Studies of Electron-Transfer Reactions Induced by the Reductive Quenching of Tris(2,2′-bipyrazine)ruthenium(II)

Abstract The oxidation reaction of the oxalate ion (C2O42−) by the peroxodisulfate ion (S2O82−) is greatly accelerated by irradiation with visible light in an aqueous solution containing tris(2,2′-bipyrazine)ruthenium(II) ([Ru(bpz)3]2+). The mechanism constitutes a chain reaction initiated by a reductive quenching of photoexcited [Ru(bpz)3]2+ with C2O42−. The rate of reaction increases with an increase of the [Ru(bpz)3]2+ concentration or incident light intensity. On the other hand, the reaction rate hardly depends not only on the concentrations of C2O42− and S2O82−, but also on the ionic strength and temperature. The [Ru(bpz)3]2+ acts as a photo-catalyst, although the absorption spectra of the reaction solution are slightly changed during the photoreaction. An analysis of the absorption spectra by a graphic method indicates that another absorbing species than [Ru(bpz)3]2+ is formed in the reaction solution. Such a complex has no photocatalytic effect for the redox reaction between S2O82− and C2O42−. The concentration of the produced complex is always coincident with ca. 0.7% of that of the S2O82− reacted. The reaction mechanism and rate law are clarified to account for the results obtained.

Kinetics of the oxidation reaction of arsenious acid by peroxodisulfate ion, induced by irradiation with visible light of aqueous solutions containing tris(2,2′-bipyridine)ruthenium(II) ion

The oxidation reaction of arsenious acid (H 3AsO 3) by the peroxodisulfate ion (S 2O 8 2−) is greatly accelerated by irradiation with visible light of aqueous acid solutions containing the tris(2,2′-bipyridine)ruthenium(II) ion (Ru(bpy) 3] 2+). The [Ru(bpy) 3] 2+ ion acts as a photocatalyst during the reaction. The mechanism of the reaction consists of a chain reaction being initiated by the quenching reaction of the photoexcited ruthenium(II) complex ion ([Ru(bpy) 3] 2+*) with S 2O 8 2− ion, followed by the oxidation reaction of arsenious acid by the SO 4 − radical and Rub(bpy 3) 3+. The rate law is expressed by −d[S 2O 8 2−]/d t= k q I aø[S 2O 8 2−]/( k o+ k q[S 2O 8 2−]) and the bimolecular quenching rate constants k q are determined by kinetic experiments under various conditions. The rate constants of the reaction between [Ru(bpy) 3] 3+ and arsenious acid are evaluated at 25 °C and ionic strength of 0.05 mol dm −3 with stopped-flow method to be 6.3, 1.2 × 10 3, 2.2 × 10 3 and 1.1 × 10 4 dm 3 mol −1 s −1 at pH 2.6, 4.0, 6.5 and 8.1, respectively.

ChemInform Abstract: Ring‐Closure Reactions Initiated by the Peroxodisulfate Ion Oxidation of Diphenyl Diselenide.

AbstractThe oxidation of diphenyl diselenide (I) with peroxodisulfate represents an efficient method to produce phenylselenium cations in the absence of nucleophilic counterions.

ChemInform Abstract: Light‐Induced Electron‐Transfer Reactions. Part 5. Kinetics of the Oxidation of Ethylenediaminetetraacetatocobaltate(II) Complexes by Peroxodisulfate Ion, Induced by Irradiation with Visible Light of Aqueous Solutions Containing Tris(2,2′‐bipyridine)ruthenium(II) Ion.

AbstractIt is demonstrated that the tris(2,2'‐bipyridine)ruthenium(II) cation ((Ru(bpy)3)2+) acts as a photosensitizer and ‐catalyst for reaction A, and the mechanism consists of a chain reaction which is initiated by the quenching reaction of the photoexcited Ru(II) complex ((Ru(bpy)3)2+*) by S2O82‐.

Light-induced Electron-transfer Reactions. 5. Kinetics of the Oxidation of Ethylenediaminetetraacetatocobaltate(II) Complexes by Peroxodisulfate Ion, Induced by Irradiation with Visible Light of Aqueous Solutions Containing Tris(2,2′-bipyridine)ruthenium(II) Ion

Abstract The oxidation reaction of ethylenediaminetetraacetatocobaltate(II) ([Co(edta)]2−) by peroxodisulfate ion (S2O82−) is greatly accelerated by irradiation with visible light of aqueous solutions containing tris(2,2′-bipyridine)ruthenium(II) ion ([Ru(bpy)3]2+). The overall reaction is 2[Co(edta)]2−+S2O82− →2[Co(edta)]−+2SO42−. The [Ru(bpy)3]2+ ion acts as a photosensitizer and -catalyst for this reaction, and the mechanism consists of a chain reaction being initiated by the quenching reaction of the photoexcited ruthenium(II) complex ion ([Ru(bpy)3]2+*) by S2O82− ion. The mechanism of the reaction is presented to account for the results obtained.