Polarographic determination of sulfur compounds in pulping liquors

Renard, Jean J.; Kubes, G. J.; Bolker, H. I.

doi:10.1021/ac60358a018

Cited by 39 publications

(25 citation statements)

References 16 publications

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“…In this work thiosulfate was studied in the concentration range from 1 x M. In seawater conditions (pH 8.3), a welldefined peak of thiosulfate was observed at the potentials between -0.12 and -0.15 V (vs. Ag/AgCl), which is the same potential range as observed with the acetate buffered solutions [l, 261. In more alkaline solutions (pH 10-1 l), as reported previously [26], no peak for thiosulfate was observed due to the large quantity of hydroxyl ions present, acting as depolarizers and thus producing a large oxidation peak, centered around zero volts 191. A typical voltammogram of thiosulfate in 0.5 M NaC1/3 x 1 O-' M NaHC03, pH 8.3, is shown in Figure lb.…”

Section: Ciglenetki B Cosovicsupporting

confidence: 76%

Electrochemical determination of thiosulfate in seawater in the presence of elemental sulfur and sulfide

Ciglenečki

Ćosović

1997

Electroanalysis

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Linear sweep voltammetry (LSV) has been used for the direct determination of thiosulfate in the mixture with other sulfur species (sulfide. elemental sulfur) in 0.5 M NaCV3 x 10-'M NaHC03, pH 8.3 as supporting electrolyte and in natural seawater samples. The determination is based on anodic depolarization reaction between sulfur and the mercury electrode. Investigations were carried out over wide concentration ranges, from to 10-4M of thiosulfate in the solution. In seawater conditions (pH 8.3) thiosulfate displays a voltammetric peak at about -0.15 V, and sulfide andor elemental sulfur between -0.6 and -0.7 V (vs. Ag/AgCl). Based on the appearance of the voltammetric peaks of thiosulfate and sulfide at different potentials, and using different experimental conditions, i.e., accumulation at different starting potentials [ E = 0 or E = -0.2 V (vs. Ag/AgCI)J, a method for the direct determination of thiosulfate and sulfide in the mixture has been proposed. The direct method of thiosulfate determination in seawater can be used if the concentrations of sulfide are lower than 5 x lo-' M. Higher concentrations of sulfide have to be decreased by acidifying and degassing the sample to prevent interferences. The method was applied for the analysis of sulfur species in marine samples from anoxic environment.

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Section: Ciglenetki B Cosovicsupporting

confidence: 76%

Electrochemical determination of thiosulfate in seawater in the presence of elemental sulfur and sulfide

Ciglenečki

Ćosović

1997

Electroanalysis

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“…5). In general, their concentration can be considered relatively constant over the whole temperature range examined, implying that catechols are involved in the oxidation process as intermediates.Their participation in an oxygen delignification has been suggested by Gellerstedt and Lindfors (30) and Renard et al (31,32). It is likely that while there is a supply of guaiacyl units in the system, these intermediates would form and then be oxidized in a continuous fashion.…”

Section: Oxidative Demethoxylation Reactionsmentioning

confidence: 80%

“…Lignin oxidation reactions may induce the formation of carboxylic acids via a number of pathways either as monomeric fragments or functional groups attached at the end of side chains of the lignin macromolecules (12,31,32). The most significant pathway involves side-chain elimination and ring-opening reactions in phenolic centres.…”

Section: Formation Of Carboxylic Acids Within Residual Kraft Ligninmentioning

confidence: 99%

Article

Asgari¹,

Argyropoulos²

1998

Can. J. Chem.

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The complex interaction of softwood residual kraft lignin with oxygen at elevated temperatures, pressures, and pH's was investigated by isolating and systematically oxidizing the lignin, as a function of time and temperature. The isolation of the oxidized lignin was carried out using a multistep procedure developed specifically to recover all species. Detailed quantitative 31 P NMR measurements provided, for the first time, three-dimensional plots describing the formation and (or) elimination of the various functional groups. Oxidative demethoxylation reactions were found to induce the formation of catechols, which are, most likely, reactive intermediates of the oxidation. The rate of carboxylic acid formation and guaiacyl phenol elimination was found to follow two distinct phases: a rapid initial phase followed by a slower phase. More specifically, the rate of carboxylic acid group formation was found to dramatically increase as the reaction temperature increased, analogous to the profiles obtained for the elimination of guaiacyl phenolic units. At reaction temperatures typical of conventional commercial oxygen delignification installations (80-100°C), only minor oxidation was found to occur within the lignin. At these temperatures, increasing the reaction time did not significantly aid the formation of carboxylic acid groups on lignin despite the idealized twophase homogeneous conditions. The technological ramifications of these data imply that a three-phase oxygen delignification system, operating at temperatures below 100°C, causes only minor oxidative changes to the structure of the lignin in the fibre. It was also possible to isolate the effect of alkali and temperature on the structure of residual kraft lignin through experiments in which pressurized oxygen was replaced by nitrogen. These data revealed a concealed set of alkali-induced condensation and fragmentation reactions.Résumé : En procédant à son isolement et son oxydation systématique en fonction du temps et de la pression, on a étudié l'interaction complexe de la lignine kraft résiduelle de bois mou avec l'oxygène à des températures, pressions et pH élevés. On a réalisé l'isolation de la lignine oxydée en appliquant une méthode en plusieurs étapes développées spécifiquement pour récupérer toutes les espèces. Des mesures quantitatives détaillées de RMN du 31 P ont permis d'obtenir pour la première fois des courbes tridimensionnelles décrivant la formation et (ou) l'élimination de divers groupes fonctionnels. On a trouvé que les réactions de déméthoxylation oxydante induisent la formation de catéchols qui sont vraisemblablement des intermédiaires réactifs dans l'oxydation. On a trouvé que la vitesse de formation de l'acide carboxylique et d'élimination de guaïacol phénolique suit deux phases distinctes : une phase initiale rapide suivie d'une phase plus lente. D'une façon plus spécifique, on a trouvé que la vitesse de formation d'acide carboxylique augmente d'une façon dramatique lorsqu'on élève la température; on a obtenu des profils analogues pour...

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“…Alkaline electrolytes are normally the choice for inorganic sulfide determinations [9,10,25] ). However, acidic electrolytes produced better peak shapes and separations between the sulfide forms than did the alkaline ones.…”

Section: à2mentioning

confidence: 99%

Voltammetric Determination of Low‐Molecular‐Weight Sulfur Compounds in Hydrothermal Vent Fluids – Studies with Hydrogen Sulfide, Methanethiol, Ethanethiol and Propanethiol

et al. 2010

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Determination of sulfide compounds in hydrothermal vent fluid samples was performed by DPCSV. The methodology was applied to speciate sulfides via primitive and first-derivative curve interpretation. Hydrogen sulfide, methanethiol, and propanethiol were simultaneously assayed in samples containing no ethanethiol. In the presence of ethanethiol, the organic sulfides were determined without speciation. Sulfides were determined in an acidic electrolyte, and detection limits ranging from 0.1 to 1.1 mmol L À1 were calculated. The method was tested in real hydrothermal vent fluid samples, with recoveries ranging from 86.9% (R -SH) to 115.3% (H 2 S). Interference of the metallic species present in seawater was investigated.

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Polarographic determination of sulfur compounds in pulping liquors

Cited by 39 publications

References 16 publications

Electrochemical determination of thiosulfate in seawater in the presence of elemental sulfur and sulfide

Electrochemical determination of thiosulfate in seawater in the presence of elemental sulfur and sulfide

Article

Voltammetric Determination of Low‐Molecular‐Weight Sulfur Compounds in Hydrothermal Vent Fluids – Studies with Hydrogen Sulfide, Methanethiol, Ethanethiol and Propanethiol

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