A rotating disc voltammetry study of the 1,8-dihydroxyanthraquinone mediated reduction of colloidal indigo

Vuorema, Anne; John, P. S.; Jenkins, A. Toby A.; Marken, Frank

doi:10.1007/s10008-006-0149-4

Cited by 22 publications

(25 citation statements)

References 16 publications

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“…The non-uniform nature of diffusion at the leading edge and at the trailing edge of electrodes in these flow cells requires multi-dimensional computational algorithms to link the experimentally measured steady state limiting currents [9,10] (or transients [11]) with the microscopic details of the electrode process. For uniformly accessible hydrodynamic electrodes (such as those used in rotating disc or rocking disc voltammetry [12,13,14]) a one-dimensional simulation model based on the knowledge of the average diffusion layer thickness can be sufficient [15]. Even cases of turbulent mass transport with an in average uniformly accessible electrode (e.g.…”

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confidence: 99%

Hydrodynamic Rocking Disc Electrode Study of the TEMPO‐mediated Catalytic Oxidation of Primary Alcohols

et al. 2016

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The hydrodynamically thinned diffusion layer at a sinusoidally rocking disc is approximately uniform and can be expressed in terms of a diffusion layer thickness δRoDE=9.0D13ν16Θf with D, the diffusion coefficient of the redox active species, v, the kinematic viscosity, Θ, the total rocking angle (here 90 degrees), and f, the rocking frequency (ranging here from 0.83 to 25 Hz). For the one‐electron oxidation of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) in aqueous carbonate buffer pH 9.5, it is shown that there is quantitative agreement between the expression for the diffusion layer thickness and experimental data. Next, for seven primary alcohols, the catalytic TEMPO‐mediated oxidation mechanism is investigated under rocking disc conditions. Chemical rate constants are evaluated (by varying the diffusion layer thickness) employing the DigiElch4.F simulation package. Trends in the chemical rate constants (compared with DFT calculations) suggest enhanced reactivity for methanol versus higher primary alcohols and for aromatic versus non‐aromatic primary alcohols. Rocking disc voltammetry allows quantitative mechanistic analysis in the laminar flow regime.

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Hydrodynamic Rocking Disc Electrode Study of the TEMPO‐mediated Catalytic Oxidation of Primary Alcohols

et al. 2016

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“…Hydrodynamic concentration monitoring techniques have been based on, for example, rotating disc voltammetry [12], jet voltammetry [24], microwave enhanced voltammetry [25], sonovoltammetry [26], and vibrating electrode systems [27]. Vibrating probe systems are simple devices with no special requirements in terms of cell geometry or sample pretreatment and without complex moving parts.…”

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confidence: 99%

“…Sodium dithionite has been for long the main industrial reducing agent but its consumption in the vat contributes to environmentally harmful wastes from the dyeworks. There is interest in alternative chemical and electrochemical means of reduction [9][10][11][12]. Glucose has been investigated previously for sulphur dye reduction [13] and it is considered to be a possible alternative reducing agent for indigo [14].…”

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confidence: 99%

Electrochemical determination of plant-derived leuco-indigo after chemical reduction by glucose

et al. 2008

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Electrochemical determination of redox active dye species is demonstrated in indigo samples contaminated with high levels of organic and inorganic impurities. The use of a hydrodynamic electrode system based on a vibrating probe (250 Hz, 200 lm lateral amplitude) allows time-independent diffusion controlled signals to be enhanced and reliable concentration data to be obtained under steady state conditions at relatively fast scan rates up to 4 V s -1 . In this work the indigo content of a complex plant-derived indigo sample (dye content typically 30%) is determined after indigo is reduced by addition of glucose in aqueous 0.2 M NaOH. The soluble leuco-indigo is measured by its oxidation response at a vibrating electrode. The vibrating electrode, which consisted of a laterally vibrating 500 lm diameter gold disc, is calibrated with Fe(CN) 6 3-/4-in 0.1 M KCl and employed for indigo determination at 55, 65, and 75°C in 0.2 M NaOH. Determinations of the indigo content of 25 different samples of plant-derived indigo are compared with those obtained by conventional spectrophotometry. This comparison suggests a significant improvement by the electrochemical method, which appears to be less sensitive to impurities.

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“…9,10-Anthraquinoides with formal redox potential more negative than À700 mV (vs. Ag/AgCl, 3 M KCl) were shown to be suitable to serve as a mediator for the indirect cathodic reduction of dispersed organic dyestuffs [9,13]. The use of reversible redox couples for indirect cathodic reduction of dispersed vat dyes and sulfur dyes is currently under research by several groups [8,9,[12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

The reduction of dispersed indigo by cathodically formed 1,2,4-trihydroxynaphthalene

2009

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A rotating disc voltammetry study of the 1,8-dihydroxyanthraquinone mediated reduction of colloidal indigo

Cited by 22 publications

References 16 publications

Hydrodynamic Rocking Disc Electrode Study of the TEMPO‐mediated Catalytic Oxidation of Primary Alcohols

Hydrodynamic Rocking Disc Electrode Study of the TEMPO‐mediated Catalytic Oxidation of Primary Alcohols

Electrochemical determination of plant-derived leuco-indigo after chemical reduction by glucose

The reduction of dispersed indigo by cathodically formed 1,2,4-trihydroxynaphthalene

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