Fast step-potential pulse chronopotentiometry

Hussam, Abul

doi:10.1021/ac00175a027

Cited by 10 publications

(4 citation statements)

References 24 publications

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“…For arsenic analysis the instrument uses a staircase anodic stripping voltammetry (SASV). The preparation of electrodes, analytical protocols, and method validation were based on published results, [18][19][20][21][22][23] and that of a modified EPA method 7063: Arsenic in Aqueous Samples and Extracts by Anodic Stripping Voltammetry (ASV). [24] The method of standard addition was employed to eliminate matrix effect of solution.…”

Section: Methodsmentioning

confidence: 99%

Chemical Fate of Arsenic and Other Metals in Groundwater of Bangladesh: Experimental Measurement and Chemical Equilibrium Model

Hussam

Habibuddowla²,

Alauddin

et al. 2003

Journal of Environmental Science and Health, Part A

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The presence of toxic level of inorganic arsenic in groundwater used for drinking in Bangladesh and neighboring India is unfolding as one of the worst natural disaster in the region. The purpose of this work is to ascertain the chemical fate of arsenic and other metals in groundwater of Bangladesh. A combination of techniques was used to measure 24 metals, 6 anions, E h , pH, dissolved oxygen, conductivity, and temperature to understand the distribution of components which were then used in computational chemical equilibrium model, MINEQLþ, for detailed speciation. It was found that the fate of arsenic and its speciation were inextricably linked to the formation of hydrous ferric oxide (HFO) and its kinetic. The HFO induced natural attenuation removes 50-75% of total arsenic in first 24 h through a first order kinetics. Adsorption on HFO is the predominant mode of removal of arsenic, MARCEL DEKKER, INC. • 270 MADISON AVENUE • NEW YORK, NY 10016iron, manganese, and most trace metals. The equilibrium model points to the presence of excess active sites for the removal of arsenic. MINEQLþ shows that significantly higher concentration of HFO forming iron is required to remove arsenic below maximum contamination level (MCL) of 50 mg/L than predicted by stoichiometry. The practical implication of this work is the prediction of water quality based on models.

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Section: Methodsmentioning

confidence: 99%

Chemical Fate of Arsenic and Other Metals in Groundwater of Bangladesh: Experimental Measurement and Chemical Equilibrium Model

Hussam

Habibuddowla²,

Alauddin

et al. 2003

Journal of Environmental Science and Health, Part A

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“…A DC pulse method , was used to elucidate the polarized states of the hybrid electrodes during charging/discharging (see the Supporting Information for details). The cells were charged or discharged at a constant rate of x C until reaching a state of charge of 50%.…”

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confidence: 99%

Ultrafast Charge/Discharge by a 99.9% Conventional Lithium Iron Phosphate Electrode Containing 0.1% Redox-Active Fluoflavin Polymer

Hatakeyama‐Sato

Akahane

et al. 2020

ACS Energy Lett.

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Exceptionally large output (current density over 20 mA/cm2) is achieved by a 99.9 wt % conventional LiFePO4 cathode for lithium ion batteries. Adding just 0.1 wt % redox-active fluoflavin polymer to the electrode improves the electrochemical performance dramatically. The polymer’s redox potentials of 3.3 and 3.7 V vs Li/Li+, sandwiching that of LiFePO4 (3.4 V), are critical in accelerating the charge and discharge processes by electrochemical mediation. The lower overvoltage also helps to suppress electrode degradation and improve the cycle life of the cell (over 1000 cycles). The DC pulse technique reveals the transient, dynamic electrochemical mediation, which cannot be observed by conventional steady-state impedance spectroscopy. These dramatic improvements in material properties achieved by the catalytic amount of the organic additive (0.1 wt %) give new insights into organic/inorganic hybrid chemistry and may lead to the development of energy-related materials with improved properties.

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“…Diffusion coefficients in microemulsion solutions were also measured by chronocoulometry, , with a large-amplitude double potential step. Measurements were made using a custom-built computerized electrochemical system and a BAS electrochemical analyzer, Model 100B. In a typical experiment with ferrocene, the potential is stepped from an initial value, 0 mV, at which no redox process occurs at the electrode ( i = 0) to a second final value 600 mV, where diffusion-controlled oxidation occurs and is enforced for a fixed period (the pulse width).…”

Section: Methodsmentioning

confidence: 99%

Electrochemical Investigation of Amphiphilic Cobalt(III) Complexes and Ferrocene Derivatives in Sodium Dodecyl Sulfate Microemulsions

1997

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Cyclic voltammetry and chronocoulometry have been used to measure diffusion coefficients (D 0) and half-wave potentials (E 1/2) of a series of amphiphilic cobalt complexes and ferrocene derivatives in sodium dodecyl sulfate (SDS)/dodecane/water/1-pentanol/NaBr microemulsions. The electrochemical behavior of the cobalt(III) complexes, [Co(phen)3](ClO4)3, [Co(4,7-Me2-phen)3]Cl3, and [Co(4,7-phen2-phen)3]Cl3, has been compared with that of bis(pentamethylcyclopentadienyl)iron, Fe[C5(CH3)5]2 (PMFc), and (ferrocenylmethyl)trimethylammonium bromide, [C5H5FeC5H4CH2N(CH3)3]Br ([TMAFc]Br), in similar microemulsion environments. The dependence of measured D 0 and E 1/2 values on microemulsion composition has been used to provide information on the dynamic structure of the microemulsions and to examine the details of the solubilization processes involved for the different redox probes. D 0 values obtained for [Co(phen)3]3+ (4.7 (±1.6) × 10-7 cm2/s), [Co(4,7-Me2-phen)3]3+ (1.1 (±0.2) × 10-7 cm2/s), and [Co(4,7-phen2-phen)3]3+ (1.4 (±0.3) × 10-7 cm2/s) are largely independent of microemulsion composition varying in water content from 87 to 35%. Such behavior is consistent with association of the complexes with the charged surfactant phase of the microemulsion, though the smaller D 0 values obtained with the hydrophobic methyl- and phenyl-substituted complexes suggest some partitioning into the oil phase. For PMFc and [TMAFc]Br, the dependence of D 0 values on the oil volume fractions has been related to changes in the hydrodynamic radii of the O/W droplets. Estimates of the interfacial area per surfactant head group at the droplet surface have also been made. In contrast to the cobalt(III) complexes, higher D 0 values are observed for PMFc (1.8 × 10-6 cm2/s) and [TMAFc]Br (9.1 × 10-7 cm2/s) in low water content microemulsions. Differences are discussed in terms of possible microstructures existing at these compositions. Binding constants, K 1, and partition coefficients, K d, have also been determined for the association of TMAFc2+ and the ferrocenium cation, Fc+, with SDS micelles from the dependence of measured D 0 values on the SDS concentration. K 1 values obtained for Fc+ (120 (±5) M-1) and TMAFc2+ (1180 (±240) M-1) are compared with values previously determined for ferrocene itself and for amphiphilic cobalt complexes.

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Fast step-potential pulse chronopotentiometry

Cited by 10 publications

References 24 publications

Chemical Fate of Arsenic and Other Metals in Groundwater of Bangladesh: Experimental Measurement and Chemical Equilibrium Model

Chemical Fate of Arsenic and Other Metals in Groundwater of Bangladesh: Experimental Measurement and Chemical Equilibrium Model

Ultrafast Charge/Discharge by a 99.9% Conventional Lithium Iron Phosphate Electrode Containing 0.1% Redox-Active Fluoflavin Polymer

Electrochemical Investigation of Amphiphilic Cobalt(III) Complexes and Ferrocene Derivatives in Sodium Dodecyl Sulfate Microemulsions

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