Voltammetry for Reduction of Hydrogen Ions from Mixtures of Mono- and Polyprotic Acids at Platinum Microelectrodes

Daniele, Salvatore; Lavagnini, Irma; Baldo, and M. Antonietta; Magno, Franco

doi:10.1021/ac970666k

Cited by 46 publications

(67 citation statements)

References 23 publications

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“…Both approaches showed a linear relationship between current density and phosphate concentration. This linear dependency has already been observed by other authors in the steady state limiting reduction current with other weak acids such as acetic, ascorbic, monochloroacetic, lactic and HSO À 4 [43][44][45]. Nevertheless, the dependency between current density and weak acid concentration has not always been found to be linear [34,35] because higher acid concentration induced a higher free proton concentration (reaction (8)) and, following Eq.…”

Section: Voltammetric Studymentioning

confidence: 60%

“…The electrochemical reduction of phosphates and other weak acids on various electrodes has been the subject of several investigations [29,[34][35][36][37][38][39][40][41][42][43][44][45]. The most widely accepted mechanism for the reduction of weak acids is of the CE (chemical-electrochemical) type, where the dissociation of the acid takes place before the electrochemical reduction of free protons [32][33][34]:…”

Section: Weak Acid Reduction Mechanismsmentioning

confidence: 99%

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Role of the reversible electrochemical deprotonation of phosphate species in anaerobic biocorrosion of steels

2007

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Sulphate reducing bacteria are known to play a major role in anaerobic microbiological influenced corrosion of steels, but mechanisms behind their influence are still source of debates as certain phenomena remain unexplained. Some experiments have shown that hydrogen consumption by SRB or hydrogenase increased the corrosion rate of mild steel. This was observed only in the presence of phosphate species. Here the cathodic behaviour of phosphate species on steel was studied to elucidate the role of phosphate in anaerobic corrosion of steel. Results showed: a linear correlation between reduction waves in linear voltammetry and phosphate concentration at a constant pH value; that phosphate ions induced considerable anaerobic corrosion of mild steel, which was sensitive to hydrogen concentration in the solution; and that the corrosion potential of stainless steel in presence of phosphate was shifted to more negative values as molecular hydrogen was added to the atmosphere in the reaction vessel. Phosphate species, and possibly other weak acids present in biofilms, are suggested to play an important role in the anaerobic corrosion of steels via a reversible mechanism of electrochemical deprotonation that may be accelerated by hydrogen removal.

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Section: Voltammetric Studymentioning

confidence: 60%

Section: Weak Acid Reduction Mechanismsmentioning

confidence: 99%

Role of the reversible electrochemical deprotonation of phosphate species in anaerobic biocorrosion of steels

2007

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“…Furthermore, a reversible behavior has been found to occur at platinum microdisks working under steady-state conditions, as adsorption phenomena or other kinetic effects were negligible [8,14]. The reduction process of a weak acid, HA, is preceded by its dissociation to form the electroactive species, H þ (CE mechanism) [8,11,14] …”

Section: Introductionmentioning

confidence: 99%

“…A more complex voltammetric behavior has been found to occur for mixtures of a strong and a weak acid, where two waves, separated to a different extent, could be observed only under given conditions [11,20].…”

Section: Introductionmentioning

confidence: 99%

Low Frequency Square‐Wave Voltammetry of Weak Acids at Platinum Microelectrodes

2005

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The reduction process of monoprotic weak acids (lactic and acetic acid, and dihydrogen phosphate ion) and mixtures of a strong and a weak acid (perchloric and one of the above weak acids) have been investigated by square-wave voltammetry (SWV) at a platinum microelectrode 12.5 mm radius. The SW measurements have been performed at low frequencies (i.e., 3 Hz), where the heterogeneous electron transfer process, involving hydrogen evolution (2H þ þ 2e ¼ H 2 ), is essentially reversible, and non-planar diffusion conditions prevail in the mass transport. Under these conditions, the forward and the reverse current-potential profiles are sigmoidal, whereas the net current-potential profile is peak shaped. The influence of dissociation constant and analytical concentration of the weak acid on the features of the square-wave voltammograms has been examined in detail. In general, both these characteristics of the weak acids affect the square-wave parameters peak potential (E p ), width at half height (W 1/2 ) and net peak current (i p ) in a complex manner. Their dependence on concentration is due to the 2 : 1 stoichiometry of the heterogeneous electron transfer, while the dissociation constant contribution arises because of the CE mechanism involved in the overall electrode process. The kinetic of the homogeneous reaction has been investigated by the use of the forward current plateau (achieved by the end of the sweep) along with a theoretical equation. Mixtures of a strong and a weak acid can provide one or two waves, depending on the acid strength and on the analytical concentration of each acid. Peak potential differences of about 80 mV are needed to discern two peaks. Calibration plots, examined for all the weak acids, have shown that linearity may exist only over relatively small concentration ranges.

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“…To our knowledge, these works did not get an important feedback, even if an abnormal behaviour have commonly been remarked in phosphatecontaining solutions around the cathodic potential values where proton reduction occurs. A probable so-called ''reduction of phosphate'' ions has sometimes been evoked to give a name to this anomalous behaviour [4,5], but the theory seems not to have been developed from the early proposal.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical deprotonation of phosphate on stainless steel

Silva

Basseguy

Bergel

2004

Electrochimica Acta

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Voltammetric experiments performed in phosphate buffer at constant pH 8.0 on platinum and stainless steel revealed clear reduction currents, which were correlated to the concentrations of phosphate. On the basis of the reactions proposed previously, a model was elaborated, assuming that both H 2 PO 4 À and HPO 4 2À underwent cathodic deprotonation, and including the acid-base equilibriums. A kinetic model was derived by analogy with the equations generally used for hydrogen evolution. Numerical fitting of the experimental data confirmed that the phosphate species may act as an efficient catalyst of hydrogen evolution via electrochemical deprotonation. This reaction may introduce an unexpected reversible pathway of hydrogen formation in the mechanisms of anaerobic corrosion. The possible new insights offered by the electrochemical deprotonation of phosphate in microbially influenced corrosion was finally discussed.

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Voltammetry for Reduction of Hydrogen Ions from Mixtures of Mono- and Polyprotic Acids at Platinum Microelectrodes

Cited by 46 publications

References 23 publications

Role of the reversible electrochemical deprotonation of phosphate species in anaerobic biocorrosion of steels

Role of the reversible electrochemical deprotonation of phosphate species in anaerobic biocorrosion of steels

Low Frequency Square‐Wave Voltammetry of Weak Acids at Platinum Microelectrodes

Electrochemical deprotonation of phosphate on stainless steel

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